User's Guide

SureCall | 48346 Milmont Drive, Fremont CA 94538 | 1-888-365-6283 | [e-mail]
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Chapter 3: Planning The Installation
Antenna Safety Precautions:
You can mix and match dome and directional antennas as needed to obtain proper coverage throughout the building
or area where you need to boost the signal. If you use a Yagi exterior antenna, you should normally aim it away from all
interior antennas, regardless of separation, to prevent oscillation.
3.5 Calculating Signal Strength
You can calculate the number of antennas you will need using the following parameters (in dB):
• Outside signal level (OSL): This is the signal strength at the exterior antenna location and will always be a negative
number that will usually fall between -50 and -100 dBm. Calls will drop at levels of about -100 dB and lower. A
system installed in an area where the signal is -85 or worse will require some detailed engineering to achieve an
acceptable solution.
• Outside antenna gain (OAG): This is the signal boost provided by the exterior antenna and is always a positive
number with SureCall antennas.
OAG Gain
SC-288W omni +3
CAUTION: SIGNAL OSCILLATION CAN
CAUSE RADIO INTERFERENCE WITH
RADIO TOWERS AND RESULT IN CIVIL
AND/OR CRIMINAL PENALTIES.
OK
Antenna Aiming
Chapter 3: Planning The Installation