She programmed the computer to send out a distress signal on a frequency monitored by all Romulan vessels.

With a little tinkering and a lot of luck, Todd was able to adjust the Gringg communication system to the frequencies monitored by Spacedep.

ELTs for general aviation were constructed to transmit on 121.5 MHz, a frequency monitored by airliners and other aircraft.

Communication takes place by walkie-talkie, with frequencies monitored "by various security agencies," said one intelligence official.

Quickly the agency realized that they could identify the actual frequency being monitored if they produced their own transmissions and listened for the change in the superhet tone.

International distress frequencies: frequencies monitored by Coast Guard and other authorities for distress calls.

Additional frequencies, not normally monitored, can be used.

The military station operator will announce the specific amateur-band frequency being monitored.