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We, at the LPWS have often
been accused of being jammers, but this is far from the truth.
Admittedly, there is the playing of music on repeaters, but these are
usually idle until one of our members comes along with a jolly tune (see the
selection for download!).
An analogy of what occurs could be the following:-
You stand on a river bridge calmly throwing stones into the water, a few
anglers a mile or so away hear this and pack up and walk down to the area of
the river beneath the bridge and set up their rods. They then complain that
you are disturbing the fish!
The same is true for repeaters, there's no one on it until there is a break
in the music, then everyone has come along to shout and swear or just key
the mike, usually you can leave this repeater for minutes at a time and they
will amuse themselves in the mistaken idea that they are jamming out your
music. Whilst they are doing this, you can have a go on another frequency
and start the whole process off again elsewhere. When the "sensible" hams
monitoring the new repeater have joined in the jam the music, it is usually
time to go back to the first one and give it a "top-up" as they might be
getting tired. This can be kept going for ages, with LPWS input as low as 1%
of the total traffic, with a quick visit to the other frequencies to keep
the mayhem going.
This can be likened this to a circus act where the plate spinner
keeps the plates going by tweaking the bamboo rods they are on, just
as they are about to fall, a quick spin and they are back up to
speed. An expert can keep as many as 5 repeaters blocked all at the
same time with as much as
99% of the jamming coming from the so called "sensible" radio amateurs
When it comes to jamming
though, we are quite plainly second division when compared to the world
masters, the former Soviet Union.
Our friends in former
Soviet Republics have quite kindly emailed the following material, for
which we are most grateful!
This article deals with events which occurred in the Soviet Union after World War II. The
Iron Curtain had been lowered. The peoples trapped in the Soviet Union were not to get any
kind of information from abroad. The Communists were able to prevent people from moving
through the Iron Curtain. But radio waves did not succumb to their regulations and
penetrated the Curtain. This was a source of serious worry for the authorities what
would happen, now that info was coming in!? Something had to be done. And a solution was
Communists have always been frightened by radio receivers and photo cameras. If the taking
of photos was always feared and forbidden, then the situation with listening to the radio
was a bit different. In 1940-1941 it was forbidden, and radio receivers were confiscated.
Later, radios were permitted. But in 1950-1951, the Soviets began to use special radio
transmitters to jam the broadcasts which penetrated the USSR from abroad, in the languages
of the nations which were trapped in the Soviet Union.
A special network of radio transmitters was constructed all over the Soviet Union for this
very purpose. Jamming was done in the whole spectrum of broadcasting
long waves to short waves 13th meter. We know that jammers existed also in the
peoples democracies, but we dont have any information about them.
The jammers not only covered the nation which they were meant for, but their effect could
be felt even in Europe, beyond the Iron Curtain (what insolence!). Just recently, a
traveller from Germany told me how their short waves used to be full of the clutter from
Russian jamming transmitters. But now their airwaves are clean.
One means of preventing the listening of foreign broadcasts was to limit the number of
short wave bands that radio receivers could pick up. Radio receivers manufactured in the
Soviet Union lacked part of the shortwave spectrum. They could not pick up the
used for transmitting during the day. If there are 8 shortwave transmission bands
11 13 16 19 25 31 41 49 m
25 21 18 15 12 9 7 6 MHz
and the most commonly used ones are 16-49m, then Soviet radio receivers could pick up only
shortwave bands 25-49m.
The following article gives a picture of how radio broadcasts were jammed in
Estonia during the Soviet era. A similar system functioned throughout the
This story gets its start from the fact that, in 1955, I graduated from the Tallinn
Electromechanical Technical School, as a radio specialist. In those days, graduates were
assigned to a job for three years, by a special government commission (we called the
system a slave market). I was lucky to get a job in Tallinn, at the Estonian SSR Radio
Centre, which was part of the Ministry of Communications.
I was assigned, along with a schoolmate, to Radio Centre site nr. 65, on Sitsi Hill. It
was located on Kopli Street, at the Kopli-Tööstuse intersection, just before Kopli
Street starts going downhill. Before the War, during independence, this had been the Ranna
Radio Station. The antenna masts had been constructed by my teacher from the Technical
School, engineer Albert Põdrus. In the foundation of one of the masts there was even a
brass plate bearing Põdruss name.
