Tuesday, October 8, 2019

DRM service from Komsomolsk na Amur, Khabarovsk Krai, Russia

UPDATED 20191013 to include video of reception:

Here is a "boots on the ground" report from Brother Brendan in the Great State of Washington...

Whats on Air?

In September, Russian broadcasting authorities for Chukhotkha began DRM test transmissions from Komsomolsk na Amur on at least one frequency (12025 kHz), with two others (11615 kHz & 15735 kHz) also listed but not heard. The tests so far are a bit sporadic, but generally found on local weekdays. Programming material currently consists of music, mostly instrumental, with no ID heard or seen. DreaM shows no broadcaster header, only “------” and “Other Language” so if you see that, you’re golden! BPS is usually 17.46kbps, but I have seen tests at lower rates for brief periods. The DRM transmissions can be broken by periods of analog carrier, N0N, and then back to DRM. See the screenshot for a look.

The Concept

The Chukhotkha Region is the very Far East portion of the Russian Federation, just across the Bering Sea from the state of Alaska. The time zone is GMT +12, and you can’t get any further “east” than that. The very small population is widely dispersed across a vast area, and is ill-served by the few existing broadcast stations, most of which appear to be FM, with no MW or LW listed now. What little information has been announced about this project does report that data services via the Journaline app will also be an important feature for news and other announcements. Stay tuned, as always.

These DRM tests are being transmitted from 50.647291°  136.931613° (from Google Earth – this is the transmitter building – antenna farm surrounds to the north, east, and southeast). This location is prime for reaching Chukhotkha with just one ionospheric hop, and should serve well. The current transmissions are listed as using just 25 kilowatts, but some information indicates that higher outputs are possible. The antenna array is directional, with the beam heading 34 degrees true. For a static target, this type of setup is ideal, and should result in high circuit reliability.

What I’m Seeing Here

Currently this service is very much still in the experimental stage. I would hazard a guess that a signal strength survey might be underway, as the DRM signal versus analog alternation of a carrier would be good for receiver site statistics gathering. Having seen only 12025 kHz in service so far, it also seems that the 25m band is working well with little need for lower or higher frequencies. However, my observation period is limited to their local morning and afternoon hours at my location, and I am not able to observe their later hours when the band is closed for me. Now that the fall DX season is upon us, I am seeing higher signal strengths, on the order of 18dB+ for the SNR. This afternoon (PDT), the 2nd, I had 20-22dB SNR for an hour and a half, and while there were dropouts, reliability came out to be 95.05%. Not bad for being on the wrong side of the Pacific Ocean/»Tихий океан».

In future days, as winter deepens in the Northern Hemisphere, I would hope to see some lower frequency testing: Chukhotkha has about 22 hours of daylight in deep winter, and it’s sub-polar, so propagation will be interesting anywhere outside the intended reception zone.

Some Thoughts

I certainly hope that this becomes a regular feature of the airwaves. While not for North America, it is managing to make it this far: the short-path is 4100 miles/6620 km, no mean feat for 25kW. I think the results so far are very encouraging and look forward to regular service and the data broadcasts as well. This Russian project has some similarities to the US Coast Guard ANSIS Project that tested DRM as a maritime broadcast service for the Arctic Ocean region. The main difference is that this service has voice channel use, the Coast Guards’ did not, and was just for data. We shall certainly see what happens.

My Location

My listening location is located in the northernmost corner of the state of Washington. While ‘officially’ urban, it’s fairly quiet RFI wise, and the houses are not ultra-densely packed. I have a saltwater horizon from the southeast horizon to the western horizon, which helps quite a bit.

My current antenna is the proverbial “random-wire,” not just for the unknown length but the random building materials and minimalist hardware. Two zip-wire legs, about 50 feet long, some salvaged 60 year-old 300 Ohm TV twinlead, into a 9:1 balun. Amazingly, it works, and well. Every time I’ve tried to improve it, it hasn’t worked and I return it to the original form. Costing me only time to build, I am no longer complaining about having a simple dipole that has a noise floor of ~-120 to -130dB, albeit with some limited MW imaging and some all-too specific RFI issues.

On the receiver side, I’m using an Airspy HF+ Discovery, with SDR-Console v3.0.14 as the software. DreaM v2.11 is the current build in use here. DreaM is tied to a virtual cable, which acts as both output from the Discovery, and the input to DreaM for demodulating. Virtual cables are the only way to route audio in my opinion for digital mode use.

If anyone would like to hear the world from a Pacific Northwest viewpoint, my KiwiSDR can be found at this IP:

This receiver uses the same antenna as my own gear: I have a MiniCircuits splitter feeding both sides from the common antenna input. Coverage is from 0 to 30MHz, although the antenna favors the lower half of that range.

73s and happy DReaMing!
Brendan Wahl WA7HL

Thanks Brother Brendan for your testimony! Let's hope that this service continues and serves to benefit the development of a global HF DRM network!