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FLDIGI 3.0.3 - Desensing by strong signals

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  • Joe Cupano
    Like probably many of you, I gave FLDIGI a good workout in the RTTY RU. Between that, some macros, and Xlog, I was operating smoothly. The only issue I was
    Message 1 of 30 , Jan 4, 2009
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      Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
      Between that, some macros, and Xlog, I
      was operating smoothly.

      The only issue I was running into was with strong signals "desensing" my
      ability to read weaker signals.
      For example, I am looking at the waterfall and see lots of yellow speckling
      given band noise amongst the
      three RTTY signals I see. I will see a fourth strong signal come on and
      "blue out" much of the noise and
      have the remaining signals "look" weaker. Any suggestions ?

      Info on my setup:

      - AMD 1 GHZ machine with 768 MB RAM
      - SBLive! Soundcard using Line-In and Rear-out ports
      - Xubuntu 8.0.4
      - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
      - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on data port
      enabled

      Thanks and 73s,

      - Joe, NE2Z
    • w1hkj
      ... You are seeing the result of AGC capture by the stronger signal. RTTY folks like to run max power when they can. Not something that PSK users have to
      Message 2 of 30 , Jan 4, 2009
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        Joe Cupano wrote:
        > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
        > Between that, some macros, and Xlog, I
        > was operating smoothly.
        >
        > The only issue I was running into was with strong signals "desensing" my
        > ability to read weaker signals.
        > For example, I am looking at the waterfall and see lots of yellow speckling
        > given band noise amongst the
        > three RTTY signals I see. I will see a fourth strong signal come on and
        > "blue out" much of the noise and
        > have the remaining signals "look" weaker. Any suggestions ?
        >
        > Info on my setup:
        >
        > - AMD 1 GHZ machine with 768 MB RAM
        > - SBLive! Soundcard using Line-In and Rear-out ports
        > - Xubuntu 8.0.4
        > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
        > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on data port
        > enabled
        >
        > Thanks and 73s,
        >
        > - Joe, NE2Z
        >
        You are seeing the result of AGC capture by the stronger signal. RTTY
        folks like to run max power when they can. Not something that PSK users
        have to worry about very often.

        You might want to try turning of the AGC if you transceiver allows
        that. Then you will need to use filters and the RF gain control to
        avoid overdriving the IF stages. That is the way that many CW ops would
        cope with the KW next door problem.

        Dave
      • Ed
        ... If you are going to operate a contest like the RTTY RU you need some good tight filters. Running in a contest with SSB filters wide open will give exactly
        Message 3 of 30 , Jan 4, 2009
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          Joe Cupano wrote:
          > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
          > Between that, some macros, and Xlog, I
          > was operating smoothly.
          >
          > The only issue I was running into was with strong signals "desensing" my
          > ability to read weaker signals.
          > For example, I am looking at the waterfall and see lots of yellow speckling
          > given band noise amongst the
          > three RTTY signals I see. I will see a fourth strong signal come on and
          > "blue out" much of the noise and
          > have the remaining signals "look" weaker. Any suggestions ?
          >
          > Info on my setup:
          >
          > - AMD 1 GHZ machine with 768 MB RAM
          > - SBLive! Soundcard using Line-In and Rear-out ports
          > - Xubuntu 8.0.4
          > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
          > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on data port
          > enabled
          >
          > Thanks and 73s,
          >
          > - Joe, NE2Z

          If you are going to operate a contest like the RTTY RU you need some
          good tight filters. Running in a contest with SSB filters wide open will
          give exactly what you saw.

          I use a 500Hz CW filter, a DSP filter and a LP audio filter. Cut back on
          the sound card gain and use the rigs RF Gain control. You will be
          surprised how well fldigi decodes when using this type of filtering.

          Here's a tip, use Pulse Audio it seems to decode better than OSS or Port
          Audio.

          Another tip if you are doing S&P, turn off the AFC in fldigi.

          If you see the yellow speckling, your gain is set too high somewhere in
          the audio chain.

          I never look at a S meter, probably one of the most useless pieces of
          ham gear there is, right behind a microphone.....roger beep.

          Play with your AGC settings, mine is set on fast unless I left it off
          when working weak signal CW.


          Ed W3NR
        • Martin Ewing
          ... Dave, With the Orion, you can get rid of most QRM issues by DSP bandpass adjustments. Is anyone working on bandpass control via fldigi? For DSP rigs (like
          Message 4 of 30 , Jan 4, 2009
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            On Sun, Jan 4, 2009 at 9:05 PM, w1hkj <w1hkj@...> wrote:
            Joe Cupano wrote:
            > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
            > Between that, some macros, and Xlog, I
            > was operating smoothly.
            >
            > The only issue I was running into was with strong signals "desensing" my
            > ability to read weaker signals.
            > For example, I am looking at the waterfall and see lots of yellow speckling
            > given band noise amongst the
            > three RTTY signals I see. I will see a fourth strong signal come on and
            > "blue out" much of the noise and
            > have the remaining signals "look" weaker. Any suggestions ?
            >
            > Info on my setup:
            >
            > - AMD 1 GHZ machine with 768 MB RAM
            > - SBLive! Soundcard using Line-In and Rear-out ports
            > - Xubuntu 8.0.4
            > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
            > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on data port
            > enabled
            >
            > Thanks and 73s,
            >
            > - Joe, NE2Z
            >
            You are seeing the result of AGC capture by the stronger signal.  RTTY
            folks like to run max power when they can.  Not something that PSK users
            have to worry about very often.

            You might want to try turning of the AGC if you transceiver allows
            that.  Then you will need to use filters and the RF gain control to
            avoid overdriving the IF stages.  That is the way that many CW ops would
            cope with the KW next door problem.

            Dave

            Dave,

            With the Orion, you can get rid of most QRM issues by DSP bandpass adjustments.

            Is anyone working on bandpass control via fldigi?  For DSP rigs (like Orion), it is straightforward to adapt the passband continuously to fit the desired digi signal and block out the rest.  (Other rigs give discrete filter widths.) This suggests a bandpass zoom button that might go next to the QSY button.

            I have a separate Python widget that does this, more or less, but it would be great to integrate that into fldigi. http://aa6e.net/software/ofilter

            73
            Martin
            AA6E


            --
            Martin Ewing, AA6E
            Branford, CT
          • w1hkj
            ... Filter bandwidth control is the most convoluted of all the control codes (when you look at all of the various transceiver types). Fldigi s rig control
            Message 5 of 30 , Jan 4, 2009
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              Martin Ewing wrote:
              Dave,

              With the Orion, you can get rid of most QRM issues by DSP bandpass adjustments.

