Midian Electronics MTSD-3, Manual

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HARDWARE ALIGNMENT
Bandwidth: If tones A and B are close to one another it may be necessary to narrow the bandwidth of the
decoder by adjusting R-21. With JU1 uninstalled and generating the B tone to the decoder, adjust R-21 to where
U2 Pin 8 does not change from low to high.
Audio Input Level: If there is not enough level going into the decoder it may be necessary to reduce the value of
R-5.
Momentary Output Time: The MTSD-3 gives a 3 second momentary output by default. To increase this time
increase the value of C-9 or decrease the value of R-31 to decrease the time. Please note that this will also affect
the timing of the transpond timing.
Tone Decode Time: The acquisition timing of the MTSD-3 is for 750 msec to 1 second A tone. To lengthen the
time, increase the value of R-25 or decrease the value of R-25 to decrease the time. R-29 controls the acquisition
timing for the B tone and is affected in the same way as R-25.
OPERATION
Decode: Upon decoding of the proper 2-tone sequence the following events will occur:
Momentary Horn Output: The horn output will go low for 3 seconds.
Alert Tone Output: The 2400 Hz alert tone output will generate a tone for 3 seconds.
Transpond Output: The transpond output will go low for 1 second. This is used to activate the PTT of the
radio, so that the alert tone will be sent over the air.
LSQ Output: This line will go from +12 VDC to a float condition.
Latched -SQ Output: This line will go from a ground to a float.
Latched Call Output: This line will go from +12 VDC to ground.
Resetting of Latched Outputs:
Power: Cycling the power off and then back on will reset the outputs.
Monitor Input 1: If this input is used, taking the input from a ground, taken high or to a float, and then
taking this line back to ground will reset the latched outputs.
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