Kenwood TK-7150 - Manual (Page 15)

TK-7150
15
5-3. DSP Circuit
The DSP circuit filters transmit/receive audio signal and
encode/decode signalling (QT, DQT, MSK, DTMF, 2-Tone,
LTR ID). This circuit consists of IC710, IC706, IC707, IC708,
IC709 and IC713.
The receive audio signal is converted from analog to digital
by IC713 with a sampling frequency of 19.2kHz. The digitized
audio signal is sent to DSP (IC710) to process the signalling
signal and audio signal. The processed digital audio signal is
fed to CODEC (IC713), converted from digital to analog, and
the analog signal is output from pin 16 (AOUTR).
The transmit audio signal coming from IC714 (A/2) is am-
plified by IC712 (B/2), fed to pin 3 (AINL) of CODEC (IC713),
and converted from analog to digital at a sampling frequency
of 19.2kHz. The digitized transmit audio signal is AGC-pro-
cessed, pre-emphasized and filtered at 300Hz to 3kHz by
DSP (IC710), and the resulting signal is feed back to CODEC
(IC713), and converted from digital to analog, and the analog
signal is output from pin 15 (AOUTL).
IC706, IC707, IC708 and IC709 are interface IC between
the CPU operated at 5.0V and the DSP operated at 3.3V.
5-4. Power Supply Circuit
The voltage is always applied from +B. D103 protects
IC102 (DFF) against overvoltage.
Pulses from power switch are input to the IC102 clock line
and the CPU (IC701). These clock pulses reverse the output
High (radio : turn off) → Low (radio : turn on), do not reverse
the output Low → High. The CPU (IC701) output the pulse to
IC102 set line to reverse the output Low → High.
IGN is input to the IC102 reset line and the CPU (IC701).
When the IC102 reset voltage rise, the output goes Low (ra-
D103
AVR
D106
SW
D102
SW
Q102
SW
Q101
SW
D104
SW
IC102
DFF
Q111
SW
Q112,113
SW
IC701
CPU
D105
SW
Q109,110
SW
D109
AVR
Q710
SW
Q108
SW
Q713
SW
R112
IGN PSW
+B
Q103
SW
SB
Fig. 6 Power supply circuit
dio : turn on). When IGN falls, the CPU (IC701) output the
pulse to IC102 set line to reverse the output Low → High
after the programmed time expire (Timed power off func-
tion).
If 24V is supplied to the radio by mistake, Q102 turns on,
Q101 turns off, the power is forced to be turned off.
This circuit consists of IC104 (8V), IC105 (5V), IC106
(3.3V), IC108 (3.3V) and IC107 (1.8V).
6. Display Circuit
The display unit consists of CPU (IC904), LCD assembly,
LED, and other components.
Channels are changed by the rotary switch (S1). The up/
down signals from the rotary switch enter the CPU (IC904),
and converted to a serial data signal, and are sent to the CPU
(IC701) in the TX-RX unit. The on/off signals of keys other
than the power switch, and the PTT and HOOK signals, are
converted to serial data and sent to the CPU (IC701) in the
TX-RX unit.
Data is displayed on the 12 digits and 3 digits dot matrix
alphanumeric display.
7. RS-232C Circuit
The RS-232C circuit connects the RS-232C serial port of a
personal computer directly to this model to perform FPU op-
eration (Read and Write). The FPU operation can also be per-
formed by connecting a programming cable (KPG-46) to the
local microphone on the front panel. The 232C driver IC
(IC703) changes the TTL-232C level. The firmware can only
be rewritten with the local microphone on the front panel.
PF1
D910
PF2 PF3 PF4 PF5 PF6
POWER
SW
RST
PSW
SB AVR
IC901
5V
RST
X901
12MHz
SW
SW
AF VR
D909
D908
SW
SW
D911
D913
D914
SW Q904 Q908
Key back lamp
Q903
REF
D907
SB
IC904
CPU
LCD
PTT
HK
Q907
D915
RX LED
SW
Q906
D912
TX LED
Q902
BEAT SHIFT
IRS
ES2
DM
1 8
MIC PTT SB HK ME
E
8LC
MIC
INT SP
Rotary SW
J901
Fig. 7 Display circuit
CIRCUIT DESCRIPTION