TS-990S
35
CIRCUIT DESCRIPTION
8-8. AGC Voltage Output Circuit
The AGC voltage output (MAGCV) for the main signal re-
ception is sent from the TXMRX-DSP to the R channel of the
DAC (IC397) at an fs of 96kHz. The signal output from the
R channel of the DAC is sent from the MAGCV connector
(CN101) to the RX unit (X55-313 A/2 CN28) via the control
unit (X53-452 CN32 and CN72) after passing through the
buffer amplifi er (IC681).
The AGC voltage output (SAGCV) for the sub signal re-
ception is sent from the SRX-DSP to the L channel of the
DAC (IC388) at an fs of 48kHz. The signal output from the
L channel of the DAC is sent from the SAGCV connector
(CN671) to the TX-RX unit (X57-827 A/2 CN2) after the sig-
nal passes through the buffer amplifi er (IC662).
Fig. 40 Signal for the band scope and decoder use and the AGC voltage output path
8-7. Signal Path for the Band Scope and Decoder
Use
The IF signals (MSCPI and SSCPI) for the band scope
use and decoder use are sent to each DAC from the SRX-
DSP.
The DAC (IC385) converts the MSCPI signal to an analog
signal at an fs of 48kHz. The signal output from the R chan-
nel of the DAC is sent to the control unit (X53-452 CN450)
from the MSCPI connector (CN662) after passing through
the active fi lter (IC669).
The DAC (IC385) converts the SSCPI signal to an analog
signal at an fs of 48kHz. The signal output from the R chan-
nel of the DAC is sent to the control unit (X53-452 CN451)
from the SSCPI connector (CN669) after passing through
the active fi lter (IC656).
9. Control Circuit
9-1. Outline
The control circuit consists of the main MCU (IC46) along
with the EEPROM (IC47), reset IC (IC44), RTC IC (IC49),
extension output ICs (IC31 to IC34, IC36 to IC39, IC42, and
IC43), scope MCU (IC380), and scope DSP (IC381).
9-2. Main MCU and Its Periphery
The main MCU (IC46) operates at a power supply volt-
age of 3.3V and a clock frequency of 88.4736MHz obtained
by multiplying 11.0592MHz in the main MCU by eight. Fur-
thermore, the number of output ports is insuffi cient. There-
fore, 10 expansion ICs are prepared to compensate for 80
ports.
The 3.3 V power supply must be always supplied. There-
fore, this power supply is different from other power supplies.
The main MCU is connected with the EEPROM (IC47) for
backup use, clock count RTC IC (IC49), and reset IC (IC44) .
The EEPROM mainly stores adjustment data, MAC address,
and various set values. In order to suppress the standby
power consumption of the transceiver when the transceiver
is turned OFF, a setting (turned ON by default for models
shipped for European countries) allows the main MCU to go
into stop mode to reduce the standby current.
This mode is available to models shipped for countries
other than European countries.
The UART mainly performs other MCU communication at
a baud rate of 115,200 bps.
9-3. Scope MCU and Its Periphery
The scope MCU (IC380) is powered by a supply voltage
of 3.3 V and operated at a clock frequency of 18.432MHz
sourced by a crystal oscillator that oscillates at the same fre-
quency. The scope MCU is mainly in output timing and reset
control of the drawing data of the scope DSP (IC381). Addi-
tionally, the scope MCU is in the PLL and DDS control of the
scope unit (X42-343 A/10) and the switching of the BPF for
IF use.
IC300
SRX-DSP
IC385
DAC
Rch
IC397
DAC
Rch
IC388
DAC
L/R
IC669
(A/2)
IC669
(B/2)
Active LPF
CN662
MSCPI
IC662(B/2)
Buffer
IC656
(A/2)
IC656
(B/2)
Active LPF
IC681(B/2)
Buffer
CN671
SAGCV
MAGCV
CN101
CN669
SSCPI
IC202
TXMRX-
DSP
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