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Updated Audio Receivers (markdown)

Brumi-2021
2025-04-06 16:40:10 +02:00
parent 061d5d39b4
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Audio-Receivers.md

@@ -15,7 +15,7 @@ Inside audio baseband spectrum , there is a sub-carrier audio tone , modulated i
(Audio Baseband with f_subcarrier fsc (1900Hz) FSK mod +-400Hz ; Shift White pixel +400 Hz = 2.300 Hz , Shift Black pixel -400 Hz = 1.500 Hz)
Hackrf has poor sensitivity to receive directly those HF Wefax signals, (mainly broadcasted in HF band : 3 Mhz to 16 Mhz)
Normally we should better add a front up-converter with better HF pre-amplifiers, pre-selector HF filters and a reasonable good enough HF antenna.
Normally we should add to the Hackrf receiver a front up-converter with better HF filtered pre-amplifiers, and a reasonable good enough HF antenna.
WEFAX's format is a derivative of the [Automatic Picture Transmission (APT)](https://www.sigidwiki.com/wiki/Automatic_Picture_Transmission_(APT)) originally developed for transmission from the polar satellites of the USA.
WEFAX has 60, 90, 100, 120, 180 and 240 LPM (Lines per minute) speeds, and two IOC (Index of Cooperation) modes, IOC 576 and IOC 288. Most weather forecasts are sent in IOC 576 , 120 LPM . Our initial target is WEFAX-IOC576 standard. https://www.sigidwiki.com/wiki/WEFAX.
Here you can see the actual Worldwide Weather fax HF Stations with his frequencies , and exact GMT map transmission time .