In the course of tinkering with many radio related activities, I became very interested in weather and the satellite images that are sent down from NOAA satellites. These are the same satellite images that were used by weather stations across the country for many years to show and project weather patterns. Besides the real-time information that is made available to me, I was just amazed at the prospect of being able to pick up pictures directly from satellites and get their view of the earth.
When I was finally able to figure out the image capture and processing the files, there was a process of going outside, processing the images, then uploading them somewhere. It was like an easter egg each time but it took considerable effort…especially given that there are 6-8 passes per day. I needed to figure out a better way to do it. In this project there were three different things that needed to be solved: 1) reception 2) processing, and 3) image display and management.
On the reception front, I built a specially designed antenna called a quadrifilar helix (QFH) antenna that efficiently picks up the circularly polarized satellite signals. There are a lot of different reasons for doing this, suffice it to say that it creates good signals but requires special antennas too.
To process the images, I created software that leveraged some existing tools to capture and process all of the data. The workflow is somewhat as follows:
Satellite AOS -> Scheduler starts listening -> Audio is piped to a file -> Satellite LOS -> File is processed by satellite image decoder -> Images uploaded to the web
All of this is powered off a Raspberry Pi 3 with a USB dongle that can receive the radio waves called an RTL-SDR. This is all enclosed in a small plastic toolbox and stored under my grill outside :)