Service manual

Service Manual SD170E Series
Page 25 of 44
Ext. Mod. signal flow in Transmitter
Level
Detector
Analog S/W
MC14053B
Data BPF
Sub-Audio LPF
MF6
Z1
Z
Y1
Y
Adj. Level
MCU
Check Audio In
Tone En
Audio In
Mod Out
Sub-Audio
Encoder
Y0
Z0
X1
X
X0
High : Audio In
Low : No Audio
Data Enable
Data In
Analog S/W
MC14053B
Sub-Audio LPF
MF6
Z1
Z
Y1
Y
MCU
Y0
Z0
X1
X
X0
Pre-Selector
RF Board
Sub-Audio LPF
4th Order
AF
IF IC
SA605DK
RSSI
Comparator
MF6Tone Detector
RSSI
Audio Out
Busy
Ext. Mod. signal flow in Receiver
BPF
30Hz ~ 5KHz
External modulated signal flow diagram
FFSK & GMSK
Two optional modem boards are available, ACC-513E, GMSK and ACC-514E, FFSK for SD-
170E to improve the efficiency for data transmission and offer maximum flexibility for user
application. Selection of the required modulation option is made installing wanted modem to
radio and programming several modem parameters through PC-programmer, ACC-916.
Modem board provides the facility to connect a computerized controller via an RS-232 level
serial data interface (i.e. Communication port COM1, COM2, etc. for PCs) to its Slave MCU.
Received data from controller (DTE) will then drive the FFSK or GMSK modulator and allow
transmission of serial data. It also provides FFSK or GMSK demodulator for the reception of
FFSK or GMSK modulated data signals. These are converted to RS-232 level serial data
stream for supply to a computerized controller.
In application of Sub-audio squelch, it can‟t apply to GMSK modulated signal because of their
frequency confliction. But, FFSK modulated signal can be mixed with sub-audio because it
consists of two different continuous tones which frequency spectra are on the audio
frequency region.
Brief block signal flow diagrams for each optional modem board are the following (See Figure
2.4. and Figure 2.5.).