jammingwatch: 11月 2007

2007年11月29日木曜日

Jamming the Germans

BBC Heritage on behalf of Ken Lansdowne's memory of 01/01/1940 - 30/12/1940

In the latter years of World War 2 I joined the BBC as a 'Youth in Transmitters' at Brookmans Park. I was shown round the control room and, having a keen interest in electronics, I was soon familiar with the amplifiers and peak programme meters. One instrument in the control room mystified me. It was labelled 'Noise Generator', and its finish was not up to the usual BBC standard.

I asked various engineers what its function was, and was told the following: If the Germans captured a UK broadcasting station either by invasion or by a commando-type raid, they could cause chaos by transmitting false information or instructions to the population - as we did to the Germans by the Aspidistra transmitter. To prevent this, if a station was captured, other BBC stations would change frequency, sit on the captured station and jam it. The jamming noise was produced by the device labelled ‘Noise Generator’.

The device was switched on for my benefit, the 'on' switch being operated by a key which was kept in a secure place. The sound it produced was a rhythmic wailing noise which no doubt would have been most effective in jamming the subversive programme. All the medium wave transmitters were equipped with a noise generator, made no doubt in a hurry in 1940 when invasion was believed to be imminent.

I was warned that this was most secret, and that if I disclosed the fact that the BBC had a jamming network there would be dire consequences.

It was many years after the war before I mentioned it, and the people to whom I spoke flatly denied it had ever existed.

There the matter rested until just before I retired, when I was asked to look through a pile of hand-written documents prior to them being shredded, and to my astonishment I found the circuit of the Noise Generator. The circuit design was simple but clever, and the date of the plans, June 3 1940, is significant. The Low Countries had been invaded, and France was capitulating. The prospects for Britain were very bleak, and these devices were obviously designed and made in a great hurry.

The designer was C.G. Mayo, who was a very brilliant engineer who worked as I did in Research Department at Kingswood Warren. He never mentioned his wartime work, and by the time I found his design he had died. What a pity - it would have been fascinating to know the background to the installation of the network. Such a network would have to be authorised at a high level, and no doubt the minutes of such authorising will be gathering dust somewhere in the BBC archives.

I have an interest in old valve equipment, and working from the circuit using the same valves and components I have built a precise replica of the unit. When I switched it on it produced exactly the same sound I remembered from sixty years before. I have now passed this on to the BBC Heritage Collection.

This memory was submitted to the Memoryshare web service by the BBC Heritage Team on behalf of Ken Lansdowne.

This memory was added on:: 29/10/2007
Last updated:: 06/11/2007 12:36:57
Location:: Beds Herts Bucks

2007年11月27日火曜日

VOA Amharic, Oromo Shows Jammed; Ethiopia Denies Responsibility
By Peter Heinlein Addis Ababa 26 November 2007

Heinlein report - Download MP3 (538k)
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Short wave radio monitors have confirmed that VOA broadcasts to Ethiopia in the Amharic and Afan Oromo languages have been jammed for the past two weeks. VOA Correspondent in Addis Ababa Peter Heinlein reports Ethiopia's government denies responsibility for the interference.

Listeners to VOA's Amharic Service began complaining about November 12 that they could not hear the one-hour nightly broadcast. Amharic is the language of commerce and the main official language in Ethiopia.

In recent days, the reports from listeners and monitors confirmed that all five short-wave frequencies used by VOA are being jammed. Broadcasts by the other major western broadcaster in Amharic, Germany's Deutsche Welle, have also been blocked.

The BBC monitoring service says its experts have determined that the direction from which the jamming originates indicates the signals are being transmitted from within Ethiopia.

In a telephone interview with VOA, Ethiopia's Information Ministry spokesman Zemedkun Tekle says he doubts the government is involved in jamming.

"I do not think this one is true. Of course I have seen the media reporting saying that, but we do not need, the government does not need to waste its time on doing so," he said. "I myself have not come across audiences who are saying so, but the relevant body may speak on the details, but I do not think this story is true."

The two Amharic Service broadcasts are known to have a substantial audience in the Ethiopian capital, which is a hot bed of anti-government sentiment.

Monitors also report jamming of VOA's Oromo Service, which broadcasts on the same frequencies. Oromo is the language spoken by Ethiopia's largest ethnic group.

Ethiopia is known to be blocking broadcasts from its neighbor and rival Eritrea. Monitors report the jamming has intensified in recent weeks, as tensions have risen along their disputed border.

A status report issued by the umbrella organization that oversees Voice of America, the Broadcasting Board of Governors, says VOA broadcasts to Ethiopia have previously been jammed during civil unrest in 2005, but the jamming was stopped in mid-2006.

The Voice of America is a multi-media international broadcasting service funded by the U.S. government. VOA broadcasts more than 1,000 hours of news and other programming every week to an estimated worldwide audience of more than 115 million people.

2007年11月22日木曜日

Ethiopian jamming hits Voice of America, Deutsche Welle

November 20th, 2007 - 11:07 UTC by Andy

BBC Monitoring (BBCM) can confirm that two major Western broadcasters are suffering consistent jamming of their transmissions to Ethiopia. Jamming is deliberate interference aimed at preventing the target broadcast from being heard. The standard technique is to transmit an irritating noise or continuous music on the same channel as the target.

