Geolocation aid and system
A method and system for geolocation using a street light system having transponding technology. A predetermined band of radio frequencies employing spread spectrum technology is used to identify locations relative to an individual street light.
1. A method for identifying positions within a geolocation system comprising:
transmitting an interrogation signal from a vehicle;
detecting the interrogation signal by a luminaire associate within at least one smart street light, wherein the smart street light has knowledge of a predetermined power spectral density shape of the interrogation signal transmitted by the vehicle;
sending a response from the smart street light;
receiving the response by the vehicle; and
measuring outputs of a plurality of bandpass filters employed with the luminaire associate and thereby estimating a position of the vehicle within the geolocation system from the interrogation signal detected by the luminaire associate.
2. The method of claim 1 further comprising listening, prior transmitting, to determine that no interfering signals are present.
3. The method of claim 1 wherein the interrogation and the response signals are direct sequence (DS) spread spectrum signals within a 57-64 GHz spectrum of frequencies.
4. The method of claim 3 wherein sending further comprises shaping the power of the response DS signal such that the vehicle will receive a DS signal with a response signal power spectral density that is approximately flat over a main lobe of the DS signal.
5. The method of claim 3 further comprising computing using a computational device operatively coupled to the vehicle to calculate a round trip signal propagation time between the vehicle transmission of the interrogation signal and reception of the response from the smart street light.
6. The method of claim 5 wherein the response carries a positioning estimate of the vehicle relative to the smart street light and the computational device uses the positioning estimate and the round trip signal propagation time to estimate position of the vehicle.
7. The method of claim 1 further comprising:
measuring, after detecting, the power spectral density of the interrogation signal received by the smart street light to determine a difference in a shape of the power spectral density for the interrogation signal received by the smart street light as compared to the predetermined power spectral density shape used to transmit the interrogation signal; and
determining a distance traveled by the interrogation signal received by the smart street light by determining attenuation as a function of distance required to create the difference in the shape of the power spectral density.
8. The method of claim 7 wherein measuring further comprises comparing outputs from a plurality of band pass filters to the predetermined power spectral density shape.
9. The method of claim 1 further comprising the vehicle originating a second signal that is received by the smart street light and inserted into a communication network.
10. A system for identifying locations within a geolocation system comprising:
a vehicle having a communication system operatively coupled to a transmitter that is configured to transmit an interrogation signal;
at least one street light having a luminaire associate that detects the interrogation signal and sends a response signal;
a receiver operatively coupled to the communication system, that receives the response signal; and
a computational device operatively coupled to the communication system that calculates a time period between transmission of the interrogation signal and reception of the response signal,
wherein the luminaire associate comprises a processing device that is configured to estimate a distance from the vehicle to the luminaire associate, and
further wherein the processing device estimates the distance by measuring a shape of the power spectral density of the interrogation signal detected by the luminaire associate and compares the shape with prior knowledge of the power spectral density shape for the interrogation signal as transmitted.
11. The system of claim 10 wherein the interrogation and the response signals are direct sequence (DS) spread spectrum signals within a 57-64 GHz spectrum of frequencies.
12. The system of claim 11 wherein the processing device compares the shape of the power spectral density of the interrogation signal detected by the luminaire associate to power spectral densities indicative of distances traveled by signals within the 57-64 GHz spectrum of frequencies.
13. The system of claim 11 wherein the luminaire associate shapes power of the response DS signal such that the vehicle will receive a DS signal with a response signal power spectral density that is approximately flat over a main lobe of the DS signal.
14. The system of claim 11 wherein the response carries a positioning estimate of the vehicle relative to the luminaire associate and the computational device uses the positioning estimate and the time period to estimate position of the vehicle.
15. The system of claim 10 further comprising the communication system listening for transmissions and wherein the transmitter waits to transmit the interrogation signal until there are no detectable transmissions.
16. The system of claim 10 further comprising the communication system originating a second signal that is received by the luminaire associate and inserted into a communication network.
17. The system of claim 10 wherein the response from the luminaire associate carries information useful to vehicles.