Patent ID: 8466805

Claim:
An emergency vehicle comprising: a siren signal generator configured to emit an electronic siren signal; a siren loudspeaker coupled to the siren signal generator and configured to emit an audible siren sound in response to receiving the electronic siren signal, the loudspeaker having two inputs; an impedance detector coupled to the two inputs of the loudspeaker and configured to: measure impedance across the two inputs of the loudspeaker; and output a loudspeaker presence signal if the measured impedance is within a predetermined range; a siren signal detector coupled to the siren signal generator and configured to emit a siren signal presence signal in response to verifying that the electronic siren signal has a set of predetermined siren signal characteristics; logic circuitry configured to emit an enable signal in response to receiving both the loudspeaker presence signal and the siren signal presence signal; and a radio frequency transmitter configured to transmit a radio frequency notification signal in response to receiving the enable signal; wherein the verifying step includes verifying that the electronic siren signal is a Society of Automotive Engineers (S.A.E.) approved or industry accepted variation siren signal.