Meteorcomm 54530001 User Manual

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FCC TYPE ACCEPTANCE DOCUMENTATION

FOR THE

MCC-54530001 REMOTE EMERGENCY DEVICE (RED)

December 15, 1998

METEOR COMMUNICATIONS CORPORATION

8631 South 212th Street

Kent, WA. 98031

Tel: 253-872-2521 Fax: 253-872-7662

TABLE OF CONTENTS

INTRODUCTION 3 DESCRIPTION 3 SPECIFICATIONS 3 OPERATION 4 THEORY OF OPERATION 5

Block Diagram 5 Power Switch and Battery Status Indicator 6 5 Volt Regulator 6 Microcontroller 6 Differential Data Encoder 6 Data Filter 6 Transmit Crystal Oscillator 6 Phase Modulator 6 RF Power Amplifier 7 Harmonic Filter 7 Loop Antenna 7

TEST PROCEDURE 8

APPENDIX A 10

Drawings

APPENDIX B 14

Test Results Form

APPENDIX C 15

Final Assembly Pictures

APPENDIX D 16

Printed Circuit Assembly Pictures

APPENDIX E 17

FCC Identification Label Source Control Drawing

INTRODUCTION

The Meteor Communications Corporation (MCC) Remote Emergency Device (RED) is a low power, RF transmitter, designed for use with the MCC-545A RF Modem. The unit was developed as a personal emergency-signaling device that provides short-range connectivity between the user and a nearby 545A.

DESCRIPTION

The RED is a battery operated, handheld device with a minimum operational range of 1,500 feet. In an emergency, the operator presses the red button on the unit to transmit an alert message. There is also a test button and battery indicator to periodically determine the functional status of the unit. When not in use, the unit can be clipped to the user's belt.

SPECIFICATIONS

Transmitter

Frequency Range 36-50MHz Frequency Stability +/- 20ppm (-30 to +60 o C) Transmit Power 250mW (at 9VDC) Rated Emission 16KOG1WWN Spurious and Harmonic Emissions -37dBc Modulation BPSK Data Rate 4k bps Transmit Data Sequence Duration 300ms

Antenna Gain -36 dBd

Power Requirements

Voltage 9VDC Transmit Current 250mA

Battery Life (Alkaline)

Continuous Transmit 2 hours Standby 5 years

Dimensions 4.0"L x 2.4"W x 1.4"H

Weight 5 ounces

OPERATION

Battery The RED requires a 9-volt alkaline battery to operate. It is installed through an access panel on the back of the unit. A light on the front of the unit provides a visual indication of the battery's status whenever the test button is pressed. It will light as long as the battery voltage is greater than 8VDC.

Message Transmission The RED will transmit two types of messages to the 545A, alert or test. Both messages are automatically sent 10 times with each button push for redundancy. In the event of an emergency, press the large, red button on the front of the unit to send an alert message. To test unit functionality, press the small, black button on the side of the unit to send a test message. To ensure message transmission, the buttons must be held down at least 100ms. When the button is released, the unit will complete its transmission cycle and then power down. If the button is held down, the unit will transmit message sequences continuously.

Range The operational range of the RED is affected by its distance from the receiver, the type of terrain in between, and the noise floor at the receiver. The RED is specified at 1,500 feet over level terrain, with a noise floor off 0.1uV at the 545A. Any deviation from these conditions will produce variations in the operational range of the unit accordingly.

THEORY OF OPERATION

The MCC RED is a low-power (250mW) radio transmitter designed for one-way data communications in the low VHF band (36-50 MHz). Information is transmitted in Binary Phase Shift Key (BPSK) form, using a monolithic quadrature modulator. See Appendix A for assembly and schematic drawings.

Block Diagram

LOOP ANTENN A

4.096MHZ CRYSTAL

TRANSMIT CRYSTAL OSCI LLATOR

P R OGR AMMI N G I / O

MI CROC ONTR OLLER

9 VO LT B ATTER Y

PHASE MODU LATO R

DATA FILTER

DIFFERENTIAL DATA ENCODER

9 VOLTS

POWER SW I TCH

RF POWE R AMPLIFIER

5 VOLTS

VOLTAGE REGU LATO R

H ARMONIC FILTER

BATTERY STATU S IND ICATOR

TEST SWITC H

ALERT SWITC H

Power Switch and Battery Status Indicator Whenever switch SW1 or S2 is pressed, components Q1, Q2, CR1, R2, R3, R5, and R6 switch battery power to all the circuits, except for the final power amplifier stage, which is always connected. The circuits include the 5-volt regulator, and the first and second stages of the power amplifier circuit. Whenever S2 is pressed, power is also routed to the light emitting diode CR2, through components CR3, and R24 as a visual indication of the battery status. The indicator will not light when the battery voltage is below 8 volts.

