From fc9ed0b077fe8ee5c3280c6f3dfb9931b7d0629b Mon Sep 17 00:00:00 2001 From: Brumi-2021 <86470699+Brumi-2021@users.noreply.github.com> Date: Fri, 7 Mar 2025 23:22:17 +0100 Subject: [PATCH] Updated Audio Receivers (markdown) --- Audio-Receivers.md | 1 + 1 file changed, 1 insertion(+) diff --git a/Audio-Receivers.md b/Audio-Receivers.md index 5ade022..8039354 100644 --- a/Audio-Receivers.md +++ b/Audio-Receivers.md @@ -43,6 +43,7 @@ The Key Items on the App that can be seen or selected with the cursor and change * **NFM:** Bandwidth Settings of 16k,11k,8k5. Note there is no setting for the more common 6k5 used in European Spectrum plans. Next item is SQ: which is shown in the format of 40/99 allow the noise squelch point to be set Between 0-99. Typically, around 40-50 is a good threshold. * **Gain:** The RF Amp settings. The Spectrum view is +/-20k. * **USB+FM:** It is used to demodulate Wefax (HF Weather fax transmissions) , demodulating the signal in two steps, first demodulating the tuned RF signal in USB , extracting audio tones. And then demodulating again those FM modulated subcarrier audio tones, to extract APT low scan weather fax map signal. (that signal can be recorded into audio.wav file . Still current mayhem fw can not decoded the picture -we need external programs, but coming soon, please wait ...) +For a correct demodulation , we need to tune that published frequency applying negative offset (- 1.900Khz) , tuning and aligning the top max freq. "white" carrier (published) with top part aligned with top "yellow" mark, , as the following drawing, ![image](https://github.com/user-attachments/assets/3b76e009-d64f-495f-8976-1858502248ec) ![image](https://github.com/user-attachments/assets/58acad5c-5abe-4b2b-858f-eb8aed06a228)