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Re: [Raspberry_Pi_4-Ham_RADIO] Raspberry Pi as WSPR transmitter up to 250Mhz

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  • Rick Simpson
    You guys discussing using the Pi as an RF transmitter intrigue me. Can you point me to a site that discusses how the Pi can generate and control frequencies
    Message 1 of 25 , Mar 26 8:49 AM
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      You guys discussing using the Pi as an RF transmitter intrigue me. Can you point me to a site that discusses how the Pi can generate and control frequencies way above its clock rate?
       
      Rick
      K3IND
       
       
      ----- Original Message -----
      From: Guido
      Sent: Tuesday, March 26, 2013 10:38 AM
      Subject: Re: [Raspberry_Pi_4-Ham_RADIO] Raspberry Pi as WSPR transmitter up to 250Mhz

       

      Good afternoon Eddie,

      Thanks again for performing these tests, very helpful. 
      OK, I understand that the higher clock rates now causing symbols not being aligned properly due to rounding errors, need to fix this when have time.
      For now I have reverted to previous clock rate which should work fine again as before.

      73, Guido
      PE1NNZ


      On Tue, Mar 26, 2013 at 1:54 PM, psk31 <psk31@...> wrote:
      Good Morning Guido / All

      Thanks for your work on this interesting project, thank you also for adding selectable TX periods.
      I am very happy to test.

      For those who like me haven't done any serious Linux for a while, installing the new version is merely a case of deleting the WSprryPi folder and re installing from github.

      To power the RasPi for Radio use, I have in mind a large 5Volt regulator running from my shack 12Volt float charged battery supply, I avoid all mains borne noise in this way. For the moment I am using a 2Amp Switch mode Mains supply which came with the RasPi.

      I have tried the new version on 24MHz. There is a bug here, one of the WSPR data units has feelings of grandeur and exhibits an 8Hz shift.

      28MHz . Was very successful on the previous version, on this version there are no decodes despite all looking OK.

      10MHz. Was fine previously, on this version there are no decodes.

      7MHz . Decodes fine on both versions.

      73 Eddie G3ZJO



      On 26/03/2013 10:20, Guido wrote:
       
      Good morning Eddie, et al,

      Thanks all for your interest in this project and performing these tests.
      A good USB power supply is required to prevent 100 Hz side bands. 
      Most probably this 100Hz created in the rectification stage of your USB 
      power supply and then mixed with the clock signal on GPIO4. I am 
      interested to know you measurement results when using another regulated 
      power supply.

      The PLL fractional divider stage in the RPi and the alternation algorithm in 
      WsprryPi are other potential sources of spurs. I found that increasing the 
      clock of modulating the fractional divider reduces the number of spurs, 
      especially on higher frequencies (30MHz and up); but unfortunately it also 
      decrease the frequency resolution making below the required WSPR 
      symbol bandwidth. If you like to measure spuri, please try my new version 
      If you change n_iter value in code and re-compile, you may try 50 and 70Mhz, 
      it is currently blocked.

      The new version has also a feature that lets you control the duty cycle of 
      your TX; a set of frequencies can be added where 0 frequency stands for
      a two minute interval where TX is disabled. E.g 25% duty cycle:

            sudo ./wspr G3ZJO FN20 10 7040074 0 0 0

      73, Guido
      PE1NNZ


    • Daniel Ankers
      ... Hi Rick, The Pi has a PLL and fractional divider combo built into it which is intended to be used as a general purpose clock. The PLL runs at 2GHz and is
      Message 2 of 25 , Mar 27 4:08 AM
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        On 26 March 2013 15:49, Rick Simpson <goatguy101@...> wrote:
         

        You guys discussing using the Pi as an RF transmitter intrigue me. Can you point me to a site that discusses how the Pi can generate and control frequencies way above its clock rate?
         
        Rick
        K3IND


        Hi Rick,

        The Pi has a PLL and fractional divider combo built into it which is intended to be used as a general purpose clock.  The PLL runs at 2GHz and is then divided by 4 before being fed into the programmable divider - one of the designers states this here: http://raspberrypi.org/phpBB3/viewtopic.php?f=37&t=25301&p=234081#p234081

        Regards,
        Dan MD1CLV
      • Ron Wright
        I would be reluctant to use a computer clock for an RF source, that is for any distance. Often lots of work goes into a computer design to reduce the
        Message 3 of 25 , Mar 27 6:07 AM
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          I would be reluctant to use a computer clock for an RF source, that is for any distance.  Often lots of work goes into a computer design to reduce the radiation to meet FCC part 15 to prevent interference to other devices. Good shielded connectors and good PC board layout with good ground is used.   Us Hams have seen what some computers do to our shack rigs, hi.  Plasma TVs have been known to radiate lots of bad energy, a display problem.

