Decoding the whole DGPS band
For years, Chris Smolinski of Black Cat Systems offers a fine selection of Mac software, among them many pieces for hams and shortwave listeners.
He now presented an unique software dubbed Amalgamated DGPS which decodes, analyzes and visualizes all DGPS stations on long wave at once. This is done from an I/Q wav file of e.g. Perseus SDR. DGPS stand for “Differential Global Positioning System” and is a system of long wave transmitters in the range of 283,5 to 324,5 kHz transmitting FSK data in 100 and 200 Baud to correct for GPS signals. Look here for a short introduction to this topic.
[Einen deutschsprachigen Test der aktualisierten Software habe ich in der April- Ausgabe 2017 der Fachzeitschrift FUNKAMATEUR veröffentlicht.]
These transmitters are of regional coverage, like non-directional beacons, or NDB, in the same band. This makes them interesting for DXing and propagation studies as well.
All you have to do is to let the software analyze your I/Q files of a receiving sessions. Yes, it is automatically “chaining” your files. You then get a detailed list of decoded stations with some additional data. You also can visualize these data, as I did in the screenshot at the top. This is based on a 15 hours’ session resulting in 56 wav files of 675 MB each.
The software runs on both, Mac/iOS and Windows. On both systems it works fine, covering .0 and .5 kHz channels as well as both baud rates.