              Is anyone working on bandpass control via fldigi?  For DSP rigs (like Orion), it is straightforward to adapt the passband continuously to fit the desired digi signal and block out the rest.  (Other rigs give discrete filter widths.) This suggests a bandpass zoom button that might go next to the QSY button.

              I have a separate Python widget that does this, more or less, but it would be great to integrate that into fldigi. http://aa6e.net/software/ofilter

              73
              Martin
              AA6E
              Filter bandwidth control is the most convoluted of all the control codes (when you look at all of the various transceiver types).  Fldigi's rig control whether via rigCAT or hamlib tries to find a common ground that give sufficient control.  We can all reach over the rig and make a few adjustments unless we have the rig on a remote windblown mountain top and we are sipping Pina' Coladas in Puerto Rico.

              Dave
            • Steve Friis
              Use the narrowest filter your receiver has that will pass one RTTY signal. Tune using the rig s VFO. Steve/WM5Z No one can change the past, but we all
              Message 6 of 30 , Jan 4, 2009
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                Use the narrowest filter your receiver has that will pass one RTTY
                signal. Tune using the rig's VFO.

                Steve/WM5Z
                No one can change the past, but we all influence the future.
                Remember, you too can have a computer like a wigwam, No windows, no gates.
                Linux User Number 481782 <http://counter.li.org/>



                Joe Cupano wrote:
                > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
                > Between that, some macros, and Xlog, I
                > was operating smoothly.
                >
                > The only issue I was running into was with strong signals "desensing" my
                > ability to read weaker signals.
                > For example, I am looking at the waterfall and see lots of yellow speckling
                > given band noise amongst the
                > three RTTY signals I see. I will see a fourth strong signal come on and
                > "blue out" much of the noise and
                > have the remaining signals "look" weaker. Any suggestions ?
                >
                > Info on my setup:
                >
                > - AMD 1 GHZ machine with 768 MB RAM
                > - SBLive! Soundcard using Line-In and Rear-out ports
                > - Xubuntu 8.0.4
                > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
                > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on data port
                > enabled
                >
                > Thanks and 73s,
                >
                > - Joe, NE2Z
                >
                >
                >
                > ------------------------------------
                >
                > Yahoo! Groups Links
                >
                >
                >
                >
                >
              • Joe Cupano
                Thanks Dave, I wanted to be sure I was not missing some tweaking under the FLDIGI- config for RTTY. Everything was fine when looking in on a huddled mass of
                Message 7 of 30 , Jan 4, 2009
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                  Thanks Dave,

                  I wanted to be sure I was not missing some tweaking under the FLDIGI->config
                  for RTTY.
                  Everything was fine when looking in on a huddled mass of PSK31 signals on
                  20m just below the
                  RTTY fray :)

                  My low tech way around it was tuning the strong signals out of the waterfall
                  where they were far
                  enough apart. Will try the path you suggested next time.

                  Had a great time with FLDIGI in the contest

                  73s,

                  - Joe, NE2Z








                  -----Original Message-----
                  From: w1hkj [mailto:w1hkj@...]
                  Sent: Sunday, January 04, 2009 9:05 PM
                  To: linuxham@yahoogroups.com
                  Subject: Re: [linuxham] FLDIGI 3.0.3 - Desensing by strong signals

                  Joe Cupano wrote:
                  > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
                  > Between that, some macros, and Xlog, I was operating smoothly.
                  >
                  > The only issue I was running into was with strong signals "desensing"
                  > my ability to read weaker signals.
                  > For example, I am looking at the waterfall and see lots of yellow
                  > speckling given band noise amongst the three RTTY signals I see. I
                  > will see a fourth strong signal come on and "blue out" much of the
                  > noise and have the remaining signals "look" weaker. Any suggestions ?
                  >
                  > Info on my setup:
                  >
                  > - AMD 1 GHZ machine with 768 MB RAM
                  > - SBLive! Soundcard using Line-In and Rear-out ports
                  > - Xubuntu 8.0.4
                  > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
                  > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on data
                  > port enabled
                  >
                  > Thanks and 73s,
                  >
                  > - Joe, NE2Z
                  >
                  You are seeing the result of AGC capture by the stronger signal. RTTY folks
                  like to run max power when they can. Not something that PSK users have to
                  worry about very often.

                  You might want to try turning of the AGC if you transceiver allows that.
                  Then you will need to use filters and the RF gain control to avoid
                  overdriving the IF stages. That is the way that many CW ops would cope with
                  the KW next door problem.

                  Dave

                  ------------------------------------

                  Yahoo! Groups Links




                  No virus found in this incoming message.
                  Checked by AVG - http://www.avg.com
                  Version: 8.0.176 / Virus Database: 270.10.2/1874 - Release Date: 1/4/2009
                  4:32 PM
                • Joe Cupano
                  Thanks Ed, - Joe ... From: Ed [mailto:autek@comcast.net] Sent: Sunday, January 04, 2009 9:17 PM To: linuxham@yahoogroups.com Subject: Re: [linuxham] FLDIGI
                  Message 8 of 30 , Jan 4, 2009
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                    Thanks Ed,

                    - Joe

                    -----Original Message-----
                    From: Ed [mailto:autek@...]
                    Sent: Sunday, January 04, 2009 9:17 PM
                    To: linuxham@yahoogroups.com
                    Subject: Re: [linuxham] FLDIGI 3.0.3 - Desensing by strong signals

                    Joe Cupano wrote:
                    > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
                    > Between that, some macros, and Xlog, I was operating smoothly.
                    >
                    > The only issue I was running into was with strong signals "desensing"
                    > my ability to read weaker signals.
                    > For example, I am looking at the waterfall and see lots of yellow
                    > speckling given band noise amongst the three RTTY signals I see. I
                    > will see a fourth strong signal come on and "blue out" much of the
                    > noise and have the remaining signals "look" weaker. Any suggestions ?
                    >
                    > Info on my setup:
                    >
                    > - AMD 1 GHZ machine with 768 MB RAM
                    > - SBLive! Soundcard using Line-In and Rear-out ports
                    > - Xubuntu 8.0.4
                    > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
                    > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on data
                    > port enabled
                    >
                    > Thanks and 73s,
                    >
                    > - Joe, NE2Z

                    If you are going to operate a contest like the RTTY RU you need some good
                    tight filters. Running in a contest with SSB filters wide open will give
                    exactly what you saw.

                    I use a 500Hz CW filter, a DSP filter and a LP audio filter. Cut back on the
                    sound card gain and use the rigs RF Gain control. You will be surprised how
                    well fldigi decodes when using this type of filtering.