The number 65 indicated that it was a secret broadcasting station, with the task of
jamming foreign radio broadcasts. There were four such broadcasting stations in Estonia:
nr. 602 in Tallinn, near Tõnismäe, on Luha Street, which had 3 distinctive pronged masts
(one of which survives to this day); one in Tartu on Tiigi Street; and one in Pärnu. I no
longer remember their code numbers. In addition to these, Estonian Radios existing
broadcasting stations could also be used for jamming.
Of the Sitsi broadcasting station, only the main building still exists. Although we had
been officially assigned to work there, for a whole month we werent permitted into
the control room, which was the most secret spot in that building. In the course of that
month, the KGB checked out our suitability for special assignments, as that kind of work
was called in those days. They obviously couldnt prove that we had committed any
anti-Soviet crimes, and we were finally allowed to start working. It seems rather odd that
a security check wasnt done until after we were assigned to work there.
The jamming process itself was the following. The jamming of the Voice of America, Radio
Free Europe, etc. was not just done through the aforementioned broadcasting stations. The
whole process was much more complicated. The headquarters was of course in Moscow.
This is how it functioned in Estonia: every Estonian jamming center (Tallinn, Tartu,
Pärnu) consisted of two departments a so-called radio bureau and an objekt.
The radio bureau was actually a monitoring centre, where the VOA and other broadcasts were
listened to round the clock. When necessary, they gave the objekt (broadcasting
station) instructions to start jamming.
The objekts were the aforementioned broadcasting stations (65, 602, etc.), which
contained a wide assortment of short-, medium-, and long wave transmitting equipment.
The Tallinn radio bureau was located at 12 Kreutzwaldi Street, on the III floor of the
Ministry of Communications building. On every table there was a large Russian
type shortwave receiver equipped with a sensitive panoramic oscillograph. At every
receiver sat a female Russian operator, wearing headphones. There was also one medium- and
long wave receiver, which was used only occasionally. In the radio bureau they had the
broadcasting schedules of the Estonian and Russian programs of VOA, RFE, etc. These were
listened to constantly, and when necessary, the objekts were told to turn on their
And now, a little bit about the objekts
These were nothing more than broadcasting stations which contained various transmitters.
For instance, broadcasting station nr. 65 consisted of:
shortwave transmitters 1kW 10pcs
US military 1-1 transmitter SCR 1pc
medium wave transmitter
Uragan 10kW 1pc (water cooled)
long wave transmitter Storm 3kW 1pc (air cooled)
and 2 smaller k-1 transmitters which were rarely ever used
Objekt nr. 65 was headed by a Russian woman named Gorelova, who had graduated from
the Leningrad Communications Institute.
Objekt nr. 602 consisted of 10 4kW shortwave transmitters. This was also headed by
a Russian woman.
The Tartu and Pärnu objekts consisted mostly of US military SCR type shortwave
The objekts and transmitters were numbered in sequence. The numeration of the
was as follows:
the older type, equipped with 1-1 transmitters:
nr. 65 in Tallinn, Sitsi Hill
nr. 66 probably in Tartu
nr. 67 probably in Pärnu
the rest of the
objekts of this type were located outside of Estonia.
The newer type, equipped with more powerful transmitters:
nr. 602 in Tallinn, on Luha Street. This was the only broadcasting station of its
type in Estonia.
Numeration of transmitters: every transmitter had its own number. The numbers were
assigned in sequence, within each city, irrespective of how many objekts
in that city. Therefore, transmitters nr. 1-10 were located at objekt nr. 602,
transmitters nr. 11-26 at objekt nr. 65. Nr. 1-10 were, for instance, 1-1 4kW
transmitters, nr. 11, on the other hand, a Uragan transmitter.
The radio bureaus (Tartu and Pärnu had their own radio bureaus) communicated with the
via special direct telephone lines.
The Noise Generator.
The noise with which we jammed the incoming broadcasts was produced by a special
generator. This was known as the GMD generator meshajushtshego deitsvija, in
direct translation, the interference activity generator. Each objekt had a GMD, and
each radio bureau had one as a back-up. After every minute of producing interference
noise, each generator would also transmit its call sign. For instance, objekt
call sign was the Morse code letter for Y, objekt 602s, the Morse letter for
A GMD unit actually consists of four separate generators, each one with a twin triode 6N7
G1 gives the frequency 135Hz
G2 gives the frequency 320Hz
G3 gives the frequency 3Hz
G4 gives the frequency 5Hz
All of them are multivibrators, therefore, impulse current generators.
