The Empire of Noise

[Alfredo_T]

I recently watched an interesting documentary on the history of radio jamming, entitled “The Empire of Noise.” (https://www.youtube.com/v/nXV4nTfGHuI) This documentary is pretty comprehensive, covering the SW/LW/MW jamming that has been around since the late 1920s and delving into more recent types of jamming, including FM radio, over-the-air TV, satellite TV, and Internet filtering.

My favorite part about the documentary is that actual airchecks of jammers are used throughout. This brought back memories because I have heard a variety of these types of jammers on AM and the shortwave bands over the years.

[mwdxer1]

I remember back in the 60s and 70s all of the jamming on Short Wave. There were those mystery stations like the “Kiss Me Honey Honey” station that played the song over and over again.

[Alfredo_T]

In the 1980s, I recall hearing two types of jammers on shortwave:

1) One that sounded like an engine (played in the video at various points).
2) A carrier frequency modulated at 60 Hz (no samples of this one are in the video). My guess is that this would most likely have come from Cuba, where the power line frequency is 60 Hz. This jammer would pop up at various places on the HF spectrum, and one night I even heard it pop up on mediumwave at 1290 kHz (causing slight interference to a popular local station).

In more recent years, I have heard:

1) Firedrake – A nonstop loop of lively Chinese festival style music
2) The Havana Gurgler (the sound is reminiscent of bubbles)
3) Hopping carrier jammer – a carrier that makes discrete frequency jumps in a fixed pattern
4) Narrowband FM on mediumwave (at 1500 kHz)
5) White noise (at 1140 kHz)
6) Cuban stations deliberately using US clear channel frequencies (such as Cuban music playing under WSB).

[shipwreck]

Don’t forget the old Soviet jammers that sounded like a B52 engine in those old movies.

[Alfredo_T]

Like this one http://www.radiojamming.puslapiai.lt/sound/sound_noisegenerator.mp3 ?

[NOTE: The Website http://www.radiojamming.info contains audio clips and other information.]

[Dan Packard]

Yes, interesting documentary Alfredo. Also how different countries use(d) different types of jamming – Cuba, the swinging carrier; Soviets, the B-52 buzzer; and China, National Music.

A kaleidoscope of sounds while twirling the shortwave dial.

[Alfredo_T]

I am still scratching my head over how the B-52 buzzer and the Havana Gurgler signals were produced. These are much tougher to reverse-engineer than the other schemes, and nobody seems to have managed to dig up technical documentation on them (the level of technical detail presented in the video regarding some of the other schemes is pretty amazing).

I accidentally reverse engineered the 60 Hz FM jammer while sweep aligning an FM tuner. The sweep generator I used was an old tube unit that was modulated by the power line frequency. I was using a shortwave radio tuned near 10.7 MHz to verify that I had the generator tuned correctly and to estimate the span of the frequency sweep. I noted that the sound I heard coming from the shortwave radio was the same raspy buzzing sound I had heard back in the 80s, and that the strength of the signal is fairly constant over a band of frequencies (the deviation of the FM signal) but falls very rapidly outside that band of frequencies. This characteristic makes this type of jammer very effective at knocking out the desired station while causing minimal interference to other stations nearby on the dial.

[Andy Brown]

[Andy Brown]

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