SmartTrunk Systems ST-1000C Service Manual
ST-1000C (400Mhz ~ 470Mhz)
UHF FM COMPACT DIGITAL TRANSCEIVER
SERVICE MANUAL
SmarTrunk Systems, INC.
ST-1000C SM R1.1a
ST-1000C SM R 1.0 SMARTRUNK SYSTEMS, INC.
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Table of Contents
1. Specifications: ............................................................................................................................. 4
2. ST-1000 EXPLODED VIEW ............................................................................................................ 5
3. ST-1000 SIMPLIFIED DIAGRAM.................................................................................................... 6
4. - ST-1000 RF DESCRIPTION .............................................................................................................. 7
4.1. Circuit Configuration ............................................................................................................... 8
4.2. Receiver System ...................................................................................................................... 8
4.2.1. Front-end RF Receiver ......................................................................................................... 8
4.2.2. ANALOG Audio Processing .................................................................................................. 8
4.2.3. Virtual Squelch Circuit ......................................................................................................... 8
4.2.4. Virtual VOLUME CONTROL .................................................................................................. 9
4.2.5. Sub audio signaling .............................................................................................................. 9
4.2.6. ANALOG AUDIBLE SIGNALING ............................................................................................. 9
4.2.7. DIGITAL AUDIO PROCESSING............................................................................................... 9
4.3. Transmitter System ............................................................................................................... 10
4.3.1. ANALOG TX SIGNAL ........................................................................................................... 10
4.3.2. DIGITAL TX AUDIO: ............................................................................................................ 10
4.3.3. Driver and Final Amplifier Stages ...................................................................................... 10
4.3.4. Automatic Transmit Power Control ................................................................................... 11
5. RC-1000 ALIGNMENT ................................................................................................................ 12
5.1. Introduction .......................................................................................................................... 12
6. COMPLIMENTARY USER ALIGNMENT........................................................................................ 13
6.1. OPTION ALIGNMENT: ............................................................................................................ 13
6.1.1. SQUELCH LEVEL: ................................................................................................................ 13
6.1.2. ANNUNCIATION ................................................................................................................ 13
6.1.3. Tones ................................................................................................................................. 14
6.1.4. Voice activated transmission ............................................................................................. 14
6.1.4.1. VOX sensitivity level ...................................................................................................... 14
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6.1.4.2. VOX inhibit on receive ................................................................................................... 14
6.1.4.3. VOX delay ...................................................................................................................... 15
6.1.5. Battery save ...................................................................................................................... 15
6.1.6. Microphone sensitivity ...................................................................................................... 15
7. ST-1000 SCHEMATIC ................................................................................................................. 17
11 ST-1000 COMPONENT LOCATOR................................................................................................... 18
11.1 ST-1000 TOP LAYER COMPONENTS LOCATION ......................................................................... 18
11.2 ST-1000 BOTTOM LAYER COMPONENTS LOCATION ................................................................. 19
12 ST-1000 PCB LAYOUT .................................................................................................................... 20
12.1 ST-1000 TOP LAYER PCB LAYOUT .............................................................................................. 20
12.2 ST-1000 BOTTOM LAYER PCB LAYOUT ...................................................................................... 21
12.3 ST-1000 PCB GROUND LAYER .................................................................................................... 22
12.4 ST-1000 PCB POWER LAYER ...................................................................................................... 23
13 ST-1000 BOM ................................................................................................................................ 24
14 ST-1000C MECHANICAL BOM........................................................................................................ 30
15 ACCESSORY PORT: ......................................................................................................................... 32
16 ST-1000 SERVICE MANUAL REVISIONS .......................................................................................... 34
ST-1000C SM R 1.0 SMARTRUNK SYSTEMS, INC.
