User`s manual
100-M0056X2B    11 of 28 
www.cobham.com/gms 
15  Not connected   
16  USB power, Reset 
17  USB Data -   
18  USB Data +   
19  USB Gnd   
20-29  Not connected   
30  PA_Shut_DN  Provides TTL level [+3V] signal for control of external 
PA 
31  RS232 Control Tx   
32  RS232 Control-Rx   
33  RS232 GND   
34-36  Not connected   
37  Audio right +   
38  Audio right -   
39
Audio right line opt.  Pin 39 is connected to pin 38 for audio right channel 
input impedance of 600 ohms , balance in (mic or line 
level) 
40  Audio right GND   
41  Audio left +   
42  Audio left -   
43  Audio left line opt  Pin 43 is connected to pin 42 for audio left channel 
input impedance of 600 ohms; balance in (mic or line 
level). 
44  Audio left GND   
6.1.2  Frequency Select Switches 
There are four external rotary switches mounted into the chassis of the MDT-B (see 
Figure 2). They are used to control RF frequency selection. Frequency selection can also 
be controlled through GMS control software; see section 6. The rotary switches can be 
disable or enable using GMS control software; refer to section 6.3.3.2 under 
Configuration/Special Setup/Others. The most significant switch (SW100) represents 
1000MHz (0-9) units, the second switch (SW101) represents 100 MHz (0-9) units, the 
third switch (SW102) represents 10 MHz (0-9) units and the fourth switch (SW103) 
represents 1 MHz (0-9) units. Hence the highest switch selection can be 9999 MHz and 
the lowest is 0000 MHz. For example with the switches in the following positions, the 
frequency will read 2014 MHz: 
0
9 1
6
2
3
4
5
7
8
0
9 1
6
2
3
4
5
7
8
0
9 1
6
2
3
4
5
7
8
0
9 1
6
2
3
4
5
7
8
2
0 1 4
SW100
And with the switches in the following positions the frequency will read 924MHz: 










