INSTALLATION AND OPERATION INSTRUCTIONS — PERSONAL ALARM SYSTEM
10
2.2.4
The transmitted signal is ultrasonic (very high frequency sound), consisting of
two different but precise signals in a preset modulation pattern. Figure 2-1 shows the
transmitter block diagram. The approximate frequency of each signal is 40 kHz. Two
frequencies are used to reduce the nuisance alarms that have plagued earlier ultra
sonic alarm systems. An ultrasonic frequency is chosen because the signal will not
penetrate walls and, therefore, provides the location of the person in trouble.
BATTERY
OSC.
POWER
AMPLIFIER
TRANSDUCER
SWITCH
ENCODER
Figure 2-1 PAS-120 Transmitter
2.2.5
Battery power for the PAT/S is provided by a 9V Lithium battery capable of
providing power for up to 100 hours of continuous transmitting time or several years
in normal operation. The PAT/C is powered by A 9V Lithium battery pack which
provides an operating life of about 1 year. Battery voltage is constantly monitored, and
a low battery indication is given when battery capacity falls below a preset limit.
However, the battery life should not be relied upon without periodic testing.
Senstar
manufactures a simple plug-in tester that allows you to quickly check the
operation of each transmitter. To ensure the transmitter is in perfect working condition,
the test should be conducted on each transmitter daily.
2.2.6
Please see the Personal Alarm Transmitter Operation Guide in the Appendix.
