| 摘要 |
A simple and effective apparatus and method is disclosed for identifying the presence of an emergency vehicle in the immediate vicinity of a motor vehicle. This apparatus may be readily mounted and will not produce false alarms. The apparatus comprises: a transmitting unit, positioned within the emergency vehicle and having an activation circuit that turns on a digital identification data encoder that modulates an R.F. transmitter producing a digital data stream which is connected to a broadcast antenna; and, a receiving unit, carried by a motor vehicle so that it may be warned if the emergency vehicle is in its immediate vicinity having and having a R.F. receiver that demodulates a received digital data stream and then activates an alert pulse generator which is connected to an alarm means if the digital identification code matches the digital identification encoded in the transmitting unit. In a preferred aspect of this invention the digital identification data encoder modulates the R.F. transmitter with a data byte containing bits which identify the transmitting unit and the receiving unit comprises a data decoder which doubly checks the received digital data stream so that the alarm means only will be activated when two sequentially received data bytes are identical, thereby virtually eliminating any possibility of false activation of the alarm means.
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