400 – 512 MHz Mobile Data Radio Owner’s Manual Date Prepared: March 1, 2000 Document Control #: DC-94 Version: C-1 (Special Release) Copyright 2000-2002 IPMobileNet, Inc.
TABLE OF CONTENTS SECTION 1: THEORY OF OPERATION ................................................................................. 3 General Block Diagram................................................................................................ 3 General Block Diagram Definitions..................................................................... 3 DT450 Mobile Data Radio Board Circuitry ......................................................... 5 Microcontroller.......................................
SECTION 1: THEORY OF OPERATION General Block Diagram DATA Input / Output MicroController Injection Synthesizer Transmitter Transmit Processing Baseband Routing Receiver 1 Modem Receiver 2 General Block Diagram Definitions For increased data security, the modem supports the U.S. Government developed Digital Encryption Standard (DES) data encryption and decryption protocols.
SECTION 1: THEORY OF OPERATION The modem supports a 115.2 Kbps data transmission rate on the serial port, SLIP protocol, and up to 19.2 Kbps over-the-air rate. Within a single chip it provides forward error correction and detection, bit interleaving for more robust data communications, and third generation collision detection and correction capabilities. Injection Synthesizer Provides programmable, ultra stable signals for the radio.
SECTION 1: THEORY OF OPERATION DT450 Mobile Data Radio Board Circuitry The DT450 Mobile Data Radio works within a frequency range of 400 to 512 MHz. The following section provides detail views and key areas on the DT450 Mobile Data Radio circuit board especially useful during troubleshooting. Microcontroller The microcontroller (U43) is a major component of the radio as it manages the operation of the radio loading the selected transmit/receive frequencies into the injection sythesizer.
SECTION 1: THEORY OF OPERATION Injection Synthesizer The synthesizer chip (U3) is the major contributor of the injection synthesizer. This device contains the key components of a phase locked loop (PLL), including a 1.1 GHz prescaler, programmable divider, and phase detector. The selected frequencies are loaded into U3 as a clocked serial bit stream via the PLL DATA and PLL CLOCK inputs. The microcontroller provides the serial data.
SECTION 1: THEORY OF OPERATION Incoming signals pass through a double-tuned filter (FT4A) that selectively provides a high degree of outof-band signal rejection. A low noise amplifier (U6A) amplifies the selected signals and a triple-tuned filter (FT3A) provides additional selectivity. An RF amplifier chip (Q6A) further amplifies the signal. The output from Q6A passes through another triple-tuned filter (FT2A) and it goes to the mixer (U29A).
SECTION 1: THEORY OF OPERATION Baseband Routing This circuitry selects audio from the appropriate receiver to route to the modem for demodulation. Power and Ground Power from the vehicle’s battery appears at the VBATT pad. The supply line powers a series of voltage regulators and the transmitter control circuitry, as follows: Voltage regulator VR3 provides a continuous 5-volts for the microcontroller, RS232 interface, and modem circuitry.
SECTION 1: THEORY OF OPERATION This section is identical to the Receiver 1 IF with the exception of the local oscillator circuitry. Incoming 45 MHz signals appearing at 2NDIF pass through an amplifier and an LC matching circuit mixer. Local oscillator injection is provided by the Receiver 1 IF subsystem. The mixer output passes through a 455 KHz ceramic filter (FL6B). It is then amplified and passed through another ceramic filter (FL7B) to a second gain stage. The IF output drives a quadrature detector.
SECTION 2: FACTORY TEST PROCEDURE Equipment List The following table lists the equipment required to perform the DT450 Mobile Data Radio Factory Test Procedure: QTY 2 1 DESCRIPTION MANUFACTURER PC’s One for Mobile One for Base Service Monitor – Communication Test Set Windows 9X w/ IPMessage AVR 1 Digital multi-meter 1 DC power supply w/ ammeter, 13.
SECTION 2: FACTORY TEST PROCEDURE Programming and Configuring the Mobile Data Radio Once the appropriate equipment for performing the factory test are gathered, perform the following steps to program and configure an DT450 Mobile Data Radio: Step 1 Enter the following information on the Mobile Data Radio Performance Test Data Sheet: Radio Serial number Date test being performed Tester's Name Step 2 Program the radio to the current Firmware revision using the AVR programming utility.
SECTION 2: FACTORY TEST PROCEDURE Adjustment / Alignment Procedures Receiver Injection Perform the following steps to adjust the receiver injection and injection frequency: Step 1 Select the TX TEST function on the service monitor. Connect a scope probe from the monitor’s antenna input connector. This configuration looks at leakage energy from the VCO so that a frequency reading can be obtained.
SECTION 2: FACTORY TEST PROCEDURE Step 5 Adjust each pole of filters (FT3A and FT2A) for maximum RSSI voltage. Go back and forth between these adjustments until no further increase is noted. Step 6 Adjust the trimmer capacitor (CV1A) for maximum RSSI voltage. Record this value on the Mobile Data Radio Performance Test Data Sheet. Step 7 Connect the scope probe to the service monitor’s audio input. Step 8 Connect the probe to test point (TP1) in the radio.
SECTION 2: FACTORY TEST PROCEDURE Step 8 Select the SINAD measurement on the service monitor and read the results. SINAD should be 12 dBm or better for an RF input of –119 dBm. Step 9 Measure the AC level of the recovered modulation at TP1. Record this value on the Mobile Data Radio Performance Test Data Sheet. Step 10 Move the DMM test probe to TP1. Step 11 Adjust pot R19B for a reading of 2.500 (+/-10 mV) VDC. Step 12 The previous two (2) adjustments are interactive.
SECTION 2: FACTORY TEST PROCEDURE Step 7 In the lower message window type unlock=password (entering the appropriate password) and click on the Send button. This command unlocks the radio Firmware for programming. It will be necessary to send this command periodically as the radio automatically locks after three (3) minutes. Step 8 Locate and make note of the TX Power = NNN parameter in the upper message window of IP Message.
SECTION 2: FACTORY TEST PROCEDURE Power Setting Step 1 Verify the RF jumper cable from the service monitor is connected to the radio’s TX/RX1 input. Step 2 Set monitor to read RF power output. WARNING! Damage to the service monitor can result during the following adjustments unless the unit has an internal dummy load. Verify the monitor has an internal dummy load before performing any other test. Otherwise, use an external dummy load with the service monitor.
APPENDIX A: DT450 CIRCUIT BOARD DIAGRAM DT450 Mobile Data Radio FCC Label Placement FCC Label Placement DT450 Mobile Data Radio FCC Label ~\Technical Documentation\System Manuals\FCC-Reports\DT450-FCCRpt.
SECTION 2: FACTORY TEST PROCEDURE ~\Technical Documentation\System Manuals\FCC-Reports\DT450-FCCRpt.