Troposcatter communication system

I found this interesting article on the inter-tubes the other day and thought that I would share.  It is about a dis-used site from the Soviet era Troposcatter communication system called “SEVER.” There are many more pictures of equipment including MUX, transmitters, antennas, buildings etc, at that link.

Soviet SEVER troposcatter communications antenna
Soviet SEVER troposcatter communications antenna, courtesy ralphmirebs.livejournal.com

Like many of it’s counterparts in the US, this system has quite a bit of information available, including an interesting blog and associated web site which has lots of interesting information.  Some of it is in Russian, which mine is a little bit rusty, but here is what I could find out:

This is site 6/60, call sign Poloska and is located in Amderma, Nenets Autonomous okrug. That is way up north along the Barents Sea.  This site was in use from about 1965 until 2001, when it was closed down.  It communicated with site 5/60, which was 264 km away.

Amderma map with SEVER 6/60 location
Amderma map with SEVER 6/60 location, courtesy of trrlsever.org

Troposcatter was used widely before satellites came into availability.  It used decimeter wavelengths (approximately 2 GHz) and lots of power with very high gain antennas. Basically the earth and the troposphere were used as reflectors, creating a type of duct.  It is noted the the SEVER and the GOREEZONT (HORIZONT) systems used both space and frequency diversity as a part of their system.  Frequency diversity means that there were as many as five identical signals transmitted on different frequencies at the same time.  Space diversity means that two or more transmit and receive antennas were used, as can be seen in the picture.  This site was run by the military, but would have likely carried civilian communications as well.

SEVER troposcatter communication system
SEVER troposcatter communication system

Basically it was a way to maintain communications across vast distances when wired or microwave systems were not practical or possible. The US used such systems on the DEW line and across the Pacific Ocean between Hawaii and Okinawa.  I remember the big Troposcatter dishes up on the hill behind the Navy housing area above Agana.

US Pacific Troposcatter communications system
US Pacific Troposcatter communications system, courtesy of Wikipedia

These systems were massive and expensive to build, operate and maintain.  From the looks of the pictures, site 6/60 generated all of it’s electricity with diesel generator sets. Fiber optic cable is an improvement of several orders of magnitude over this technology.

It is always interesting to see how things used to be done and give thanks to those that went along before us.  Last night I was grumbling about the network latency when watching a youtube video.  It was terrible, but in retrospect, not really that bad.

Clove Mountain

We take care of a non-broadcast radio site on Clove Mountain, NY. This is a fairly prominent terrain feature and has something else interesting next to the tower site. This old fire tower:

Clove Mountain fire tower, Clove Mountain, NY
Clove Mountain fire tower, Clove Mountain, NY

That is an Aermotor LS-60 fire tower, constructed in 1932. For an eighty year old structure, it is a remarkably good shape. In New York State, fire towers were used for spotting up until 1990, although I believe the last season this one was used was 1988.

Clove Mountain fire tower, clove mountain, NY
Clove Mountain fire tower, clove mountain, NY

Clove mountain is about 1,400 feet above sea level and 800 to 1000 feet above the surrounding terrain. From the top, on a clear day, the view was approximately 30-45 miles depending on terrain obstacles. A forest ranger would be constantly scanning the area looking for signs of fire. If he saw something, there was a range finder that would give the range and azimuth. He would then reference a map and call the fire department responsible for that location.  The fire tower was equipped with electric and a wired telephone.

Clove Mountain view to Northwest
Clove Mountain view to Northwest

This picture was taken on a cloudy day, thus the view is somewhat restricted.

Stairs looking down
Stairs looking down

It would be nice if this were preserved and not allowed to deteriorate any further. Several of these sites have been placed on the National Register of Historic Places.

Clove Mountain Ranger cabin
Clove Mountain Ranger cabin

Below the tower is this ranger cabin. Presumably, during the busy season somebody stayed up here 24/7. There was electricity and a refrigerator, but no running water.  Off to the side is a bedroom.  Over the years, people have broken into the fire tower and this cabin and smashed things for no reason.  It would be nice to preserve all of this for future generations to see, but it is likely these pictures will have to do.

