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multi decode same station

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  • n4abn
    With WSJTX v1.1,r3459 I am getting multi decodes of the same station sometimes. Stations must be transmitting harmonics? For example one of the stations
    Message 1 of 8 , Jul 15, 2013
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      With WSJTX v1.1,r3459 I am getting multi decodes of the same station sometimes. Stations must be transmitting harmonics? For example one of the stations decode window shows 1440, 1460, 2100, 2662df all from the same station. Is this a glitch in the program that hasn't been fixed yet?


      73 Eddy N4ABN
    • Joe Subich, W4TV
      Multiple decodes of the same station seem to occur only on very strong signals (in most cases +20) and are related either to hum on that station s signal or
      Message 2 of 8 , Jul 16, 2013
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        Multiple decodes of the same station seem to occur only on very strong
        signals (in most cases > +20) and are related either to hum on that
        station's signal or more likely to hum in the *receiving station's*
        sound card.

        There are certain inexpensive amateur sound card products that skip the
        V/2 reference regulator recommended by the sound chip manufacturer. The
        V/2 reference is also required for the op-amps used in the audio chains.
        Those same sound card products also lack sufficient filtering on the USB
        power line allowing the typical 2 x line frequency ripple to modulate
        both transmit and receive audio.

        73,

        ... Joe, W4TV


        On 7/16/2013 12:13 AM, digisignal@... wrote:
        > With WSJTX v1.1,r3459 I am getting multi decodes of the same station
        > sometimes. Stations must be transmitting harmonics? For example one of
        > the stations decode window shows 1440, 1460, 2100, 2662df all from the
        > same station. Is this a glitch in the program that hasn't been fixed
        > yet?
        > 73 Eddy N4ABN
        >
      • Joe Subich, W4TV
        ... Have you ever use JT9 before? The multiple decodes are well documented from the very beginning whilst other modes do not show that issue since their
        Message 3 of 8 , Jul 16, 2013
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          > I know it's not the sound card because I've been using SignaLink USB
          > for years now and it's never had multiple decodes of the same station
          > on the waterfall.

          Have you ever use JT9 before? The multiple decodes are well documented
          from the very beginning whilst other modes do not show that issue since
          their spectra are all more than 100/120 Hz wide which obscures the
          spurious sidebands.

          I can, and have, generated the issue with the inexpensive amateur sound
          cards on the bench. It is completely repeatable and easy to cure just
          by adding the recommended 2.3V regulator to the V/2 bus and increasing
          the filtering on the V(USB) line. Less than $2.00 in parts increases
          dynamic range (both lower noise floor and spurious removal) in those
          devices by 30 dB.

