RSPdx documentation?

[FrankOParticipant]

After a wait, an RSPdx arrived on my doorstep this afternoon.

Is there any documentation for it? I’ve used RSP2’s and a duo, but would like to understand some of the new features such as HDR mode for the MF/LF spectrum, notch filters, etc.

[Andy2Participant]

Hi Frank. I don’t think there’s much detailed info yet, but this month’s RADCOM has a review of the DX and it deals with the HR mode and extra filtering. If you know any radio amateurs who are RSGB members they may let you have a read!
I’m sure the article will appear in the ‘reviews’ section on this site before too long.

[FrankOParticipant]

Thanks, Andy. I’m looking at the December 2019 RadCom, where on page 14 there is a brief product announcement of a few paragraphs but not really a review per se. Is that what you were referring to, or is there a more extensive review elsewhere?

[Andy2Participant]

Frank, it’s the Jan 2020 edition you need. I’s a two-page review. Not exactly in-depth, but it does deal with the new front-end.

[FrankOParticipant]

Ah, great. It appears that December 2019 is the most recent issue currently on the RSGB website. I’ll keep an eye out for the January edition.

[G4ABQAdmin]

Yes, The RSGB waits a couple of weeks after sending out the printed edition, before it provides the electronic version.

[FrankOParticipant]

As luck would have it, I just received the paper January RadCom today. (As a relatively new member located in North America, I don’t yet have a sense on how long it will generally take for them to arrive here.)

I see the review mentions that “The new HDR modes also get a separate menu entry in SDRuno with ten HDR bands listed.” I’ve glanced around briefly, but am not yet finding this — can anyone point out how to get to this menu? Also, the location of the selector for the 500 kHz low-pass filter would be a great help.

[SDRplayParticipant]

The 500 kHz low-pass filter is automatically selected when the LO frequency is less than 500 kHz

In SDRuno, look at the keypad in the RX control panel. The RSPdx has a new band button group called HDR – select the band you are interested in, and SDRuno will set up the hardware correctly for you.

Then increase the RF gain as much as you can without causing ADC overload (you will get a warning in the main panel if Overload occurs)

SDRplay Support

[FrankOParticipant]

Thanks very much, that’s a great help.

If I want to tune across as much of the sub-500 kHz spectrum as possible, are there any suggestions on optimal frequency for the LO? For example, would performance be similar if the LO were placed on say, 490 kHz as compared to placing it at the very bottom of the RSPdx frequency range (I’m not remembering exactly what that is offhand)? Or will results be better if the LO is placed within some tens of kHz of the current listening frequency, and then moved as the listening frequency is moved?

[SDRplayParticipant]

In SDRuno, there are specific HDR bands including “LOW” which has a centre frequency of 250 kHz and a bandwidth of 500 kHz so that it covers all of 0 – 500 kHz, but there are other specific bands to target specific parts of that spectrum including the LW band.

[FrankOParticipant]

Great, thanks, I see all that now. I’ll do some experiments with the HDR bands and see how it performs.

[G4ABQAdmin]

The key sections on the RSPdx sub 2MHz HDR mode, in the current version of the SDRuno maunual are on pages 81 and 38: https://www.sdrplay.com/docs/SDRplay_SDRuno_User_Manual.pdf

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