The Compact DSP Test Set is designed to operate safely in situations
where telephone wiring may be carrying digital traffic, voltage feed to
remote electronics or the hazardous voltages that result from fault
conditions or misuse of the cable.
When set to OFF mode, on connection to a circuit,the test set sounds
an alarm to alert the user to the presence of voltages above 75V DC
(nominal). These voltages are normally present on circuits carrying
digital services. If the circuit is active, the user can select MONITOR
mode and listen to the sound to determine if the circuit is carrying
digital services without disrupting the traffic.
Selecting TALK mode will stop the alarm signal and loop the line without
damage to the test set. If the alarm signal persists, it indicates that
the voltage on the line is above 120V (nominal). In this case the line is
not looped avoiding damage to the test set as well as alerting the user
to the presence of voltages.