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SPECIFICATION
ST-1000C
GENERAL
Frequency Range [Mhz]
400 TO 470
Channels
16
Power [Vdc]
6.4 to 8.8
Dimensions [mm]
120(H)x33(D)x57(W)
Weight [gr] (oz)
190 - (6.7)
Temperature range
- 30 °C ~ 60 °C (-22°F ~ +140°F)
Signaling
51 CTCSS tones / 183 DCS tones / 65533 SDR IDs
Display
No
Emergency call
No
GPS
No
Channel Scan
Yes
BCLO / BTLO
Yes
Power Saver control
Yes
TOT
Yes
Radio Kill/Alive
Yes
Adjustable Power Selection
H/L
Key lock
No
Password
Yes
Key Function selection
Yes
TRANSMIT
MAX RF power
2 W
Frequency Stability
>1PPM
Bandwidth [Khz]
12.5/25
Adjacent Channel Power
-65dBC (typ)
SNR
45dB typ
Analog harmonic distortion
5% typ (AF 1Khz, 60% deviation)
Data transmit rate
2400/4800bps
Max frequency deviation
2.5Khz@12.5Khz BW/5Khz@25Khz BW
Analog Modulation type
11K0F3E, 25K0F3E
FDMA Digital emissions
8K30F1E, 8K30F1D, 8K30F1W
Ext. Mic. Impedance
600 Ohms
RECEIVER
Analog Sensitivity
0.25uV (12dB Sinad)
Digital Sensitivity
0.3uV (5% BER)
Image rejection
60dB typ
Adjacent Channel selectivity
60dB typ @25KHz BW
HUM and NOISE ratio
40dB
Speaker Audio Power
1W
External audio power
1W
1. Specifications:
Specifications subject to change without notice or obligation
2. ST-1000 EXPLODED VIEW
3. ST-1000 SIMPLIFIED DIAGRAM
LPF
Ant Sw
D1/D4
Final
AMP
Q2
Power
Detection
D2
Driver
Q3
Buffer
AMP
Q1
TX CTRL
[U3]
CLOCK
[Y2]
POWER
CTRL
[U3]
FLASH
MEMORY
[U4]
RAM
MEMORY
[U7]
PWM
SIDE
KEYS
SERIAL
PORT
Main Processor
[U8]
Radio
U1
MIC
AMP
[U11]
AUDIO
PA
[U9]
Notes:
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4. - ST-1000 RF DESCRIPTION
4.1. Circuit Configuration
The receiver is a single receiver
with built-in DSP fully integrated.
Incoming signals from the
antenna, after passing through
LPF filter, are fed direct to the DSP
down converter to get the
baseband voice from 0Hz to
3500Hz.
Demodulated signals are fed to the
DSP processor where are filtered
and conditioned. This processor
also includes a high efficiency FSK
modem.
For digital demodulation, once the
data is decoded, and free of errors,
it is fed into the into a vocoder
firmware module, which converts
the data to voice.
Analog voice from the analog path
or the analog voice recovered from
the vocoder firmware, are fed into
an audio power amplifier direct
from a digital to analog converter.
Transmit signal frequency is
generated by integrated VCO and
PLL. RF frequency generated by
the integrated RF chip is amplified
into a 3-step amplifier then filtered
by a low pass filter to be applied to
the antenna.
4.2. Receiver System
4.2.1. Front-end RF Receiver
Incoming RF signals from the
antenna are delivered to the
Receiver Unit and pass through a
Low-pass filter, antenna switching
diode, and then fed to the receiver
(U1) passing through a limiter
BPF.
4.2.2. ANALOG Audio Processing
The RF signal is tuned by U1,
which includes a base band DSP
audio processing, recovering flat
audio from DC up to 3500 hz.
The detected audio is amplified,
filtered and conditioned inside of
U8 which also includes a deemphasize filtering shape for
received audio signals by firmware.
The output of the filtered and
conditioned audio is delivered to
an audio power amplifier (U9) then
to the speaker passing through the
external audio connector switch.
4.2.3. Virtual Squelch Circuit
S/N ratio is measured by the
receiver (U1) as the result of the
analysis of the signal and the noise
of the carrier. The output is sent to
the main processor as a digital
frame, which is analyzed by radio
LPF
SWITCH
PROTECTION
FILTER
RECEIVER
[U1]
RECEIVER
[U1]
MAIN
PROCESSOR
[U8]
AMPLIFIER
[U9]
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firmware, removing noise then
qualifying the signal level. If the
signal level is higher than the
expected for the current
programmed squelch threshold,
then the processor analyzes the
expected signaling programmed on
the current channel table.
