Simrad ARGUS FMCW 3G, User Manual

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ARGUS FMCW radar | Argus Radar Operator Manual
ARGUS FMCW radar
This chapter contains the main characteristics of the ARGUS FMCW radar system, its operating
principles, range of use and limits.
The ARGUS system has been implemented with a new source, the FMCW radar, so as to make
the perception of obstacles in proximity to the craft during navigation. In fact, thanks to the
ARGUS FMCW radar, it is possible to see obstacles at a distance of 5 metres (useful solution for
manoeuvres in ports, gulfs, or in areas with relatively close obstacles).
ARGUS FMCW radar
General
Warning: The ARGUS FMCW radar is outside the range of IMO approval, by the way its
used in the additional PPI, it does not compromise the correct approved functionalties of
the radar.
The ARGUS FMCW radar uses FMCW (Frequency Modulated Continuous Wave) radar tech-
nology. The current normal radar generates microwave pulses with a thermionic device
called a magnetron. This technology transmits bursts of high power microwave energy
periodically, and the radar detector listens to the echoes coming back from each pulse. As
the radar rotates, these echoes are built into a 360 degree image. Firstly it is solid state – i.e.
the transmitter is a semiconductor device, not based on magnetron technology. Secondly, it
transmits a 1ms long signal of increasing frequency, rather than a short duration pulse. Thirdly,
it measures the distance to a target not by timing the returned echoes, but by measuring the
difference between the current transmitted frequency and echoed frequency. Hence FMCW –
Frequency Modulated Continuous Wave. The building up of the image over 360 degrees and
the processing of the radar data is the same as for a magnetron radar.
FMCW = Frequency Modulated Continuous Wave
The scanner transmits a ‘rising tone’ (Tx wave) with linearly increasing frequency. The wave
propagates out from the transmitter retaining the frequency it had when it was transmitted. If
it r
eflects off an object, it will return to the receiver, still at the frequency it had when originally
transmitted. Meanwhile, the transmitter continues to output an increasing frequency.
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