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Re: [perseus_SDR] The Next Generation

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  • Lasse Moell
    Werner, I must be somewhat of a Simpleton... Having, say 4 or even 8 channels input, how do do one acheive proper DF with 10 kHz to 30 MHz?? Those antenna
    Message 1 of 20 , Jul 28, 2013
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      Werner,
      I must be somewhat of a Simpleton...
      Having, say 4 or even 8 channels input, how do do one acheive proper DF with 10 kHz to 30 MHz??

      Those antenna systems I have seen operating at HF has been pretty large and they spent a lot of time calibrating, even using a helicopter.

      Supressing noise and interference, would be nice but it is much simpler than a working DF station.

      If someone can give some information on how to get a multi channel DF to work, without having to have an enormous estate for antennas and a simpel way to calibrate over both frequency and AZ, I would love to hear about it, really!!

      /Lasse SM5GLC


      On 28 jul 2013 13:49 "Werner Karn" <werner.karn@...> wrote:

      >
      >
      > with multichannel input for phasing and direction finding, I think
      > Nico could sell another 3000 SDR.
      >
      >
      >
      >
      > 73,
      >
      >
      >
      >
      > Werner
      >
      > Am Samstag, 27. Juli 2013 schrieb Matthias Bopp :
      >
    • Werner Karn
      Lasse, Typical systems could use 4 or 8 antennas of the same type ( as noise cancelling will need equal amplitude, if not to be adjusted by software). Once the
      Message 2 of 20 , Jul 28, 2013
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        Lasse,

        Typical systems could use 4 or 8 antennas
        of the same type ( as noise cancelling will need equal amplitude, if not to be adjusted by software). Once the 4 or 8 receivers work coherently, the direction of the signal is a function of the frequency, distance between antennas and resulting phase difference. 
        Antenna distance should not exceed half of the shortest wavelength. Max. frequency ratio is probably 1:10, For accuracy you don't need a helicopter, it's just a matter of having a good compass or known angle to a transmitter and/or measuring the exact position of each antenna with GPS within 1cm or less or exact distance and angle to each other.
        I think with Perseus SDR you would just need to let the LO of the different channels run with different phases.

        73,

        Werner

        Am Sonntag, 28. Juli 2013 schrieb Lasse Moell :
         

        Werner,
        I must be somewhat of a Simpleton...
        Having, say 4 or even 8 channels input, how do do one acheive proper DF with 10 kHz to 30 MHz??

        Those antenna systems I have seen operating at HF has been pretty large and they spent a lot of time calibrating, even using a helicopter.

        Supressing noise and interference, would be nice but it is much simpler than a working DF station.

        If someone can give some information on how to get a multi channel DF to work, without having to have an enormous estate for antennas and a simpel way to calibrate over both frequency and AZ, I would love to hear about it, really!!

        /Lasse SM5GLC

        On 28 jul 2013 13:49 "Werner Karn" <werner.karn@...> wrote:

        >
        >
        > with multichannel input for phasing and direction finding, I think
        > Nico could sell another 3000 SDR.
        >
        >
        >
        >
        > 73,
        >
        >
        >
        >
        > Werner
        >
        > Am Samstag, 27. Juli 2013 schrieb Matthias Bopp :
        >

      • Lasse Moell
        Werner, you make it sound so easy :) A wide-band DF-system for HF is no simple task! I have seen several commercial systems offerings that performance suffers
        Message 3 of 20 , Jul 28, 2013
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          Werner,
          you make it sound so easy :)

          A wide-band DF-system for HF is no simple task! I have seen several commercial systems offerings that performance suffers badly. Sure it can be done, but the question remain, will it have accuracy enough to be a valuable tool for the average Ham?

          And the is the question of s/w vs. antenna... should we use MUSIC, interferometric or Adcock/WatsonWatt?  The software will be pretty complex!

          Still it IS a really fun and interesting topic, If this can be done with simple h/w, I'll be first in line to try it out :)

          Cheers
          Lasse SM5GLC

          On 28 jul 2013 23:19 "Werner Karn" <werner.karn@...> wrote:

           

          Lasse,


          Typical systems could use 4 or 8 antennas
          of the same type ( as noise cancelling will need equal amplitude, if not to be adjusted by software). Once the 4 or 8 receivers work coherently, the direction of the signal is a function of the frequency, distance between antennas and resulting phase difference. 
          Antenna distance should not exceed half of the shortest wavelength. Max. frequency ratio is probably 1:10, For accuracy you don't need a helicopter, it's just a matter of having a good compass or known angle to a transmitter and/or measuring the exact position of each antenna with GPS within 1cm or less or exact distance and angle to each other.
          I think with Perseus SDR you would just need to let the LO of the different channels run with different phases.

          73,

          Werner

          Am Sonntag, 28. Juli 2013 schrieb Lasse Moell :
           

          Werner,
          I must be somewhat of a Simpleton...
          Having, say 4 or even 8 channels input, how do do one acheive proper DF with 10 kHz to 30 MHz??

          Those antenna systems I have seen operating at HF has been pretty large and they spent a lot of time calibrating, even using a helicopter.

          Supressing noise and interference, would be nice but it is much simpler than a working DF station.

          If someone can give some information on how to get a multi channel DF to work, without having to have an enormous estate for antennas and a simpel way to calibrate over both frequency and AZ, I would love to hear about it, really!!