Suppression of ideas

I found this video called Empire of Noise about broadcast radio jamming. It seems to be about ten years old and is a post cold war documentary about the jamming of radio signals by the USSR, Warsaw Pact counties and China.  It is an interesting look into the extent and expense that governments will go to to suppress counter thought and ideas.

The video is quite long, and there are stretches of jamming noise that can be annoying, but perhaps that is the point.  It is worth the time if interested in history and radio broadcasting.  You know what they say about history; those that do not understand history are destined to repeat it.

A few of the highlights:

  • The former Soviet Union had the most extensive jamming network of anyone on Earth.  There were groundwave jamming centers in eighty one Soviet cities which consisted of approximately 10-15 transmitters each in the 5 KW covering the medium and shortwave frequencies.
  • Each groundwave jamming station consisted of a transmitter site and a receiver/control site.  The receiver site possessed lists of frequencies to monitor, when objectionable material was heard, the jamming transmitters were turned on.
  • There was a skywave jamming network consisting of 13 jamming stations with 10 or more 100-200 KW transmitter in each.  There were some transmitters in the 1,000 KW power range.  These were located in Krasnodar, Lvov, Nikolaev, Yerevan, Alma-Ata, Grigoriopol, Sovieck, Novosibrisk, Tashkent, Khanbarovsk, Servdlosk and Moscow (some of these names may have changed).  These operated in a similar fashion to the groundwave jammers.
  • After sign off of government stations, Soviet jammers sent a blanketing signal on the IF frequency (most likely 455 KHz) of receivers to effectively block them from receiving any station while USSR government stations were off the air.
  • Baltic states had 11 jamming stations with approximately 140 transmitters
  • Ukraine had approximately 300 Jamming transmitter.
  • Warsaw Pact countries had extensive medium frequency jamming networks.
  • It is estimated it takes about 20 times the transmitted power to jam any one signal.

The entire jamming network was hugely expensive to equip and operate, costing several tens of millions of dollars per year.

It is interesting that the US position in all of this was:

Everyone has the right to seek, receive and impart information through any media and regardless of frontiers.   Jamming of radio broadcasts is condemned as the denial of the right of persons to be fully informed concerning news, opinions and ideas.

Sounds perfectly reasonable.  The free exchange of ideas and information over the internet is something that should be guarded carefully and should not be restricted or censored.  Perhaps somebody should inform congress.

Restoration work on an RCA transmitter

I read through this article about the ongoing restoration work of an RCA SSB T-3 transmitter and found it interesting.  The RCA T-3 transmitter is a 20 KW SSB/ISB HF (2-28 MHz) unit designed for point to point telephony service.  Because SSB requires class A or AB low distortion amplifiers, this is a large unit, even for its age and power levels.

From the looks of the before pictures, this transmitter was in sorry shape.

Here is a brief video of transmitter start up:

These units were designed to be switched on and run at 100% duty cycle from most of their operating lives. That is some heavy iron there.  This particular unit was made in 1959. More here and video part 2:

Anyway, before geosynchronous satellites, HF point to point transmitters were used to make long distance phone call connections and send data and pictures back and forth over long distances. Out in Hicksville, Long Island, Press Wireless ran a data and fax system that used HF for long haul data transmission.  Much of the WWII reporting from Europe and the Pacific Theaters was carried over this system.

Text would be printed out on a mechanical teletype machine at something like 60 words per minute, which was considered fast for the time:

Tuning across the band, one can often hear Radio Teletype (RTTY or RATT) which uses a 5 bit baudot code, 170 Hz shift with 2125 HZ representing a Mark or 1 bit and 2295 Hz representing a Space or 0 bit, which is bit different from the Bell 103 modem specifications. This is what it sounds like at 75 Baud:

So slow you can almost copy that by hand.

The RCA H (SSB T-3) unit above was independent side band (ISB), which means that either side band or both could be modulated independently of the other, thus two channels of information could be transmitted.  SSB bandwidth is about 2.7 KHz, which is good for telephone grade audio or low speed data.

I sort of wish I was living in California again, I’d lend a hand.