Hi Glen, Very difficult question, hi! I left the commercial arena more than 12 years ago, so that have to use my old mixed surplus test equipment, certainly not competitive with today's requirements, but good enough for ham radio. The old R&S RMS-Powermeter with a tru-sensor provides a nominal accuracy of +/- 5 %. A PEP- module for this RMS meter offers similar accuracy for sinusoidal waveforms. From time to time I check the R&S meter with my (old) HP 435A and a reference circuit. The most accurate test equipment is finally my HPSDR setup. The feedback loop for the pre-distortion delivers an exact and well defined portion of the TX power to the RX input in real-time. As the ADC is driven to full scale or in minimum 15 dB below the failure is within +/- 0.3 dB for average or PEP indication (total dynamic range > 120 dB). For the exciting tests with Alfred, HB9EPU, to get a feeling how capable freeDV at small SNRs is, I always watch the displayed spectrum of the incoming signal. The FFT bin width is 2,93 Hz, that means that a signal is still visible, but no longer audible after processing in the phones. Therefore it was amazing, that freeDV seems to produce reasonable readability still with SNR =0 dB.
73, Helmut p.s. No experience with AD8362. Boonton (Wireless Telecom Group) offers a nice USB Peak Power Sensor. -----Ursprüngliche Nachricht----- Von: glen english [mailto:[email protected]] Gesendet: Mittwoch, 23. September 2015 01:26 An: [email protected] Betreff: Re: [Freetel-codec2] Tuning Aid 700B mode Helmut How well does your power meter respond to high peak to average signals, IE faithfully measuring peak and PEP ? I've been involved in this with DRM and DVB. something to watch, anyway. Maybe use a TRUPWR (R) device like the AD8362 to measure it. 73 On 23/09/2015 5:58 AM, wully wrote: > Hi all > > Helmut, dc6ny, and I have done some more tests yesterday. The band > starts opening again (wonderful: we always want to test 700B). > As stated earlier, we never had any problem with the 700B-tuning: cohpsk > locks quicker than the fdmdv, at least, this is the impression we get > from our experiences. Yesterday, I started to reduce my power (measured > by an LP-100A just before the antenna coupler) when txing in 700B. > Helmut detected the signal and I reported about my power seting: Full > drive started with 58Watts peak. Then I reduced the power to 100mW peak > (reading the quickly changing "average" of LP-100A). This was the last > setting, that I could read on the LP-100A, my relative powerseting was > at 7 out of 256. Then I reduced to 6, then to 5, to 4, to 3, to 2. After > this experiment, Helmut reported, that he could fully decode the signal > at 6, but at 5 only about 50% and lower no decoding anymore. We > estimated, that setting 6 was about 50 mWatt. ---------------------------------------------------------------------------- -- _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2 ------------------------------------------------------------------------------ Monitor Your Dynamic Infrastructure at Any Scale With Datadog! Get real-time metrics from all of your servers, apps and tools in one place. SourceForge users - Click here to start your Free Trial of Datadog now! http://pubads.g.doubleclick.net/gampad/clk?id=241902991&iu=/4140 _______________________________________________ Freetel-codec2 mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/freetel-codec2
