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Using SDR# as spectrum analyzer

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  • dennisfarr
    Not sure if my posts are going out or not, I put something up earlier that didn t appear. Anyway, I ve been testing the SW on an RTL-SDR as an inexpensive
    Message 1 of 16 , 12 Mar

      Not sure if my posts are going out or not, I put something up earlier that didn't appear.

      Anyway, I've been testing the SW on an RTL-SDR as an inexpensive spectrum analyzer.

      I was having some problems, but I think I've worked them out.  It does give good relative

      readings which are helpful in VHF amplifier testing and band pass filter testing.

      Still not sure what the notation 'dBFS' means when looking at the peaks on the screen.

      Any input would be helpful.

      BTW, the combination of SDR# and RTL-SDR has a gain of about 37dB for the indicated

      signal.

      Dennis

    • Bob
      I think you ll find dBFS is dB full scale, meaning signal level relative to the maximum arbitrary value reflected on the screen display.
      Message 2 of 16 , 12 Mar
        I think you'll find dBFS is dB full scale, meaning signal level relative to the maximum arbitrary value reflected on the screen display.
      • Doug
        ... I just bought an SDR dongle which was supposed to come with spectrum analyzer software, but did not, just the usual useless European TV stuff. Does anyone
        Message 3 of 16 , 12 Mar



          On 03/12/2017 06:55 PM, byeos@... [SDRSharp] wrote:
           

          Not sure if my posts are going out or not, I put something up earlier that didn't appear.

          Anyway, I've been testing the SW on an RTL-SDR as an inexpensive spectrum analyzer.

          I was having some problems, but I think I've worked them out.  It does give good relative

          readings which are helpful in VHF amplifier testing and band pass filter testing.

          Still not sure what the notation 'dBFS' means when looking at the peaks on the screen.

          Any input would be helpful.

          BTW, the combination of SDR# and RTL-SDR has a gain of about 37dB for the indicated

          signal.

          Dennis



          I just bought an SDR dongle which was supposed to come with spectrum analyzer software, but did not, just the usual useless European TV stuff. Does anyone have actual
          SA software for one of these things that he would be willing to share? Even better would be if the s/w would run on Linux.

          --doug, WA2SAY
        • Shirley Márquez Dúlcey
          ... dBFS means dB referenced to the full scale reading of SDR#. Full scale is 0dB, so any received signal will have a negative value relative to that. What the
          Message 4 of 16 , 12 Mar

            Still not sure what the notation 'dBFS' means when looking at the peaks on the screen.

            Any input would be helpful.


            dBFS means dB referenced to the full scale reading of SDR#. Full scale is 0dB, so any received signal will have a negative value relative to that. What the minimum reading is will vary depending on what receiving hardware you are using; on an RTL-SDR stick it's likely to be somewhere in the neighborhood of -60dBFS, whereas if you're using a Softrock with a high quality sound card on a very quiet band it may be as low as -120dBFS; that won't even be visible with the default range setting.

             

          • Henry Abbott
            Hi Dennis, I would like môre info on how you do this. As far as I remember, one can only access the “Spectrum Analyzer” when you have selected Airspy, not
            Message 5 of 16 , 12 Mar

              Hi Dennis,

               

              I would like môre info on how you do this. As far as I remember, one can only access the “Spectrum Analyzer” when you have selected Airspy, not with RTL-SDR so how have you fooled SW or otherwise?

               

              Sincerely,

              Henry

               

              From: SDRSharp@... [mailto:SDRSharp@...]
              Sent: 13 March 2017 12:56 AM
              To: SDRSharp@...
              Subject: [SDR#] Using SDR# as spectrum analyzer

               

               

              Not sure if my posts are going out or not, I put something up earlier that didn't appear.

              Anyway, I've been testing the SW on an RTL-SDR as an inexpensive spectrum analyzer.

              I was having some problems, but I think I've worked them out.  It does give good relative

              readings which are helpful in VHF amplifier testing and band pass filter testing.

              Still not sure what the notation 'dBFS' means when looking at the peaks on the screen.

              Any input would be helpful.

              BTW, the combination of SDR# and RTL-SDR has a gain of about 37dB for the indicated

              signal.

              Dennis

            • David Lundberg
              Read this already? https://en.wikipedia.org/wiki/DBFS // David
              Message 6 of 16 , 12 Mar
                Read this already? 


