Using the Realtek RTL2832U DVB-T USB dongle to receive
Automatic Picture Transmission imagery
from NOAA weather satellites using APTDecoder
The dvb-t usb dongle demonstrated here has tuner E4000 (ezcap USB 2.0 DVB-T/DAB/FM dongle).
After installing the sdrsharp software select from the device list RTL-SDR/USB and click on the Configure button.
In the device configurator (RTL-SDR Controller window) tick option Tuner AGC and tune to the satellie frequency. Use either WFM or NFM and set bandwidth to ~50 kHz.
APT bandwidth is 39 kHz @ doppler 0 kHz). We found the WFM demodulator option to be less noisy.
If you use 39 kHz bandwidth then you also need to re-tune your dongle due to doppler frequency shift.
To decode/record sound: Sound must be present either at MIC or Line IN. By default, the sdr-sharp software output to speakers.
In our case, we connected a jumper cable from Headphones to Mic (or Line IN) of the soundcard. Now we, APTDecoder, can hear and decipher signals to an image.
In APTDecoder, adjust your input sound level to preferred, -8...-4 dB, when the satellite is below your horizon.
First test: Antenna @ 2 meter in the forrest and signal amplified. RG58 lenght ~15 m (50 ft).
Second test: Antenna @ 15 meter (roof mounted just under tree tops). Signal not amplified. RG58 lenght ~20 m (65 ft).
APTDecoder software is deprecated! We use GNU Radio.
Download APTDecoder and Jerry Martes antenna documents