6
INSTALLATION
RADAR INSTALLATION & ALIGNMENT
Sensitivity Level
The radar has two sensitivity levels to allow it to
operate in most situations. The sensitivity level is
adjusted using the *SL command. If the radar is being
used to monitor only two lanes of a road then the low
sensitivity level should be chosen. This is particularly
important in an urban environment where the radar
may pick up reflections and falsely trigger the camera
that will take a picture of a non-existent or incorrect
vehicle. This is illustrated opposite where the radar
has triggered the camera because it has detected a
speeding car from its reflected signal off a building.
By setting the sensitivity level of the radar to low, this
weak reflected signal is often not detected.
High sensitivity false detections in an urban environment
To reduce further the possibility of detecting reflections the radar should not be pointed at any large vertical flat
surfaces which may reflect the radars transmissions. This is particularly true if the surface is metal.
When the radar is monitoring 3 or more lanes the high sensitivity mode of the radar maybe used. The radar,
even in low sensitivity mode, will detect most vehicles on a four lane road but some targets with small radar
signal returns may not be detected in the far lanes e.g. motorcycles.
Dual Direction Mode
The radar can be set in a mode to detect speeding vehicles travelling in both directions. This is possible because
the radar has a very good direction sensing capability that allows it to detect vehicles travelling in both directions
at the same time as long as they have different speeds. Each direction is tracked totally independently. In this
mode the vehicle travelling on the opposite side of the road may not be detected correctly because the signal is
blocked by a vehicle nearer to the radar. It is therefore recommended that the radar is setup to detect vehicles
on the far side of the road using beam entry messages and nearby targets using the beam exit messages. The
diagram below shows what can happen in an incorrect setup. In an incorrect setup the vehicle in the far lane is
detected correctly and a beam entry message is sent. This message would not be used to take a photo though
as the rear number plate cannot be seen yet. However, moments later a car travelling in a lane nearer to the
radar blocks the signal from the far vehicle and so the radar sends a beam exit message and the system would
then take a photo. However the far vehicle is not in view and therefore no conviction can be made. In the correct
setup though as soon as the radar detects the speeding far vehicle a beam entry message is sent and a photo
is taken, although the vehicle will still have to be in the beam for a significant amount of time so that it is not
rejected for being too short a vehicle. Moments later the near vehicle blocks the signal from the far target and
a premature beam exit message is
sent but a photo has already been
taken and a safe conviction may
be made. Note in this mode it is
possible for the target messages
to be interleaved between each
other when targets are travelling in
the beam at the same time but in
different directions.
