Daniels Electronics OSR-3H061, Инструкция по эксплуатации

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Enhanced FM Synthesizer Instruction Manual
IM10-OS3AH
29 - 71.4 MHz - Theory of Operation
9
Synthesizer Digital Circuitry (Digital Board)
The synthesizer’s digital board circuitry
generates control signals utilized within the
synthesizer. The microcontroller U4 on the digital
board: communicates with the synthesizer’s
PLL IC U10 on the analog board; monitors
the synthesizer lock detect; manages the PTT
input and output; and determines the operating
frequency by reading the channel code number
information from either the four rotary binary
coded decimal (BCD) switches mounted on
the transmitter or receiver’s main board, or by
reading the four externally driven channel select
lines. The microcontroller U4 is also designed
to communicate with Daniels’ Synthesizer
Channel Programmer (CP-SC-3) through I/O
lines TX Data (P1-17), RX Data (P1-9) and
Bootstrap (P2-2). This external programmer
places the operating program in non-volatile
microprocessor memory and programs up
to 15 user defi ned channel code numbers.
An internal “watchdog” timer provides robust
software protection in all operating modes.
Data communication between the digital and
analog circuit boards is achieved through
four optical transmitters (U5 through U8)
and one optical receiver (U9). The optical
interface provides a fully isolated inter-
board data communications link designed
to prevent digital noise from interfering
with the sensitive PLL circuitry.
BCD Switch Frequency Control
Selection of the desired synthesizer output
frequency is straightforward. If all four of the
CHANNEL SELECT lines (CHAN SEL3-CHAN
SEL0) are pulled low (to GND), the synthesizer
will scan the four BCD switches (FSW1- FSW4)
located on the receiver or transmitter main
boards via connections SW1 COM-SW4 COM
and PC4-PC7 and establish the operating
frequency from these switches. The four
CHANNEL SELECT lines, CHAN SEL3-CHAN
SEL0, are connected via the MT-3 transmitter
or receiver main board module connector to the
M3 motherboard subrack. These lines are by
default normally pulled low (to GND) via jumpers
located on the M3 motherboard subrack.
If any one of the CHANNEL SELECT lines are
pulled high (to +9.5VDC), then the synthesizer’s
frequency of operation will be determined
by the CHANNEL SELECT lines and not the
BCD switches. Up to 15 separate channel
frequencies can be pre-programmed into a
‘table’ in non-volatile microprocessor memory
and accessed through binary interpretation
of the CHANNEL SELECT lines. The most
signifi cant bit (MSB) in the CHANNEL SELECT
binary code is represented by CHAN SEL3 and
the least signifi cant bit (LSB) is represented
by CHAN SEL0. For example, if all CHANNEL
SELECT lines are pulled high, (i.e. binary
‘1111’) then the 15th frequency entry in the
internal channel table will be selected. The
channel table is normally pre-programmed
at the factory to user specifi cations, but may
be programmed in the fi eld using Daniels’
Synthesizer Channel Programmer (CP-SC-3).
In transmitters, the synthesizer operating
frequency is the transmitter operating
frequency. For receivers the synthesizer’s
operating frequency is 21.4MHz above the
receiver frequency. Refer to the Channel
Designation Table Manual for a channel
code number versus frequency table.