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TM-V7A/E
CIRCUIT DESCRIPTION
@1C407 (RD system)
SW No.
SW name
Function
0
CTCSS decoder input
"L" : OFF
"H" : RDV connection
1
CTCSS decoder input
"L" > OFF
"H" : RDU connection
2
Not used (Always set to OFF)
3 | Notused (Always set to OFF)
4
MIC RDV squelch control
"L": CLOSE
"H" : BUSY
5
MiC RDU squelch control
"L": CLOSE
"H" : BUSY
6
Not used (Always set to OFF)
7
Not used (Always set to OFF)
8
MIC RDV squelch control
"L": CLOSE
"H" : BUSY
9
MIC RDU squelch control
"L": CLOSE
"H" : BUSY
10
| Not used (Always set to OFF)
11 _| Not used (Always set to OFF)
Data Terminal and Peripheral Circuits
J402
(data
terminal)
is the
data
communications
terminal on the front.
It handies transmission control, data
input/output, and squelch signals.
There are two data communications
modes:
9600bps
mode and 1200bps mode.
9600bps mode communications
are GMSK
and
G3RUH
packet communications.
Unlike
with
1200bps
AFSK,
with
this
type
of
high-speed
modulation, frequency modulation is carried out after the
@Transmission signals
Transmission modulation signals enter from PKD of the
data terminals (J501). The path to the modulation depends
on whether communications are 9600bps mode or not.
These paths are shown as ®,
When PKS of the data terminais (J402) is low, the path
switches to ® and ©.
When
PTT is active, the path
switches to ©.
The
modulation
input levels etc. are in
Table 8. For 9600bps mode, the frequency shift depends
on the input signal level, so there is an amplitude limiting
circuit to hold the signal below 4 Vp-p to avoid extreme
shifts.
@Reception signals
PR9 is the 9600bps
data communications
reception
output.
It outputs the FM
detection circuit output (RD
Table7
®, and © in Figure 12.
SW No.
sw%
OE
12
| PTT BAND RDV control
"L" : Transmit band is 430
"H" : Transmit band is 144
13.
| PTT BAND RDU control
"L": Transmit band is 144
"H" : Transmit band is 430
14 | Not used (Always set to OFF)
15 __| Not used (Always set to OFF)
16
| DTMF decoder input
"L": OFF
"H" : RDV connection
17
| DTMF decoder input
"L' : OFF
"H" : RDV connection
18 {| Not used (Always set to OFF)
19
| Not used (Always set to OFF)
20
Not used (Always set to OFF)
21
Not used (Always set to OFF)
22
| DTMF decoder switching
"L": RD input
input
"H" ; MIC input
23
| DTMF decoder switching
"L": RD input
input
"H" : MIC input
digital base band signals (rectangular wave) are passed
through a band limiting filter.
For 9600bps
GMSK
for
example, compared to 4800Hz signals (nearly sine wave
signals passed through a filter), these
signals have a
hissing sound like digital modulation when listened to by ear.
Different types of modulation, such as GMSK and G3RUH,
are distinguished by the type of band limiting filter.
The amplitude of the PKD signal from the data terminals
(J402) is limited by D506 and D507.
Thanks to this circuit, the PKD signal does not go above 4
Vp-p and the frequency shift does not fluctuate extremely.
Pin No.
|Pin name
Specification
bps switching
1200bps
g600bps
1
PKD
Modulation input | 40mVp-p
2Vp-p
Frequency shift
| 3+0.5kHz
| 2.2+0.5kHz
4
PRe
Output level 500mVp-p/1 0kQ
|
Always output during reception
Output level 500mVp-p/10kQ
5
PR1
Not output when squeich off
signals) through
a buffer amp
(Q506:
2SC4738
(GR)).
These signals are always output whether the squelch is
open or closed.
Table8 DATA terminal input/output level
PR1
is the 1200bps data communications
reception
output.
It outputs the FM
detection
circuit output (RDT
signals) through a buffer amp (Q508:
2SC4738
(GR)).
These signals are always output whether the squelch is
open or closed.
18
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