Configuring HDSDR for Panadapter use with RSP2

Having fitted an IF Tap (see other blog post) to my Icom 7100 I needed to configure some SDR software to provide the user interface. My SDR I the SDRPLAY RSP2 which is an amazing bit of kit I have been using as a receiver in it's own right, but it has two SMA inputs, so I figured I could use the 2nd one to take the IF output from the 7100.

Having tried to get SDRUno to work as a panadapter and failed (various issues too lengthy to go into) I tried HDSDR and it is perfect, so here are the settings I ended up making.

The result is a real-time spectrum display which you can just click on and it will tune the radio to that frequency. 

You have to download and configure OmniRig which is another exercise, and well worth it if you're into rig control.

So here we go.

First we have to define the SDRPlay as the input device:

Then we tell it the SDR is an IF input and which OmniRig (1 or 2) the radio is controlled by. By selecting 'Full Sync in both directions' when we tune the radio HDSDR will update to show the correct frequency, and when we tune HDSDR the radio will follow. Perfect!

We need to define the IF frequency, in my case for the Icom 7100 this is 124.487 MHz. You can enter different offsets for different modes if the IF varies for each, I guess it depends how you tap the IF.

I chose not to sync the modulation mode as I simply want to use the panadapter to view the spectrum, not decode, and so it suits me to leave HDSDR on CW regardless of the mode the rig is set to.

On some IF Taps (including the IC-7100) the spectrum display is inverted. By this I mean a signal showing as +10 KCs up from the centre on the spectrum display is actually 10 KCs down in frequency. To correct this tick the 'Swap I and Q Channel' options.

Clicking the EXTIO button (to the right of the frequency display) shows the SDRPlay configuration dialog (or other device specific dialog I guess).

The SDRPlay configuration is as follows. Note mine is set to use ANT B as this connects to the radios IF, ANT A I have connected to a receive antenna. Under the profiles tab you can save the settings so it  is possible to have a configuration for use as IF and another for Shortwave Rx and another for VHF/UHF receive etc..

The end result is pretty cool. You can see the various signals on the spectrum display, click on one, the radio re-tunes to make that the centre frequency. You can also tune by using the mouse scroll wheel and adjust the granularity of tune by selecting the digit on the frequency display. The amount of spectrum displayed can be adjusted/zoomed easily to show the whole band or just the section you are interested in.