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Updated NOAA (markdown)

Brumi-2021
2025-05-11 23:11:27 +02:00
parent b8e04d1247
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NOAA.md

@@ -12,7 +12,7 @@ NOAA Polar Operational Environmental Satellites (POES) have an orbital period of
The [APT signal](https://www.sigidwiki.com/wiki/Automatic_Picture_Transmission_%28APT%29#Frequencies) is a 256-level amplitude-modulated 2400 Hz subcarrier, which is then frequency modulated onto the 137 MHz-band RF carrier. The satellite is broadcasting it with an effective radiated power of approximately 5 watts (37 dBm) at 800 kms from the ground earth . These signals are frequency modulated (FM) and carry low-resolution weather imagery. To receive those signals , we may need omnidirectional QFH 137 Mhz antenna band or proper dipole + bandpass amplifier.
The [APT signal](https://www.sigidwiki.com/wiki/Automatic_Picture_Transmission_%28APT%29#Frequencies) is a 256-level amplitude-modulated 2400 Hz subcarrier, which is then frequency modulated onto the 137 MHz-band RF carrier. The satellite is broadcasting it with an effective radiated power of approximately 5 watts (37 dBm) at 800 kms from the ground earth . These signals are frequency modulated (FM) and carry low-resolution weather imagery.
The analogue APT weather map transmission was invented in the 60's
![image](https://github.com/user-attachments/assets/433e3db3-e541-42e4-bd0f-57ed64aed841)
@@ -41,7 +41,9 @@ APT signal format : 120 lines / minute , sending two pictures at the same time
# Usage
With our NOAA App, we need to tune any of the 3 x current NOAA Satellite frequencies , and check at what exact time , the satellite will be visible in his orbital pass. (there are many programms and web links to check the pass to your local place ) .
Hackrf has not enough sensitivity to receive directly those NOAA APT maps with the stock rod antenna. To receive those signals , the best would be to use an omnidirectional QFH 137 Mhz antenna band ,or a proper 137 Mhz dipole + bandpass amplifier.
You can tune , inputting directly any of the 3 x above current NOAA Satellite frequencies ,and check at what exact time , the satellite will be visible in his orbital pass. (there are many programms and web links to check the pass to your local place ) .
Here you have, some predict and tracking web links examples :
To check [NOAA 15](https://www.n2yo.com/satellite/?s=25338), real time tracking position or next 10 day prediction passes to your location (based on your IP).
@@ -50,6 +52,9 @@ To check [NOAA 18](https://www.n2yo.com/satellite/?s=28654), real time tracking
To check [NOAA 19](https://www.n2yo.com/satellite/?s=33591), real time tracking position or next 10 day prediction passes to your location (based on your IP).
You need to adjust proper LNA , RF GAIN , VGA till getting proper signal (not weak, not saturating) , and you can adjust the audio volume till recognizing the usual beep , beep sound indicating frame A, frame B every 0.25segs. Once the RF signal adjustment is done, you can press START button for starting to capture the decoded APT weather map , and press STOP when you lose the satellite signal .
Then the .bmp image file will be created inside SD CARD , \BMP folder.
Here some example of local test replay decoded maps from that Mayhem NOAA Application , that we can record in .bmp image format
![image](https://github.com/user-attachments/assets/2eedb52f-791e-4525-9510-f7217bd51ebc)