Cold war relic – Engineering Radio

The Voice of America; expended goodwill edition.

Radio Liberty and Radio Free Europe were The main sources of Western information behind the Iron Curtain during the Cold War. While the VOA, RFE, and RL used HF, there were also FM relays in the mix. If you wanted to know what the US Government’s position was on any topic, VOA, RFE, and RL were the information sources.

I wrote several articles about this in the past:

So what happened? Why has the current administration shuttered those services?

There are several good reasons why many government broadcasters have reduced or eliminated shortwave:

Fewer people care about the US Government’s position
Changes in geopolitics
Reduced listenership to HF Shortwave Broadcasts due to technical difficulty
Large double-sideband AM transmitters are expensive to operate and maintain and therefore are a target for reducing expenses
HF transmitter sites require a lot of land and physical infrastructure, which is also expensive to maintain
New distribution technology is easier for the end user and less expensive to operate

Many people, particularly young people, do not know the difference between an over-the-air broadcast and an internet stream. Buying a special receiver, putting up some indoor or outdoor antenna, then tuning around several different frequency bands to find something worth listening to, seems like a lot of work. These days, there are few shortwave broadcasts worth listening to, especially in the English language.

The BBC greatly reduced HF distribution of The World Service starting in 2005, favoring more internet-based distribution. Radio Canada International completely went off the air in 2012, scrapping its extensive transmitter site in Sackville NB in 2014. Radio Australia signed off in 2017. Deutsche Welle mostly left the HF band in 2011 while reducing its FM in 2016. The Voice of Russia ended HF broadcasts in 2014.

The only state-owned shortwave broadcaster that has expanded is Radio China International.

VOA Greenville B has some very old transmitters. The newest units date from the late 1980s or early 1990s. The oldest are the two original Continental 420As, dating from 1960, and are original to the building. When I visited there in 2017, two transmitters were on the air, the BBC and the AEG broadcasting at half power to Cuba and Africa respectively. The rest were shut down. The Continentals were difficult to change frequencies on because of the Doherty modulation. The GEs were long in the tooth, but at least serviceable due to the stock of spare parts from site A. I think the overseas sites in the Philippines and Sao Tome are similar.

Many have pointed out, and rightly so, the Internet censorship issue. Terrestrial radio broadcasting is often the best or only way to circumvent the suppression of information. Kim Elliot pointed this out in his Radio World article “Why we need Shortwave 2.0” All of those points are valid.

What can be done? Implementing DRM30 as a worldwide HF broadcasting standard would be a step in the right direction. DRM30 can send ancillary data, including Radiogram type news bulletins. DRM30 is much more energy efficient than DSB AM because there is no carrier, which wastes half or more of the transmitted power on a carrier that contains no information. Instead of a giant transmitter site, with curtain arrays, a more distributed transmission system with several frequencies on the air at the same time uses lower-powered transmitters, simpler antenna systems such as Rotating Log Period Arrays (RLPA), or non-directional vertical towers. This would require some changes to the FCC rules, but now is the time for that.

TV’s ATSC 1 has something called a “Transport Stream ID,” (TSID) which is a unique number assigned to each broadcaster. Wide-band SDRs are capable of scanning across many HF bands. Implementing something similar for DRM30 HF broadcasts would not be that difficult. Shortwave Listeners just program the HF TSID to lock onto the digital broadcast of their choice, if it is available. This would make HF Broadcasting available to most non-technical people looking for information. Most of this can be done with existing technology. However, DRM still (almost 2 decades later) lacks receivers. There is a development on that front as well: RF2Digital support module. The point is that there are many good ways to improve the technology, keep HF broadcasting relevant, and bypass attempts at internet censorship.

What will be done?

This does not have much application for broadcast radio, other than the technical facilities are fascinating. I did once hear the slow speed version on 500 KHz distress and calling frequency, which is below the broadcast band. DUGA-3 Over The Horizon Radar (OTH) was a Soviet early warning radar system that operated on HF (between 3-30 MHz). When I was in military communications, stationed on Guam, we were often plagued with the “woodpecker” sound, oftentimes pegging the signal strength meter on whatever frequency we were using. On any typical day, at least once or twice we would have to change frequencies due to the “RAT TATATATATATATATATATATATATAT!” coming in over the top of what we were trying to do. Anyone who listened to shortwave radio or was a ham radio operator from the mid 70’s on through 1989 will be familiar with the sound.

The NATO classification for the system was STEELYARD. I don’t know if it is a coincidence or not, but the name fits the system design. There were three systems, one located near Chornobyl, inside the evacuation zone, which was abandoned intact. The second was near in Ukraine, outside of the Chornobyl exclusion zone, and the third was on the Russian Pacific coast, near the island of Sakhalin.

Basically, it operated in the HF frequency range, 3-30 MHz with a power of about 10 million watts (some sources up to 40 MW). The propagation conditions were continuously monitored with an ionospheric chirp sounder (the civilian version looks something like this). The best frequency for the target area was then chosen and used without regard to band plans or frequency planning. In fact, often the Soviet shortwave propaganda station Radio Moscow was also interfered with. The target areas were the missile launching and testing areas used by the US and Great Britain. The object resolution was about 15 km, which is not that good, but good enough to determine the origin and flight path of a potential missile.

Distant view STEELYARD OTHR array, Chernobyl, Ukraine

The remains of the DUGA-3 array near Chornobyl represent some real engineering feats. First off, the tall towers are 146 meters (479 feet tall), the short towers are 90 meters tall (295 feet) and the system is aligned in a row 750 meters (2,460 feet long). The taller towers are for lower frequencies because they have larger transmit antenna elements, thus the shorter towers are for higher frequencies.

Side view STEELYARD OTHR, Chernobyl, Ukraine

The array itself is quite an impressive close-up. The cage like devices are the radiating elements of the antenna. The elements are feed by open wire feed line from the bottom of the tower. Behind the radiating elements, you can see a series of wires, these acted as a reflector, directing the energy transmitted out the front of the array.

Considering the wind load, these are substantial towers. I would say the wind load on the face of the tower would be almost equivalent to flat plate. The towers are strongly back-braced.

The ionospheric chirp sounder receive antenna is also located at a site known as “The Circle.” An ionospheric chirp sounder sweeps the HF spectrum from one location and is received in a second location. This gives real-time radio propagation information. The Circle is about ten miles away from the STEELYARD array.

Ionospheric chirp sounder antenna, Ukraine

The other DUGA-3 radar stations were scraped after the system was turned off in 1989, this one was abandoned intact. Over the years looters have made off with most of the transmitter and receiver apparatus, wiring and associated scrap metal. Only the towers remain and empty buildings remain.

Pictures from Lost Places, more pictures and information there.

Tag: Cold war relic

Golos Ameriki

STEELYARD Over The Horizon Radar