          73,

          ... Joe, W4TV


          On 7/16/2013 3:06 PM, digisignal@... wrote:
          > Hi Joe,
          >
          > I know it's not the sound card because I've been using SignaLink USB
          > for years now and it's never had multiple decodes of the same station
          > on the waterfall. I've been using WSJT programs, JT65-HF
          > programs,MultiPSK programs,WSPR programs, and none of them have ever
          > given a multiple decode of the same station on the waterfall.
          >
          > 73 Eddy N4ABN
          > On Tuesday, July 16, 2013 at 2:47 PM, "Joe Subich, W4TV" wrote:> It's
          > probably the software is in beta and hasn't got all the bugs
          >> worked out
          >
          > The software most certainly is not "at fault" - it is copying exactly
          > what it receives from the sound card. You will find that most of the
          > decodes show levels significantly below the "main" one - that is clear
          > indication that they are spurs generated either in the transmitter or
          > the receiver (sound card).
          >
          > These spurs have been noted since JT9 first appeared and simply do
          > not show up with other protocols because they are wide enough that
          > the "main" signal hides the spurs that fall within its passband.
          >
          > Any halfway competent technician can demonstrate the spurious
          > products approximately 40 to 45 dB below the desired signal generated
          > by these inexpensive sound devices ... similarly driving one of those
          > devices with a 4V P-P sine wave will clearly show the spurious receive
          > products when viewed with quality audio spectrum software. Instead of
          > 90+ dB spurious free dynamic range produced by a quality sound card,
          > these inexpensive products consistently demonstrate spurious products
          > around 40 dB relative to maximum output/maximum input and noise
          > limited
          > dynamic range (noise floor to maximum signal) in the low to mid 50 dB
          > category.
          >
          > 73,
          >
          > ... Joe, W4TV
          > On 7/16/2013 11:15 AM, digisignal@... wrote:
          >> Hi Joe,
          >>
          >> I can't believe it's my sound card because I've never seen it before
          >> on any of the other programs I use. It's probably the software is in
          >> beta and hasn't got all the bugs worked out of it and the sending
          >> station over driving.
          >>
          >> 73 Eddy N4ABN
          >>
          >> On Tuesday, July 16, 2013 at 9:27 AM, "Joe Subich, W4TV"
          >> wrote:Multiple decodes of the same station seem to occur only on
          > very
          >> strong
          >> signals (in most cases > +20) and are related either to hum on that
          >> station's signal or more likely to hum in the *receiving station's*
          >> sound card.
          >>
          >> There are certain inexpensive amateur sound card products that skip
          >> the
          >> V/2 reference regulator recommended by the sound chip manufacturer.
          >> The
          >> V/2 reference is also required for the op-amps used in the audio
          >> chains.
          >> Those same sound card products also lack sufficient filtering on the
          >> USB
          >> power line allowing the typical 2 x line frequency ripple to
          > modulate
          >> both transmit and receive audio.
          >>
          >> 73,
          >>
          >> ... Joe, W4TV
          >> On 7/16/2013 12:13 AM, digisignal@... wrote:
          >>> With WSJTX v1.1,r3459 I am getting multi decodes of the same
          >> station
          >>> sometimes. Stations must be transmitting harmonics? For example one
          >> of
          >>> the stations decode window shows 1440, 1460, 2100, 2662df all from
          >> the
          >>> same station. Is this a glitch in the program that hasn't been
          >> fixed
          >>> yet?
          >>> 73 Eddy N4ABN
          >>>
        • Joe Subich, W4TV
          ... +10 dB doesn t mean the other station was over driving his transmitter - and you don t get multiple decodes from overdrive unless the audio is so strong
          Message 4 of 8 , Jul 16, 2013
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            > I believe he was over driving his output because his signal db was
            > 10+ and more.

            +10 dB doesn't mean the other station was over driving his transmitter
            - and you don't get multiple decodes from overdrive unless the audio
            is so strong that *garbage in your sound card* modulates that incoming
            signal and you see the resulting products. I regularly copy signals
            at +20 or more that are absolutely clean because my sound card is
            clean and does not create spurious products with strong signals.

            Stations that overdrive the audio input of their rig typically have
            harmonics (particularly if they are in the lower half of the JT65A
            spectrum) that can't be decoded and very strange "rough" sounding
            audio - like the square wave they are in fact generating. JT65 and
            JT9 are singe tone modulations and can be run into RF clipping without
            causing IMD like is the case with PSK31 or other multi-tone modes.

            Again, when you see the multiple decodes, I'm sure you will find one
            that is > +10 and the others are around -20 or somewhat less. That
            35 to 40 dB difference is the spurious dynamic range of *your* sound
            card.

            > Are you talking about installing a regulator inside of the SignaLink?

            I'm talking about installing the manufacturer recommended regulator on
            the V/2 reference for any USB sound device that lacks it. I'm also
            talking about increasing the filter cap on the V(USB) line ... many
            inexpensive USB sound devices lack them although price is not always
            a clue. I've seen the regulator in $19 USB sound dongles and I've
            seen none in $150 devices.

