She manages to send an SOS signal to the Captain.

"I didn't want to alarm them until we checked out that SOS signal."

Your technicians should be able to build a radio that would send out a simple SOS signal.

The newspaper reports that the crew sent out four SOS signals before dropping from radar.

She was much more the sort of girl who heard the faint SOS signals and organized the rescue operation.

Here is an example of an SOS signal; the portions in parentheses are an explanation only.

Fletcher would not send an SOS signal without good reason.

The continuous hissing of the SOS signal grew louder by the minute, then suddenly it stopped.

"The SOS signal comes from somewhere close to the robot colony," he reported.

However they received the SOS signals from the missing ship and will first go to rescue it.