Southwest Microwave 380 Users Manual

Southwest Microwave, Inc.

Security Systems Division

TECHNICAL MANUAL

MODEL 380

OUTDOOR MICROWAVE TRANSCEIVER

SOUTHWEST MICROWAVE, INC.

9055 S. McKemy Street Tempe, Arizona 85284-2946 TEL (480) 783-0201 FAX (480) 783-0401

TABLE OF CONTENTS

INTRODUCTION

OPERATION

THEORY

SPECIFICATIONS

SITE PREPARATION

LOCATION OF TRANSCEIVERS

MULTIPLE UNIT INSTALLATIONS

MOUNTING

POWER WIRING

CONNECTIONS

ALIGNMENT AND TEST

PREVENTATIVE MAINTENANCE

OPTIONAL EQUIPMENT

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WARRANTY AND RETURN INFORMATION

NOTE: This manual is for Models 380 and 380-33453 March 2003

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INTRODUCTION_____________________________________________________________

Model 380 Outdoor Microwave Transceiver incorporates state-of-the-art technology and innovative electronic circuitry to provide reliable detection in the outdoor environment. A unique continuously variable Range Cutoff (RCO) circuit allows maximum detection range to be established independently of object size, thereby eliminating alarms caused by large objects beyond the desired detection range. Model 380 is also equipped with Zero Range Suppression (ZRS) circuitry that reduces sensitivity to small objects very close to the transceiver so that alarms due to rain or vibration are minimized.

Model 380 includes synchronization and addressing circuitry that enables simultaneous operation of up to 16 units without mutual interference. The Model 380 is also built with staggered RF frequencies (Channel A and B) to help minimize mutual interference. Model 380 may be mounted to a variety of posts or wall structures by means of its universal-mounting bracket. A military style multi-pin connector, at the rear of the transceiver housing, permits remote monitoring and diagnostics of critical system parameters.

OPERATION_________________________________________________________________

Model 380 includes both transmitter and receiver in a single enclosure. The transmitter radiates microwave energy that is reflected back into the receiver by objects within the detection zone. The observed detection zone is established by two controls - Sensitivity and Range. Figure 1A shows the zone of detection (horizontal pattern) for an upright man when Model 380 is mounted 2.5 feet (.75 meters) above smooth earth with its beam oriented parallel to the ground. The Range control adjusts the maximum range of the system and the Sensitivity control primarily adjusts the width. Figure 1B shows the vertical pattern for the same configuration, note that the detection zone does not extend into the small area immediately under Model 380.

This area varies with the Sensitivity setting as shown in Figure 2. In order to provide uninterrupted detection of a man walking or crawling on his hands and knees, an additional unit must provide overlap protection such as shown in Figure

3. Detection of a man crawling "commando-style" may require additional overlap or special site preparation.

Sensitivity should always be adjusted to the absolute lowest setting that will meet site security requirements. Excessively high sensitivity may cause nuisance alarms from high grass, small birds or windblown debris in the detection zone. Model 380 responds to any motion within the detection zone.

A) HORIZONTAL PATTERN

SENSITIVITY MAXIMUM

SENSITIVITY MINIMUM

50' MIN (15m)

ACTIVE

DETECTION

PATTERN

RCO

CONTINUOUSLY

VARIABLE

CUTOFF

200' MAX

(122m)

PATTERN HEIGHT

15' MAX (3.4m)

B) VERTICAL PATTERN

Figure 1 - Model 380 Detection Pattern

THEORY_____________________________________________________________________

A microwave transceiver transmits microwave energy into the detection zone, and objects in the zone reflect energy back to its receiver. Whenever an object is moving, the Doppler effect shifts the frequency of its reflection and the transceiver generates an alarm whenever it detects a frequency shift in the reflected energy. The size of a frequencyshifted reflection that will cause alarms is varied by the Sensitivity control causing the detection zone for any particular object to vary as shown in Figure 1. Note that Figure 1 applies to an upright walking man. The detection zone for a large object such as a truck would be larger and for a small object such as a man, crawling would be smaller.

In Model 380, the transmitter is periodically turned on and off, but the receiver is turned on only for a short period after the transmitter is turned on. Because microwave energy always travels at nearly the speed of light, elapsed time between transmission and reception provides an accurate measurement of range (distance) from Model 380 to whatever object is being illuminated. By turning the receiver on only during the period corresponding to maximum desired range, reflections from objects beyond this range are ignored, even if the reflections are very large. In Model 380, the range control determines the time that the receiver observes the reflections and thus sets the maximum (RCO) distance as shown in Figure 1.

