Форум радиолюбителей ДВ

PS2: Instead of the hex editor, you can simply change the "File samplerate [Hz]" entry at the top of the SpecLab file-analysis requester, e.g. from 480 to 48000.

73, Markus

Here are some explanations on how I demodulated the slow-voice transmission from R2BM.
 
The "PSK mode" transmission is effectively amplitude-limited audio ("Jimi Hendrix" style), transmitted as dual-sideband with suppressed carrier with an XOR function. To avoid the need of carrier reconstruction, I listened only to the upper sideband, ignoring the lower one.
 
For the experiment, I reused one of the wav files which are normally sent to jt9.exe for FW-5 decodes (21:20 to 21:25 UT). These are periodically recorded with 136 kHz dial frequency and 12 kHz samplerate. The samplerate of the file was forged to 1200000 samples per second, using a hex editor (804F1200 at offset 18h and 009F2400 at 0Ch). It was then read by SpecLab ("Analyze and play file with DSP"), with "play in an endless loop" enabled, allowing convenient realtime playback and adjustments.
 
In this mode, SpecLab shows a short repeating spectrogram from 0 to 600 kHz, with the desired SSB signal above 158 kHz. In the first blackbox, the signal is processed in a bandpass filter (fc = 161 kHz, bw = 6 kHz, Butterworth) and frequency shifter (shift=-158000 Hz, bw=6000 Hz), producing audible voice at the DAC output. For the recording of L6, I activated "use different samplerate for output, 12000, low quality) in audio settings.
 
For future voice transmissions, you might consider sending single-sideband mode, which would be more efficient in terms of bandwidth and power. An amplitude-limited (phase-only) version can also be transmitted using a class-D nonlinear PA.

73, Markus (DF6NM)

Last night the oscillator behaved relatively well. Although Igor's signal is not very strong here in Nuremberg, almost every sequence was detected.

73, Markus

DF6NM JN59nj  Opera Deep Search  137.45 - 137.55 kHz  23.02.2026  9:39 UT
   date      time   call   distance  frequency bandwidth  snr    correlation
----------------------------------------------------------------------------
2026-02-23 04:00:03 EW8RD   1345km 137493.506Hz   2mHz -44.8dBOp  97% 17.7dB
2026-02-23 03:27:17 EW8RD   1345km 137493.505Hz   2mHz -43.6dBOp 100% 17.9dB
2026-02-23 02:54:29 EW8RD   1345km 137493.506Hz   2mHz -44.1dBOp  92% 18.0dB
2026-02-23 01:48:56 EW8RD   1345km 137493.510Hz   2mHz -43.6dBOp 100% 17.4dB
2026-02-23 01:16:10 EW8RD   1345km 137493.509Hz   2mHz -45.0dBOp  98% 17.3dB
2026-02-23 00:43:22 EW8RD   1345km 137493.507Hz   3mHz -46.3dBOp  89% 16.3dB
2026-02-23 00:10:36 EW8RD   1345km 137493.506Hz   1mHz -45.4dBOp  81% 16.6dB
2026-02-22 23:37:50 EW8RD   1345km 137493.506Hz   2mHz -46.3dBOp 100% 17.7dB
2026-02-22 23:05:04 EW8RD   1345km 137493.505Hz   3mHz -48.0dBOp  94% 15.7dB
2026-02-22 22:32:16 EW8RD   1345km 137493.506Hz   4mHz -48.1dBOp  86% 15.8dB

Two minute WSPR transmissions from R2BM do not decode. Maybe something is wrong with the timing or samplerate?

73, Markus

This is from DL0AO:

260130 1600 0 -12 0.8 0.137580 R2BM KO85 30 0 15
260130 1645 0 -8 0.1 0.137580 R2BM KO85 30 0 15
260130 1700 0 -39 -0.8 0.137546 R2BAS KO85 7 0 15
260130 1730 0 -8 0.3 0.137580 R2BM KO85 30 0 15
260130 1745 0 -8 -0.4 0.137570 G4SDG IO92 20 0 15
260130 1800 0 -40 -0.8 0.137546 R2BAS KO85 7 0 15
260130 1815 0 -8 0.4 0.137580 R2BM KO85 30 0 15
260130 1900 0 -8 0.6 0.137580 R2BM KO85 30 0 15
260130 1915 0 -8 -0.1 0.137570 G4SDG IO92 20 0 15
260130 1915 0 -36 0.6 0.137508 UA6AQN KN96 3 0 15
260130 1915 0 -40 -0.8 0.137546 R2BAS KO85 7 0 15
260130 1930 0 -35 0.6 0.137508 UA6AQN KN96 3 0 15
260130 1930 0 -37 -0.8 0.137546 R2BAS KO85 7 0 15
260130 1945 0 -10 0.6 0.137580 R2BM KO85 30 0 15
260130 2000 0 -10 0.0 0.137570 G4SDG IO92 20 0 15
260130 2000 0 -38 -0.8 0.137546 R2BAS KO85 7 0 15
260130 2015 0 -38 -0.8 0.137546 R2BAS KO85 7 0 15
260130 2030 0 -10 1.2 0.137580 R2BM KO85 30 0 15
260130 2030 0 -38 1.4 0.137508 UA6AQN KN96 3 0 15
260130 2045 0 -37 -0.6 0.137546 R2BAS KO85 7 0 15
260130 2100 0 -38 -0.8 0.137546 R2BAS KO85 7 0 15
260130 2100 0 -39 0.6 0.137508 UA6AQN KN96 3 0 15
260130 2115 0 -11 0.4 0.137580 R2BM KO85 30 0 15
260130 2115 0 -39 0.6 0.137508 UA6AQN KN96 3 0 15
260130 2130 0 -39 -0.8 0.137546 R2BAS KO85 7 0 15
260130 2200 0 -11 0.3 0.137580 R2BM KO85 30 0 15
260130 2215 0 -13 -0.3 0.137570 G4SDG IO92 20 0 15
260130 2215 0 -39 0.3 0.137508 UA6AQN KN96 3 0 15
260130 2245 0 -10 0.6 0.137580 R2BM KO85 30 0 15

73, Markus

QRSS received at DL0AO between 20 and 21 UT.
73, Markus (DF6NM)

R2BM now calling in FST4.

73, Markus (DF6NM)

Tonight, RN3AUS appeared four times at DL0AO, in DFCW, Opera-DS, FW-15, and DFCW again.

   date      time   call   distance  frequency bandwidth  snr    correlation
2025-09-13 22:01:44 RN3AUS  1790km 137533.041Hz  42mHz -56.7dBOp  96% 15.7dB

    Timestamp      Call      MHz   SNR Drift Grid  Pwr  Reporter RGrid   km   az    Mode
2025-09-13 22:15  RN3AUS  0.137533 -39  0  KO85fn  0.05  DL0AO  JN59vk  1791  258  F-900/W-15

Well done, Alex!

73, Markus (DF6NM)