Info about I/Q data vía virtual audio cable (CWSkimmer)

[aportela]

Hello,

I have a question about the general operation of how I/Q data is dumped for third-party software as specified in this section of the documentation:

https://www.sdr-radio.com/cw-skimmer#Co ... figuration

I would need if someone uses this option please clarify a few questions I have:

From what I understand from the documentation, communication with cwskimmer is done through 2 channels, first we need an audio device ("virtual", with Voicemeter or similar and a virtual cable as well) and then a serial configuration.

On the one hand, the I/Q data goes through the virtual audio device and on the other hand, somehow the CWSkimmer software controls or exchanges "extra" information and data through the serial port with the SDR console (perhaps a control similar to the Kenwood TS-2000 protocol, although I have not found any information about this), does anyone have any information that can guide me on a basic basis of the structure of the operation of this last exchange of information between the SDR console and CWSkimmer through the serial port?

All this comes from the following (maybe it doesn't make any sense, I don't know), it has occurred to me that to expand the remote control that I am developing based on the TS-2000 protocol of the sdr console maybe I could show a waterfall with the I / Q information that is exported for the integration with CWSkimmer but the truth is I have no idea how this integration actually works, I mean, if I have configured to send for example 48 Khz of I / Q bandwidth, is this data always centered (24+24) on the current frequency of the SDR console? and if I modify the frequency in the SDR console (not cwskimmer) the I / Q data that is sent to the CWSkimmer is sent modified centered on the new frequency or on the contrary, is all this modification control only allowed to be done from CWSkimmer?

[Max]

if I have configured to send for example 48 Khz of I / Q bandwidth, is this data always centered (24+24) on the current frequency of the SDR console? and if I modify the frequency in the SDR console (not cwskimmer) the I / Q data that is sent to the CWSkimmer is sent modified centered on the new frequency or on the contrary, is all this modification control only allowed to be done from CWSkimmer?

I'm not sure I totally understand what you are asking. All I can say is that the centre frequency of SDR Console can be seen by the centre position of the gray translucent bar at the bottom of the waterfall display. It's this frequency that will be at the centre of the CW Skimmer waterfall i.e. the base frequency of the IQ data. That's as far as I recall anyway. Anything your do in SDRC to change that centre frequency (like if in SDRC you have "auto-centre" engaged on the waterfall for example) will change that centre position of the CWS waterfall.

As you say, however, the prime mode of any skimmer is to operate it from the Skimmer side, not the other way around. It's counterintuitive to tune a frequency on SDRC when in "Skimmer mode".

Have you already purchased CWS? If not, I would suggest you do not and instead at the very least take a good look at SDC Skimmer by Ukrainian based Yuri UT4LW. It's a far more comprehensive program. Skims CW, RTTY and PSK, is far less of a resource hog (when I ran CWS it took silly amounts of resources to run) and also there are many other modules in SDC Skimmer that may be of interest. Furthermore the decoder is superb (better than CWS) and it is donationware, so you pay what its worth to you. Yuri is fast and responsive when dealing with registration. He is also always across the Google Groups support group.

https://www.youtube.com/watch?v=_gceAUupgg4

I feel CWS is somewhat past its time. As far as I know it's had no development for years. SDC Skimmer is in a constant improvement cycle and it works very well with SDR Console.

Anyway, just my opinion of course at the end of the day. Others may differ.

If interested maybe take a look at my post from a few months back here:

https://sdr-radio.groups.io/g/main/message/73950

73

Max

[aportela]

if I have configured to send for example 48 Khz of I / Q bandwidth, is this data always centered (24+24) on the current frequency of the SDR console? and if I modify the frequency in the SDR console (not cwskimmer) the I / Q data that is sent to the CWSkimmer is sent modified centered on the new frequency or on the contrary, is all this modification control only allowed to be done from CWSkimmer?

I'm not sure I totally understand what you are asking. All I can say is that the centre frequency of SDR Console can be seen by the centre position of the gray translucent bar at the bottom of the waterfall display. It's this frequency that will be at the centre of the CW Skimmer waterfall i.e. the base frequency of the IQ data. That's as far as I recall anyway. Anything your do in SDRC to change that centre frequency (like if in SDRC you have "auto-centre" engaged on the waterfall for example) will change that centre position of the CWS waterfall.

Thanks, that information you gave me about changes made in the sdr console being updated in the cwskimmer makes me understand that maybe I could try to use only that I/Q data to generate a waterfall of a part of the spectrum centered at the current frequency (ignoring the serial channel).

From here I will continue investigating to see if I can decode and display it with a reasonable CPU cost on the microcontroller and then evaluate the integration with the current remote control.

Again, thanks, you saved me from having to install and test all the software integration just to find out how the system worked.

Regarding the rest of things, I just want to comment that I am not interested in using CWSkimmer or alternatives, my only interest is to be able to use the CWSkimmer "connection" of SDR Console for something different (in my case, to display a waterfall on a remote control I am developing)

[Max]

Regarding the rest of things, I just want to comment that I am not interested in using CWSkimmer or alternatives, my only interest is to be able to use the CWSkimmer "connection" of SDR Console for something different (in my case, to display a waterfall on a remote control I am developing)

Ah yes, I see now. I am not the most technically competent person to give this information but it is what I have gleaned from both observing the behaviour of SDRC and also discussions on here with Simon.

Basically the gray "span" window/slider at the bottom of the waterfall shows the centre frequency of the hardware SDR at all times and hence (as far as I understand it) the base frequency of the IQ output.

Therefore another possibly relevant feature that may interest you is the "Lock Radio". This locks the LO/centre frequency of the SDR regardless of inputs to the waterfall. i.e. it allows you to tune within the available span of the SDR without re-centreing the SDR hardware radio. I think under certain circumstances/operations it can "unlock" though (sorry, Simon has mentioned what the logic is but I forget exactly - Possibly recalling Memory/Favourite or inputting a frequency change by keypad? - you could find this out by deduction) so needs to be used by observation.

LockRadio.jpg (19.95 KiB) Viewed 20914 times

73

Max

[aportela]

Thanks, I didn't know about those "lock" options, I'll take a look at them to see if they're useful to me.