            73,

            ... Joe, W4TV


            On 7/16/2013 6:10 PM, digisignal@... wrote:
            > Joe,
            >
            > Yes I've used JT9 before. I've only started using it daily for a
            > couple of days now. The multiple decode happened from the same station
            > a couple of times. He moved on the waterfall a few different places
            > and each time he decoded several times in one sequence. I believe he
            > was over driving his output because his signal db was 10+ and more.
            >
            > Are you talking about installing a regulator inside of the SignaLink?
            > I've got the paper work on it in a drawer somewhere. I'm not sure I
            > could find it. Probably would have to look it up on the net.
            >
            > 73 Eddy N4ABN
            > On Tuesday, July 16, 2013 at 5:59 PM, "Joe Subich, W4TV" wrote:> I
            > know it's not the sound card because I've been using SignaLink USB
            > > for years now and it's never had multiple decodes of the same
            > station
            > > on the waterfall.
            >
            > Have you ever use JT9 before? The multiple decodes are well
            > documented
            > from the very beginning whilst other modes do not show that issue
            > since
            > their spectra are all more than 100/120 Hz wide which obscures the
            > spurious sidebands.
            >
            > I can, and have, generated the issue with the inexpensive amateur
            > sound
            > cards on the bench. It is completely repeatable and easy to cure just
            > by adding the recommended 2.3V regulator to the V/2 bus and increasing
            > the filtering on the V(USB) line. Less than $2.00 in parts increases
            > dynamic range (both lower noise floor and spurious removal) in those
            > devices by 30 dB.
            >
            > 73,
            >
            > ... Joe, W4TV
            > On 7/16/2013 3:06 PM, digisignal@... wrote:
            >> Hi Joe,
            >>
            >> I know it's not the sound card because I've been using SignaLink USB
            >> for years now and it's never had multiple decodes of the same
            > station
            >> on the waterfall. I've been using WSJT programs, JT65-HF
            >> programs,MultiPSK programs,WSPR programs, and none of them have ever
            >> given a multiple decode of the same station on the waterfall.
            >>
            >> 73 Eddy N4ABN
            >> On Tuesday, July 16, 2013 at 2:47 PM, "Joe Subich, W4TV" wrote:>
            > It's
            >> probably the software is in beta and hasn't got all the bugs
            >>> worked out
            >>
            >> The software most certainly is not "at fault" - it is copying
            > exactly
            >> what it receives from the sound card. You will find that most of
            > the
            >> decodes show levels significantly below the "main" one - that is
            > clear
            >> indication that they are spurs generated either in the transmitter
            > or
            >> the receiver (sound card).
            >>
            >> These spurs have been noted since JT9 first appeared and simply do
            >> not show up with other protocols because they are wide enough that
            >> the "main" signal hides the spurs that fall within its passband.
            >>
            >> Any halfway competent technician can demonstrate the spurious
            >> products approximately 40 to 45 dB below the desired signal
            > generated
            >> by these inexpensive sound devices ... similarly driving one of
            > those
            >> devices with a 4V P-P sine wave will clearly show the spurious
            > receive
            >> products when viewed with quality audio spectrum software. Instead
            > of
            >> 90+ dB spurious free dynamic range produced by a quality sound card,
            >> these inexpensive products consistently demonstrate spurious
            > products
            >> around 40 dB relative to maximum output/maximum input and noise
            >> limited
            >> dynamic range (noise floor to maximum signal) in the low to mid 50
            > dB
            >> category.
            >>
            >> 73,
            >>
            >> ... Joe, W4TV
            >> On 7/16/2013 11:15 AM, digisignal@... wrote:
            >>> Hi Joe,
            >>>
            >>> I can't believe it's my sound card because I've never seen it
            > before
            >>> on any of the other programs I use. It's probably the software is
            > in
            >>> beta and hasn't got all the bugs worked out of it and the sending
            >>> station over driving.
            >>>
            >>> 73 Eddy N4ABN
            >>>
            >>> On Tuesday, July 16, 2013 at 9:27 AM, "Joe Subich, W4TV"
            >>> wrote:Multiple decodes of the same station seem to occur only on
            >> very
            >>> strong
            >>> signals (in most cases > +20) and are related either to hum on that
            >>> station's signal or more likely to hum in the *receiving station's*
            >>> sound card.
            >>>
            >>> There are certain inexpensive amateur sound card products that skip
            >>> the
            >>> V/2 reference regulator recommended by the sound chip manufacturer.
            >>> The
            >>> V/2 reference is also required for the op-amps used in the audio
            >>> chains.
            >>> Those same sound card products also lack sufficient filtering on
            > the
            >>> USB
            >>> power line allowing the typical 2 x line frequency ripple to
            >> modulate
            >>> both transmit and receive audio.
            >>>
            >>> 73,
            >>>
            >>> ... Joe, W4TV
            >>> On 7/16/2013 12:13 AM, digisignal@... wrote:
            >>>> With WSJTX v1.1,r3459 I am getting multi decodes of the same
            >>> station
            >>>> sometimes. Stations must be transmitting harmonics? For example
            > one
            >>> of
            >>>> the stations decode window shows 1440, 1460, 2100, 2662df all from
            >>> the
            >>>> same station. Is this a glitch in the program that hasn't been
            >>> fixed
            >>>> yet?
            >>>> 73 Eddy N4ABN
            >>>>
          • Joe Subich, W4TV
            ... I get the information on the USB sound chips needing the V/2 regulator and a certain level of filtering on the V(usb) supply from the data sheet on the USB
            Message 5 of 8 , Jul 16, 2013
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              > Where do you get this information?

