On Wed, 18 Sep 2002, Major Variola (ret) wrote:

In some parts of rural america, folks signal the presence of cops by flashing their headlights when driving.

Occurs to me that would be a cool function for SDR: press code for or say "cop". For N seconds, phone periodically sends "cop" message picked up by other phones, ignored by base station [1]. Phone also listens for these local broadcasts. Upon hearing a suprathreshold number of "cop" messages the phone alerts its owner.

Better than a radar detector for emissionless, but visible, cops. Over the hill coverage. Issues of spoofing, trust, consensus familiar to readers here.

[1] (different band entirely? UWB? B-tooth? FRS? )

Nice idea, but it won't ever achieve a critical mass of adoptees. Oinking one's headlights to signify the presense of a cop in waiting is a well established convention unlikely to be replaced by complicated technology. People who want to play with gizmos to avoid becoming revenue sources will buy radar detectors (unless they live in places like VA, where it is illegal to possess radar detection devices.) -MW-