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--- hotspot_dmr_decode_trouble [2022/03/06 15:42] – alexswl
+++ hotspot_dmr_decode_trouble [2022/03/06 16:36] (current) – alexswl
@@ Line 3: / Line 3: @@
 For simplicities sake, to get a relatively frequent stream of data, I have opted to enable DMR2YSF mode on my hotspot which will let me listen to an active YSF reflector, AmericaLink, over DMR.
-When in normal YSF mode, the data the hotspot is transmitting can be decoded retty cleanly and consistently using SDRangel's DSD Demodulator.
+When in normal YSF mode, the data the hotspot is transmitting can be decoded pretty cleanly and consistently using SDRangel's DSD Demodulator.
 When in DMR2YSF mode, I am having trouble getting clean decodes. Here are the pieces of software I have tried:
@@ Line 33: / Line 33: @@
 To my knowledge there is no consistent carrier frequency in DMR, which leads me to wonder if the hotspot's modem is at fault (sending out weird data over RF in spikes) or the waterfall is incorrect (which seems unlikely as nothing around the spike is messed up).
+====== Test Tone ======
+PiStar comes with a command called pistar-mmdvmcal which allows you to tweak settings of the modem manually to calibrate it, and it then spits out the values for you to type into the pistar dashboard to save your calibration.
+Built into this test tool is a DMR test mode called DMR Simplex 1031 Hz Test Pattern (CC1 ID1 TG9) which as you can guess sends out a DMR signal in which the voice audio contains a 1031 Hz audible tone.
+DSD+ again successfully decodes this single tone transmission for 10 to 30 seconds producing a clean sounding beep, then loses lock:
+{{:test_tone_failure.png?nolink|}}
+DSD demod is able to see the signal and recognises it as DMR, however it keeps losing lock (without consistentcy) and never produces a beep tone or any audio at all (audio is working, because selecting random noise causes no-squelch decode weirdness and random digital noise glitching which is normal):
+{{:test_tone_complete_decode_failure.png?nolink|}}
+{{:demod_lock.jpg?nolink|}}
 ====== Any ideas? ======
-I am quite stumped by this one. My only guess here is that DMR2YSF is causing on the fly delays which result in the modem being starved of data producing no proper RF for a moment and a failure to decode. I am unable to test normal DMR mode without YSF for the moment as I do not have a DMR capable radio to key the hotspot up.
+I am quite stumped by this one. <del>My only guess here is that DMR2YSF is causing on the fly delays which result in the modem being starved of data producing no proper RF for a moment and a failure to decode. I am unable to test normal DMR mode without YSF for the moment as I do not have a DMR capable radio to key the hotspot up.</del> This has been quite discounted by the test tone failure.
 Here is a baseband recording I took: https://we.tl/t-TKzvQMO56V
 If the baseband link expires and you want a copy, please let me know (I'm Alex on Discord). One thing to note about the baseband is DSD+ will not decode it properly, it merely outputs those errors on each packet 1 (which might be useful in the diagnosis) and SDRangel's DSD Demodulator can decode it, but with those consistent glitched as always.