          The main reason I would be cautious in using a computer clock or software generated source is computers deal with square waves, or near square.  These are rich in harmonics and something one does not want being radiated.  However, there are applications for such like a signal source for test bench servicing, but for communications not sure how one could make a clean source without good filters.

          73, ron, n9ee/r

          Ron Wright, N9EE/R
          BSEE
          Micro Computer Concepts
          352-683-4476
          mccrpt@...



          To: Raspberry_Pi_4-Ham_RADIO@yahoogroups.com
          From: md1clv@...
          Date: Wed, 27 Mar 2013 11:08:16 +0000
          Subject: Re: [Raspberry_Pi_4-Ham_RADIO] Raspberry Pi as WSPR transmitter up to 250Mhz

           
          On 26 March 2013 15:49, Rick Simpson <goatguy101@...> wrote:

           

          You guys discussing using the Pi as an RF transmitter intrigue me. Can you point me to a site that discusses how the Pi can generate and control frequencies way above its clock rate?
           
          Rick
          K3IND


          Hi Rick,

          The Pi has a PLL and fractional divider combo built into it which is intended to be used as a general purpose clock.  The PLL runs at 2GHz and is then divided by 4 before being fed into the programmable divider - one of the designers states this here: http://raspberrypi.org/phpBB3/viewtopic.php?f=37&t=25301&p=234081#p234081

          Regards,
          Dan MD1CLV

        • psk31
          ... Hi Dan, plus All When thanking Guido yesterday for his work on the WsprryPi project, I neglected to include your work, I did mean to but unfortunately
          Message 4 of 25 , Mar 27 12:50 PM
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            On 27/03/2013 11:08, Daniel Ankers wrote:
            The Pi has a PLL and fractional divider combo built into it which is intended to be used as a general purpose clock.  The PLL runs at 2GHz and is then divided by 4 before being fed into the programmable divider - one of the designers states this here: http://raspberrypi.org/phpBB3/viewtopic.php?f=37&t=25301&p=234081#p234081

            Regards,
            Dan MD1CLV
            Hi Dan, plus All

            When thanking Guido yesterday for his work on the WsprryPi project, I neglected to include your work, I did mean to but unfortunately often my thoughts get lost somewhere. I haven't yet tried your version, I do intend to.

            WsprryPi Power Supply Tests

            Today I have concentrated my efforts on the Power Supply for the RaspPi to see how much improvement there is in the 'hum' sidebands if a clean supply is used.

            I used a 5 Volt Regulator with  the usual input and output capacitors connected to my 13.8Volt float charged battery shack supply, powering the RaspPi via the mini USB socket. The reduction in  sidebands was clear, however the keyboard went wild inputting strings of random characters. Now where have I heard of this before, reports of "when I used the RasPi with a powered hub made by X, I got random keyboard operation".
            Connecting to my shack supply connects to my Antenna Earth, something which will be necessary if and when the Wsprry goes on air. Normally everything on the Pi floats and they get away with it, maybe bonding the supply negative to earth changes the characteristics for pickup of mains supply noise.
            Next I tried a 12Volt gel battery as the power source, same wiring but now floating above earth, the keyboard worked fine, 100Hz sidebands were down measuring -21dB on 7MHz.

            So with a clean supply to the RasPi it was still producing what looked like mains related, modulated sidebands. Once WsprrPi was running
            I switched off the USB powered hub, the sidebands vanished below detectable levels on 7MHz. Most likely the rubbish from the Switching Regulator was also causing the keyboard problem when the set up was earthed.

            Solution, my original thought. Powering everything from the shack supply. I used a large heatsink with 2 mounting places for the original 5Volt regulator. I added another regulator with the usual capacitors and  for good luck decoupled the separate outputs which feed two USB sockets with a 1000pF and 1000uF each. The powered hub now receives its power via a USB lead.

            Conclusion, to use the RasPi as a DDS / QRP transmitter it is essential that a clean power supply system is used, for the computer and peripherals too,  not surprising really.

            73
            Eddie G3ZJO



             
          • psk31
            ... Hi Guido / Group Following today s PSU building work there are some nice improvements, results so far for LF, MF and HF Bands. Test set up, a very short
            Message 5 of 25 , Mar 27 2:16 PM
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              On 26/03/2013 10:20, Guido wrote:
              I am 
              interested to know you measurement results when using another regulated 
              power supply.
              Hi Guido / Group

              Following today's PSU building work there are some nice improvements, results so far for LF, MF and HF Bands.