In case of not any signaling is
required, or the signal has been
detected, the processor opens the
virtual audio path, unmuting the
audio amplifier (U9).
4.2.4. Virtual VOLUME CONTROL
The potentiometer position (RV1) is
measured by one analog to digital
converter on the main processor
(U8. The firmware immediately
adjusts the processor path gain to
get the appropriate overall circuitry
volume control.
Minimum volume, emergency and
private audio level are controlled
only by software overriding the
information received from the DAC
on U8.
4.2.5. Sub audio signaling
Received sub audio signaling as
CTCSS and DCS are received and
processed and detected by the
receiver (U1). Once decoded, the
sub audio signaling is reported to
the processor where the firmware
compares it with the value
programmed into the current
channel programming.
If the received signaling matches
the channel programming, then
the main processor (U8) opens the
audio patch.
4.2.6. ANALOG AUDIBLE SIGNALING
DTMF signals, MDC1200 and tone
signals are processed and decoded
by the main processor (U8).
Decoded information or received
tone is analyzed by firmware on
the main processor (U8).
4.2.7. DIGITAL AUDIO PROCESSING
Digital received information is
processed by the receiver DSP (U1)
then delivered to the main
processor (U8), which includes a
very sensitive FSK modem.
Data decoded by the modem
firmware is transferred to the main
code, which de-encrypts the
information, checks the integrity,
corrects the wrong bits and extract
the audio information form the
received frame.
The portion of the data received,
error free, is moved to the vocoder
firmware module internally into
the main processor (U8).
The vocoder firmware re-builds the
audio from the compressed data
then applies filter it, adjust the
volume and fed it to the audio
power amplifier (U10) through one
RECEIVER
[U1]
AMPLIFIER
[U10]
MAIN
PROCESSOR
[U8]
VOCODER
U6]
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high definition digital to analog
converter.
4.3. Transmitter System
4.3.1. ANALOG TX SIGNAL
The AF signal from the internal
microphone (MK1) or external
microphone (J4) are processed as
differential signal, then it is
conditioned and transformed into
common mode by the microphone
pre-amplifier (U11).
The result of the conditioned inband filtered signal is fed to the
Main Processor (U8), which
provides audio gain control,
compander, emphasize, limitation,
encryption, etc. by software
algorithms.
The high audio band of the signals
from 300 to 3500 Hz are directly
fed to the transmitter (U1), which
performs a direct modulation of a
generated carrier.
Low frequency signaling audio is
fed directly to Y1 VC TXCO main
clock generator and U1 with a
corresponding balance controlled
by software.
4.3.2. DIGITAL TX AUDIO:
The AF signal from the internal
microphone (MK1) or external
microphone (J4) are fed directly to
the main processor (U8), which
perform the signal filtering, the
data codification, into especial
firmware block. The result of the
digitized information is processed
by a FEC (Frame Error Correction)
module, adding spare bits to
ensure high robustness to the
data, then it is encrypted and the
user related information as user ID
is added.
The final data frame is fed to the
modem code, which generates the
FDMA signals, controlling the
modulation of the Transmitter (U1)
through the VC TXCO for DC to
low frequencies and the direct
modulation for higher frequencies.
4.3.3. Driver and Final Amplifier Stages
Final RF is amplified on Q1
(2SC3356) then filtered to be fed to
Q3 (2SK3475) then finally
amplified by Q2 (2SK3476) up to 2
watts output power.
The transmit signal then passes
through the antenna switch D1
(BAR88) and is low-pass filtered to
suppress harmonic spurious
radiation before delivery to the
antenna.
AMPLIFIER
[U11]
MAIN
PROCESSOR
[U8]
TRANSMITTER
[U1]
VC TXCO
[Y1]
TRANSMITTER
[U1]
VC TXCO
[Y1]
MAIN
PROCESSOR
[U8]
AMPLIFIER
[U11]
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4.3.4. Automatic Transmit Power
Control
The RF power detector (BAS70)
detects transmitted feedback then
sends the readout to audio
processor U8. The special firmware
module compares the transmitted
power against the referred level
stored on current channel memory
adjusting the power control level
generated as reference by one DAC
output on the same processor (U8)
then amplified by U3 (MCP6241U)
controlling the gate current on Q1
and Q17.
Notes:
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