Systems and methods for blind opportunistic navigation, cognitive deciphering of partially known signals of opportunity, and blind Doppler estimation from LEO satellite signals
View Patent ↗Systems, device configurations, and processes are provided for blind opportunistic navigation (BON) including cognitive deciphering of partially known signals of opportunity and blind Doppler estimation from LEO satellite signal. In one embodiment a method includes receiving a signal of opportunity and using a framework for BON. In one embodiment, the framework includes performing blind Doppler estimation and tracking, performing coherent integration, and performing blind beacon detection/tracking. Coherent integration may be performed once a blind estimate of the Doppler is produced, and detecting symbols of a beacon sequence is performed for at least one of acquiring, tracking, and navigating with the received signal of opportunity. According to another embodiment, a method for blind Doppler estimation, includes receiving a signal of opportunity, performing an initial wipe-off operation, performing a blind residual Doppler estimation, and performing a Doppler ambiguity resolution.
1 . A method for blind opportunistic navigation, the method comprising:
receiving, by a device, at least one signal of opportunity;
performing, by the device, at least one operation to estimate a Doppler frequency of the at least one signal;
performing, by the device, at least one operation for coherent integration of the at least one signal using the estimate of Doppler frequency, wherein coherent integration estimates at least one beacon sequence of the at least one signal;
detecting, by the device, at least one symbol of a beacon sequence of the at least one signal; and
controlling, by the device, navigation using the at least one beacon sequence.
2 . The method of claim 1 , wherein receiving at least one signal of opportunity includes receiving multiple signals in a bandwidth of interest, and wherein the at least one signal includes a synchronization beacon for receiver timing and carrier recovery.
3 . The method of claim 1 , wherein estimating Doppler frequency includes performing one or more operations to detect joint signal activity and to classify modulation of the at least one signal, wipe-off the data symbols from the at least one signal, and to determine a frequency of the at least one signal.
4 . The method of claim 1 , wherein estimating Doppler frequency includes tracking Doppler frequency of a plurality of signals of opportunity and detecting symbols of a beacon sequence for the plurality of signals of opportunity.
5 . The method of claim 1 , wherein Doppler frequency, modulation type, and length and symbols of a beacon signal of the at least one signal are unknown to the device, and wherein coherent integration includes integrating successive transmissions of a beacon signal using estimates of Doppler frequency and code phase to track the at least one signal of opportunity.
6 . The method of claim 1 , wherein coherent integration is performed to detect symbols of a beacon sequence of the at least one signal of opportunity, including determining presence of a beacon signal and tracking Doppler frequency of multiple signals of opportunity to determine the beacon sequence.
7 . The method of claim 1 , wherein coherent integration is performed for a number of complete cycles of beacon and synchronization signals to accumulate energy and to compensate for the low signal to noise ratios.
8 . The method of claim 1 , wherein detecting at least one symbol of a beacon sequence by correlating successive frames to determine occurrence of a transition, sampled using a chirp rare and processing accumulated frames using a tree based algorithm.
9 . The method of claim 1 , wherein controlling navigation includes determining a code phase estimate in meters as a pseudorange estimate of device position.
10 . The method of claim 1 , wherein controlling navigation includes stacking measurement vectors for sources of the at least one signal of opportunity to determine position of the device relative to source of the signal of opportunity.
11 . A device configured for blind opportunistic navigation, the device comprising:
a receiver configured to receive at least one signal of opportunity; and
a controller configured to
perform at least one operation to estimate a Doppler frequency of the at least one signal;
perform at least one operation for coherent integration of the at least one signal using the estimate of Doppler frequency, wherein coherent integration estimates at least one beacon sequence of the at least one signal;
detect at least one symbol of a beacon sequence of the at least one signal; and
control navigation using the at least one beacon sequence.
12 . The device of claim 11 , wherein receiving at least one signal of opportunity includes receiving multiple signals in a bandwidth of interest, and wherein the at least one signal includes a synchronization beacon for receiver timing and carrier recovery.
13 . The device of claim 11 , wherein estimating Doppler frequency includes performing one or more operations to detect joint signal activity and to classify modulation of the at least one signal, wipe-off the data symbols from the at least one signal, and to determine a frequency of the at least one signal.
14 . The device of claim 11 , wherein estimating Doppler frequency includes tracking Doppler frequency of a plurality of signals of opportunity and detecting symbols of a beacon sequence for the plurality of signals of opportunity.
15 . The device of claim 11 , wherein Doppler frequency, modulation type, and length and symbols of a beacon signal of the at least one signal are unknown to the device, and wherein coherent integration includes integrating successive transmissions of a beacon signal using estimates of Doppler frequency and code phase to track the at least one signal of opportunity.
16 . The device of claim 11 , wherein coherent integration is performed to detect symbols of a beacon sequence of the at least one signal of opportunity, including determining presence of a beacon signal and tracking Doppler frequency of multiple signals of opportunity to determine the beacon sequence.
17 . The device of claim 11 , wherein coherent integration is performed for a number of complete cycles of beacon and synchronization signals to accumulate energy and to compensate for the low signal to noise ratios.
18 . The device of claim 11 , wherein detecting at least one symbol of a beacon sequence by correlating successive frames to determine occurrence of a transition, sampled using a chirp rare and processing accumulated frames using a tree based algorithm.
19 . The device of claim 11 , wherein controlling navigation includes determining a code phase estimate in meters as a pseudorange estimate of device position.
20 . The device of claim 11 , wherein controlling navigation includes stacking measurement vectors for sources of the at least one signal of opportunity to determine position of the device relative to source of the signal of opportunity.