                    Here's a tip, use Pulse Audio it seems to decode better than OSS or Port
                    Audio.

                    Another tip if you are doing S&P, turn off the AFC in fldigi.

                    If you see the yellow speckling, your gain is set too high somewhere in the
                    audio chain.

                    I never look at a S meter, probably one of the most useless pieces of ham
                    gear there is, right behind a microphone.....roger beep.

                    Play with your AGC settings, mine is set on fast unless I left it off when
                    working weak signal CW.


                    Ed W3NR


                    ------------------------------------

                    Yahoo! Groups Links




                    No virus found in this incoming message.
                    Checked by AVG - http://www.avg.com
                    Version: 8.0.176 / Virus Database: 270.10.2/1874 - Release Date: 1/4/2009
                    4:32 PM
                  • Rick Kunath
                    ... Yes, that s the way a wideband waterfall clicking operating scenario works in a RTTY contest. There is always desense. I use the RTTY mode in the rig, have
                    Message 9 of 30 , Jan 4, 2009
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                      On Sunday 04 January 2009 9:50:59 pm Joe Cupano wrote:

                      > I wanted to be sure I was not missing some tweaking under the
                      > FLDIGI->config for RTTY.
                      > Everything was fine when looking in on a huddled mass of PSK31 signals on
                      > 20m just below the
                      > RTTY fray :)

                      Yes, that's the way a wideband waterfall clicking operating scenario works in
                      a RTTY contest. There is always desense.

                      I use the RTTY mode in the rig, have the narrow filter in, and tune the rig. I
                      don't waterfall click.

                      But I can see that having a wide band and bandwidth control after a signal is
                      selected, could really be a plus for Fldigi. I hadn't thought about that
                      before it was mentioned.

                      RIck Kunath, k9ao
                    • Leigh L. Klotz, Jr WA5ZNU
                      Martin, I did the QSY button in gmfsk and worked with Dave to port it to fldigi. I was stymied by hamlib and its lack of support for the K2 filters. With my
                      Message 10 of 30 , Jan 4, 2009
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                        Martin,
                        I did the QSY button in gmfsk and worked with Dave to port it to
                        fldigi. I was stymied by hamlib and its lack of support for the K2
                        filters.
                        With my new rig (K3) the DSP filters are settable on different center
                        frequencies, but not many people have rigs with these capabilities.
                        Personally, I just press QSY and then tap the XFIL button a couple of
                        times. It's not risen to the point where I'm motivated to dive into
                        Dave's Rigcat code and think of some abstractions to cover rigs such as
                        the K3 and Orion.

                        I suppose if it's QSY+Narrow, as opposed to Narrow-at-current-QRG, it's
                        a wider set of rigs and the abstraction for rigcat's XML control files
                        is simpler.

                        Leigh/WA5ZNU
                        >
                        > With the Orion, you can get rid of most QRM issues by DSP bandpass
                        > adjustments.
                        >
                        > Is anyone working on bandpass control via fldigi? For DSP rigs (like
                        > Orion), it is straightforward to adapt the passband continuously to
                        > fit the desired digi signal and block out the rest. (Other rigs give
                        > discrete filter widths.) This suggests a bandpass zoom button that
                        > might go next to the QSY button.
                        >
                        > I have a separate Python widget that does this, more or less, but it
                        > would be great to integrate that into fldigi.
                        > http://aa6e.net/software/ofilter
                        >
                        > 73
                        > Martin
                        > AA6E
                        >
                      • w1hkj
                        ... That is exactly the process I use with the IC746PRO and before that with the ArgonautV. Both of these rigs support variable filters with variable IF
                        Message 11 of 30 , Jan 4, 2009
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                          Leigh L. Klotz, Jr WA5ZNU wrote:
                          > Martin,
                          > I did the QSY button in gmfsk and worked with Dave to port it to
                          > fldigi. I was stymied by hamlib and its lack of support for the K2
                          > filters.
                          > With my new rig (K3) the DSP filters are settable on different center
                          > frequencies, but not many people have rigs with these capabilities.
                          > Personally, I just press QSY and then tap the XFIL button a couple of
                          > times. It's not risen to the point where I'm motivated to dive into
                          > Dave's Rigcat code and think of some abstractions to cover rigs such as
                          > the K3 and Orion.
                          >
                          That is exactly the process I use with the IC746PRO and before that with
                          the ArgonautV. Both of these rigs support variable filters with
                          variable IF shift. But the QSY function and then reduce the bandwidth
                          at the rig works quickly and is independent of the many factors
                          associated with a CAT command sequence to do to the same thing.

                          Dave
                        • Martin Ewing
                          ... On the Orion, there s very flexible bandwidth/shifting capability, but it s a pain to use from the front panel. You have to use two separate decoder
                          Message 12 of 30 , Jan 4, 2009
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                            On Sun, Jan 4, 2009 at 10:44 PM, w1hkj <w1hkj@...> wrote:
                            Leigh L. Klotz, Jr WA5ZNU wrote:
                            > Martin,
                            > I did the QSY button in gmfsk and worked with Dave to port it to
                            > fldigi.   I was stymied by hamlib and its lack of support for the K2
                            > filters.
                            > With my new rig (K3) the DSP filters are settable on different center
                            > frequencies, but not many people have rigs with these capabilities.
                            > Personally, I just press QSY and then tap the XFIL button a couple of
                            > times.  It's not risen to the point where I'm motivated to dive into
                            > Dave's Rigcat code and think of some abstractions to cover rigs such as
                            > the K3 and Orion.
                            >
                            That is exactly the process I use with the IC746PRO and before that with
                            the ArgonautV.  Both of these rigs support variable filters with
                            variable IF shift.  But the QSY function and then reduce the bandwidth
                            at the rig works quickly and is independent of the many factors
                            associated with a CAT command sequence to do to the same thing.

                            Dave

                            On the Orion, there's very flexible bandwidth/shifting capability, but it's a pain to use from the front panel.  You have to use two separate decoder controls (or one decoder for BW, punch it, then adjust IF shift), and it takes many turns of the knob to get the bandpass zeroed in on a PSK signal, for example. There are no simple bandwidth presets.  It is a simple thing to do over the command interface, and we provide this in Hamlib.  Hamlib also provides Wide, Normal, Narrow presets for the Orion and most other rigs.  I think something could be done in fldigi, but it might be hard to standardize the behavior across even all DSP rigs.  I can imagine a "NRW" button to put a preset narrow passband around the current tuning point. Click once to get the narrow response, click again to get 3 kHz passband.

