User Manual
Table Of Contents
- 1GENERAL
- 1.1Introduction
- 1.2Interim Operation
- 1.3Manual Organization
- 1.4VT-4R400 Transmitter Family Models
- 1.5Performance Specifications
- 1.5.1General
- 1.5.2Audio Specifications
- 1.5.3Physical Specifications
- 2THEORY OF OPERATION
- 2.1General
- 2.2Power Supply
- 2.3High Speed Serial Interconnect
- 2.4Audio Circuits
- 2.5PTT Circuitry
- 2.6Microprocessor Board
- 2.7Channel and Bank Selection
- 2.7.1Channel Select Line Mapping
- 2.8Jumper Functions and standard configuration
- 2.9Hang Timer Selection
- 2.10Kerchunk noise selection
- 2.11Test Points
- 2.12Connector Pinouts
- 2.12.1Connector J9
- 2.12.2Connector P1
- 2.13Transmitter Programming
- 2.13.1Transmitter Wide Options
- 2.13.1.1Frequency Band
- 2.13.1.2Source ID
- 2.13.1.3Secure Hardware Equipped
- 2.13.1.4Timeout Options
- 2.13.2Channel Wide Settings
- 2.13.2.1Channel Name
- 2.13.2.2Frequency
- 2.13.2.3Analog Bandwidth
- 2.13.2.4Deviation
- 2.13.2.5Channel Type
- 2.13.2.6Audio Pre-emphasis
- 2.13.2.7Timeout Value
- 2.13.2.8Project 25 Squelch Settings: Network Access Code (NAC)
- 2.13.2.9Project 25 Squelch Settings: Talk Group ID (TGID)
- 2.13.2.10Analog Signaling Settings: Signaling
- 2.13.2.11Analog Signaling Settings: CTCSS Tone
- 2.13.2.12Analog Signaling Settings: Reverse Burst
- 2.13.2.13Analog Signaling Settings: DCS Code
- 2.13.2.14Analog Signaling Settings: Turnoff Code
- 2.13.2.15Analog Squelch Settings: Invert DCS
- 3Transmitter Assembly and Adjustment
- 3.1Frequency Change
- 3.2Minor Frequency Change
- 3.3Major Frequency Change
- 3.4Digital Signal Processor Board Alignment
- 3.4.1Radio Service Software
- 3.4.2Radio Programming Interface Module Interconnection
- 3.4.3Reference Oscillator Adjustment
- 3.4.4Transmitter Deviation Balance Adjustment
- 3.4.5Transmitter Deviation Limit Adjustment
- 3.4.6Audio Level Alignment
- 3.4.7Amplifier Alignment
- 3.5Recommended Test Equipment List
- 3.6Repair Note
- 3.7Printed Circuit board Numbering Convention
- 4Repeater System Configuration
- 4.1Interim Repeater
- 4.1.1Repeater Interconnect Cable Pinout
- 4.2Project 25 Compliant Repeater
- 4.3Repeater System Troubleshooting
- 5ILLUSTRATIONS
- 5.1Digital Repeater Transmitter Front Panel
- 5.2Digital Repeater Transmitter Exploded View
- 5.3Digital Repeater Transmitter Block Diagram (Interim Mode)
- 5.4Digital Repeater Transmitter Schematic Diagram
- 5.5Digital Repeater Transmitter Main Board Component Layout (Bottom)
- 5.6Digital Repeater Transmitter Main Board Component Layout (Top)
- 5.7Digital Repeater Microprocessor Board Component Layout (Bottom)
- 5.8Digital Repeater Microprocessor Board Component Layout (Top)
- 6PARTS LIST
- 6.1Digital Repeater Transmitter Main Board Parts List
- 6.1.1Digital Repeater Transmitter Main Board Electrical Parts List
- 6.1.2Digital Repeater Transmitter Main Board Mechanical Parts List
- 6.2Digital Repeater Microprocessor Board Parts List
- 6.2.1Digital Repeater Microprocessor Board Electrical Parts List
- 6.2.2Digital Transmitter Additional PCBs
- 7REVISION HISTORY
DE
DANIELS
ELECTRONICS
2-2 VT-4R150 VHF Project 25
Digital
Transmitter
Instruction
Manual
2.3 High
Speed
Serial
Interconnect
Fully
compliant
Project 25
operation
will be supported by the
transmitter
via a firmware upgrade.
At that time, IC U4 will be enabled. It provides a high speed
bi-direction
LVDS
(Low
Voltage
Differential
Signaling)
port on front panel jack
J1.
Each signal path uses a
balanced
current loop to
achieve
high serial bit rates with low noise. These
signaling
paths will provide a means for
digital
and analog RF signals to be passed from
receiver
to
transmitter
for
repeatin
g.
2.4 Audio
Circuits
Op amp U3a serves a mixer for audio signals from the
microphone
connector
MIC1,
unbalanced
audio1 input, and the “kerchunk” audio signal
generated
by the
Microprocessor
Board.
Level
adjustment
is provided by
potentiometer
R11. Separate control of the
microphone
input
level
and
DC biasing is provided by
potentiometer
R9.
2.5 PTT
Circuitry
The
transmitter
may be keyed by
either
grounding the PTT* input at P1-B10 & Z10, by moving
the front panel power switch to the “KEY TX” position, or by
pulling
the
ANALOG_COR*
or
DIGITAL_COR*
inputs low. These inputs are
monitored
by microprocessor U6 and used in
conjunction
with the position of the front panel “MIC
MODE”
switch to
generate
a sequence of
signals to the
Digital
Signal Processor Board which will cause it to key up in
either
P25
Digital
or
Analog
mode.
2.6 Microprocessor
Board
The microprocessor board contains
U6,
a 68HC11E2
microcontroller.
U6 is responsible for
monitoring
all sources of Push-To-Talk information, the Bank
Select
Input, and the
Mic
Mode
front panel switch. It
generates
bank
select
and PTT signals to the
Digital
Signal Processor Board,
the “kerchunk” audio signal, and drives the front panel LEDs to
indicate
that the
transmitter
is
active
in
either
P25
Digital
or
Analog
mode. U6 also monitors the state of the Hang
Time
select
jumpers to
determine
whether the
transmitter
should
remain
keyed after a source of PTT
disappears, and whether a “kerchunk” noise should be inserted at the end of the transmission.
2.7
Channel
and Bank
Selection
Four
channel
select
lines CSEL0-3 are named on the M-3 motherboard, and are brought into the
receiver
module by pins on
connector
P1,
allowing
selection
of 16
different
channels. These
signals
normally
float high (+5V) in the receiver, but are
typically
pulled low by jumpers on the M-
3
motherboard
to
select
channel
1 by default. In addition, a bank
select
input is provided to switch
between Bank A and B, each of which has 16 channels. In the
Interim
mode of operation, the
bank
select
input has no effect. A
convention
has been adopted to use Bank A channels as analog
channels, and Bank B channels as P25
Digital
channels. Using this convention, it is possible to
have an MT-4
Interim
Receiver
connected
to the
transmitter
to form a
repeater
that repeats an
incoming
voice signal in the same mode in which it is received. The LEDs on the
transmitter
front
panel will
correctly
indicate
Analog
or
Digital
operation
as long as this
convention
is followed. In
addition, the
Mic
Mode switch on the front panel will
operate
correctly,
selecting
Bank A for
analog channels, and Bank B for
digital
channels, as long as this
convention
is followed.