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How can PowerSDR S-Meter be corrected to read S9 at -93 dBm instead of -73 dBm on VHF/UHF?

kp4md
kp4md Member ✭
edited March 2017 in FLEX Series (Legacy) Radios
The IARU Region 1 Technical Recommendation R.1 defines -93 dBm as S9 on VHF/UHF frequencies above 30 MHz and -73 dBm below 30 MHz.  
How can the PowerSDR S-meter readings be adjusted to correctly indicate S9 at -93 dBm when above 30 MHz in accordance with this specification?
http://www.listenersguide.org.uk/swl/articles/?article=lg17#.U0s3nFVdWQk

Answers

  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited March 2017
    That is not a feature of PowerSDR.  If you have a 50 MHz signal source that is calibrated to -93 dBm, you can re-calibrate the S-meter, but it will be off for the HF bands.
  • kp4md
    kp4md Member ✭
    edited March 2017
    This means that PowerSDR S-meter readings currently are in error on 50 MHz and when used with VHF or UHF transverters.  
    Until and if this discrepancy is corrected in the PowerSDR software, we must remember to add 3.3 S-units (20 dB) to the PowerSDR S-meter reading in order to give accurate S-meter reports above 30 MHz.  Thanks.
  • Tim - W4TME
    Tim - W4TME Administrator, FlexRadio Employee admin
    edited December 2016
    Yes, but just the S-meter reading, not the integrated power in the RX passband filter that is expressed in dBm.  That measurement is accurate.

    I have given several signal strength reports in dBm and that usually results in a very nice conversation on how I can accurately measure their signal strength.

  • kp4md
    kp4md Member ✭
    edited February 2016
    True.  For those of us who would like to provide equivalent reciprocal signal strength reports in S units, an alternative is to decrease the RX Gain values by 20 in the XVTR Setup form (Alt-X).  That will yield accurate S-unit readings but dBm readings that are inflated by 20 dB.
  • kp4md
    kp4md Member ✭
    edited February 2016
    Thanks to FlexRadio Systems for making the PowerSDR source code available to those of us who continue to enjoy using PowerSDR with the "Legacy" FlexRadios 1500, 3000 and 5000.  
    Darrin Kohn KE9NS offers on his web page http://www.ke9ns.com/flexpage.html downloads of new revisions to PowerSDR that correct the VHF S-meter issue and that fix and add other features.


    https://www.youtube.com/watch?v=Ognskm5nEDo
     to PowerSDR 2.7.2


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