                            The QSY button has its own quirks on the Orion, since "QSY" can only set the VFO freq modulo the "tuning step", but fldigi sets to the Hz.  I have to set my tuning step to 1 Hz to get "QSY" to work well, but 1 Hz is too fine for much manual tuning.  So there's no free lunch.
                            --
                            Martin Ewing, AA6E
                            Branford, CT
                          • Ian Wade
                            From: Ed Date: Sun, 4 Jan 2009 Time: 21:16:34 ... Agreed on all points. For the LP audio filter, I happen to have an old MFJ-784B tunable
                            Message 13 of 30 , Jan 5, 2009
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                              From: Ed <autek@...>
                              Date: Sun, 4 Jan 2009 Time: 21:16:34
                              >
                              >If you are going to operate a contest like the RTTY RU you need some
                              >good tight filters. Running in a contest with SSB filters wide open will
                              >give exactly what you saw.
                              >
                              >I use a 500Hz CW filter, a DSP filter and a LP audio filter. Cut back on
                              >the sound card gain and use the rigs RF Gain control. You will be
                              >surprised how well fldigi decodes when using this type of filtering.
                              >
                              >Here's a tip, use Pulse Audio it seems to decode better than OSS or Port
                              >Audio.
                              >
                              >Another tip if you are doing S&P, turn off the AFC in fldigi.
                              >
                              >If you see the yellow speckling, your gain is set too high somewhere in
                              >the audio chain.
                              >
                              >I never look at a S meter, probably one of the most useless pieces of
                              >ham gear there is, right behind a microphone.....roger beep.
                              >
                              >Play with your AGC settings, mine is set on fast unless I left it off
                              >when working weak signal CW.
                              >

                              Agreed on all points. For the LP audio filter, I happen to have an old
                              MFJ-784B tunable DSP filter, which lets me narrow the bandwidth down to
                              a few Hz. Then fldigi only sees the wanted signal, and nothing else.
                              Magic!

                              --
                              73
                              Ian, G3NRW
                            • Simon Brown (KNS)
                              Although there may be desensing a good digital program will still detect and decode well as long as the strong signal is not causing problems for the radio or
                              Message 14 of 30 , Jan 5, 2009
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                                Although there may be desensing a good digital program will still detect and
                                decode well as long as the strong signal is not causing problems for the
                                radio or the soundcard.

                                You need a soundcard with a dynamic range at least as good as the radio, any
                                decent (!) soundcard will be this good.

                                In general it's daft to use a poor 10$ soundcard with a good 5,000$ radio.

                                Simon Brown, HB9DRV
                                www.ham-radio-deluxe.com

                                ----- Original Message -----
                                From: "Ian Wade" <g3nrw@...>
                                >
                                > Agreed on all points. For the LP audio filter, I happen to have an old
                                > MFJ-784B tunable DSP filter, which lets me narrow the bandwidth down to
                                > a few Hz. Then fldigi only sees the wanted signal, and nothing else.
                                > Magic!
                                >
                              • Ed
                                ... As you all know I m anything but a programmer, so this may be the dumb idea of the day. In fldigi we have the option to set the low frequency cutoff, could
                                Message 15 of 30 , Jan 5, 2009
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                                  w1hkj wrote:
                                  > Leigh L. Klotz, Jr WA5ZNU wrote:
                                  >> Martin,
                                  >> I did the QSY button in gmfsk and worked with Dave to port it to
                                  >> fldigi. I was stymied by hamlib and its lack of support for the K2
                                  >> filters.
                                  >> With my new rig (K3) the DSP filters are settable on different center
                                  >> frequencies, but not many people have rigs with these capabilities.
                                  >> Personally, I just press QSY and then tap the XFIL button a couple of
                                  >> times. It's not risen to the point where I'm motivated to dive into
                                  >> Dave's Rigcat code and think of some abstractions to cover rigs such as
                                  >> the K3 and Orion.
                                  >>
                                  > That is exactly the process I use with the IC746PRO and before that with
                                  > the ArgonautV. Both of these rigs support variable filters with
                                  > variable IF shift. But the QSY function and then reduce the bandwidth
                                  > at the rig works quickly and is independent of the many factors
                                  > associated with a CAT command sequence to do to the same thing.
                                  >
                                  > Dave
                                  >

                                  As you all know I'm anything but a programmer, so this may be the dumb
                                  idea of the day. In fldigi we have the option to set the low frequency
                                  cutoff, could this be extended to include the high frequency also ?

                                  Ed W3NR
                                • w1hkj
                                  In version 3.03 you set the upper cutoff by using the command line switch: --wfall-width WIDTH WIDTH may be 2000 to 4000 in Hz, recommend 50 Hz increments.
                                  Message 16 of 30 , Jan 5, 2009
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                                    In version 3.03 you set the upper cutoff by using the command line switch:

                                    --wfall-width WIDTH
                                    WIDTH may be 2000 to 4000 in Hz, recommend 50 Hz increments.

                                    which both reduces / expands the upper end visibility and also impacts
                                    on the cpu load (small is less).

                                    In the next version this will be a configuration dialog item.

                                    73, Dave, W1HKJ
                                  • Martin Ewing
                                    ... Yes, fldigi can reduce its waterfall window, but this does not make your receiver (upstream) more selective. Any strong signal in the Rx IF passband is
                                    Message 17 of 30 , Jan 5, 2009
                                    • 0 Attachment
                                      On Mon, Jan 5, 2009 at 6:24 AM, Ed <autek@...> wrote:
                                      w1hkj wrote:
                                      > Leigh L. Klotz, Jr WA5ZNU wrote:
                                      >> Martin,
                                      >> I did the QSY button in gmfsk and worked with Dave to port it to
                                      >> fldigi.   I was stymied by hamlib and its lack of support for the K2
                                      >> filters.
                                      >> With my new rig (K3) the DSP filters are settable on different center
                                      >> frequencies, but not many people have rigs with these capabilities.
                                      >> Personally, I just press QSY and then tap the XFIL button a couple of
                                      >> times.  It's not risen to the point where I'm motivated to dive into
                                      >> Dave's Rigcat code and think of some abstractions to cover rigs such as
                                      >> the K3 and Orion.
                                      >>
                                      > That is exactly the process I use with the IC746PRO and before that with
                                      > the ArgonautV.  Both of these rigs support variable filters with
                                      > variable IF shift.  But the QSY function and then reduce the bandwidth
                                      > at the rig works quickly and is independent of the many factors
                                      > associated with a CAT command sequence to do to the same thing.
                                      >
                                      > Dave
                                      >

                                      As you all know I'm anything but a programmer, so this may be the dumb
                                      idea of the day. In fldigi we have the option to set the low frequency
                                      cutoff, could this be extended to include the high frequency also ?

