Energy efficient ultra-wideband impulse radio systems and methods
Ultra-Wideband (UWB) technology exploits modulated coded impulses over a wide frequency spectrum with very low power over a short distance for digital data transmission. Such UWB systems through their receivers may operate in the presence of interfering signals and should provide for robust communications. Accordingly, an accurate and sharp filter that operates at low power is required and beneficially one that does not require a highly accurate power heavy clock. Further, many UWB applications require location and/or range finding of other elements and it would therefore be beneficial to provide a UWB based range finding and/or location capability removing the requirement to add additional device complexity and, typically significant, power consumption.
1 . A non-transitory computer readable medium storing computer executable instructions, the computer executable instructions when executed by a digital signal processing (DSP) circuit cause the DSP circuit to execute a process comprising:
establishing an energy within integration time windows that are established in dependence upon a clock signal generated by a clock source forming part of a first wireless transceiver of a system with the DSP circuit;
establishing an estimate of an elapsed time between transmission of a signal transmitted by the first wireless transceiver and receipt of an echo signal generated by a second wireless transceiver in response to the signal transmitted by the first wireless receiver where the estimate of the elapsed time is established in dependence upon an energy distribution determined by the DSP circuit for two consecutive integration time windows during which the echo signal is received; and
establishing a range between the first wireless transceiver and the second wireless transceiver with another process employing the estimate of the elapsed time established by the DSP.
2 . The non-transitory computer readable medium storing computer executable instructions according to claim 1 , wherein the first wireless transceiver comprises at least:
a filter circuit comprising an input port electrically coupled to an antenna for receiving wireless signals according to a defined wireless standard and an output port where the filter circuit processes the received wireless signals to generate processed wireless signals;
a clock source; and
an energy detector circuit electrically coupled to the output port of the filter circuit and the clock source; and
the DSP circuit is coupled to the energy detector circuit.
3 . The non-transitory computer readable medium storing computer executable instructions according to claim 1 , wherein either:
the energy distribution is established by dividing the energy within a second integration time window of the two consecutive integration time windows by the sum of the two consecutive integration time windows;
or:
the energy distribution is established by dividing the energy within a second integration time window of the two consecutive integration time windows by the sum of the two consecutive integration time windows; and
the estimate of the elapsed time is established by multiplying energy distribution by the time of each integration time window.
4 . The non-transitory computer readable medium storing computer executable instructions according to claim 1 , wherein the first wireless transceiver is not synchronized with the second wireless transceiver.
5 . A non-transitory computer readable medium storing computer executable instructions, the computer executable instructions when executed by a digital signal processing (DSP) circuit cause the DSP circuit to execute a process comprising:
transmitting a signal from a first wireless transceiver associated with the DSP circuit to a second wireless transceiver, where the signal triggers an echo signal to be generated by the second wireless transceiver which is subsequently received by the first wireless receiver;
establishing an energy within integration time windows that are established in dependence upon a clock signal generated by a clock source forming part of the first wireless transceiver and the output of an energy detector circuit forming part of the first wireless transceiver;
establishing an estimate of an elapsed time between transmission of the signal and receipt of the echo signal, the estimate of the elapsed time being established in dependence upon an energy distribution determined by the DSP circuit for two consecutive integration time windows during which the echo signal is received; and
establishing a range between the first wireless transceiver and the second wireless transceiver with another process employing the estimate of the elapsed time.
6 . The non-transitory computer readable medium storing computer executable instructions according to claim 5 , wherein either:
the energy distribution is established by dividing the energy within a second integration time window of the two consecutive integration time windows by the sum of the two consecutive integration time windows;
or:
the energy distribution is established by dividing the energy within a second integration time window of the two consecutive integration time windows by the sum of the two consecutive integration time windows; and
the estimate of the elapsed time is established by multiplying energy distribution by the time of each integration time window.
7 . The non-transitory computer readable medium storing computer executable instructions according to claim 5 , wherein the first wireless transceiver is not synchronized with the second wireless transceiver.
8 . A non-transitory computer readable medium storing computer executable instructions, the computer executable instructions when executed by a digital signal processing (DSP) circuit cause the DSP circuit to execute a process comprising:
transmitting a first packet comprising a plurality of pulse bundles from a first wireless transceiver associated with the DSP circuit;
starting a first timer associated upon transmission of the last pulse bundle of the plurality of pulse bundles;
processing a plurality of other pulse bundles forming a second packet received from a second wireless transceiver at a detector circuit forming part of the first wireless transceiver;
synchronizing to a predetermined pulse within a last pulse bundle of the plurality of other pulse bundles of the second packet using a synchronization circuit forming part of the first wireless transceiver;
stopping the first timer upon determining detection of the predetermined pulse within the last pulse bundle of the plurality of other pulse bundles of the second packet; and
calculating a time of flight in dependence upon the elapsed time of the first timer.
