QTech Data Systems DATRAN Q80 Telemetry Radio - Manual (Page 16)

TECHNICAL NOTES TECHNICAL NOTES TECHNICAL NOTES TECHNICAL NOTES
www.qtech.co.nz Tel 03 3663713
Circuit details of Radio Interface.
The opto isolators OPT1 and OPT2 provide isolation of the Maxon radio transmit key and busy lines between the
Q80 module and associated equipment.
Tra Tra Tra Transmitter Key nsmitter Key nsmitter Key nsmitter Key
The Maxon radio transmitter is keyed ON by pulling the TXKEY line to ground. The transmitter keyed KY LED3 will
turn ON. The TXKEY line ON current is approximately 10mA.
Receive Busy Receive Busy Receive Busy Receive Busy
The Maxon radio busy output line switches opto isolator OPT2 ON via transistors Q4 and Q5 when the radio
receiver is busy. The busy/mute MU LED2 will turn ON. The busy output line BUSY will sink current to ground via
the opto isolator output transistor. The BUSY output line can sink a maximum of 10mA.
Transmitter Audio Level Transmitter Audio Level Transmitter Audio Level Transmitter Audio Level
Potentiometer VR2 is used to set the Maxon radio transmit audio level. The required level is –3dBm for +/- 3kHz
(+/1.8 kHz) transmitter deviation.
Note Set +/- 3 kHz deviation for 25 kHz channel spacing and +/- 1.8 kHz for 12.5 kHz channel spacing i.e.
narrow band channel. These are the required levels when the Q80 Module is to be used with
QTech RTU
modules.
Receiv Receiv Receiv Receiver Audio level er Audio level er Audio level er Audio level
Potentiometer VR1 is used to set the received audio level. The required audio level is +/- 3kHz (1800Hz) deviation
of Maxon radio received signal produces –15dBm audio output.
Note Set +/- 3 kHz deviation for 25 kHz channel spacing and +/- 1.8 kHz for 12.5 kHz channel spacing i.e.
narrow band channel. These are the required levels when the Q80 Module is to be used with
QTech RTU
modules.
Audio Level Adjustment Audio Level Adjustment Audio Level Adjustment Audio Level Adjustment
The transmit and receive audio levels are preset by QTech prior to delivery and should not normally require
adjustment.
Note The 600 ohm modem line terminating resistor in the QTech RTU modules should be removed, i.e. not
installed.
To set the transmit and receive audio levels proceed as follows: