User Manual

SECTION 1: THEORY OF OPERATION
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IP8 HPV Data Transceiver Section Descriptions
This section provides detailed descriptions of each of the sections within the IP8 HPV Data Transceiver.
Refer to Appendix A to view the IP8 HPV Data Transceiver Circuit Board Diagram (Top and Bottom
views).
Microcontroller
The microcontroller 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. It also controls the operation of the
modem, and determines which receiver provides a better signal from a given transmission. It provides
transmit time-out protection in the event a fault causes the radio to halt in the transmit mode.
It utilizes a reduced instruction set computer (RISC) architecture which provides low power operation and
a powerful instruction set. Other features include:
• Watchdog timer
• Serial UART
• Two 8-bit timers
• 2 KB EEPROM storage
Support circuitry
The support circuitry consists of the following:
 A Supervisor Control Chip providing power-on reset.
 A clock controlling the microcontroller operation and is generated by crystal Y3 and a Pierce oscillator
circuit inside the microcontroller.
 The latch decodes low order address bits from the address/data bits. It enables Address Latch
Enable (ALE) output of the microcontroller and the bits are used by the modem and synthesizer
circuitry.
 A 512Kx8 Static RAM Chip provides temporary storage of the radio’s configuration data facilitating
the technician with access to make changes.
 Glue logic, also an important part in the microcontroller section. The RAM chip select and modem
chip select command lines are created by gates that decode four (4) high order address bits, plus the
read and write command lines. The RAM is addressed by five (5) memory addresses bits decoded
by logic that decodes port address bits to produce memory address bits for the RAM chip.
Input/Output
Input/output components convert serial and handshake data from the modem section to RS232 levels,
and vice-versa. A transceiver chip is an RS232 transmitter and receiver and converts data in 5-volt logic
form to data in +/-12-volt form, as required by the RS232 standard. A charge pump power supply on the
chip converts the +5-volt DC logic power on pin 26 to the +12-volt and –12-volt levels required.
Capacitors C106-C109 generate these voltages by a charge pump. These values determine the
operating voltages.
This section also includes a DIP switch and an octal tri-state buffer. S1 provides hardware programming
for external modulation. This buffer is used only in MDT-870 applications. When enabled by S1