          /Lasse SM5GLC

          On 28 jul 2013 13:49 "Werner Karn" <werner.karn@...> wrote:

          >
          >
          > with multichannel input for phasing and direction finding, I think
          > Nico could sell another 3000 SDR.
          >
          >
          >
          >
          > 73,
          >
          >
          >
          >
          > Werner
          >
          > Am Samstag, 27. Juli 2013 schrieb Matthias Bopp :
          >

        • iv3nwv
          ... Was it an Agilent helicopter either a Rohde & Schwarz one :-D 73s Nico / IV3NWV (I m reading really interesting comments, btw)
          Message 4 of 20 , Aug 1, 2013
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            --- In perseus_SDR@yahoogroups.com, "Lasse Moell" <lasse.moell@...> wrote:

            > Those antenna systems I have seen operating at HF has been pretty large and they spent a lot of time calibrating, even using a helicopter.

            Was it an Agilent helicopter either a Rohde & Schwarz one :-D

            73s
            Nico / IV3NWV

            (I'm reading really interesting comments, btw)
          • iv3nwv
            ... they spent a lot of time calibrating, even using a helicopter. Was it an Agilent helicopter either a Rohde & Schwarz one? :-D 73s Nico / IV3NWV (I m
            Message 5 of 20 , Aug 1, 2013
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              --- In perseus_SDR@yahoogroups.com, "Lasse Moell" <lasse.moell@...> wrote:

              > Those antenna systems I have seen operating at HF has been pretty large and
              they spent a lot of time calibrating, even using a helicopter.

              Was it an Agilent helicopter either a Rohde & Schwarz one? :-D

              73s
              Nico / IV3NWV

              (I'm reading really interesting comments, btw)
            • Lasse Moell
              ... I have spent my fair share of time trying to calibrate DF-antennas for VHF/UHF. Not an easy task, even when one use state-of-the-art software simulations
              Message 6 of 20 , Aug 1, 2013
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                :)

                I have spent my fair share of time trying to calibrate DF-antennas for VHF/UHF. Not an easy task, even when one use state-of-the-art software simulations and "only" wants to verify the results. HF has its share of problems, but everything gets soo much larger :D

                Years and years ago we used to operate Plath and Telefunken systems, and seeing how skywaves mixes makes you realize even with a perfect antenna things are not "that" easy...

                Still, would be fun to play around see what is feasable using SDR tehcnique and how far one can use simple antennas and still have a usable system.

                /Lasse SM5GLC

                On 1 aug 2013 15:37 "iv3nwv" <nicopal@...> wrote:

                 


                --- In perseus_SDR@yahoogroups.com, "Lasse Moell" <lasse.moell@...> wrote:

                > Those antenna systems I have seen operating at HF has been pretty large and
                they spent a lot of time calibrating, even using a helicopter.

                Was it an Agilent helicopter either a Rohde & Schwarz one? :-D

                73s
                Nico / IV3NWV

                (I'm reading really interesting comments, btw)

              • Werner Karn
                Lasse, I believe interferometric methods are much easier to accomplish nowadays, as SDRs will run from one oszillator only without mixing and there are DDS
                Message 7 of 20 , Aug 4, 2013
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                  Lasse,

                  I believe interferometric methods are much easier to accomplish nowadays, as SDRs will run from one oszillator only without mixing and there are DDS circuits allowing for precise phase shifts, if this couldn't be done easier in the FPGA anyway. 
                  I have one of my Perseus running from a GPS controlled LO and when I input two signals from a DDS source with the same frequency, but an adjustable phase shift, allowing precise steps of less than 0,1 degrees, I get exactly the signal levels you'd expect when phasing two identical antennas. The 180 degree attenuation only depends on how equal the amplitude levels are. At less than 0.1 dB difference I get appr. - 60 dB. 
                  I was thinking of letting two of my Perseus
                  running from the same LO ( one the LO channel being phase adjustable ), however combining  the two signals in the PC is not feasible, as two USB ports and two instances running will not allow to maintain phase coherency. Combination of the two or multi channel signals must be made in the SDR FPGA before being sent as combined " same time" packages to the PC for processing. And this is where for me there is " end of story ", but I think Nico could, if he wanted. -:(
                  73,

                  Werner

                  Am Donnerstag, 1. August 2013 schrieb Lasse Moell :
                   

                  :)

                  I have spent my fair share of time trying to calibrate DF-antennas for VHF/UHF. Not an easy task, even when one use state-of-the-art software simulations and "only" wants to verify the results. HF has its share of problems, but everything gets soo much larger :D

                  Years and years ago we used to operate Plath and Telefunken systems, and seeing how skywaves mixes makes you realize even with a perfect antenna things are not "that" easy...

                  Still, would be fun to play around see what is feasable using SDR tehcnique and how far one can use simple antennas and still have a usable system.

                  /Lasse SM5GLC

                  On 1 aug 2013 15:37 "iv3nwv" <nicopal@...> wrote:

                   


                  --- In perseus_SDR@yahoogroups.com, "Lasse Moell" <lasse.moell@...> wrote:

                  > Those antenna systems I have seen operating at HF has been pretty large and
                  they spent a lot of time calibrating, even using a helicopter.

                  Was it an Agilent helicopter either a Rohde & Schwarz one? :-D

                  73s
                  Nico / IV3NWV

                  (I'm reading really interesting comments, btw)

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