User Manual

SECTION 1: THEORY OF OEPRATION
~\Technical Documentation\System Manuals\FCC-Reports\IP1HPV\IP1HPV-FCCRpt.doc Page 3
General Block Diagram
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. This capability requires
installation of third party, Internet Protocol (IP) compliant DES encryption and decryption
software on the system.
The standard IP circuit board contains ten (10) sections defined below.
The IP1 circuit board contains additional sections than those listed in this section. These
added sections will be discussed in Section 4 of this document.
Input/Output Circuitry associated with the radio’s DB9 data connector providing all the
RS232 data and handshake functions, including the necessary level
changes.
Microcontroller Manages the operation of the radio loading the selected transmit/receive
frequencies into the injection synthesizer, controls the operation of the
modem, and determines which receiver provides a better signal from a
given transmission. Also provides transmit time-out protection in the event
a fault causes the radio to halt in the transmit mode.
Transmit Processing Circuitry that amplifies the analog audio signal from the modem and uses it
to modulate the voltage controlled oscillator (VCO) and 10 MHz reference
oscillator in the injection synthesizer section. Modulating the VCO and
reference oscillator simultaneously results in a higher quality FM signal.
Modem Converts serial data into an analog audio waveform for transmission and
analog audio from the receiver to serial data. Serial data appears on the
radio’s RS232 port, which connects a Mobile Data Computer (MDC) or a
Voice Interface Unit (VIU).
Input /
Output
D
D
A
A
T
T
A
A
Micro-
Controller
Injection
Synthesizer
Transmitter
Transmit
Processin
g
Baseband
Routin
g
Receiver 1
Receiver 2 Modem