I believe the signal from the discriminator output from a VHF radio
needs to be input to a SDR (software defined radio). This is then tuned to the relevant frequencies (161.975 or 162.025MHz). The output of this goes to AISMon via a virtual cable. The output of AISMon goes to OpenCPN/Seaclear via virtual ports
. Results are good.
(1) SDR (free) > There are many around. https://sites.google.com/site/g4zfqradio/soundcard_sdr_software
Probably the simplest and easiest on you and the CPU is SDR Sharp. Easy to test by connecting an ipod into your microphone jack or just touching the input cable with your fingers.
(2) VAC Virtual Audio Cable (free) is one possibility for a link from SDR to AISMon VSPE and ComEmulDrv3 is another. The first one works for me.
(3) AISMon (free) is the signal to NMEA
converter. Download from the AISMon Yahoo Groups website under File section on left. Latest version is AISMon_2.2.0.exe
(4) VSPE (free) can set up a virtual com pair to link AISMon to OpenCPN
. There are other options mentioned above, but this one works for me. I found I needed to sacrifice one physical com port to get one virtual.
or Seaclear (free) must be set to the virtual com port as setup in the step above.
A wav file (LA_LB_Snippet.wav
) under Files section of AISMon Yahoo Groups can be used to test the AISMon > VSPE > OpenCPN connection by running a wav file in AISMon. The end result is that you will see ships appear in the LA area.
You will test more completely by connecting an Ipod into the microphone jack and seeing the blue bars reflected in the AISMon.
In setup and testing, VSPE needs to be running prior to startup of AISMon or OpenCPN
Actual results depend on aerials terrain, ships in vicinity and tuning.
The VHF radio
can be replaced by a RTL2832/E4000 DVBt dongle at around $22
Hope this gives you a basic start, more to foster further discussion and development.