5 Volt Regulator A linear voltage regulator (U1) provides 5 volts to the microcontroller, differential data encoder, data filter, crystal oscillator, and modulator circuits.

Microcontroller An 8-bit, CMOS microcontroller (U3) is used to generate the binary data sequence for transmission. It outputs the appropriate sequence whenever switch SW1 or S2 is pressed. A 4.096MHz crystal (Y2) along with capacitors C15 and C16 determine the operating frequency of the device. The microcontroller also stores the application code and user identification information in internal flash and E2PROM memory respectively.

Differential Data Encoder A CMOS J-K flip-flop (U6A) is used to differentially encode the binary date prior to entering the data filter.

Data Filter An Op-Amp (U5A) based circuit is used to filter the encoded binary data. Capacitors C10, and C13, and resistors R9, R10, and R11 form a second order, low-pass filter with a cut-off frequency of 2 kHz. Resistor R21 reduces the amount of crossover distortion from U5. R15 scales the input to the filter from 0-5VDC to 0-3.2VDC.

Transmit Crystal Oscillator A temperature compensated crystal oscillator (Y1) is used to generate the transmitter carrier signal. A trimmer capacitor located on the oscillator allows for fine frequency adjustment of approximately +/- 200Hz. The oscillator's frequency stability is better than +/- 20ppm over a temperature range of –30

C to +60o C.

Phase Modulator A monolithic quadrature modulator (U4) is used to generate the BPSK modulated carrier signal. The output of the data filter is directly connected to the in-phase (I) input of the modulator and through C36 to the quadrature (Q) input. This configuration prevents zero crossings of the phase-modulated carrier. This, together with the data filter, maintains the transmitter modulation sidebands within the limits of the FCC requirement.

RF Power Amplifier A three-stage, solid-state amplifier provides about 33dB of total gain. The first stage is implemented with a monolithic amplifier (U2). It provides about 17dB of gain. The 50ohm amplifier input is matched to the modulator output with components C8, C24 and L3. The second stage is also implemented with a monolithic amplifier (U11). It provides about 4dB of gain.

The final stage is implemented with transistor Q3. It provides about 12dB of gain. The output is series tuned with inductor L7 and trimmer capacitor C33. Because the stage operates class C, the battery voltage is directly connected to it. Only a small amount of current drain (< 50nA) is incurred, which is due to leakage through Q3.

Harmonic Filter A third order, low-pass filter attenuates the harmonics of the transmitter center frequency to a level that meets FCC requirements. At a 250mW output, the harmonics must be 37 dB below the unmodulated carrier. Capacitors C34 and C35 and inductor L8 form this filter. The cut-off frequency is set to obtain about 20 dB of attenuation at twice the transmitter center frequency.

Loop Antenna A printed circuit board loop antenna is used to radiate the RF signal from within the RED enclosure. Capacitor C1 on the board is used to tune the antenna.

TEST PROCEDURE

Equipment List

100 MHz Oscilloscope and probe with RF short ground 100 MHz Frequency counter 9VDC, 500mA Power supply Digital Multimeter (DMM)

Equipment Set Up

FREQUENCY COUNTER

POWER SU PPLY

14 GAUGE, ENAMELED , SOLID W IRE. PLACED A D J AC ENT TO TH E PC B LOO P AN TENNA. (SEE DETAIL BELOW)

DET AIL

WIR E

COAX

5 4530302 PC B

PCB LOOP AN TENN A

OSCILLOSCOPE

COAX

UUT

SCOPE PROB E W I TH R F SH OR T G R OU N D

Record the following measurements on the test results form located in Appendix B

Transmit Crystal Oscillator Frequency While pressing SW1 of the UUT, measure the oscillator frequency using a scope probe (with an RF short ground) at pin 2 of Y1. The frequency should measure within +/- 10Hz of the transmit frequency. If it doesn't, then adjust trimmer C2 on the oscillator.

Radiated Voltage Adjust trimmer potentiometer R23 fully clockwise. While pressing SW1 of the UUT, adjust trimmer capacitors C33 (on main PCA) and C1 (on antenna PCA) for maximum peak to peak voltage on the oscilloscope. The peak to peak voltage should be greater than

1.5Vpp.

Transmit Current While pressing SW1 of the UUT, record the transmit current indicated on the DMM. It should be less than 250mA.

Leakage Current With the UUT off, record the leakage current indicated on the DMM. It should be less than 1uA.

Disconnect the UUT from the 9VDC power supply. Attach the UUT enclosure cover and install a 9-volt battery.

Battery Status Indicator Push the small, black test button on the UUT. Verify that the LED lights brightly.