              Test set up, a very short wire on GPIO4 providing 0dB or greater WSPR signal.

              136KHz, 474KHz,1.9MHz Spurii below detectable levels on Spectrum Lab using Kenwood TS870 as RX.

              3.6MHz, visible sidebands but below WSPR decode level.
               
              7MHz, 100Hz sidebands -27dB.

              10MHz, Sidebands below decode levels.

              14MHz, 100Hz sidebands -25dB

              17MHz, 21MHz, Sidebands below decode levels.

              24MHz, 28MHz, Both frequencies have a close in companion WSPR modulated product, HF of the wanted signal, 100Hz WSPR modulated sidebands and a comb of spurs. I really wouldn't want to transmit this even as a QRP test transmission.

              Tomorrow I might get round to connecting some LPF's and maybe getting some reports.

              73 Eddie G3ZJO

            • Robert Nickels
              ... I ll chime in on the benefits of using a real power supply. Check hamfest under the table boxes for 5 volt open frame power supplies - they used to be
              Message 6 of 25 , Mar 28 9:09 AM
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                On 3/27/2013 4:16 PM, psk31 wrote:
                > measurement results when using another regulated
                > power supply.

                I'll chime in on the benefits of using a real power supply. Check
                hamfest "under the table boxes" for 5 volt open frame power supplies -
                they used to be free or nearly so but aren't as common nowadays. I'm
                using a 3A 5V Power One that feeds into the GPIO connector and have a
                noticeably reduced noise level when using the Pi as an SDR dongle server
                with my HF converter. I haven't tried to measure it but it was like
                flipping off a switch. For ham apps running on the Pi at home, I can't
                see any downslide to using a good regulated DC supply and preferably a
                linear rather than switcher.

                73, Bob W9RAN
              • psk31
                ... Sure thing Bob I had very good results today, although I didn t check all bands, with an old, typical CB type 3A linear PSU to feed my 5Volt USB set up. I
                Message 7 of 25 , Mar 28 10:51 AM
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                  On 28/03/2013 16:09, Robert Nickels wrote:
                  > For ham apps running on the Pi at home, I can't
                  > see any downslide to using a good regulated DC supply and preferably a
                  > linear rather than switcher.
                  Sure thing Bob I had very good results today, although I didn't check
                  all bands, with an old, typical CB type 3A linear PSU to feed my 5Volt
                  USB set up.

                  I found a couple of my QRP Low Pass Filters one for 14MHz and one for
                  7MHz. So that set the bands to test on air at this time.

                  Had an hour or so on 14MHz, with no reports so changed to 7MHz.

                  However just after I changed to 7MHz I found this report on the Data
                  Base, my first report with the Pi sneaked in at the last moment.

                  2013-03-28 16:22 G3ZJO 14.097119 -23 1 IO92ng
                  +7 0.005 LY2BOS KO24or 1736 1079

                  Now on 7Mhz the Spots are coming in from all around Europe.