G1 and G3 are the basic generators, while G2 and G4 are the sub-generators, which modulate
the frequency of the basic generators. G2 modulates G1s frequency by +-3Hz, and G4
modulates G3s frequency by +-5Hz. The noise produced by G1 and G3 are blended
together to create the constant static and blaring with which the radio broadcasts were
jammed, and which the radio listener finally heard. These Russian noise generators were
actually quite cleverly made. Although all LW, MW, and SW broadcasts were always amplitude
modulated (AM), amplitude modulation was not used for jamming, but rather frequency
modulation (FM). And this, on such a narrow strip as is needed in a band for 1 station,
that is, 9-10kHz. If the transmission bearing wave is viewed with an oscillograph, the
modulation cannot even be observed, as if it didnt exist.
The noise generator was regarded as the most secret device at the
Outwardly, it didnt differ in any way from a common amplifier. On photo nr. 3, a
generator (on the bottom) can be seen on a stand together with common amplifiers.
The noise generator, or jammer, was the last device to be explained to a new employee at
an objekt. Any other Estonian Radio Centre employee who came there and happened to
ask questions about the device, was told that it was just one of the many amplifiers in
the broadcasting station.
As a matter of fact, I had an experience like that when I was still going to Technical
School and was doing my internship at Laitse radio broadcasting station. For some reason,
they had a GMD there at the time. I stumbled upon it, and not knowing what it was, of
course made inquiries. The response was, that this was a modulation amplifier.
We were able to jam broadcasts in the long- and medium wave diapason, and shortwave
broadcasts on bands 13, 16, 19, 25, 31, 41, 49m. I even remember some of the frequencies.
In long wave, we worked on frequency 173kHz, and in medium wave, mostly on frequency 1195kHz
that was Munich.
Another episode illustrating the extreme secrecy surrounding the work. During work, we had
to make notes. We had to jot down the frequencies that the radio bureau gave us, so that
we could adjust the transmitters accordingly. After a 15 minute broadcast, we no longer
needed these notes. But we werent allowed to write down the frequencies on a regular
piece of paper, since those are thrown into the garbage, and could end up in the hands of
enemy spies. Can you imagine an American spy would be able to find out Voice of
Americas broadcasting frequencies!
For making notes, we were given special notebooks with numbered pages, which were bound
together with string, the ends of which were sealed together. When the notebook was
filled, it had to be given to the superior, upon which it was destroyed, or even placed in
The jamming itself was done in the following fashion. The radio bureau operator informed
us what frequencies to expect at what times. At the same time, she would be monitoring the
broadcasts. When we were jamming Voice of America, the operator would maintain contact
with us via the special telephone lines. Beside every transmitter, there was a telephone,
so that the technician and operator could be in constant contact. Together they would try
to get the jammer onto the exact frequency mode. We werent permitted to turn off the
jammer until the operator said so. Since our transmitters at Sitsi were not of especially
high quality, they would tend to wander off the frequency, and the Voice of America
broadcast would come in clearly. But since the radio bureau was constantly monitoring the
incoming broadcasts they would inform us of these shifts, so that we would have to make
adjustments to the transmitters. Sometimes, friends who were trying to listen to VOA would
phone us and ask us to turn the jammer off on some particular frequency. They would then
be able to listen, undisturbed, until the radio bureau discovered the shift. Since Voice
of America transmitted on several frequencies at the same time, it wasnt easy for
the radio bureau to monitor all the frequencies at the same time.
Besides the local jammers, there were also long distance jammers in Russia, Ukraine, and
who knows where else. These directional antennas would be aimed towards Estonia. Since
they were so far away, their jamming transmissions would reach us via atmospheric
reflections. The effectiveness of these long distance jammers was very dependant on the
weather and other factors affecting transmission.
Besides jamming, we also had the opportunity to transmit original broadcasts. Right
nearby, just one tram stop towards the center of town, by the Heina Street railroad
viaduct, was Tallinn Radios second programs broadcasting station, the
so-called railroad transmitter, so named because it was located in three
railroad carriages. We could substitute for them with our medium wave transmitter, which
was basically the same as theirs. And we actually did this when the railroad
transmitter was being repaired.