              I get the information on the USB sound chips needing the V/2 regulator
              and a certain level of filtering on the V(usb) supply from the data
              sheet on the USB sound chips. I determine whether the correct parts
              are used in the design of a given product by studying the schematic for
              the device or studying the device itself. I determine the level of
              performance (noise floor, maximum signal capacity, and spurious free
              dynamic range by actually measuring those values on the bench).

              There are high quality devices that can be found for relatively low
              prices and there are poor quality devices at both high and low price
              points.

              I am not "naming names" but if any device lacks the V/2 regulator and
              has insufficient filtering on the V(usb) line, it will have a poor
              spurious dynamic range.

              73,

              ... Joe, W4TV


              On 7/16/2013 9:50 PM, digisignal@... wrote:
              > Joe,
              >
              > I went to the tigertronics web site which sells SignaLink USB and
              > there's nothing on there about a regulator add on for the device. Also
              > nothing on there about the filter cap you're talking about. Where do
              > you get this information?
              >
              > 73 Eddy N4ABN
              > On Tuesday, July 16, 2013 at 8:14 PM, "Joe Subich, W4TV" wrote:> I
              > believe he was over driving his output because his signal db was
              >> 10+ and more.
              >
              > +10 dB doesn't mean the other station was over driving his transmitter
              > - and you don't get multiple decodes from overdrive unless the audio
              > is so strong that *garbage in your sound card* modulates that incoming
              > signal and you see the resulting products. I regularly copy signals
              > at +20 or more that are absolutely clean because my sound card is
              > clean and does not create spurious products with strong signals.
              >
              > Stations that overdrive the audio input of their rig typically have
              > harmonics (particularly if they are in the lower half of the JT65A
              > spectrum) that can't be decoded and very strange "rough" sounding
              > audio - like the square wave they are in fact generating. JT65 and
              > JT9 are singe tone modulations and can be run into RF clipping without
              > causing IMD like is the case with PSK31 or other multi-tone modes.
              >
              > Again, when you see the multiple decodes, I'm sure you will find one
              > that is > +10 and the others are around -20 or somewhat less. That
              > 35 to 40 dB difference is the spurious dynamic range of *your* sound
              > card.
              >
              > > Are you talking about installing a regulator inside of the
              > SignaLink?
              >
              > I'm talking about installing the manufacturer recommended regulator on
              > the V/2 reference for any USB sound device that lacks it. I'm also
              > talking about increasing the filter cap on the V(USB) line ... many
              > inexpensive USB sound devices lack them although price is not always
              > a clue. I've seen the regulator in $19 USB sound dongles and I've
              > seen none in $150 devices.
              >
              > 73,
              >
              > ... Joe, W4TV
              > On 7/16/2013 6:10 PM, digisignal@... wrote:
              >> Joe,
              >>
              >> Yes I've used JT9 before. I've only started using it daily for a
              >> couple of days now. The multiple decode happened from the same
              > station
              >> a couple of times. He moved on the waterfall a few different places
              >> and each time he decoded several times in one sequence. I believe he
              >> was over driving his output because his signal db was 10+ and more.
              >>
              >> Are you talking about installing a regulator inside of the
              > SignaLink?
              >> I've got the paper work on it in a drawer somewhere. I'm not sure I
              >> could find it. Probably would have to look it up on the net.
              >>
              >> 73 Eddy N4ABN
              >> On Tuesday, July 16, 2013 at 5:59 PM, "Joe Subich, W4TV" wrote:> I
              >> know it's not the sound card because I've been using SignaLink USB
              >> > for years now and it's never had multiple decodes of the same
              >> station
              >> > on the waterfall.
              >>
              >> Have you ever use JT9 before? The multiple decodes are well
              >> documented
              >> from the very beginning whilst other modes do not show that issue
              >> since
              >> their spectra are all more than 100/120 Hz wide which obscures the
              >> spurious sidebands.
              >>
              >> I can, and have, generated the issue with the inexpensive amateur
              >> sound
              >> cards on the bench. It is completely repeatable and easy to cure
              > just
              >> by adding the recommended 2.3V regulator to the V/2 bus and
              > increasing
              >> the filtering on the V(USB) line. Less than $2.00 in parts