                                      Ed W3NR

                                      Yes, fldigi can reduce its waterfall window, but this does not make your receiver (upstream) more selective.   Any strong signal in the Rx IF passband is going to "desense" your desired signal, regardless of what fldigi does.

                                      That's why I'd like to see fldigi "take control" of the Rx a little more -- to adjust its bandpass to just what fldigi is interested in.  There are practical problems with that, so I don't know if it's going to happen.

                                      73 Martin AA6E


                                      --
                                      Martin Ewing, AA6E
                                      Branford, CT
                                    • Steve Friis
                                      That would probably mean a much stronger control than is now being implemented through RigCat. You would have to implement it for each radio since no 2 models
                                      Message 18 of 30 , Jan 5, 2009
                                      • 0 Attachment
                                        That would probably mean a much stronger control than is now being
                                        implemented through RigCat. You would have to implement it for each
                                        radio since no 2 models within a brand are the same, from what I've
                                        seen. For example, the RigCat file for the FT-450 is different than the
                                        FT-2000, right? They might even be different than an FT-950 and the
                                        FT-9000. And Yaesu does it different than Kenwood, who does it different
                                        than Kachina, etc. It would really be great, if incorporated but
                                        wouldn't that put an end to point and click with the mouse like we now
                                        do, for example in PSK31?

                                        Just trying to get a handle on how it would work.

                                        Steve/WM5Z
                                        No one can change the past, but we all influence the future.
                                        Remember, you too can have a computer like a wigwam, No windows, no gates.
                                        Linux User Number 481782 <http://counter.li.org/>


                                        >
                                        > Yes, fldigi can reduce its waterfall window, but this does not make
                                        > your receiver (upstream) more selective. Any strong signal in the Rx
                                        > IF passband is going to "desense" your desired signal, regardless of
                                        > what fldigi does.
                                        >
                                        > That's why I'd like to see fldigi "take control" of the Rx a little
                                        > more -- to adjust its bandpass to just what fldigi is interested in.
                                        > There are practical problems with that, so I don't know if it's going
                                        > to happen.
                                        >
                                        > 73 Martin AA6E
                                        >
                                        >
                                        > --
                                        > Martin Ewing, AA6E
                                        > Branford, CT
                                        >
                                      • Martin Ewing
                                        Steve, I don t know much about RigCat, but Hamlib provides a BW control API. It may not be implemented uniformly across rigs. It can t be, really, because
                                        Message 19 of 30 , Jan 5, 2009
                                        • 0 Attachment
                                          Steve,
                                          I don't know much about RigCat, but Hamlib provides a BW control API.  It may not be implemented uniformly across rigs.  It can't be, really, because rig capabilities are all over the place.  However, you can request a certain bandpass and offset, and Hamlib will try to do something.  The results will be best on "good" DSP rigs, but something useful may happen even on rigs with 2 or 3 filter settings.  It can get complicated if a rig provides for switchable IF filtering plus DSP.  Such is life.

                                          Point and click is the right goal.  It's a hassle to manage the bandpass on the Orion's front panel, if you want to use it for precise fldgi-like tuning.  With point and click, you could be able to place an adjustable narrow bandpass window you wherever you want on the waterfall, and instantly switch between that and a "wide" 3 kHz band.  A simpler button-based solution would be easier to code and would give you 80% of the value.

                                          73 Martin AA6E

                                          On Mon, Jan 5, 2009 at 11:45 AM, Steve Friis <wm5z@...> wrote:
                                          That would probably mean a much stronger control than is now being
                                          implemented through RigCat. You would have to implement it for each
                                          radio since no 2 models within a brand are the same, from what I've
                                          seen. For example, the RigCat file for the FT-450 is different than the
                                          FT-2000, right? They might even be different than an FT-950 and the
                                          FT-9000. And Yaesu does it different than Kenwood, who does it different
                                          than Kachina, etc. It would really be great, if incorporated but
                                          wouldn't that put an end to point and click with the mouse like we now
                                          do, for example in PSK31?

                                          Just trying to get a handle on how it would work.

                                          Steve/WM5Z
                                          No one can change the past, but we all influence the future.
                                          Remember, you too can have a computer like a wigwam, No windows, no gates.
                                          Linux User Number 481782 <http://counter.li.org/>


                                          >
                                          > Yes, fldigi can reduce its waterfall window, but this does not make
                                          > your receiver (upstream) more selective.   Any strong signal in the Rx
                                          > IF passband is going to "desense" your desired signal, regardless of
                                          > what fldigi does.
                                          >
                                          > That's why I'd like to see fldigi "take control" of the Rx a little
                                          > more -- to adjust its bandpass to just what fldigi is interested in.
                                          > There are practical problems with that, so I don't know if it's going
                                          > to happen.
                                          >
                                          > 73 Martin AA6E
                                          >
                                          >
                                          > --
                                          > Martin Ewing, AA6E
                                          > Branford, CT
                                          >

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                                          --
                                          Martin Ewing, AA6E
                                          Branford, CT
                                        • Nate Bargmann
                                          ... And they re all different from any older Yaesu rig from the FT-817 and older. And as RigCAT is presently implemented, it is not possible to support the
                                          Message 20 of 30 , Jan 5, 2009
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                                            * Steve Friis <wm5z@...> [2009 Jan 05 10:46 -0600]:
                                            > That would probably mean a much stronger control than is now being
                                            > implemented through RigCat. You would have to implement it for each
                                            > radio since no 2 models within a brand are the same, from what I've
                                            > seen. For example, the RigCat file for the FT-450 is different than the
                                            > FT-2000, right? They might even be different than an FT-950 and the
                                            > FT-9000.

                                            And they're all different from any older Yaesu rig from the FT-817 and
                                            older. And as RigCAT is presently implemented, it is not possible to
                                            support the FT-920 so '920 owners must use Hamlib.

                                            > And Yaesu does it different than Kenwood, who does it different
                                            > than Kachina, etc. It would really be great, if incorporated but
                                            > wouldn't that put an end to point and click with the mouse like we now
                                            > do, for example in PSK31?

                                            As Martin already wrote, there is a bandwidth API in Hamlib. It may be
                                            useful to Fldigi or not. On some radios narrow filters are only
                                            available in CW or RTTY modes which don't normally accept AFSK/PSK input.
                                            Some newer models have a DATA or PACKET mode that may allow the use of
                                            narrow filters and AFSK/PSK input from a special jack.

                                            > Just trying to get a handle on how it would work.

                                            For some radios it would be just fine and on others no improvement. It
                                            just depends on the radio. But that should not disuade the Fldigi
                                            authors from implementing advanced control features for advanced radios
                                            as they see fit. If work needs to be done in Hamlib to accomodate that
                                            support, I think we'll see that happen as well.

