User's Guide

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11
Planning
Separate interior antennas based on the calculations shown in Section 3.5. You may 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 are using 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 -100dBm. Calls will drop at levels
of about -100dB 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.
CAUTION: SIGNAL OSCILLATION CAN CAUSE RADIO
INTERFERENCE WITH CELLULAR TOWERS AND RE-
SULT IN CIVIL AND/OR CRIMINAL PENALTIES.
SC-288W omni +3
OAG Gain