                  2013-03-28 17:40 G3ZJO 7.040083 -15 1 IO92ng
                  +7 0.005 PI4THT JO32kf 527 327
                  2013-03-28 17:36 G3ZJO 7.040084 -20 1 IO92ng
                  +7 0.005 DK6UG JN49cm 706 439
                  2013-03-28 17:36 G3ZJO 7.040099 -16 0 IO92ng
                  +7 0.005 ON7KO JO21ce 370 230
                  2013-03-28 17:36 G3ZJO 7.040081 -19 0 IO92ng
                  +7 0.005 OZ7IT JO65df 924 574
                  2013-03-28 17:32 G3ZJO 7.040066 -18 0 IO92ng
                  +7 0.005 PA7EY JO22jj 385 239
                  2013-03-28 17:32 G3ZJO 7.040093 -18 0 IO92ng
                  +7 0.005 F4CWN/2 JN03kn 977 607
                  2013-03-28 17:32 G3ZJO 7.040088 -20 1 IO92ng
                  +7 0.005 EI9GNB IO51sv 520 323
                  2013-03-28 17:32 G3ZJO 7.040081 -17 0 IO92ng
                  +7 0.005 OZ7IT JO65df 924 574
                  2013-03-28 17:32 G3ZJO 7.040084 -21 0 IO92ng
                  +7 0.005 DK6UG JN49cm 706 439
                  2013-03-28 17:32 G3ZJO 7.040082 -16 0 IO92ng
                  +7 0.005 PI4THT JO32kf 527 327
                  2013-03-28 17:32 G3ZJO 7.040098 -24 1 IO92ng
                  +7 0.005 ON7KO JO21ce 370 230
                  2013-03-28 17:28 G3ZJO 7.040088 -21 1 IO92ng
                  +7 0.005 EI9GNB IO51sv 520 323
                  2013-03-28 17:28 G3ZJO 7.040082 -21 0 IO92ng
                  +7 0.005 F1JRD/3 JN03on 981 610
                  2013-03-28 17:28 G3ZJO 7.040067 -17 0 IO92ng
                  +7 0.005 PA7EY JO22jj 385 239
                  2013-03-28 17:28 G3ZJO 7.040084 -20 1 IO92ng
                  +7 0.005 DK6UG JN49cm 706 439
                  2013-03-28 17:28 G3ZJO 7.040083 -16 1 IO92ng
                  +7 0.005 PI4THT JO32kf 527 327
                  2013-03-28 17:20 G3ZJO 7.040080 -27 0 IO92ng
                  +7 0.005 IK1WVQ JN44cb 1133 704
                  2013-03-28 17:20 G3ZJO 7.040081 -15 0 IO92ng
                  +7 0.005 OZ7IT JO65df 924 574
                  2013-03-28 17:20 G3ZJO 7.040088 -21 0 IO92ng
                  +7 0.005 EI9GNB IO51sv 520 323
                  2013-03-28 17:20 G3ZJO 7.040067 -16 1 IO92ng
                  +7 0.005 PA7EY JO22jj 385 239
                  2013-03-28 17:20 G3ZJO 7.040099 -19 1 IO92ng
                  +7 0.005 ON7KO JO21ce 370 230
                  2013-03-28 17:20 G3ZJO 7.040083 -17 0 IO92ng
                  +7 0.005 PI4THT JO32kf 527 327
                  2013-03-28 17:16 G3ZJO 7.040067 -17 1 IO92ng
                  +7 0.005 PA7EY JO22jj 385 239
                  2013-03-28 17:16 G3ZJO 7.040083 -18 0 IO92ng
                  +7 0.005 PI4THT JO32kf 527 327
                  2013-03-28 17:12 G3ZJO 7.040083 -18 0 IO92ng
                  +7 0.005 PI4THT JO32kf 527 327
                  2013-03-28 17:12 G3ZJO 7.040067 -19 0 IO92ng
                  +7 0.005 PA7EY JO22jj 385 239

                  No surprises there, I am a keen QRP'er but pretty impressive that the Pi
                  is doing everything. I must set the power correct I measure about 15mW,
                  5mW is just an old habit of mine.

                  73 Eddie G3ZJO
                • Robert Nickels
                  ... Not for an experienced guy like you Eddie, but I m in awe! I m off to make LPF - would appreciate any suggestion as to which band(s) are best -
                  Message 8 of 25 , Mar 28 6:55 PM
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                    On 3/28/2013 12:51 PM, psk31 wrote:
                    > No surprises there,

                    Not for an experienced guy like you Eddie, but I'm in awe! I'm off
                    to make LPF - would appreciate any suggestion as to which band(s) are
                    best - otherwise I'll probably try 20 meters. Will be my first
                    go-round with WSPR.

                    Nice work, all!

                    73, Bob W9RAN
                  • Guido
                    There is an update of WsprryPi, now supporting some new features that was requested by few: 1. the slower brother of WSPR-2 is supported called WSPR-15. To use
                    Message 9 of 25 , Apr 1, 2013
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                      There is an update of WsprryPi, now supporting some new features that was requested by few:

                      1. the slower brother of WSPR-2 is supported called WSPR-15. To use it, specify a frequency in the 25Hz sub-band that is just above the regular wspr band:
                           LF   137400 - 137600
                                137600 - 137625 (WSPR-15)
                           MF   475600 - 475800
                                475800 - 475825 (WSPR-15)
                          160m  1838000 - 1838200
                                1838200 - 1838225 (WSPR-15)

                      2. it is now possible to specify either a prefix or suffix in the callsign.
                      Prefix may contain up to three characters before the callsign, e.g: EA8/PE1NNZ or F/PE1NNZ.
                      Suffixes may contain a single alphanumeric character or double digit, e.g: PE1NNZ/p, PE1NNZ/1, PE1NNZ/99

                      New features can be downloaded in github: https://github.com/threeme3/WsprryPi.git

                      73, Guido
                      PE1NNZ


                      On Fri, Mar 29, 2013 at 2:55 AM, Robert Nickels <w9ran@...> wrote:
                      On 3/28/2013 12:51 PM, psk31 wrote:
                      > No surprises there,

                      Not for an experienced guy like you Eddie, but I'm in awe!     I'm off
                      to make LPF - would appreciate any suggestion as to which band(s) are
                      best - otherwise I'll probably try 20 meters.   Will be my first
                      go-round with WSPR.

