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GRAPTGNU Radio based APT, LRPT and HRPT receiver.

Back in the nineties I have had a lot of fun receiving NOAA weather satellites transmitting APT on 137 MHz. Those days I was using a winradio (that I still have) and a sound card based software decoder. Since I have now started to experiment with GNU Radio and also invested in a USRP with various daughterboards, I though it would be interesting to receive NOAA APT again — this time using a decoder done at the SDR layer, i.e. without the need for a sound card decoder.

While this project may seem trivial to a DSP guru, being a newbie in the area I find the challenge to be worthy and provide a good opportunity to learn using GNU Radio and Software Defined Radios in general.

The APT Format

APT is an acronym for Automatic Picture Transmission.

To be written. Until then see the diagrams under the WX Sat category and Wikipedia entry.

The LRPT Format

To be written.

See Wikipedia] entry and LRPT spec at EUMETSAT.

The HRPT Format

To be written.

See Wikipedia entry.

System Architecture

To be written

Experiment Phases and Milestones

There are several approaches to this experiment and one of the key questions is whether I should follow the Python or C++ path. Until I figure that out, I will take it in small steps, starting with functional prototypes in python.

Experiment 1 – RF Validation
Using the available hardware we check that we can receive APT transmission from NOAA satellites. Experiment details and results can be found here.

Software Design

To be written