                                            73, de Nate >>

                                            --

                                            "The optimist proclaims that we live in the best of all
                                            possible worlds. The pessimist fears this is true."

                                            Ham radio, Linux, bikes, and more: http://n0nb.us/index.html
                                          • w1hkj
                                            ... As the buck stops here guy for fldigi development I think I should say a few more words regarding the the inclusion of bandwidth control. It is available
                                            Message 21 of 30 , Jan 5, 2009
                                            • 0 Attachment
                                              Martin Ewing wrote:
                                              Steve,
                                              I don't know much about RigCat, but Hamlib provides a BW control API.  It may not be implemented uniformly across rigs.  It can't be, really, because rig capabilities are all over the place.  However, you can request a certain bandpass and offset, and Hamlib will try to do something.  The results will be best on "good" DSP rigs, but something useful may happen even on rigs with 2 or 3 filter settings.  It can get complicated if a rig provides for switchable IF filtering plus DSP.  Such is life.

                                              Point and click is the right goal.  It's a hassle to manage the bandpass on the Orion's front panel, if you want to use it for precise fldgi-like tuning.  With point and click, you could be able to place an adjustable narrow bandpass window you wherever you want on the waterfall, and instantly switch between that and a "wide" 3 kHz band.  A simpler button-based solution would be easier to code and would give you 80% of the value.

                                              73 Martin AA6E


                                              As the buck stops here guy for fldigi development I think I should say a few more words regarding the the inclusion of bandwidth control.

                                              It is available on those rigs that the current rigCAT implementation can handle.  See for example:

                                              IC-7000.xml
                                              IC-703.xml
                                              IC-746PRO.xml
                                              IC-756PROII.xml
                                              K2.xml
                                              K3.xml
                                              TT-516.xml
                                              TT-535.xml

                                              If the Orion' command structure fits within these then you can certainly expect to write an xml that will work with your transceiver.

                                              The newer class of transceivers, independent of manufacturer, have made bandwidth selection much more available from a computer controlled interface.  This is because they are nearly all using internal digital signal processing.  The vintage rigs (over 10 years old for this discussion) that use crystal or mechanical filters do not usually have the same ease of control.  Even the more modern rigs do not all support good filter selection.  My little FT-450 for example as a very nice CW / RTTY filter that would really work great for PSK or other digital modes.  Unfortunately it can't be used in those modes.  A limitation of the firmware and hardware in a radio under $1000.  You can't expect a Mercedes when you buy a Chevrolet.

                                              I will always consider the submission of new support code for fldigi.  This is an open development arena.  If you are skilled in creating C++ and interested in helping to improve fldigi just apply to either myself directly or via this forum.

                                              73,
                                              Dave
                                            • Steve Friis
                                              Heard and noted. I take pity on you programmers : ( From a users point of view, we just want something that works. I variable bandwidth where the rig is
                                              Message 22 of 30 , Jan 5, 2009
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                                                Heard and noted. I take pity on you programmers :'(

                                                From a users point of view, we just want something that works. I
                                                variable bandwidth where the rig is capable, like the FT-950 can provide
                                                is great. But, even being able to switch filters from within the program
                                                for a rig like the FT-1K Field would be sweet too. ;-)

                                                As for RigCat, I have only seen that used with fldigi. gRIG and gMFSK
                                                both use hamlib. I'm not sure if there is a hamlib library for all of
                                                the rigs I own, but I know there is a RigCat for them. If I had to, I
                                                could figure out how to modify the RigCat file, but I'm not sure if I
                                                could work on the hamlib file.

                                                I have to hand it to the guys working on the fldigi program. They sure
                                                have been attentive to the wants and desires of the user community, both
                                                Linux and Windoz side.

                                                Steve/WM5Z
                                                No one can change the past, but we all influence the future.
                                                Remember, you too can have a computer like a wigwam, No windows, no gates.
                                                Linux User Number 481782 <http://counter.li.org/>



                                                Martin Ewing wrote:
                                                > Steve,
                                                > I don't know much about RigCat, but Hamlib provides a BW control API.
                                                > It may not be implemented uniformly across rigs. It can't be, really,
                                                > because rig capabilities are all over the place. However, you can
                                                > request a certain bandpass and offset, and Hamlib will try to do
                                                > something. The results will be best on "good" DSP rigs, but something
                                                > useful may happen even on rigs with 2 or 3 filter settings. It can
                                                > get complicated if a rig provides for switchable IF filtering plus
                                                > DSP. Such is life.
                                                >
                                                > Point and click is the right goal. It's a hassle to manage the
                                                > bandpass on the Orion's front panel, if you want to use it for precise
                                                > fldgi-like tuning. With point and click, you could be able to place
                                                > an adjustable narrow bandpass window you wherever you want on the
                                                > waterfall, and instantly switch between that and a "wide" 3 kHz band.
                                                > A simpler button-based solution would be easier to code and would give
                                                > you 80% of the value.
                                                >
                                                >
                                              • R. Kevin Stover
                                                Unfortunately that s the way it is with sound card digi modes. My waterfall goes black when the Ham a couple blocks away decides to get on PSK. It s the same
                                                Message 23 of 30 , Jan 7, 2009
                                                • 0 Attachment
                                                  Unfortunately that's the way it is with sound card digi modes.
                                                  My waterfall goes black when the Ham a couple blocks away decides to
                                                  get on PSK. It's the same no matter what software you use.

                                                  --- In linuxham@yahoogroups.com, "Joe Cupano" <joec@...> wrote:
                                                  >
                                                  >
                                                  > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
                                                  > Between that, some macros, and Xlog, I
                                                  > was operating smoothly.
                                                  >
                                                  > The only issue I was running into was with strong signals "desensing" my
                                                  > ability to read weaker signals.
                                                  > For example, I am looking at the waterfall and see lots of yellow
                                                  speckling
                                                  > given band noise amongst the
                                                  > three RTTY signals I see. I will see a fourth strong signal come on and
                                                  > "blue out" much of the noise and
                                                  > have the remaining signals "look" weaker. Any suggestions ?
                                                  >
                                                  > Info on my setup:
                                                  >
                                                  > - AMD 1 GHZ machine with 768 MB RAM
                                                  > - SBLive! Soundcard using Line-In and Rear-out ports
                                                  > - Xubuntu 8.0.4
                                                  > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
                                                  > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on
                                                  data port
                                                  > enabled
                                                  >
                                                  > Thanks and 73s,
                                                  >
                                                  > - Joe, NE2Z
                                                  >
                                                • Brian Lloyd
                                                  ... Well, yes and no. The key thing is to ensure that the AGC only responds to the desired signal. The simplest way to do that is to narrow the IF filter until
                                                  Message 24 of 30 , Jan 7, 2009
                                                  • 0 Attachment
                                                    On Wed, Jan 7, 2009 at 9:46 AM, R. Kevin Stover <rkstover@...> wrote:
                                                    > Unfortunately that's the way it is with sound card digi modes.
                                                    > My waterfall goes black when the Ham a couple blocks away decides to
                                                    > get on PSK. It's the same no matter what software you use.

