(newbie question) How can I search for DRM stations in a KiwiSDR share?

mahaju

Hello

I am completely new to KiwiSDR and SDR in general
I would like to do a few experiments first before purchasing a KiwiSDR
I want to listen to a few DRM stations from one of the shared KiwiSDR sites

I already know how to use a Virtual Audio Cable to send the output audio from browser displaying the the shared KiwiSDR site to Dream decoder (https://hobbyradio.se/en/drm/kiwisdr.html)
I know how to load a shared KiwiSDR from the KiwiSDR list (https://sdr.hu/) and map (https://sdr.hu/map) sites

However I am more interested in DRM, and I would like to tune into a DRM station from one of the shared KiwiSDR's and listen to it on Dream
I have been searching for hours but I have not been able to find any DRM stations

Is there any easy way to search for DRM broadcasts, or does any one here have a link to a shared KiwiSDR that is definitely receiving DRM broadcasts?
So far, I have found out from here (http://kiwisdr.com/quickstart/#id-faq-drm) that DRM signals show up as a particular pattern on the spectrum view and the waterfall
However, I have been searching for hours, especially in KiwiSDR's from countries such as UK and India where I believe the government itself is promoting DRM adoption, but I haven't been able to find any

Is there an easy way to find DRM broadcasts, or can someone link me to one please? I want to send the DRM audio output from the browser to Dream through a virtual cable and listen to the decoded audio signal in my speaker.

jks

There is a weak one right now on 11.970 MHz in the 25m broadcast band. This from a Kiwi in The Netherlands. Probably too weak to decode unless you can find a Kiwi with better reception. I agree that finding DRM broadcasts is harder than it should be. All the online schedules seem to be outdated.

jks

Update: the Kiwi in Kuwait has an excellent, strong signal. The DRM signal itself is supposed to be coming from Kuwait according to http://www.hfcc.org/drm

mahaju

Could you share the link to the Kiwi please?

jks

The Kuwait Kiwi is too close (gets signal distortion). Try Indonesia: http://swloi33.proxy.kiwisdr.com:8073/?f=11970.00iqz8
I am decoding DRM successfully there.

benson

Once you connect to a certain Kiwi receiver in the geographical area of interest you can try search for any DRM marked labels via "Shift + @". The owner may have already marked frequently active DRM stations. See http://forum.kiwisdr.com/discussion/comment/6286#Comment_6286.

best regards, Ben

benson

Here is one from mainland China currently on the air: http://192.168.1.8:8073/?f=13825.00iqz7

benson

That won't work for you, this link does: http://swloi33.proxy.kiwisdr.com:8073/?f=13825.00iqz7

mahaju

Thanks for the all the replies
I had a look at http://swloi33.proxy.kiwisdr.com:8073/?f=13825.00iqz7
I am attaching my screenshots as well
The waterfall pattern looks like DRM pattern mentioned in KiwiSDR's website as well (http://kiwisdr.com/quickstart/#id-faq-drm)
I have diverted the browser output to Virtual cable, and I am using Virtual cable as input to Dream, and speaker as output of Dream
I cannot get any output at all



Could someone tell me what I am doing wrong please?
(I found the Kuwait SDR (there was only one) but couldn't get anything on it, and by the time I visited http://swloi33.proxy.kiwisdr.com:8073/?f=11970.00iqz8 the DRM broadcast seems to have stopped)

G8JNJ

Dream decoding is tricky, once you have found a station you have to fiddle with the audio level, exact frequency (look for the frequency error in Dream), SDR agc settings and RX bandwidth to get the best and most consistent audio with the least dropouts.

You can try my KiWi

http://southwest.ddns.net:8073//?f=3964.9

which is the French RFI broadcast on 3965KHz and is usually fairly consistent. I use the full 12KHz I/Q bandwidth.

I'm listening to this at the moment, but the signal level is varying and I'm only hearing audio for about 30% of the time, however this may improve later today as propagation changes.



You may also like to try Sodira http://dsp4swls.de/indexeng.html which occasionally works better than Dream and can provide further diagnostic info.

Regards,

Martin - G8JNJ

G8JNJ

I notice that I have a bit of interference in the middle of the DRM signal on my SDR, but one of my mates has a better signal on his KiWi

http://sdr.loginto.me:8074/?f=3964.90iqz12

Regards,

Martin - G8JNJ

jks

@mahaju: From your screenshot it looks like you are configuring Dream for SSB input and not I/Q input. See how your "input PSD" graph shows energy from 0 to 5 kHz whereas Martin's shows -5 to 0 to +5 kHz? You have to configure Dream to use "I/Q input positive (0 Hz IF)" mode. And then also use IQ mode on the Kiwi.

Because I use a Mac I'm forced to use Dream 1.11 so I can only tell you what I do to configure. Dream 2.1 (or whatever) on Windows might be different (can anyone clarify?) On Mac I start Dream from the command line. If you do "(dream) -h" it shows a complete list of options. I use "(dream) -I 1 -c 5". The "-I 1" selects my VAC as sound-in device. The "-c 5" selects the "I/Q input positive (0 Hz IF)" mode.

KA7U

I set the AGC sliders, Threshold, Slope, and Decay, all the way to the left, but I leave the AGC button selected. The settings for the Audio button are NB off, Comp off, LMS filter settings are not used, and the volume is at the default level. I find these settings tend to decode reliably at S-5+ levels if multipath and interference are not to severe.
Ron
KA7U

mahaju

Thanks for the help everyone

I used @jks's suggestion and lauched Dream from command line and start it with the option I / Q input positive (0 Hz IF) [this is dream -c 6 in Dream 2.1.1 for Windows) and it is decoding properly without having to fiddle with the volume controls on the KiwiSDR website

The link is http://southwest.ddns.net:8073//?f=3964.9 suggested by @G8JNJ

jks

An interesting graph to look at in the "chart selector" menu (scroll to the bottom) is the "History > SNR/Audio" graph. I've found you need an SNR of > 15 dB to get reliable decoding. And also selective fading that is not too severe.

In general I'm kind of surprised DRM doesn't perform better on HF than it does. It's almost like the broadcasters are sacrificing extra error correction, that's really needed on HF, for sound quality. Running it like they would on MWBC for local reception. And the result is lots of dropouts on HF. But I'm really unqualified to be talking about such things. Any experts out there?

Bjarne

Reply from a non-expert - it's many years since I tested DRM properly but I remember I could decode at around 11 dB SNR, but not stable. Selective fading does kill DRM reception. A possible remedy for that is diversity reception. I thought maybe it could be possible with two co-located Kiwis, mixing the resulting audios into Dream. But when testing on my own two, via internet, I do hear that the signals are audibly out of sync and so will likely not decode as DRM. The only other affordable hardware with diversity reception I know of is the RSPDuo with their latest software. I don't know if anyone tried to decode DRM though.

Bjarne Mjelde

KA7U

WINB @ 15119.86 KHz has been broadcasting half of a DRM signal, or the USB, not sure how to describe this mode. The lower side has been just carriers. I'm not quite able to decode it this morning. My 210' dipole was taken in a micro-burst wind storm, so I'm using only the active loop antenna and it isn't quite on the same gain level. But as you can see, by dropping off the LSB or the I part of IQ and using the Right Channel of the IQ audio input, I'm nearly able to decode an S3 signal. Actually as I'm typing, it is occasionally decoding and putting out audio. So if it would only come up a another 5dbm. LOL
Ron
KA7U