TK-3180
11
6-2. Low battery warning
The battery voltage is monitored by the microprocessor
(IC502 pin 126 : BATTLVL). When the battery voltage falls
below the voltage set by the Low Battery Warning adjust-
ment during the transmission, the red LED blinks to notify the
operator that it is time to replace the battery (When the “On
TX” option (default setting) under the Battery Warning / sta-
tus function in the FPU is selected.). If the battery voltage
falls below 5.8V, the transceiver does not transmit and the
warning tone beeps while the PTT switch is pressed.
Low battery warning
Battery condition
The red LED blinks during
The battery voltage is low but
the transmission.
the transceiver is still usable.
The red LED blinks and
The battery voltage is low and
the warning tone beeps while
the transceiver is not usable
the PTT switch is pressed.
to make calls.
6-3. Battery type detection
The transceiver automatically detects the battery type,
measuring the resistance between the S-terminal and GND
terminal on the battery pack and changes the supplied volt-
age to the S-terminal as below. The microprocessor then de-
tects the battery type.
Resistor value
Battery type
Input voltage of S-terminal
Open
Ni-Cd
4.5~5.0V
150k
Ω
Ni-MH
2.0~3.34V
47k
Ω
Li-ion
0.8~2.0V
Short
Battery case
0~0.8V
6-4. Key input
When any key is pressed, KI1 or KI2 become Low. And
CPU (IC502) set Q1 to Q9 “Low” sequentially. The CPU de-
tects which key is pressed, according to the voltage of KI1
and Kl2 and Q1 to Q9 timing.
7. Signaling Circuit
7-1. Encode
■
Low-speed data (QT, DQT, LTR)
Low-speed data is output from pin 33 of the CPU. The
signal passes through a low-pass filter (IC601 1/2), and goes
to the summing amplifier (IC600 2/2). The signal is mixed
with the audio signal and goes to the VCO and TCXO (X1)
modulation input after passing through the D/A converter
(IC605) for BAL adjustment.
SW
SW
SW
SUM
SUM
BUFF
AMP
VCO
TCXO
RXAF
MOD
6
5
7
EXTLIMIN
RX Audio
IC606
LPF
IC601
(1/2)
IC600 (2/2)
IC602 (1/2)
I2
O2
O1
I1
I6
O6
AF AMP
IC605
IC607
AQUA-L
HSDO
IC502
CPU
33
LSDO
■
High-speed data (2-tone, 5-tone, DTMF)
High-speed data (HSD) is output from pin 7 of the CPU.
The signal passes through a low-pass CR filter and provides a
TX HSD tone and a RX HSD tone. TX HSD deviation making
an adjustment by microprocessor is passed through the
switch (IC606) and then applied to the audio processor
(IC607).
The signal is mixed with the audio signal and goes to the
VCO and TCXO. The RX HSD tone is passed a summing am-
plifier (IC607). The D/A converter (IC605) for audio control,
audio power amplifier and then to the speaker.
■
MSK
MSK signal is output from pin 6 of IC607. The signal
passes through the D/A converter (IC605) for the MSK devia-
tion adjustment, and is routed to the VCO. When encoding
MSK, the microphone input signal is muted.
6
3
S2
B
S1
A
C
S
7
*
8
0
9
#
5
2
4
1
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Vss
Vdd
LCK
DATA
CLK
Vss
SO
Q10
Q9
Q8
IC500
KI1
KI2
CK
DT
SPSTB
IC502
CPU
Fig. 11
Key input
Fig. 12
Encode
CIRCUIT DESCRIPTION