                // David


              • Shirley Márquez Dúlcey
                In one sense, the 0dBFS value is not arbitrary. We re talking about digital receivers here, so the maximum possible input value that the A/D converter can
                Message 7 of 16 , 13 Mar
                  In one sense, the 0dBFS value is not arbitrary. We're talking about digital receivers here, so the maximum possible input value that the A/D converter can represent is well defined. That value is 0dBFS.

                  But in another sense it's arbitrary, because there is no defined relationship between that value and the amplitude of the signal coming from the antenna. If your hardware has a gain setting that affects the amount of amplification or attenuation before the A/D, as RTL-SDR dongles do, the relationship between 0dBFS and signal strength at the antenna is not constant but will change with the gain setting.

                  Having the input signal ever exceed 0dBFS is very bad. The converter will clip it to 0dBFS because it's unable to represent any higher value. That clipping will cause severe audible distortion for most types of signal. If your signals are regularly exceeding 0dBFS you should adjust the gain if possible, incorporate attenuation in front of the receiver, or use a less effective antenna. Some A/D converters misbehave when signals approach 0dBFS so you might have to keep them a bit lower than that; -1 or -2 dBFS peaks are usually safe.

                  I think you'll find dBFS is dB full scale, meaning signal level relative to the maximum arbitrary value reflected on the screen display.

                • Waverunner
                  Hi. Have a look to this good vidéo from Mike Molotov https://youtu.be/EDbS-zlLPxw It can be usefull Regards Eric Pruvot Le 12 mars 2017 11:55 PM,
                  Message 8 of 16 , 13 Mar
                    Hi.
                    Have a look to this good vidéo  from Mike Molotov
                    https://youtu.be/EDbS-zlLPxw
                    It can be usefull
                    Regards
                    Eric Pruvot

                    Le 12 mars 2017 11:55 PM, "byeos@... [SDRSharp]" <SDRSharp@...> a écrit :
                     

                    Not sure if my posts are going out or not, I put something up earlier that didn't appear.

                    Anyway, I've been testing the SW on an RTL-SDR as an inexpensive spectrum analyzer.

                    I was having some problems, but I think I've worked them out.  It does give good relative

                    readings which are helpful in VHF amplifier testing and band pass filter testing.

                    Still not sure what the notation 'dBFS' means when looking at the peaks on the screen.

                    Any input would be helpful.

                    BTW, the combination of SDR# and RTL-SDR has a gain of about 37dB for the indicated

                    signal.

                    Dennis


                  • dennisfarr
                    I may use the term spectrum analyzer loosely. What I do is set the frequency in SDR# for multiple spots in the area I want to observe, then record the readings
                    Message 9 of 16 , 13 Mar
                      I may use the term spectrum analyzer loosely.
                      What I do is set the frequency in SDR# for multiple spots in the area I want to observe, then record the readings in excel.
                      For example, I'm doing work centered on 1420.4 MHz, so I take readings every 50MHz starting at 1GHz up to 2GHz.

                      Hope that helps.
                      Dennis
                    • peterb670
                      Hi Dennis, A bit OT perhaps - just a thought - have you looked at ... https://eartoearoak.com/software/rtlsdr-scanner
                      Message 10 of 16 , 13 Mar
                        Hi Dennis,

                        A bit OT perhaps - just a thought  -  have you looked at ...

                        https://eartoearoak.com/software/rtlsdr-scanner

                        you can use it to scan a predefined region, and export the scan output as a CSV file.

                        Pete.

                        ---In SDRSharp@..., <dennisfarr@...> wrote :

                        I may use the term spectrum analyzer loosely.
                        What I do is set the frequency in SDR# for multiple spots in the area I want to observe, then record the readings in excel.
                        For example, I'm doing work centered on 1420.4 MHz, so I take readings every 50MHz starting at 1GHz up to 2GHz.

                        Hope that helps.
                        Dennis
                      • Ton Muller
                        So i tested out spyserver on a WAN area. tested version, 1525 (current is 1533) Upstream is 4Mbit. Pros.: fast connecting to remote spyserver HF only. Cons:
                        Message 11 of 16 , 25 Mar
                          So i tested out spyserver on a WAN area.
                          tested version, 1525 (current is 1533)


                          Upstream is 4Mbit.


                          Pros.: fast connecting to remote spyserver HF only.


