Traffic preemption system communication method
A remotely-controlled traffic-preemption system and method includes an encoder circuit, an optical source, an optical detector, and a decoder circuit. The encoder circuit is adapted to generate a set of signal pulses. At least one bit of a data word is encoded as a function of amplitude modulation of a first subset of the set of signal pulses and at least another bit of the data word is encoded as a function of frequency modulation of a second subset of the set of signal pulses. The optical source is adapted to transmit a set of light pulses having a respective light pulse for each signal pulse of the set of signal pulses. The optical detector is adapted to receive the set of light pulses. The decoder circuit is adapted to generate the data word from the set of light pulses received at the optical detector.
1. A remotely-controlled traffic-preemption system, comprising:
an encoder circuit adapted to generate a set of signal pulses, wherein at least one bit of a data word is encoded as a function of amplitude modulation of a first subset ot the set of signal pulses and at least another bit of the data word is encoded as a function of frequency modulation of a second subset of the set of signal pulses;
an optical source adapted to transmit a set of light pulses having a respective light pulse for each signal pulse of the set of signal pulses;
an optical detector adapted to receive the set of light pulses; and
a decoder circuit adapted to generate the data word from the set or light pulses received at the optical detector.
2. The system of claim 1 , wherein the encoder circuit and the decoder circuit are each further adapted to modify the optical pulses included in the first and second subsets responsive to a key.
3. The system of claim 1 , wherein the optical source is mounted to a vehicle and the data word includes a vehicle identification code associated with the vehicle.
4. The system of claim 1 , wherein the decoder circuit is further adapted to issue a traffic-preemption command for an associated traffic light responsive to the data word.
5. The system of claim 1 , wherein the first subset of the set of the signal pulses and the second subset of the set of the signal pulses do not share any signal pulse.
6. The system of claim 1 , wherein the first subset of the set of the signal pulses and the second subset of the set of the signal pulses share at least one signal pulse.
7. A communication method for use in a remotely-control traffic-preemption system, the method comprising:
encoding at least one bit of a data word as a function of amplitude modulation of a first subset of a set of optical pulses; and
encoding at least another bit of the data word as a function of frequency modulation of a second subset of the set of optical pulses;
transferring the set of optical pulses to an optical detector; and
decoding the data word from the optical pulses received at the optical detector.
8. The communication method of claim 7 , further comprising modifying the optical pulses included in the first and second subsets in response to a key.
9. The communication method of claim 7 , wherein an optical emitter is mounted to a vehicle, the data word includes a vehicle identification code associated with the vehicle, and transferring the set of optical pulses to the optical detector includes transmitting the set of optical pulses from the optical emitter and receiving the set of optical pulses at the optical detector.
10. The communication method of claim 7 , further comprising attempting to validate the data word and selecting a phase for an associated traffic light in response to the validation of the data word.
11. The communication method of claim 7 , wherein the first subset of the set of the optical pulses and the second subset of the set of the optical pulses do not share any signal pulse.
12. The communication method of claim 7 , wherein the first subset of the set of the optical pulses and the second subset of the set of the optical pulses share at least one signal pulse.
13. An optical emitter for a remotely-controlled traffic-preemption system, the optical emitter comprising:
an encoder circuit adapted to generate a set of signal pulses, wherein at least one bit of a data word is encoded as a function of amplitude modulation of a first subset of the set of signal pulses and at least another bit of the data word is encoded as a function of frequency modulation of a second subset of the set of signal pulses; and
an optical source adapted to transmit a set of light pulses having a respective light pulse for each signal pulse of the set of signal pulses.
14. The system of claim 13 , wherein the encoder circuit is further adapted to modify the optical pulses included in the first and second subsets responsive to a key.
15. The optical emitter of claim 13 , wherein the optical source is mounted to a vehicle and the data word includes a vehicle identification code associated with the vehicle.
16. The optical emitter of claim 13 , wherein the first subset of the set of the signal pulses and the second subset of the set of the signal pulses do not share any signal pulse.
17. The optical emitter of claim 13 , wherein the first subset of the set of the signal pulses and the second subset of the set of the signal pulses share at least one signal pulse.
18. A phase selector for a remotely-controlled traffic-preemption system, the phase selector comprising:
an optical detector adapted to receive the set of light pulses, wherein at least one bit of a data word is encoded as a function of amplitude modulation of a first subset of the set of light pulses and at least another bit of the data word is encoded as a function of frequency modulation of a second subset of the set of light pulses; and
a decoder circuit adapted to generate the data word from the set of light pulses received at the optical detector.
19. The phase selector of claim 18 , wherein the data word includes a vehicle identification code associated with a vehicle transmitting the set of light pulses and the decoder circuit is further adapted to attempt to validate the vehicle identification code.
20. The phase selector of claim 19 , wherein the decoder circuit is further adapted to issue a command selecting a phase for an associated traffic light responsive to the validation of the vehicle identification code.