TK-2317
27
5-4. Key Input
Keys and channel selector circuit.
The signal from the keys and channel selector are direct-
ly input to the MCU, as shown in Figure 10.
6. Signaling Circuit
6-1. Encode
■
Low-speed data (QT, DQT)
Low-speed data is output from pin 2 of the MCU. The sig-
nal passes through the low pass CR fi lter, and goes to the
baseband IC (IC812). The signal is mixed with the audio sig-
nal and goes to the VCO and TCXO (X1) modulation input
after passing through the D/A converter inside the baseband
IC (IC812) for BAL adjustment.
CIRCUIT DESCRIPTION /
电路说明
C
B
A
S
KEY1O
KEY2O
KEY3O
KEY4O
KEY1I
KEY2I
KEY3I
KEY4I
EN2
EN1
Selector
IC820
MCU
PF2
PF1
PTT
Side1
Side2
PTT
HSDENC
LSDO
IC820
MCU
IC812
Baseband IC
TCXO
3
2
21
MIC
23
MOD1
VCO
24
MOD2
18
ALT
Fig. 10 Key input /
图 10 键输入
Fig. 11 Encode /
图 11 编码
5-4. 键输入
键和信道选择电路。
如图 10 所示,
键和信道选择器的信号被直接输入微处理器。
6. 信令电路
6-1. 编码
■低速数据 (QT,DQT)
低速数据从微处理器的针脚 2(LSDO) 输出。信号通过低通
CR 滤波器器,并且送到基带 I C ( I C812)。此信号与音频信号
混合,在基带 I C ( I C812) 中进行信号处理之后,进入 V C O 和
TCXO(X1) 调制输入。