                                                    Well, yes and no. The key thing is to ensure that the AGC only
                                                    responds to the desired signal. The simplest way to do that is to
                                                    narrow the IF filter until the receiver only passes the desired
                                                    signal. I have a Flex 5000 and this is what I do when digging out a
                                                    weak signal, even PSK. (PSK is not my favorite mode but I do operate
                                                    it periodically and use about a 120 Hz filter width.) So the process
                                                    is to select the desired signal and then narrow the filters around
                                                    that signal.

                                                    The right answer is for the CODEC to generate the AGC signal and feed
                                                    that back to the RF/IF stages. That way it responds *only* to the
                                                    desired signal. After that the only worry is to prevent overload of
                                                    intermediate stages from a strong but undesired signal in the
                                                    passband.

                                                    73 de Brian, WB6RQN / J79BPL
                                                  • Martin Ewing
                                                    Yes, it s a receiver problem, not software or soundcard. If you can get
                                                    Message 25 of 30 , Jan 7, 2009
                                                    • 0 Attachment
                                                      Yes, it's a receiver problem, not software or soundcard.  If you can get < 200 Hz IF selectivity and low intermod, it really helps.

                                                      On Wed, Jan 7, 2009 at 12:46 PM, R. Kevin Stover <rkstover@...> wrote:
                                                      Unfortunately that's the way it is with sound card digi modes.
                                                      My waterfall goes black when the Ham a couple blocks away decides to
                                                      get on PSK. It's the same no matter what software you use.

                                                      --- In linuxham@yahoogroups.com, "Joe Cupano" <joec@...> wrote:
                                                      >
                                                      >
                                                      > Like probably many of you, I gave FLDIGI a good workout in the RTTY RU.
                                                      > Between that, some macros, and Xlog, I
                                                      > was operating smoothly.
                                                      >
                                                      > The only issue I was running into was with strong signals "desensing" my
                                                      > ability to read weaker signals.
                                                      > For example, I am looking at the waterfall and see lots of yellow
                                                      speckling
                                                      > given band noise amongst the
                                                      > three RTTY signals I see. I will see a fourth strong signal come on and
                                                      > "blue out" much of the noise and
                                                      > have the remaining signals "look" weaker. Any suggestions ?
                                                      >
                                                      > Info on my setup:
                                                      >
                                                      > - AMD 1 GHZ machine with 768 MB RAM
                                                      > - SBLive! Soundcard using Line-In and Rear-out ports
                                                      > - Xubuntu 8.0.4
                                                      > - FLDIGI 3.0.3 configured for PortAudio. mixer enabled
                                                      > - SBLive ports cabled directly to DATA port on TS-480SAT. VOX on
                                                      data port
                                                      > enabled
                                                      >
                                                      > Thanks and 73s,
                                                      >
                                                      > - Joe, NE2Z
                                                      >



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                                                      --
                                                      Martin Ewing, AA6E
                                                      Branford, CT
                                                    • R. Kevin Stover
                                                      Brian, I agree 100%. If the user narrows down his passband he won t be seeing all the signals either. It s a double edged sword. Either see them all and hope a
                                                      Message 26 of 30 , Jan 7, 2009
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                                                        Brian,

                                                        I agree 100%.

                                                        If the user narrows down his passband he won't be seeing all the
                                                        signals either. It's a double edged sword. Either see them all and
                                                        hope a real strong signal doesn't fire up, or narrow the IF pass band
                                                        on the radio either with crystal filters or DSP and pick one signal to
                                                        hone in on.


                                                        --- In linuxham@yahoogroups.com, "Brian Lloyd" <brian-wb6rqn@...> wrote:
                                                        >
                                                        > On Wed, Jan 7, 2009 at 9:46 AM, R. Kevin Stover <rkstover@...> wrote:
                                                        > > Unfortunately that's the way it is with sound card digi modes.
                                                        > > My waterfall goes black when the Ham a couple blocks away decides to
                                                        > > get on PSK. It's the same no matter what software you use.
                                                        >
                                                        > Well, yes and no. The key thing is to ensure that the AGC only
                                                        > responds to the desired signal. The simplest way to do that is to
                                                        > narrow the IF filter until the receiver only passes the desired
                                                        > signal. I have a Flex 5000 and this is what I do when digging out a
                                                        > weak signal, even PSK. (PSK is not my favorite mode but I do operate
                                                        > it periodically and use about a 120 Hz filter width.) So the process
                                                        > is to select the desired signal and then narrow the filters around
                                                        > that signal.
                                                        >
                                                        > The right answer is for the CODEC to generate the AGC signal and feed
                                                        > that back to the RF/IF stages. That way it responds *only* to the
                                                        > desired signal. After that the only worry is to prevent overload of
                                                        > intermediate stages from a strong but undesired signal in the
                                                        > passband.
                                                        >
                                                        > 73 de Brian, WB6RQN / J79BPL
                                                        >
                                                      • Brian Lloyd
                                                        ... Yes, once you do that you can t see the other signals. Eventually we will derive the AGC within the CODEC so that, even with the wider passband that
                                                        Message 27 of 30 , Jan 7, 2009
                                                        • 0 Attachment
                                                          On Wed, Jan 7, 2009 at 3:16 PM, R. Kevin Stover <rkstover@...> wrote:
                                                          > Brian,
                                                          >
                                                          > I agree 100%.
                                                          >
                                                          > If the user narrows down his passband he won't be seeing all the
                                                          > signals either. It's a double edged sword. Either see them all and
                                                          > hope a real strong signal doesn't fire up, or narrow the IF pass band
                                                          > on the radio either with crystal filters or DSP and pick one signal to
                                                          > hone in on.

                                                          Yes, once you do that you can't see the other signals. Eventually we
                                                          will derive the AGC within the CODEC so that, even with the wider
                                                          passband that allows you to see much of the band, your AGC still only
                                                          responds to the desired signal. This does presume a receiver with a
                                                          very high dynamic range, e.g. low strong-signal IMD, high 1dB
                                                          compression point, etc., and better integration between the RF
                                                          sections and the CODEC. I think we are getting there with some of the
                                                          approaches to SDR that are coming down the pike.

