a reprint from BDXC Communications - January 2020
Thanks to Alan Gale for informing us that SDR receivers available online at sdr.hu now have the option of receiving DRM (Digital Radio Mondiale), as well as AM and LSB/USB.
This comes thanks to a software update based on Dream 2.1.1 which is being rolled out to all the KiwiSDRs. BDXC member Mike Bott who runs an SDR in Westerville, Ohio, adds that “Most of the Kiwi owners that I'm aware of allow their Kiwi to update overnight automatically. I know I let mine do this.
There are a few bugs/shortcomings in DRM at the moment, but they are being worked on SAM is on the horizon, too. Note that the nightly updates will run a tad longer than previously, but that is being addressed, too. Checking on 27 December around 1500 UTC I managed to log RFI in DRM on 3965 kHz via an SDR receiver in Carlow (Ireland), although the audio was breaking up. It seems to require a signal strength of at least S9 to produce any audio at all. Note that you can only select DRM when nobody else is using the same receiver. The AMN button now toggles between AM Narrow and AM Wide which used to have separate buttons. (DK)
DRM schedules, based on monitoring can be found at http://ab27.bplaced.net/drm.pdf Ian Kelly writes: I've tuned to a few of the UK KiwiSDRs (the directory is at https://sdr.hu/) . Some already have the DRM mode button present, though the one I often use which has a good low noise antenna set up (http://southwest.ddns.net:8073/) hasn't updated yet to include the DRM mode.
I've tried the DRM mode with some limited success on the M0AQY KiwiSDR in Somerset. Site (http://stucapon.plus.com:8073/). When you select the DRM mode, above the waterfall, you will be presented with a panel. The centre of the panel shows a timeline and will show you which broadcasters are listed as having DRM transmissions on air in real time. You can scroll down the list, until you see a station listed with a current DRM transmission, denoted by a blue bar.
Click on the bar, and you can see if you can receive it! If the waterfall shows a wide trace, there's a chance you might hear something! However, it is clear you need a strong signal to have any hope of the WebSDR having any hope of decoding any audio. The S meter needs to read at S9+10dB to be in with a chance - AM transmissions are perfectly audible at much lower levels. At the present time, I have only managed to hear any audio from one broadcaster, All India Radio on 7550 kHz. Although I got a few minutes of audio with some interruptions and stutters a few moments ago, the signal seems to have now dropped below the threshold required to resolve any audio now, except for the odd fragment of audio being looped!
If you do succeed, on the left hand side of the panel, there is some technical data, and below it, is a list of services which are being transmitted. In the case of All India Radio, there are two streams currently on air, "GOS - III" and "Vivadh Barati", both AAC streams at a rate of of 10.48 kbps - hardly hifi! The audio sounded comparable to a typical shortwave AM station at that data rate - not the crisp "FM quality" I have heard on recordings of DRM stations before.There's also a panel that appears on the bottom right of the screen, which lets you tab through the DAB frequencies, continent by continent (presumably based on the target area).
One thing to note when you are using the DRM mode, it locks the KiwiSDR to you exclusively, due to the resources required to use the DRM mode! Whereas, typically up to 4 or 8 users can simultaneously use a KiwiSDR when using other modes!
So, etiquette would dictate that you use DRM mode sparingly and don't forget to tune out when you have finished, rather than leaving it running in a browser tab, needlessly locking other users out!
(Ian Kelly/27 December 2019)
BDXC/Jan 2020)