Nuisance Alarms - TM-5-6350-262-14-10022

TM 5-6350-262-14/1

NAVELEX 0967-LP-466-9012

TO 31S9-4-36-1 Chg 2

processor/receiver

ultrasonic

passive

signal

(2) Set the RANGE control (fig. 1-1) on

synchronized to another processor.

Even if the

each transceiver by referring to table 2-2 and taking into

processors and their associated transceivers are in

consideration the number of transceivers and the

separate rooms, synchronization is necessary since

turbulent conditions associated with each transceiver.

quite often energy will "eak" from one room to another.

(3) Apply (the power from J-SIIDS control

Any one processor in a group to be synchronized

unit to the processor.

together is to be designated the master and all others

(4)

The noise level as read on the

are to be designated slaves. All slave processors shall

multimeter should indicate less than 0.15 Vac.

lie modified as directed in chapter 7. The master need

(5) Connect an oscilloscope (AN/USM-

not be modified. Each processor/transceiver system

281) between the BALANCE and REFERENCE test

shall he separately noise tested and walk tested with the

points in the processor. Set oscilloscope to DC input,

other systems turned off. Only after each system has

adjust VERTICAL, position to center trace with no input.

been separately tested shall the processors be

(6) Observe the oscilloscope. The noise

synchronized together. A synchronizing connection of

level appears as an erratic waveform fluctuating above

RG58/U coaxial cable must be made between the

and below the reference level (fig. FO-3, located at rear

master and slave and between adjacent slaves as

of manual). Fluctuations should not be more than 0.3V

shown on FO-1A. On each slave the RED reference

in either direction of the reference. The alarm threshold

transducer lead (see fig. 2-5) must he disconnected and

is at 0.8V.

insulated with electrical tape.

(7)

Disconnect the multimeter and

oscilloscope test leads.

NOTE

c. Walk Test. This test is essentially the same as

Unless the RED lead is disconnected,

the walk test as performed in the preliminary

the slave will not function properly.

adjustments, section III except that all transceivers are

connected and operating.

2-20. Nuisance Alarms

(1) As an aid during walk testing, connect

an audible sounder to the processor. Connect the

If either the processor/transceiver ultrasonic motion

positive lead to the ALARM test point and the negative

signal or the processor/receiver ultrasonic passive signal

lead to the GROUND test point (fig. 1-1).

experiences an excessive number of nuisance alarms,

(2) Walk through the entire area as covered

the cause must be investigated. A probable cause is

by each of the transceivers. Walk at a rate of

sources and entry points of ultrasonic energy in the

approximately one foot per second. While walking, the

protected area. Possible sources are motors, fans,

alarm circuit should be activated as indicated by an

bells, buzzers, and horns operating during periods when

audible sound. Shortly after coming to an absolutely

the area is secured. Possible entry points are ducts,

motionless position the alarm circuit should be

vents, cracks in walls, floors, ceilings, around windows

deactivated and then reactivated when motion is

and under doors, and similar points where the flow of air

resumed.

or the wind may inject ultrasonic energy. As an aid in

(3) Reduce the RANGE control setting of

locating ultrasonic energy sources and entry points, a

the transceiver assigned to the walk test area and repeat

transceiver with only its receive cable connected

the walk test until the range begins to drop off. The final

(transceiver terminals 3 & 4) may be used as a " niffer"

setting of the RANGE control is at the lowest acceptable

in the conduction of a noise test (para. 2-12). By

level.

systematically moving the " niffer" transceiver

(4) Perform (2) and (3) above for each

throughout all parts of the protected area, one may

transceiver in the system.

locate points of excessive ultrasonic energy. Cracks in

(5)

Remove the de power from the

floors, walls and ceilings, and around windows and door

processor.

frames should be caulked; weather stripping around

(6) Disconnect the buzzer and secure the

doors and windows should be installed or replaced, as

cover to the processor enclosure.

appropriate. Air conditioning and heating ducts and

vents should be baffled. If such measures do not

2-19. Synchronization of Processors

produce acceptable noise test results, it may be

necessary to relocate some transceivers and consider

If two or more processors are to be installed in a single

adding transceivers to the system with some or all

building, they must be synchronized together to insure

transceivers having reduced RANGE settings. After

that they are operating at the same transmit frequency.

relocation or addition of a transceiver, the noise and

Synchronization will prevent the signal generated by one

walk tests must be performed.

processor from triggering a transceiver or a

Change 2 2-11