DGPS Loggings

Today I tried out something new: DXing DGPS stations. DGPS stands for Differential GPS and is a ground-based system that operates on longwave (around 300 kHz) for augmenting the satellite-based GPS system. Standard GPS is accurate to within about 20-30 metres, but for some applications this is insufficient. For example, the pilot of a large ship navigating through a narrow channel needs to know his position much more accurately than that. Using DGPS it is possible to get a location that's accurate to less than a metre's error.

I was using software called DSC Decoder to decode the DGPS signals. The decoded signal is mostly positioning information, but each line transmitted begins with a station identifier number. I found a guide on the web, the World DGPS Database, that lists all the DGPS stations worldwide. Using this guide you can look up the stations you receive by frequency and identifier to find out where they're located.

Here are the DGPS stations I received today. I'll refer to them with IDs like DGPS-123 (meaning the station's transmitted identifier is 123):

• DGPS-118, 322 kHz, 0515-0522 UTC, good signal. Location: Youngstown, NY, USA.
• DGPS-116, 319 kHz, 0547-0548 UTC, fair signal. Detroit, MI, USA.
• DGPS-184, 291 kHz, 0551-0554 UTC, fair-poor signal, Hawk Run, PA, USA.
• DGPS-136, 297 kHz, 0600-0602 UTC, poor signal. Location: Bobo, MS, USA.

All of these are obviously new loggings, since this is the first time I've logged DGPS stations. The logging of station 136 is particularly exciting because it's from Mississipi. This demonstrates that long-range DGPS DXing is possible, and it also demonstrates that my new setup for DXing longwave is actually working.