In connection with this, we once had an interesting experience. We had to stand in, with
our medium wave transmitter Uragan, for the railroad transmitter, since
it needed to be overhauled. There was no direct link between us and the radio station. The
stations program was sent to us for transmission via the radio bureau. The radio
station and the radio bureau were located in neighbouring buildings, at 12 and 14
Kreutzwaldi Street. The radio bureau sent us the program, to the Sitsi objekt,
the direct phone line. The radio program started at 6:55 in the morning. At the same time,
6:45 7:00, the Voice of Americas morning program was coming in on
and which we were supposed to jam. But this time the jamming was supposed to be done by
the railroad transmitter, which was thereafter supposed to be taken away for
repairs. I had already set our transmitter to the radio programs frequency of
710kHz, the phone line with the radio bureau had been checked and commuted to the
modulator, and the modulator had been adjusted to amplitude modulation. To check the
transmission quality, we had a radio receiver on the table, tuned to 710kHz. But the radio
bureau forgot that the transmission stations had been changed for that day. It was 6:50,
when, over the table radio receiver, I could hear a Russian woman yelling and swearing in
Russian why isnt transmitter Uragan switched on and jamming Voice of
America! The radio bureau operator phoned us over the same modulation line, over which the
radio program should have been sent. And all this was going onto the air, for all of
Estonia to hear. When the operator finally got tired and stopped her tirade, so as to
catch her breath, I was able to inform her as to who was, on that day, doing the jamming,
and who was transmitting the radio broadcast. I knew that everything she had said had gone
onto the air. For a moment, there was total silence, and then the radio show could be
heard over the phone line. No one from radio bureau bothered us for some time.
Besides jamming, various other things were also done at the Sitsi station. The Tartu radio
stations first post-War medium wave transmitter was built there, and then transported to
Tartu. It was finally located in the Tiigi Street jamming stations building. The
transmitter was built from the same Uragan type of transmitter as we had. The
constructor was Raul Pääro.
Both before and after me, many Electromechanical Technical School graduates ended up
working at the Sitsi transmission station. For instance, the Minister of Communications
Arvo Kaldma, and Kalju Kallikivi, the director of communications at Estonian Energy.
The Sitsi transmission stations territory was surrounded by a high fence. No
outsiders were allowed to enter, not even the militia (Soviet regular police). At
the gate was a guard armed with a rifle. The security team consisted of both Estonians and
Russians. Sometimes, when it got very boring, we would go into the basement with the guard
and shoot the rifle. But this was of course done only in secret.
The Sitsi station operated round the clock, was run by four two man teams, with two
technicians on duty during every 12 hour shift, during the day from 8:00 to 20:00, at
night from 20:00 to 8:00.
One snowy winter we built a huge snowwoman in the station yard, which could even be seen
from the other side of the fence, especially from the tram window. Since the
snowwomans female anatomy was very visible, we received a written reprimand from the
Estonian Radio Centre's Chief Engineer Gnipilt.
In 1958, my three compulsory years were up, and I left
objekt nr. 65, and the
Estonian Radio Centre altogether, so as to accept a better paying position at the Estonian
Maritime Fishing Harbour's navigation centre.
1/ Shortwave transmitters 1kW. There were 10 of them.
2/ The same transmitters.
3/ The transmission stations switchboard.
4/ The medium wave transmitter Uragan.
5/ Transmission station technicians sitting inside the long wave transmitter torm.
These photos were made in the years 1956 and 1957. On photo nr. 3, on the right, at the
bottom, is the GMD. The work that was done at the objekt was of course top secret.
It was strictly forbidden to talk to any acquaintance or relative about the work. Needless
to say, photographing the objekt was just as strictly forbidden. Getting caught
could have brought with it a 25 year prison sentence. Nevertheless, we took pictures,
talked about our work, and sometimes, at night, even brought in friends to show them the
jammers. No one got caught.
We saw the construction of objekt nr. 602 with our own eyes, when we were attending
the Technical School, in 1953 1955. We could clearly see the work in progress from
the classroom windows. We asked teacher Arnold Isotamm what kind of transmission towers
these were. He wouldnt say, although he obviously knew. Now, 46 years later, I
cant say exactly what year that was. But it was most likely 1954. The general
building of the jamming stations began about 1950 1951.