Reflections from small objects such as raindrops very near the transceiver are frequently as large as reflections from a man in the detection zone. Model 380 overcomes this problem by transmitting two different microwave frequencies on alternate transmitter pulses. Because each object reflects two different frequencies, the receiver can determine the distance to each object. At zero range (in the vicinity of the radome), the phase difference between the two frequencies is approximately zero. By combining the two Doppler signals in a difference amplifier, the gain is reduced significantly.

In order to insure a continuous perimeter, it is necessary to provide sufficient overlap so that the dead zone immediately below and behind the sensor is protected. Figures 2 and 3 show required overlap information.

DEAD ZONE

50' (15.2m) 40' (12.2m) 30' (9.1m) 20' (6.1m) 10' (3.0m) 5' (1.5m)

MIN

Figure 2 - Required Overlap vs. Sensitivity

REQUIRED OVERLAP

(2.5 foot (0.8m) mounting height)

MAXIMUM SECURITY

MINIMUM SECURITY

SENSITIVITY

1/2

MAX

Overlap Area

OVERLAP AREA

Figure 3 - Overlap of Model 380 Detection Zone

Figure 4 shows a block diagram of Model 380. Logic pulses generated by the synchronization phase-locked loop (PLL) and the associated counter and 4-bit comparator provide the command for turning the transmitter on and off at a prescribed rate, and at one of 16 unique periods of time or addresses. A signal is also derived for switching the transmitter alternately between the two frequencies required for Zero Range Suppression.

The Range control sets the delay generated logic functions initiated by the turn on of the transmitter.

The transmitter is a cavity stabilized fundamental GUNN oscillator that provides 32 milliwatts (peak) of microwave power. Most of the oscillator power is transmitted into space by the parabolic antenna, but a small portion is mixed with the reflected signal and is coupled to a microwave detector within the antenna assembly. The detector is a Schottky diode that extracts the Doppler shift frequency from the reflected microwave energy.

The Doppler signal is amplified and then gated to one of two sample and hold amplifiers. The amplifiers are selected by means of S1 and S2 and are switched coincident with the alternate transmitter frequencies. SI and S2 are held closed for a period of time determined by the range cut-off circuit. Range gating is accomplished by turning on the switch at the same time the transmitter is activated. The switch is then opened at a time selected by the range cut-off circuit so that the information entering the receiver due to targets outside the range cut-off are not processed. The sampling capacitors following the switches hold their charge when the switches are opened. This provides a means for reconstructing each signal after it is sampled.

At the differential amplifier input, the phase between channels is a function of distance to the target and separation of the two transmitter frequencies. Signals arriving from RCO distance are out of phase while signals from zero distance are in phase. Thus, amplifier output is large for signals from RCO distance and small for signals from zero distance.

The differential amplifier output is amplified by a factor established by the Sensitivity control and compared with positive and negative voltage thresholds. Whenever the signal exceeds plus or minus one volt, a pulse is delivered to an integrator. After a predetermined number of pulses have been stored, the integrator output voltage exceeds alarm threshold and the alarm relay is de-energized for two seconds.

A test function is included in Model 380. When gated on by a +5 to +12 VDC command (at the terminal block), the test function provides a phantom signal into the transmitter and receiver circuits to generate an alarm and test the entire 380 detection system.

TB1-10

TB1-11

TB1-12 TB1-13

TB1-14

Fc Fd

MASTER OUTPUT

SLAVE INPUT

OSC

ADDR

4 BIT

COMP

CTR

PLL

LOCK LED

1.0 uSec

ONE SHOT

LEADING

EDGE

DETECTOR

VCO

DRIVER

SYNC

ON OFF

+5V

RCO

TIMING

FbFa

RANGE

+7V

+9V +5V

AMP

P1-C

LOW-PASS

FILTER

SENS

ALARM LED

ALARM

RELAY

TAMPER SWITCH

VCO

SUPPLY

P1-B

POWER

SUPPLY

POWER LED

THRESHOLD

P1-F

TB1-6 TB1-7 TB1-8

TB1-3 TB1-4 TB1-5

TB1-9

P1-A TB1-1 TB1-2 P1-D

P1-E

ALARM

CKTS

N.O. COM N.C.

TEST

Figure 4 - Block Diagram Model 380

+ 13 hidden pages

Southwest Microwave 380 Users Manual

Specifications and Main Features

Frequently Asked Questions

User Manual