I had noticed some louder, wide bandwidth signals , compared to CW NDB signals, in the “NDB band” and was grumbling about them covering up some possible NDB signals.
It turns out that they are DGPS (Differential GPS) stations that transmit (continuously) information about the GPS satellites, their errors and their health. Other messages are sent listing other surrounding DGPS stations, etc. Check out the DGPS guide (PDF) for more information.
I tried to decode the stations using Spectrum Lab software but cannot seem to get the terminal (decoder) program to hear the signal to decode. Everything else seems fine, the terminal is “connected” to the right point in the virtual circuit … I’m stumped.
I suspect that I have missed a step or two in the setup sequence. Note that while Spectrum Lab is quite powerful, part of that power comes from it’s complexity and ability to be configured in many ways. This means that there are many ways to set up the software … and many ways to “break” it so that it does not do what you want. I’m in the latter category right now and need to learn more!
I found that DSCdecoder (trial version) works flawlessly for DGPS signals. It also covers DSC and Navtex signals so I need to try those out as well.
There seems to be a different problem now … I do not have enough time in the evenings any more!
DGPS/Spectrum Lab
Don’t give up hope with Spectrum Lab, Brian. It does work even if it is a sprawling mess! I finally got it to decode DGPS and went on to “bag” dozens of DGPS ID’s all the way to the Mississippi using an 8-foot whip in Vancouver. SL gives you nifty DSP capabilities, has a nice waterfall, and the control panel works like Tinkertoys.
I see you tried another package and have started a DGPS list. But should you still want help with SL, I will have a look at my config when I get home and let you know what to try. I’ve loaded SL on my Vista Home Basic laptop.
MultiPSK will also decode DGPS – and lots of other neat stuff, like aircraft HFDL – but you need to register it (fee!) to get unlimited usage. It locks up after a few minutes of decoding, otherwise.