The prongs on the transmission towers of objekt nr. 602.
The people were very curious about the reasons for the
existence of the prongs on top of
the Tõnismäe jamming transmission towers.
There are four prongs on top of the tower. The prongs are nothing more than short wave
View from above.
Two prongs, standing opposite each other, form one dipole antenna (half wave dipole). Some
additions have been made to the only surviving jamming transmission tower.
The whole Sitsi
objekt territory was a triangular lot between Kopli and Tööstuse
Streets. Now it has been built full of residential buildings. At one time, there were
nothing but pastures there. Towards the city, the area ended with a church on Kopli
Street. From behind that, a fence stretched to Tööstuse Street. As a matter of fact, the
church was at first used as the control room for jamming transmitters. But quite soon, a
new building was constructed for that purpose. And the church was converted into a
residence for Radio Centre employees.
On the Sitsi site there were three masts. These werent actually antennas, just the
supporting structures. Two of them dated back to the independence era, to the days of the
Ranna Radio Station, in the sense that they had been constructed out of the waste
materials that had been left over from the construction of the Türi broadcasting station
antenna masts. During the building of the Türi transmitter, a section of one mast had
been damaged while being unloaded in Tallinn harbour. This section was discarded, but the
material was later used for the Sitsi site masts. Along with the jammers, a third mast was
also constructed, which was about 30 40 meters high. The two original masts were
higher. Unfortunately, I dont recall the exact height, but it must have been about 60
meters. The antennas of all the transmitters were hung up between these masts. The
shortwave aerials were symmetrically fed half wave dipoles; the medium- and long
aerials, unsymmetrical antennas , which were shorter than ¼ wave. Theoretically, the
masts were tall enough to put up a full ¼ wave antenna, but there just wasnt enough
space. Every transmitter had its own individual aerial, with the feeds coming out of
the central building, through the windows.
The objekt was under the authority of the Estonian SSR Radio Centre.
They were also in charge of the radio broadcast transmission stations
and the radio central studios. In those days, in 1955, there was no
I/ The objekt, or jamming station personnel consisted of the
Supervisor – Russian (for some reason always a woman, special higher
education in communications or radio technology, Party member (never
a full engineer).
2) Senior technician – Estonian- graduate of the Tallinn
Electromechanical Technical School - radio technician - not a Party
3) Shift personnel – the objekt operated round the clock - each
shift worked for 12 hours straight - there were 2 technicians in
each shift - since there were 4 shifts, then there was a total of 8
Of the shift
technicians, half were Estonians, half Russians. The Estonians, both the
men and the women, were mostly radio technicians with a Technical School
education. Not one of them was a Party member. Of the Russians, both the
men and the women, no one had a special technical education. They had
come to Estonia, after the War, with the Soviet army, some of them
having been soldiers. Some were Party members, but not all. None of them
could speak Estonian.
bureau - worked round the clock with shifts:-
Supervisor - Estonian - man - Technical School educated radio
technician - Party affiliation not known.
2) Shift personnel – 3 operators per shift - since there were 4
shifts, then there was a total of 12 operators, 1 Estonian man and
11 Russian women - none of them had a special technical education -
none of the Russians could speak Estonian.
The wages in
the transmitter stations and in the Radio Centre generally, were, at
that time, the following. A radio technicians monthly wage was 640
Roubles. We have to keep in mind, that during the Soviet era (and also
now, in independent Estonia) wages are quoted as the total amount from
which taxes have not been subtracted. In other words, we are talking
about gross earnings. 640 Roubles was a bit less than was needed to get
by on for a whole month. Sometimes the money would run out before the
next payday. During the last year of working at the jamming station, I
became a top level technician, with a wage of 860 Roubles a month. But
in comparison: when I went to work at the Tallinn Maritime Fishing
Harbour, things changed noticeably. There I was paid 1540 Roubles, which
was already quite adequate.
LPWS would like to thank members of the
press for their interest in this 100% genuine story and actual pictures. We
regret that the passage of time has made it impossible to contact our Russian
friends, and it looks as if this is the only remaining copy of this report and