That computer on your desk is leading a secret life -- as a crude but potentially dangerous radio transmitter. Its video monitor and keyboard emit high-frequency radio waves that can be detected and decoded up to a mile away with relatively simple equipment, according to Hughes STX Corp., a subsidiary of General Motors Corp.'s Hughes Aircraft unit. It says business competitors can use those signals to steal commercially and legally sensitive information.
To combat such eavesdropping, Hughes STX has come out with what it calls Stealth PCs. They run the same software as IBM PCs, but their cabinets are electrically shielded to prevent most radio waves from exiting. They also layer confusing but invisible patterns onto their normal video signals. The systems sell for about 25% more than nonshielded PC clones of the same performance and capacity. Morgan Death, a Hughes STX vice-president, says the Stealth computers are similar to those developed for use by the Pentagon but much cheaper.