User's Manual

CHAPTER 1: INTRODUCTION
2003 IPMobileNet, Inc. 11 IPSeries MR User Manual / Rev. A / 04-September-03
operating parameters, which are retained after the base station’s power
is cycled off.
Modems Convert data into an analog audio waveform for transmission and analog
audio from the receiver to serial data interface. There is one (1) modem
that is dedicated to the transmit operation and two (2) modems dedicated
to the receive operation. The modem dedicated to the transmit supports
a 115.2 KBPS data transmission rate on the serial port, SLIP protocol,
and a 19.2 KBPS OR 9.6 KBPS over-the-air data transmission rate.
Provides Forward Error Correction (FEC) and Error Detection (using
Cyclic Redundancy Check or CRC), bit interleaving for more robust data
communications, and third generation collision detection and correction
capabilities.
Diversity Reception Circuitry selects one of three (3) diversity receiver audio outputs for
processing by the modem by comparing the Received Signal Strength
Indication (RSSI) output from each receiver. Audio from the receiver
with the highest RSSI value is passed to the modems.
RX Injection The Injection Synthesizer board provides a highly stable local oscillator
signal for the three (3) receivers. This displays a serial data input/output
interface, synthesizer, and VCO.
Transmitter Consists of an exciter and a power amplifier module covering various
frequency bands in segments. The transmitter power control is included
with the power supply circuitry on the same board.
Receiver 1/Receiver 2/ Uses three (3) discrete receivers tuned to the same frequency.
Receiver 3 The three (3) receivers are required to support IPMobileNet’s base
station Diversity Reception System (DRS).
NOTE: Some installations use only two (2) receivers.
The receivers are double-conversion superhetrodynes with an
Intermediate Frequency (IF) of 45 MHz. Each receiver consists of
bandpass filters, RF amplifiers, a mixer, 45 MHz crystal filter, and a one-
chip IF system. The injection synthesizer provides the first local
oscillator signal and outputs from each receiver include RSSI and analog
audio for Diversity Reception.
Power Supply Power supply circuitry derives the various operating voltages required by
the base station. Fixed voltage regulators are employed through the
base station for this purpose.