Steve Bunting M0BPQ
I have a CCW SDR4+ and would like guidance on how to use it up with the messenger programme on 30m APRS PSK/AX25. I have the rx working with HDSR, but what is the best way to interface with the messenger SW? Should I run HDSDR and a VAC to port audio between the two bits of software? Is there a more elegant solution?
I am using a windows TV box that M6ORT has kindly prepared for me, so it doesn't have the latest and greatest chipset, but is small form and low power consumption. I cant tx unattended without a separate licence here in the UK, so for the time being I want to RX gate only and see how I can develop from there.
There are two ways to get receive audio into APRS Messenger from a SDR-4+ receiver.
The first is to run a VAC program (I use VB-Audio) to provide a "virtual" soundcard for the user to select in HDSDR and APRS Messenger.
The second option if the PC has a separate Mic socket is to select the USB Audio CODEC as the audio output card in HDSDR. Receive audio will now be available on the 3.5mm audio socket nearest to the USB sockets on the SDR-4+. Connect a 3.5mm audio cable between that socket and the PC Mic socket and select the Microphone sound card in APRS Messenger.
If you are using the SDR-4+ only on the HF APRS channel then I suggest that you set the default frequency of the receiver to 10.1476 MHz. By doing this it always starts on the correct frequency after a power outage and you only need 1 USB cable connected to the USB sound card on the outermost USB socket of the receiver. If you are not changing frequency from the default then you don't need to connect the USB cable to the other frequency control USB port.
To change the default frequency saved in the SDR-4+ receiver:
Select the ExtIO button to open the SoftRock Configuration tool.
Select the Si570 tab.
Enter 40.5904 MHz in the "Startup" box. This is 10.1476 MHz x 4.
You can test the changed default frequency by disconnecting the SDR-4+ USB cables and reconnecting them. The receiver should start up on 10.1476 MHz.
Set to USB, adjust the filter to 1500 to 2500 kHz to cover AX.25 and APRS over digimodes, set the AGC to fast and you are ready to go.