              > increases
              >> dynamic range (both lower noise floor and spurious removal) in those
              >> devices by 30 dB.
              >>
              >> 73,
              >>
              >> ... Joe, W4TV
              >> On 7/16/2013 3:06 PM, digisignal@... wrote:
              >>> Hi Joe,
              >>>
              >>> I know it's not the sound card because I've been using SignaLink
              > USB
              >>> for years now and it's never had multiple decodes of the same
              >> station
              >>> on the waterfall. I've been using WSJT programs, JT65-HF
              >>> programs,MultiPSK programs,WSPR programs, and none of them have
              > ever
              >>> given a multiple decode of the same station on the waterfall.
              >>>
              >>> 73 Eddy N4ABN
              >>> On Tuesday, July 16, 2013 at 2:47 PM, "Joe Subich, W4TV" wrote:>
              >> It's
              >>> probably the software is in beta and hasn't got all the bugs
              >>>> worked out
              >>>
              >>> The software most certainly is not "at fault" - it is copying
              >> exactly
              >>> what it receives from the sound card. You will find that most of
              >> the
              >>> decodes show levels significantly below the "main" one - that is
              >> clear
              >>> indication that they are spurs generated either in the transmitter
              >> or
              >>> the receiver (sound card).
              >>>
              >>> These spurs have been noted since JT9 first appeared and simply do
              >>> not show up with other protocols because they are wide enough that
              >>> the "main" signal hides the spurs that fall within its passband.
              >>>
              >>> Any halfway competent technician can demonstrate the spurious
              >>> products approximately 40 to 45 dB below the desired signal
              >> generated
              >>> by these inexpensive sound devices ... similarly driving one of
              >> those
              >>> devices with a 4V P-P sine wave will clearly show the spurious
              >> receive
              >>> products when viewed with quality audio spectrum software. Instead
              >> of
              >>> 90+ dB spurious free dynamic range produced by a quality sound
              > card,
              >>> these inexpensive products consistently demonstrate spurious
              >> products
              >>> around 40 dB relative to maximum output/maximum input and noise
              >>> limited
              >>> dynamic range (noise floor to maximum signal) in the low to mid 50
              >> dB
              >>> category.
              >>>
              >>> 73,
              >>>
              >>> ... Joe, W4TV
              >>> On 7/16/2013 11:15 AM, digisignal@... wrote:
              >>>> Hi Joe,
              >>>>
              >>>> I can't believe it's my sound card because I've never seen it
              >> before
              >>>> on any of the other programs I use. It's probably the software is
              >> in
              >>>> beta and hasn't got all the bugs worked out of it and the sending
              >>>> station over driving.
              >>>>
              >>>> 73 Eddy N4ABN
              >>>>
              >>>> On Tuesday, July 16, 2013 at 9:27 AM, "Joe Subich, W4TV"
              >>>> wrote:Multiple decodes of the same station seem to occur only on
              >>> very
              >>>> strong
              >>>> signals (in most cases > +20) and are related either to hum on
              > that
              >>>> station's signal or more likely to hum in the *receiving
              > station's*
              >>>> sound card.
              >>>>
              >>>> There are certain inexpensive amateur sound card products that
              > skip
              >>>> the
              >>>> V/2 reference regulator recommended by the sound chip
              > manufacturer.
              >>>> The
              >>>> V/2 reference is also required for the op-amps used in the audio
              >>>> chains.
              >>>> Those same sound card products also lack sufficient filtering on
              >> the
              >>>> USB
              >>>> power line allowing the typical 2 x line frequency ripple to
              >>> modulate
              >>>> both transmit and receive audio.
              >>>>
              >>>> 73,
              >>>>
              >>>> ... Joe, W4TV
              >>>> On 7/16/2013 12:13 AM, digisignal@... wrote:
              >>>>> With WSJTX v1.1,r3459 I am getting multi decodes of the same
              >>>> station
              >>>>> sometimes. Stations must be transmitting harmonics? For example
              >> one
              >>>> of
              >>>>> the stations decode window shows 1440, 1460, 2100, 2662df all
              > from
              >>>> the
              >>>>> same station. Is this a glitch in the program that hasn't been
              >>>> fixed
              >>>>> yet?
              >>>>> 73 Eddy N4ABN
              >>>>>
            • Chase Turner
              There is quite a bit of data located at this web address regarding the Tigertronics Signalink: http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html
              Message 6 of 8 , Jul 16, 2013
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                There is quite a bit of data located at this web address regarding the Tigertronics Signalink:


                FYI,
                Chase


                On 7/16/2013 9:50 PM, digisignal@... wrote:
                > Joe,
                >
                > I went to the tigertronics web site which sells SignaLink USB and
                > there's nothing on there about a regulator add on for the device. Also
                > nothing on there about the filter cap you're talking about. Where do
                > you get this information?
                >
                > 73 Eddy N4ABN

                --
                Chase Turner
                W4TI
              • Philip
                I ve only seen this effect once myself, last night on 14 MHz, there was a European station so strong +20dB and more you could see the splatter from his JT9
                Message 7 of 8 , Jul 17, 2013
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                  I've only seen this effect once myself, last night on 14 MHz, there was a European station so strong +20dB and more you could see the splatter from his JT9 signal across a large section of the waterfall, decoded in 3 places here.

                  I'm pretty sure he was running QRO power levels to work DX, from what I could see, compared to all the other many stations on air at the same time both JT9 and JT65.

                  73 de Philip G0ISW
                • chas cartmel
                  Saw that myself last night - a IZ0 or IZ5 station I seem to remember 73 Charlie www.G4EST.me.uk From: wsjtgroup@yahoogroups.com
                  Message 8 of 8 , Jul 17, 2013
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                    Saw that myself last night – a IZ0 or IZ5 station I seem to remember

                     

                    73

                    Charlie

                    www.G4EST.me.uk

                     

                    From: wsjtgroup@yahoogroups.com [mailto:wsjtgroup@yahoogroups.com] On Behalf Of Philip
                    Sent: 17 July 2013 11:43
                    To: digisignal@...; wsjtgroup@yahoogroups.com
                    Subject: [wsjtgroup] Re: multi decode same station

                     

                     

                    I've only seen this effect once myself, last night on 14 MHz, there was a European station so strong +20dB and more you could see the splatter from his JT9 signal across a large section of the waterfall, decoded in 3 places here.

                    I'm pretty sure he was running QRO power levels to work DX, from what I could see, compared to all the other many stations on air at the same time both JT9 and JT65.

                    73 de Philip G0ISW

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