In the latest media development to hit the Horn of Africa, the scene of numerous “radio wars” over the past quarter-century, shortwave broadcasts from Washington-based Voice of America (VOA) and Germany’s Deutsche Welle (DW) are now being jammed.

In both cases, the target of the jamming is radio programmes in Amharic, the lingua franca and main official language of Ethiopia. VOA is also suffering jamming of another of its regional language services. The deliberate interference appears to have started in the first half of this month, possibly on or around 12 November.

VOA and Cologne-based DW are funded by the US and German governments to broadcast radio and TV programmes to foreign audiences. The moves against the VOA and DW follow intensification by Ethiopia of its jamming of broadcasts from neighbouring Eritrea. The jamming of Eritrean state radio, the latest episode of which began in summer 2007, was stepped up in late September and early October, BBCM observed at the time.

Details of the jammed broadcasts

The VOA’s daily one-hour (1800-1900 gmt) service in Amharic is now being jammed. According to the opposition website Ethiopian Review - www.ethiopianreview.com - the jamming of VOA began on 12 November. BBCM observations have confirmed the presence of jamming signals on at least three of the five frequencies used by the VOA. The direction whence the jamming originates (established by the use of directional aerials) is consistent with the signals being transmitted from within Ethiopia.

VOA currently uses 9320, 9860, 11675, 11905 and 13870 kHz for its Amharic service. The service is not streamed on the Internet, but audio of recent broadcasts is available at www.voanews.com/horn.

On 19 November, VOA’s service in another major Ethiopian language, Oromo, was also observed to be jammed. VOA’s Oromo service broadcasts at 1730-1800 gmt, immediately before the Amharic transmission and on the same frequencies.

DW’s daily one-hour (1400-1500 gmt) service in Amharic is also being jammed. Noise interference has been observed on two of DW’s shortwave frequencies (11645 and 15640 kHz). DW recently added a third frequency (15660 kHz). At the start of its Amharic programme on 19 November it announced that this had been done in response to the jamming. The lead item in the news bulletin that followed was that the Ethiopian government had conducted air raids on villages in the Ogaden region in the southeast of the country. DW maintains a multimedia website for its Amharic service at www2.dw-world.de/amharic.

Opposition broadcasts

Ethiopia has also jammed various private opposition radio broadcasts. The country has been targeted for many years by such operators, which hire airtime (generally an hour a day or on certain days of the week) from commercial shortwave transmission facilities, including those based in Germany and the former Soviet Union. The number and identity of such broadcasts, and their schedules, often varies, depending on the availability of funds to hire shortwave airtime. Eritrea is also targeted by private opposition shortwave stations.

(Source: BBC Monitoring research 16-19 Nov 07)

German radio broadcasts to Ethiopia “jammed” - hobbyists

2007年11月5日月曜日

orth Korea Jams Overseas Private Radio Broadcasts

Inside North Korea

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Analysis

North Korea Jams Overseas Private Radio Broadcasts

By Namgung Min

[2007-11-05 01:39 ]

Read in Korean

A study reveals that North Korea has been jamming private radio broadcasts from South Korea dedicated to listeners in North Korea.

Northeast Asian Broadcasting Institute, a private radio broadcasting institute, disclosed in the 10th issue of its monthly “Northeast Asian Broadcasting Study,” that North Korea has been jamming most of South Korean radio programs which target North Korean listeners except “Global Korean Network” of Korean Broadcasting System (KBS), South Korea’s premier public broadcaster.

The list of radio stations which broadcast programs dedicated to North Korean people comes as follows: Radio Free Asia, Voice of America, KBS’s Global Korean Network, Free North Korea, Open Radio for North Korea, Far East Broadcasting Company, North Korea Mission Radio, Shiokaze of Japan and Radio Free Chosun.

The Institute had conducted a research on the condition of the reception of radio broadcasts dedicated to North Korean listeners through shortwave radio during the week between October 1st and 7th. The study found out that almost all radio broadcasts, targeting both North Korean listeners such as VOA and RFA and South Korean listeners such as Central Chosun broadcasting station and Pyongyang Broadcast station, experienced radio signal jamming.

Global Korean Network of Korean Broadcasting System (KBS) was the only program broadcasted without interference. It is a radio program aired on media-wave, so its frequency remains relatively stable from jamming. Moreover, in these days, the program greatly curtailed its contents specifically targeting North Korean people. Therefore, the institute argued that the North Korean authorities might have considered the program as insignificant and so ignored it.

Since the North Korean authorities continue to jam overseas private radio broadcasts dedicated North Korean people, it is important to come up with some countermeasures against the interference.

Meanwhile, the number of North Korean who listens to the foreign radio broadcasts has been increasing particularly among the young people. Many defectors said that it was KBS Liberty Radio which sounded clearest. They said they have also heard of the radio programs of VOA and Far East Broadcasting Company.

A defector, Kim Sung Chul, said, “Since 2000, the number of North Korean people who try to watch foreign films and listen to south Korean radio programs has greatly increased.” He added, “People use electrical wiring or an antenna to get a signal. It is hard for the North Korean authorities to stop the people from listening to radio even if they try to jam foreign radio broadcasts.”

Ha Tae Kyung, the head of Open Radio for North Korea said, “We need to use more radio frequencies to avoid North Korea’s jamming interference. However, many private radio stations dedicated to North Korean listeners have financial difficulties. We really need support from South Korean government.”