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Spectrum monitoring system
- this page is a stub
LOCATE ™ is a suite of integrated products for
spectrum monitoring,
direction finding, adaptive beamforming and geolocation of high frequency
signals, introduced around 2008 by Roke Manor Research
in Romsey (UK).
The system consists of various digital receivers, antennas and software.
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LOCATE is typically build around a field of
Sarsen antennas [A], arranged
in concentric circles as shown in the diagram above. Each Sarsen antenna
consists of a non-resonant vertical monopole combined with crossed loop
elements, mounted on a circular metal ground plane. In a typical setup,
there are 4 concentric circles (1, 2, 3 and 4) with 13 evenly
spaced Sarsen antennas each. Together with the reference antenna at the
center (R), this totals to 53 antennas. Each antenna provides
3 independent outputs that are connected to an array of synchronised
digital receivers.
Note that the reference antenna (R) and the inner circle of antennas (1)
are mounted onto a larger common circular groundplane (U) that also acts
as a roof for the underground receivers. Via data lines, The receivers
are connected to a remote monitoring station, where multiple workstations
can simultaneously use features like adaptive digital beam forming (ADBF)
and radio direction finding (RDF) with a resolution of 1° —
also known as Super-Resolution Direction Finding (SRDF).
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For the actual reception of the signals, two digital receivers
are available: DWR16 and the larger MCDWR16. The latter
contains up to nine DWR16 receivers in a single 2U 19" rackmount case.
Each MCDWR16 receiver provides up to 36 simultaneous independently tuned
narrowband channels, or 4 simultaneous channels for direction finding.
For larger systems, two MCDWR16 receivers can be combined.
The receivers are controlled via USB 2.0 using Windows™ software.
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The diagram below shows a typical configuration of the LOCATE system.
The signals from the antenna field are combined in the Antnna Control
Unit (ACU) and then passed to one or more MCDWR-16 receivers. For remote
access, the data from the receivers is served via TCP/IP, either to the
internet – or to a private intranet, from where the signals are delivered to
the applications (App). For more accurate direction finding, the data from
multiple installations can be combined.
For mobile direction finding, for example from a direction finding
vehicle or aboard a ship, a GPS receiver can be added to the system,
so that the data can be correlated when delivered to remote
monitoring stations. This is also known as team-based direction
finding, or LOCATE-T.
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One of the first users of LOCATE was the Dutch Ministry of Defense, who
purchased it in 2008 on behalf of the NSO (now: JSCU), for its
intercept and monitoring station in Eibergen
(Netherlands).
The system became operational in late 2009 and is still in
use today (2022).
It is part of the Dutch intercept and codebreaking operation run by
SVIC, which is now also part of the JSCU.
The image above shows the almost finished Sarsen arrays in Eibergen
in July 2009, just before the system became operational.
Image obtained from Google Streetview [2].
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© Crypto Museum. Last changed: Saturday, 13 January 2024 - 12:17 CET.
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