| |
G0FTD > OTHQRM 02.05.04 23:40l 166 Lines 8236 Bytes #999 (0) @ WW
BID : BE5048G0FTD
Read: GUEST
Subj: OTH radar article.
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<ON0AR<GB7CIP<GB7SXE
Sent: 040502/1927Z @:GB7SXE.#38.GBR.EU #:46370 [Hastings] FBB7.00i $:BE5048G0FT
From: G0FTD@GB7SXE.#38.GBR.EU
To : OTHQRM@WW
I originally sent this @GBR but I think it might be appreciated by a
wider audience.
---
Over the Horizon Radar Systems
A Media Network Special Report by Jonathan Marks & Tom Sundstrom
During the latter part of the Cold War, a Russian built over the
horizon radar system blocked out quite large chunks of the
short-wave broadcast and amateur radio bands. Indeed, receiver
manufacturers and accessory manufacturers such as Datong tried with
mixed success to build filters to get rid of what was known in most
circles as the "woodpecker".
The Russians did reduce the bandwidth and once the Gorbachev era
really got a hold, the system was only tested sporadically. The
concept works as follows: several megawatts of pulsed energy is
beamed at a low angle towards the ionosphere where it is refracted
back to earth. Some of the energy might bounce off a squadron of
attacking aircraft and be reflected back through the ionosphere to
be detected by a special receiver not far away from the transmitter
site. Normal radar uses much higher frequencies and can't see over
the horizon. The woodpecker gave the Russians an ability to see
large aircraft formations at a much further range. The US Navy also
built a system at a place called Moscow (!) Maine, but because it
used a much wider range of frequencies, so call spread spectrum
techniques. The result of that operation is to increase the general
level of background noise rather than obliterate specific sections
as the Russian system did.
We don't see much in the way of loggings of either system these
days, though if you have heard that noise recently, we'd love to
know when and on what frequency. Now there is some concern that some
listeners may lose pieces of the shortwave spectrum in the eastern
part of North America and Western Europe as the result of yet
another new radar system. Given the solar cycle maximum, listeners
elsewhere in the world may also be affected at certain times of the
day.
At the end of last year, Raytheon Systems in Canada issued a press
release. It stated in part:
WATERLOO, Ontario, Canada, (Dec. 23, 1999) -- Raytheon Systems
Canada Ltd., a subsidiary of Raytheon Company (NYSE: RTNA, RTNB),
has developed and successfully demonstrated a shore-based,
long-range High-Frequency HF) Surface Wave Radar in collaboration
with the Canadian Department of National Defence.
Designated HF SWR-503, Raytheon's surface wave radar is an oceanic
surveillance system for monitoring such illegal activities as drug
trafficking, smuggling, piracy, illicit fishing and illegal
immigration.
In addition, it may be used for tracking icebergs, environmental
protection, search and rescue, resource protection, sovereignty
monitoring and remote sensing of ocean surface currents and winds.
Because of its long-range capability, Raytheon's HF SWR-503 allows a
coastal nation to monitor surface and low-level airborne targets up
to and beyond its 200-nautical-mile Exclusive Economic Zone
Raytheon's long-range HF radar is the first land-based sensor that
can provide continuous, all-weather and real-time surveillance of
EEZ waters.
The development work of this system started in 1996 but actual
testing apparently did not begin until 1999. T. W. Davies, Project
Director, at the Canadian National Defence Headquarters in Ottawa,
wrote the following to Raytheon Canada. The letter was dated July 6, 1999.
The project includes the development of a system of two radars and
an Operations Control Centre (OCC), the measurement of the radar
performance and an assessment of the utility, to the Canadian
Forces, of the information produced by the system.
The radars are located at Cape Bonavista and Cape Race with the OCC
located in St John's Newfoundland. The radars are monitored and
controlled from the Raytheon facility in Waterloo, Ontario with
support, when required, being provided through Stratos Mobile
Networks and Northern Radar in Newfoundland. The tracker and main
display is located at the Stratos facility in St. John's with a
duplicate version located at Waterloo.
The system has undergone testing and verification of parameters
during the Performance Measurement Phase. Results are summarized as
follows:
a) Area of Coverage: Ships have been tracked from the minimum design
range of 50 kin out to the maximum design range of 450 km and over
the entire 120 degree azimuth coverage area.
b) Continuous tracking: Vessels are typically tracked from first
detection until they leave the coverage area or exceed their maximum
detection range. Hibernia and other stationary offshore oil
platforms at ranges from 180 nautical miles to 200 nautical miles
are consistently tracked.
c) Accuracy: Accuracy has been measured by using targets of
opportunity equipped with GPS systems, and by comparing visual and
airborne radar reported targets from aircraft overflying the area of
interest. Positional accuracy was typically better than 0.5 nm in
range and 1 degree in azimuth Radar derived course arid speed
predictions are typically accurate to within 1 degree and 1 kt of
that reported.
d) Radar Operations: In spite of operation within the congested HF
band, there have been no reported complaints of interference caused
by the radars since continuous operations have began.
Despite this glowing report, in fact there were complaints of
interference in the 80-metre amateur band. Martin Potter, a Canadian
Ham with the callsign VE3OAT is a Monitoring coordinator for the
International Amateur Radio Union. He reports to Media Network:
A successful action has resulted in the removal of a strong and
annoying 125 Hz "buzz" interference from the 80-metre band. The
signal was found to be from an HF over-the-horizon (OTH) radar
located near the Atlantic coast of the eastern province of
Newfoundland, Canada, and used for coastal surveillance by the
Canadian government. The radar used frequencies of 3500, 3600, or
3700 kHz at any one time and had a bandwidth of about 25 kHz. Its
distinctive 125 pulse/second signal was widely heard in eastern
Canada and the northeastern United States.
nformation gathered and shared by National MS Coordinators Don
Moman, VE6JY, of Radio Amateurs of Canada,( RAC) and Tom Hogerty,
KC1J, of American Radio Relay League (USA) was instrumental in
identifying the source of the harmful interference.
Negotiations by Jim Dean, VE3IQ, of RAC, with several departments of
the Canadian government were finally successful in having the radar
moved outside of the 80-metre Amateur band on October 7. At last
report, the radar continues to operate on frequencies outside of the
80 m band. In Canada the sub-bands 3500-3750 and 3750-3950 kHz are
exclusively allocated to the Amateur Service. Our congratulations
and hearty thanks to RAC and ARRL for their successful work on this
interference problem.
It seems incredible that after the publicity of the then-USSR's
"Woodpecker" over-the-horizon (OTH) HF radar system and the
ill-fated OTH HF radar attempt by the US Navy (USN), in Maine, that
the Government of Canada, the Canadian Department of National
Defence, and Raytheon would foist more noise upon the users of the
HF spectrum. Sweeping noise pulses by the USSR and USN systems
disrupted international broadcasters, coastal marine traffic,
overseas aircraft flight communications (including transmitters in
Gander) and radio amateur services before pressure was brought to
bear to end such services.
In January Radio Netherlands' Tom Sundstrom sent a letter, including
these comments, to Raytheon with copies to the USA's FCC and various
units in the Canadian government, inquiring if there was not an
alternative to adding more noise to the HF spectrum. So far we have
not received a reply.
---------------------------------------------------------------------------
In accordance with Radio Nederlands copying policy, I have to let you all
know the above report is from....Radio Nederlands.
----
73 - Andy, G0FTD @ GB7SXE
Message timed: 20:24 on 2004-May-02
Message sent using WinPack-AGW V6.80
Read previous mail | Read next mail
| |
