Methods and systems for ultra wideband (UWB) receivers
Ultra-Wideband (UWB) wireless technology transmits digital data as modulated coded impulses over a very wide frequency spectrum with very low power over a short distance. Accordingly, the inventors have established UWB devices which accommodate and adapt to inaccuracies, errors, or issues within the implemented electronics, hardware, firmware, and software. Beneficially, UWB receivers may accommodate offsets in absolute frequency between their frequency source and the transmitter, accommodate drift arising from phase locked loop and/or from relative clock frequency offsets of the remote transmitter and local receiver. UWB devices may also employ modulation coding schemes offering increased efficiency with respect to power, data bits per pulse transmitted, and enabled operation at higher output power whilst complying with regulatory emission requirements. Further, UWB devices may support a ranging function with range/accuracy not limited to the low frequency master clock employed within these devices enabling operation with ultra-low power consumption.
1. A method of establishing a range comprising
establishing a first phase relating to a first wireless signal received from a first node at a second node;
establishing a second phase of a second wireless signal received by the first node from the second node;
establishing a result in dependence upon an average of the first phase and an average of the second phase;
establishing a phase relating to a time of flight of wireless signals propagating between the first node and second node;
correcting the phase relating to the time of flight for a first delay within a first receiver forming part of the second node and a second delay within a second receiver forming part of the first node;
establishing the range in dependence upon the phase relating to the time of flight and an integer number of clock cycles of delay relating to the time between a predetermined point in the transmission of the first wireless signal and a predetermined point in the receipt of the second wireless signal; wherein
determining the phase of the first signal and the second signal is established in dependence upon:
establishing a first estimate of the phase by employing a plurality N integration windows for which there are two accumulators per integration window to yield 2N consecutive integration windows; and
refining the first estimate in dependence upon the energy distribution between the integration window with the highest energy and its adjacent windows;
each of the first signal and the second signal is a synchronization pattern employed in synchronizing the first node and second node to each other;
the synchronization pattern comprises N bits; and
N is an integer greater than or equal to 2.
2. A method of establishing a range comprising
establishing a first phase relating to a first wireless signal received from a first node at a second node;
establishing a second phase of a second wireless signal received by the first node from the second node;
establishing a result in dependence upon an average of the first phase and an average of the second phase;
establishing a phase relating to a time of flight of wireless signals propagating between the first node and second node;
correcting the phase relating to the time of flight for a first delay within a first receiver forming part of the second node and a second delay within a second receiver forming part of the first node;
establishing the range in dependence upon the phase relating to the time of flight and an integer number of clock cycles of delay relating to the time between a predetermined point in the transmission of the first wireless signal and a predetermined point in the receipt of the second wireless signal; wherein
establishing the second phase relating to the second wireless signal received from the second node at the first node is established with a process comprising:
transmitting a ranging signal from the second node comprising N bits;
transmitting a pulse from the second node after a delay equivalent to a defined number of bits;
receiving the ranging signal with a receiver comprising a multipath filter and detecting received energy within a plurality of integration windows, where the receiver forms part of the first node;
temporarily disabling the multipath filter after receipt of the ranging signal and increasing a gain of the receiver to detect the pulse whereby a duration of integration windows employed by the receiver is reduced to provide increased resolution of detecting the pulse and accuracy of the second phase; and
N is an integer greater than or equal to 2.
3. The method according to claim 2 , wherein
the ranging signal is a synchronization pattern employed in synchronizing the first node and second node to each other.
4. A method of establishing a range comprising
establishing a first phase relating to a first wireless signal received from a first node at a second node;
establishing a second phase of a second wireless signal received by the first node from the second node;
establishing a result in dependence upon an average of the first phase and an average of the second phase;
establishing a phase relating to a time of flight of wireless signals propagating between the first node and second node;
correcting the phase relating to the time of flight for a first delay within a first receiver forming part of the second node and a second delay within a second receiver forming part of the first node;
establishing the range in dependence upon the phase relating to the time of flight and an integer number of clock cycles of delay relating to the time between a predetermined point in the transmission of the first wireless signal and a predetermined point in the receipt of the second wireless signal; wherein
establishing the first phase relating to the first wireless signal received from the first node at the second node is established with a process comprising:
transmitting a ranging signal from the first node comprising N bits;
transmitting a pulse from the first node after a delay equivalent to a defined number of bits;
receiving the ranging signal with a receiver comprising a multipath filter and detecting received energy within a plurality of integration windows, where the receiver forms part of the second node;
temporarily disabling the multipath filter after receipt of the ranging signal and increasing a gain of the receiver to detect the pulse whereby a duration of the integration windows employed by the receiver is reduced to provide increased resolution of detecting the pulse and accuracy of the first phase; and
N is an integer greater than or equal to 2.
5. The method according to claim 4 , wherein
the ranging signal is a synchronization pattern employed in synchronizing the first node and second node to each other.
6. A method of establishing a range comprising
establishing a first phase relating to a first wireless signal received from a first node at a second node;
establishing a second phase of a second wireless signal received by the first node from the second node;
establishing a result in dependence upon an average of the first phase and an average of the second phase;
establishing a phase relating to a time of flight of wireless signals propagating between the first node and second node;
correcting the phase relating to the time of flight for a first delay within a first receiver forming part of the second node and a second delay within a second receiver forming part of the first node;
establishing the range in dependence upon the phase relating to the time of flight and an integer number of clock cycles of delay relating to the time between a predetermined point in the transmission of the first wireless signal and a predetermined point in the receipt of the second wireless signal; wherein
determining the phase of the first signal and the second signal is established in dependence upon:
establishing a first estimate of the phase by employing a plurality N integration windows for which there are two accumulators per integration window to yield 2N consecutive integration windows; and
refining the first estimate in dependence upon an energy distribution between an integration window with a highest energy and its adjacent windows; and
N is an integer greater than or equal to 2.