                          Cons: Current frequency list is uselist if u want to select a frequency
                          Why?: due the -120.000.000 shift, u could edit the freq xml by editing
                          the shift settings, or do like me, use it as reference, hehe.


                          Cons: depending on bandwide, 4mbit up here, a max value of 62 khz is
                          doable, but it has up to 30 sec tuning delay.
                          32 khz is recomended ,the delay is 8 seconds.
                          higer bandwides gives chopy audio, and lags your connection.


                          All other plugins keeps working.


                          final test: it works great,setting it up is easy, finding the shift that
                          matches your ppm drift for the spyverter is bit tricky.


                          when compression is implimented this would be a bomb in the SDR world.


                          73..
                        • jistabout
                          Yes, it is very possible to use SDR# as a very accurate spectrum analyzer. I have used an older version along with and SDRPlay RSP1 to do this. I have also
                          Message 12 of 16 , 27 Jul
                            Yes, it is very possible to use SDR# as a very accurate spectrum analyzer. I have used an older version along with and SDRPlay RSP1 to do this. I have also used this along with a noise source to accurately assess 455khz IF filters and other types of filters. And, I have used it along with a directional coupler to read return loss and tune antennas.

                             
                          • MCH
                            For an analyzer, SpectrumSpy (Part of the SDR# package) with an Airspy R2 might be much more suitable for your application. You can get some amazing bandwidth
                            Message 13 of 16 , 28 Jul
                              For an analyzer, SpectrumSpy (Part of the SDR# package) with
                              an Airspy R2 might be much more suitable for your application.
                              You can get some amazing bandwidth out of that combo with very
                              respectable sweep times.

                              Joe M.

                              On 7/27/2017 8:01 PM, darrell@... [SDRSharp] wrote:
                              >
                              >
                              > Yes, it is very possible to use SDR# as a very accurate spectrum
                              > analyzer. I have used an older version along with and SDRPlay RSP1 to do
                              > this. I have also used this along with a noise source to accurately
                              > assess 455khz IF filters and other types of filters. And, I have used it
                              > along with a directional coupler to read return loss and tune antennas.
                            • David J Taylor
                              For an analyzer, SpectrumSpy (Part of the SDR# package) with an Airspy R2 might be much more suitable for your application. You can get some amazing bandwidth
                              Message 14 of 16 , 28 Jul
                                For an analyzer, SpectrumSpy (Part of the SDR# package) with an Airspy R2
                                might be much more suitable for your application. You can get some amazing
                                bandwidth out of that combo with very respectable sweep times.

                                Joe M.
                                ====================================

                                Yes!

                                Some examples covering 50-200 MHz spans are here:

                                http://www.satsignal.eu/wxsat/dvb-s2/T1-T2.html

                                A great combination!

                                Cheers,
                                David
                                --
                                SatSignal Software - Quality software written to your requirements
                                Web: http://www.satsignal.eu
                                Email: david-taylor@...
                                Twitter: @gm8arv
                              • Dennis
                                I recently wrote a paper regarding using SDR# as a spectrum analyzer. You can find it here: http://www.farrout.org/wp/farrout/radio-telescope ... From:
                                Message 15 of 16 , 28 Jul
                                  I recently wrote a paper regarding using SDR# as a spectrum analyzer.
                                  You can find it here:
                                  http://www.farrout.org/wp/farrout/radio-telescope




                                  -----Original Message-----
                                  From: darrell@... [SDRSharp] <SDRSharp@...>
                                  To: SDRSharp <SDRSharp@...>
                                  Sent: Fri, Jul 28, 2017 4:09 am
                                  Subject: [SDR#] Re:: Using SDR# as spectrum analyzer

                                   
                                  Yes, it is very possible to use SDR# as a very accurate spectrum analyzer. I have used an older version along with and SDRPlay RSP1 to do this. I have also used this along with a noise source to accurately assess 455khz IF filters and other types of filters. And, I have used it along with a directional coupler to read return loss and tune antennas.

                                   
                                • jistabout
                                  Very good Dennis. If anybody is interested, you can see the results of my experiments with using SDR# in this fashion here:
                                  Message 16 of 16 , 28 Jul
                                    Very good Dennis.

                                    If anybody is interested, you can see the results of my experiments with using SDR# in this fashion here:

                                    http://www.sdrplay.com/community/viewtopic.php?f=7&t=1744&p=5283&hilit=spectrum+analyzer#p5283
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