User's Manual

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7. Communication System Controls
You can configure the G3™ through the serial communications
(COM) port on the rear panel to communicate with PCs, speed
signs, and in-car video systems, such as the Decatur Electronics
Responder 1000™ in-car video system . The communications cable
does not come with your order and can be purchased separately
from Decatur Electronics. See Appendix A for the more details on
the serial communications port configuration.
8. Performance Tips
Understanding potential radar interference and what to do when it
occurs can greatly improve your results.
8.1 How Radar Works
Determining a vehicle’s speed begins with the radar antenna
transmitting and directing a beam of microwave energy (radio
waves) at an approaching (or receding) target vehicle. When energy
from this beam strikes a moving vehicle, a small amount of the beam
is reflected back to the antenna.
The reflected signal frequency shifts by an amount proportional to the speed of
the target vehicle. This is known as the Doppler Effect. The radar device then
determines the target vehicle speed from the difference in frequency between
the reflected and transmitted signal.
8.2 Interference Sources and Remedies
When properly installed and operated, Doppler radar technology
is extremely accurate and reliable. However, variations in the
environment can cause situations and circumstances, which
can cause spurious (erratic and unusually low or high) speeds to
display. Signs that a speed is spurious can include the following
characteristics:
• A reading appears when no target vehicle is in the operational
range of the antenna.
• A target vehicle entering the operational range overrides the
G3 ™ User & Installation Manual