Circuit Operation - Tait TOP Operation And Service Manual

4.2

Circuit operation

Programming
Computer
SK1
KL3
Rx/Tx data
Programmer
Direct
Programming Cable
SK102 Internal options connector
GPIO port
48 TM8000 Encryption
Audio buffering, gain reduction and amplification is provided by IC U7, a
quad Op Amp. This reduces the higher Tx audio level in the TM8000 radio
down to a similar level to the TOP radio, and then amplifies it back up again
after the encryption module, to match the TM level. This allows the same
module settings for TOP or TM8000.
Note
TM8000 Rx levels similar to the TOP and the Op Amps in the
Rx path are mainly buffering the Rx audio signal.
The diagram that follows illustrates the operation of the XA2324-01
circuitry:
Microcontroller
Reset
PTT
TM8000
Options Board
Radio Microcontroller
12
Channel/Code
Channel/Code
display (up/down buttons)
GPIO1 sends PTT to the module and GPIO2 detects PTT from the
module. As the module's PTT line is common, D2 and IC U6 (a 4053)
isolate the two PTT lines and prevent the radio from locking up on Tx.
Encrypt/Decrypt
Tx/Rx
Switch
Tx / Rx
switch
RSSI AUD_TAP_OUT
F1
Green
TM8000 Main PCB
LED
Midian Encryption Programming and Service Manual
June 2006 © Tait Electronics Limited
Encryption Module
Tx/Rx
Switch
20 way edge connector
Tx / Rx
switch
AUD_TAP_IN