DB7KW

Receiving satellites

Fri, 18 Jun 2021 21:02:26 +0100

There are several weather satellites which are in a polar orbit. That means they are going from pole to pole and the earth is moving below them and this way they can visit the complete surface of the earth within a few days. And the best thing is they are sending unencrypted data back to earth in form of pictures from the surface.

The NOAA satellites are the most famous ones, but there are others like MetOp and FengYun. The NOAA satellites are using the APT (Automatic Picture Transmission) in the 2m band and HRPT (High Resolution Picture Transmission) at 1,7GHz. The MetOP and FengYun satellites use only HRPT at 1.7GHz. Check out the Frequencies page for a comprehensive list of the used frequencies.

To receive the data send by the satellites you need only a RTL-SDR stick and a helix antenna. The HRPT can be a bit difficult as 1.7GHz is near the upper limit of the RTL-SDR stick, but it should work. The helix antenna is easy to build.

Link list:

https://medium.com/swlh/decoding-noaa-satellite-images-using-50-lines-of-code-3c5d1d0a08da

https://www.rtl-sdr.com/gr-hrpt-gnu-radio-hrpt-decoder-blocks-for-noaa-meteor-metop-and-fengyun-3-weather-satellites/

https://www.rtl-sdr.com/improving-hrpt-reception-free-hrpt-decoder/

https://www.rtl-sdr.com/receiving-noaa-19-hrpt-with-a-hackrf-lna4all-and-cooking-pot-antenna/

https://github.com/altillimity/HRPT-Decoder

http://jcoppens.com/ant/qfh/calc.de.php – Rechner für QFH Antennen

https://en.wikipedia.org/wiki/High-resolution_picture_transmission

https://en.wikipedia.org/wiki/Low-rate_picture_transmission

https://www.eumetsat.int/media/43321 – HRPT specification

https://github.com/Xerbo/LeanHRPT-Decode – HRPT Decoder software

https://sgcderek.github.io/posts/beginner-hrpt-guide/#11-below-17-ghz - Guide for HRPT

https://usradioguy.com/goes-satellite-imagery-reception/

https://www.satdump.org/

https://github.com/SatDump/SatDump

StratoSat TK1 https://www.nanosats.eu/sat/stratosat-tk1 435.870MHz

https://www.a-centauri.com/articoli/easy-hrpt-guide

https://usradioguy.com/hrpt-satellite-tracking-and-capture/

https://sgcderek.github.io/blog/beginner-hrpt-guide.html

POCSAG

Sat, 13 Mar 2021 21:02:26 +0100

POCSAG is the protocol used for the pager networks.

There are several commercial providers and with DAPNET exists a network for ham radio.

DAPNET https://hampager.de/

The used frequency for DAPNET in Germany is 439.9875 MHz (https://hampager.de/dokuwiki/doku.php?id=dapnetfrq).

Easiest way to use DAPNET is to host a transmitter with a MMDVM HotSpot Board (https://github.com/juribeparada/MMDVM_HS) with PI-Star (http://www.pistar.uk/) on a Raspberry Pi Zero.

If no pager hardware is available a rtl sdr can be used.

Use GQRX as the receiver and forward the POCSAG signal to multimon-ng: nc -l -u -p 7355 | sox -t raw -esigned-integer -b 16 -r 48000 - -esigned-integer -b 16 -r 22050 -t raw - | multimon-ng -t raw -a POCSAG512 -a POCSAG1200 -a POCSAG2400 -f alpha -

This a version which should work without GQRX but is not tested and frequency has to be adjusted to Germany (https://lokcon.me/2019/06/18/rtl-sdr-pocsag) rtl_fm -M fm -f 439.9875M -s 22050 -g 100 -l 310 | multimon-ng -t raw -a POCSAG512 -a POCSAG1200 -a POCSAG2400 /dev/stdin

For test purposes you can send a POCSAG message locally from the pi-star system: sudo RemoteCommand page “” (https://forum.pistar.uk/viewtopic.php?t=746)

DB7KW

Receiving satellites

POCSAG

Antennas

Frequencies

Relais

WSPR frequencies

Satelitte frequencies

Meteor-M2

ISS

NOAA-18

NOAA-15

NOAA-19

MetOp-A

MetOp-B

FengYun-3B

FengYun-3C

StratoSat TK1

Radioastronomie

Software

Openhardware

Github Repos

Link Collection