Previous :Receiving antenna building Next :Conclusion

APT images reception¶

Now we know that our antenna is receiving correctly the APT signals, we want to decode this signal and to display the weather images. At first, we used a specific software WXtoImg which demodulate directly the APT signal and do automatically all the processing to display APT images. And then we did all the demodualtion and processing by ourself using LabView. But before, we will see how we were able to track NOAA satellites and to know when were the best passes over our city.

WXTrack¶

WXTrack is a software that was available in our laboratory. It allows to track any NOAA satellites and to get many information about the passes above a city, the duration of the pass, etc. The software interface looks like this:

We can see many information on the bottom part,about the next pass, the time and the duration, the current position, altitude and range of the satellite. We can also get the maximum elevation angle during one pass which is important for the quality of received signal. Indeed, the more the elevation angle is high, the better the quality is, as the satellite is closer to our antenna when the elevation is high.

Thanks to this software we were able to know when we can had the signals with the best quality.

WXtoImg¶

Tracking¶

We used mainly this software to decode the signal but by tunning some parameters about the minimum elevation angle we want, the minimum duration on the visibily for example, the software can also provide a list of satellite pass like this one which is very useful. It can be an alternative to WXtrack even if it is less complete.

Processing¶

The software is able to scan a signal which come from the sound card of the computer. That's why we used a radio reciever similarly to the validation step, by selecting the accurate frequency depending on the satellite above the city and we connected this receiver to the sound card thanks to an audio cable. We can see the system on this picture:

LabView¶

Previous :Receiving antenna building Next :Conclusion