                                                          73 de Brian, WB6RQN/J79BPL

                                                          >
                                                          >
                                                          > --- In linuxham@yahoogroups.com, "Brian Lloyd" <brian-wb6rqn@...> wrote:
                                                          >>
                                                          >> On Wed, Jan 7, 2009 at 9:46 AM, R. Kevin Stover <rkstover@...> wrote:
                                                          >> > Unfortunately that's the way it is with sound card digi modes.
                                                          >> > My waterfall goes black when the Ham a couple blocks away decides to
                                                          >> > get on PSK. It's the same no matter what software you use.
                                                          >>
                                                          >> Well, yes and no. The key thing is to ensure that the AGC only
                                                          >> responds to the desired signal. The simplest way to do that is to
                                                          >> narrow the IF filter until the receiver only passes the desired
                                                          >> signal. I have a Flex 5000 and this is what I do when digging out a
                                                          >> weak signal, even PSK. (PSK is not my favorite mode but I do operate
                                                          >> it periodically and use about a 120 Hz filter width.) So the process
                                                          >> is to select the desired signal and then narrow the filters around
                                                          >> that signal.
                                                          >>
                                                          >> The right answer is for the CODEC to generate the AGC signal and feed
                                                          >> that back to the RF/IF stages. That way it responds *only* to the
                                                          >> desired signal. After that the only worry is to prevent overload of
                                                          >> intermediate stages from a strong but undesired signal in the
                                                          >> passband.
                                                          >>
                                                          >> 73 de Brian, WB6RQN / J79BPL
                                                          >>
                                                          >
                                                          >
                                                          >
                                                          > ------------------------------------
                                                          >
                                                          > Yahoo! Groups Links
                                                          >
                                                          >
                                                          >
                                                          >
                                                        • Steve Friis
                                                          One caveat of using DSP to narrow the filter is that the AGC loop has to be within the DSP. This would usually only happen with receivers that have the DSP at
                                                          Message 28 of 30 , Jan 7, 2009
                                                          • 0 Attachment
                                                            One caveat of using DSP to narrow the filter is that the AGC loop has to
                                                            be within the DSP. This would usually only happen with receivers that
                                                            have the DSP at the IF level and not the AF level. Otherwise the AGC
                                                            with strong signals will still occur.

                                                            <><Steve/WM5Z><>
                                                            Location: Las Cruces, NM: DM62oh
                                                            No one can change the past, but we all influence the future.
                                                            Remember, you too can have a computer like a wigwam, No windows, no gates.
                                                            Linux User Number 481782 <http://counter.li.org/>



                                                            R. Kevin Stover wrote:
                                                            > Brian,
                                                            >
                                                            > I agree 100%.
                                                            >
                                                            > If the user narrows down his passband he won't be seeing all the
                                                            > signals either. It's a double edged sword. Either see them all and
                                                            > hope a real strong signal doesn't fire up, or narrow the IF pass band
                                                            > on the radio either with crystal filters or DSP and pick one signal to
                                                            > hone in on.
                                                            >
                                                            >
                                                            > --- In linuxham@yahoogroups.com, "Brian Lloyd" <brian-wb6rqn@...> wrote:
                                                            >
                                                            >> On Wed, Jan 7, 2009 at 9:46 AM, R. Kevin Stover <rkstover@...> wrote:
                                                            >>
                                                            >>> Unfortunately that's the way it is with sound card digi modes.
                                                            >>> My waterfall goes black when the Ham a couple blocks away decides to
                                                            >>> get on PSK. It's the same no matter what software you use.
                                                            >>>
                                                            >> Well, yes and no. The key thing is to ensure that the AGC only
                                                            >> responds to the desired signal. The simplest way to do that is to
                                                            >> narrow the IF filter until the receiver only passes the desired
                                                            >> signal. I have a Flex 5000 and this is what I do when digging out a
                                                            >> weak signal, even PSK. (PSK is not my favorite mode but I do operate
                                                            >> it periodically and use about a 120 Hz filter width.) So the process
                                                            >> is to select the desired signal and then narrow the filters around
                                                            >> that signal.
                                                            >>
                                                            >> The right answer is for the CODEC to generate the AGC signal and feed
                                                            >> that back to the RF/IF stages. That way it responds *only* to the
                                                            >> desired signal. After that the only worry is to prevent overload of
                                                            >> intermediate stages from a strong but undesired signal in the
                                                            >> passband.
                                                            >>
                                                            >> 73 de Brian, WB6RQN / J79BPL
                                                            >>
                                                            >>
                                                            >
                                                            >
                                                            >
                                                            > ------------------------------------
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                                                          • "Glenn (KØBO)"
                                                            ... Sometimes when I have a strong neighboring signal, I will put my AGC into manual and set the RF control for the desired signal ignoring the strong signal.
                                                            Message 29 of 30 , Jan 7, 2009
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                                                              Brian Lloyd wrote:
                                                              > On Wed, Jan 7, 2009 at 9:46 AM, R. Kevin Stover <rkstover@...> wrote:
                                                              >> Unfortunately that's the way it is with sound card digi modes.
                                                              >> My waterfall goes black when the Ham a couple blocks away decides to
                                                              >> get on PSK. It's the same no matter what software you use.
                                                              >
                                                              > Well, yes and no. The key thing is to ensure that the AGC only
                                                              > responds to the desired signal. The simplest way to do that is to
                                                              > narrow the IF filter until the receiver only passes the desired
                                                              > signal.

                                                              Sometimes when I have a strong neighboring signal, I will put my AGC
                                                              into manual and set the RF control for the desired signal ignoring the
                                                              strong signal. Sometimes this will make the offending strong signal
                                                              distort on the display and sound bad but the desired signal is all
                                                              that's important.

                                                              Hope this helps someone.... Glenn K0BO
                                                            • mike.thebike
                                                              ... *If* your radio has a good CW notch filter you might want to give that a try. I ve notched out a strong PSK station using the CW notch filter on my radio
                                                              Message 30 of 30 , Jan 8, 2009
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                                                                --- In linuxham@yahoogroups.com, "R. Kevin Stover" <rkstover@...> wrote:
                                                                >
                                                                > Unfortunately that's the way it is with sound card digi modes.
                                                                > My waterfall goes black when the Ham a couple blocks away decides to
                                                                > get on PSK. It's the same no matter what software you use.
                                                                >

                                                                *If* your radio has a good CW notch filter you might want to
                                                                give that a try. I've notched out a strong PSK station using
                                                                the CW notch filter on my radio and that helps a great deal.

                                                                73, Mike, K0TER
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