Decatur Electronics G3 - Communication and Performance Basics; Configuring COM Port Settings; How Radar Works (Doppler Effect)

G3
™
User’s & Installation Manual
7/October/2020
51
Always use high quality alkaline AAA batteries to power the remote.
Install batteries as shown below. Replace battery cover before
placing remote back into service.
•IftheG3isusedincoldweather,thealkalinebatteries
may not deliver enough current to drive the IR emitter
properly. In this case, use a high-quality Lithium AAA
rated for low temperature. A recommended battery is:
Energizer L92 Ultimate Lithium
7.0 Communication System Controls
You can congure 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 conguration.
8.0 Performance Tips
Understanding potential radar interference sources and what to do
when they occurs can greatly improve your results.
8.1 How Radar Works
Determining a motor vehicle’s speed begins with the radar antenna
transmitting and directing a beam of microwave energy (radio
waves) at an approaching (or receding) target motor vehicle. When
energy from this beam strikes a moving motor vehicle, a small
amount of the beam is reected back to the antenna.
The reected signal frequency shifts by an amount proportional to
the speed of the target motor vehicle. This is known as the Doppler
Eect. The radar device then determines the target motor vehicle
speed from the dierence in frequency between the reected 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motorvehicleisinthe
operational range of the antenna.
• Atargetmotorvehicleenteringtheoperationalrangeoverrides
the interference signal, causing the display speed to change
suddenly to the motor vehicle’s speed.