                      Nice work, all!

                      73, Bob W9RAN


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                    • Jon Ove Johnsen
                      Hi Guido, Thanks for the last versions of WsprryPi. There are of course always more to wish for. The communication between us has not been perfect. I will
                      Message 10 of 25 , Apr 5, 2013
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                        Hi Guido,
                        Thanks for the last versions of WsprryPi.
                        There are of course always more to wish for.
                        The communication between us has not been perfect.
                        I will try to summarize my comments.

                        1. Calibration.
                        I would like to suggest that the calibration should always be done for a particular RasPi board before any txing is performed.
                        The calibrating could be done in a few steps by the command wspr LA3JJ JO59 10 10140200 C  offset, where offset  may be + or - 1, 10 ,100 . This because to use the editor vi and a new compilation is a bit complicated. When a board has been calibrated it has been so for life, so the value should be saved in a file in the home dir and be automatically used the next time when a new version is loaded.

                        2. Hash coding.
                        To be able to run txing of longer messages hash coding concept has been used. In my Arduino applications I have still not implemented this, but instead used the program from W3PM to generate the two messages on my W7 PC. When I in advance know the location I have made sets of the relevant dual symbol codes hard coded and select-able from my Arduino LCD screen. The hash coding seemed a bit over my head. At W3PM's pages there are examples of this, but so far I will not go into this for my part. (It would have been nice to have it implemented though as my Arduino is interfaced to a GPS module and calculates the Maidenhead location continuously.)

                        3. Time sync.
                        The WsprrPi uses time sync via the internet. It would have been nice to have sync from a GPS module also to be able to run it really portable.
                        point a) here is to read and decode GPS time from a GPS module like I have done in my Arduino. Or pint b) to have an input pin (or two) on the RasPi where GPS generated minute time pulses could be received.

                        4. Multiple band operation.
                        I made a comment of this:   http://wsprnet.org/drupal/node/3994#comment-9882

                         At the moment I am visiting family at loc JP54 and as my present WsprryPi needs wired internet connection I decided not to bring it along.
                        I do hope I will be able to make it a fully portable rig in the future.
                        At the age of 70 now I am learning a little more about C and Python coding every day, but it moves on very slowly.

                        73
                        Jon Ove, la3jj

                        .

                        Fra: Guido <threeme3@...>
                        Til: Raspberry_Pi_4-Ham_RADIO@yahoogroups.com
                        Sendt: Mandag, 1. april 2013 20.04
                        Emne: Re: [Raspberry_Pi_4-Ham_RADIO] Raspberry Pi as WSPR transmitter up to 250Mhz

                         
                        There is an update of WsprryPi, now supporting some new features that was requested by few:

                        1. the slower brother of WSPR-2 is supported called WSPR-15. To use it, specify a frequency in the 25Hz sub-band that is just above the regular wspr band:
                             LF   137400 - 137600
                                  137600 - 137625 (WSPR-15)
                             MF   475600 - 475800
                                  475800 - 475825 (WSPR-15)
                            160m  1838000 - 1838200
                                  1838200 - 1838225 (WSPR-15)

                        2. it is now possible to specify either a prefix or suffix in the callsign.
                        Prefix may contain up to three characters before the callsign, e.g: EA8/PE1NNZ or F/PE1NNZ.
                        Suffixes may contain a single alphanumeric character or double digit, e.g: PE1NNZ/p, PE1NNZ/1, PE1NNZ/99

                        New features can be downloaded in github: https://github.com/threeme3/WsprryPi.git

                        73, Guido
                        PE1NNZ


                        On Fri, Mar 29, 2013 at 2:55 AM, Robert Nickels <w9ran@...> wrote:
                        On 3/28/2013 12:51 PM, psk31 wrote:
                        > No surprises there,

                        Not for an experienced guy like you Eddie, but I'm in awe!     I'm off
                        to make LPF - would appreciate any suggestion as to which band(s) are
                        best - otherwise I'll probably try 20 meters.   Will be my first
                        go-round with WSPR.

                        Nice work, all!

                        73, Bob W9RAN


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                      • ferrymanr
                        I wonder if anyone has looked into using the RPi as a DDS synthyesiser. I would guess it might be possible to create up to 25MHz but not sure whether it is
                        Message 11 of 25 , Apr 5, 2013
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                          I wonder if anyone has looked into using the RPi as a DDS synthyesiser. I would guess it might be possible to create up to 25MHz but not sure whether it is practically possible.
                          Dick G4BBH
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