9 . The non-transitory computer readable medium storing computer executable instructions according to claim 8 , wherein the computer instructions when executed by another DSP circuit forming part of the second wireless transceiver cause the another DSP circuit to execute another process comprising:
processing the plurality of pulse bundles of the first packet received from the first wireless transceiver by another detector circuit forming part of the second wireless transceiver;
synchronizing to another predetermined pulse within a last pulse bundle of the plurality of pulse bundles of the first packet using a second synchronization circuit forming part of the first wireless transceiver;
starting a second timer upon determining detection of the another predetermined pulse; and
transmitting the second packet when the second timer reaches a predetermined wait time.
10 . The non-transitory computer readable medium storing computer executable instructions according to claim 8 , wherein
the computer instructions further cause the DSP circuit to execute a timing reference process which advances which tap of a plurality of taps of a delay-locked loop (DLL) forming part of the synchronization circuit is employed by a pulse generator of the first wireless transceiver in driving the pulse generator to generate a reference pulse sequence until a correlation peak is established with the correlation circuit;
the synchronization circuit correlates a portion of the plurality of pulse bundles received by the first wireless transceiver with the reference pulse sequence generated by the reference pulse generator;
the pulse generator is driven by the DLL which itself is driven by a reference clock.
11 . A non-transitory computer readable medium storing computer executable instructions, the computer executable instructions when executed by a digital signal processing (DSP) circuit cause the DSP circuit to execute a process comprising:
establishing a range between a pair of Ultra-Wideband (UWB) transceivers comprising a first ultra-wideband (UWB) transceiver with a second UWB transceiver using another process in execution upon the first UWB transceiver and the second UWB transceiver; wherein
the another process comprises:
synchronizing the first ultra-wideband (UWB) transceiver with the second UWB transceiver;
transmitting a first packet from the first UWB transceiver comprising a plurality of UWB pulse bundles;
starting a first timer associated with the first UWB transceiver upon transmission of the last pulse bundle;
processing the received plurality of UWB pulse bundles upon the second UWB transceiver;
synchronizing to a predetermined pulse within the UWB pulse bundles of the first packet using a circuit comprising at least a first correlator and a first delay-locked loop;
starting a second timer associated with the second UWB transceiver upon determining detection of the predetermined pulse within the last pulse bundle of the plurality of pulse bundles;
transmitting a second packet from the second UWB transceiver when the second timer reaches a predetermined wait time;
processing the received plurality of UWB pulse bundles associated with the second UWB transceiver upon the first UWB transceiver;
synchronizing to a predetermined pulse within the UWB pulse bundles of the second packet using a circuit comprising at least a second correlator and a second delay-locked loop;
stopping the first timer upon determining detection of the predetermined pulse within the last pulse bundle of the plurality of pulse bundles of the second packet;
calculating the time of flight in dependence upon the elapsed time of the first timer and determining a range between the first UWB transceiver and second UWB transceiver.
12 . The non-transitory computer readable medium storing computer executable instructions according to claim 11 , wherein
the process further comprises repeating the determination of the time of flight a second time with a reduced length of the first packet and second packet.
13 . The non-transitory computer readable medium storing computer executable instructions according to claim 11 , wherein
each UWB pulse bundle of the plurality of UWB pulse bundles comprises a plurality N pulses; wherein each pulse of the N pulses is at a predetermined frequency of a plurality M frequencies, has a predetermined amplitude, and has a predetermined pulse length.
14 . A non-transitory computer readable medium storing computer executable instructions, the computer executable instructions when executed by a digital signal processing (DSP) circuit cause the DSP circuit to execute a process comprising:
establishing a range between a pair of Ultra-Wideband (UWB) transceivers comprising a first ultra-wideband (UWB) transceiver with a second UWB transceiver using another process in execution upon the first UWB transceiver and the second UWB transceiver; wherein
the another process comprises:
providing a synchronization circuit forming part of the first ultra-wideband (UWB) transceiver for synchronizing wireless communications with the second UWB transceiver comprising at least a first correlator and a first delay-locked loop;
transmitting a first packet from the first UWB transceiver comprising a plurality of first UWB pulse bundles;
starting a first timer associated with the first UWB transceiver upon transmission of the last first UWB pulse bundle of the plurality of first UWB pulse bundles;
receiving a second packet from the second UWB transceiver comprising a plurality of second UWB pulse bundles;
synchronizing to a predetermined second UWB pulse bundle within the plurality of second UWB pulse bundles of the second packet using the synchronization circuit;
stopping the first timer upon determining detection of the predetermined pulse within the last pulse bundle of the plurality of pulse bundles of the second packet; and
calculating the time of flight in dependence upon the elapsed time of the first timer and determining a range between the first UWB transceiver and second UWB transceiver.
15 . The non-transitory computer readable medium storing computer executable instructions according to claim 14 , wherein
the another process further comprises:
processing the received plurality of first UWB pulse bundles upon the second UWB transceiver;
synchronizing to a predetermined first UWB pulse bundle of the plurality of first UWB pulse bundles within the first packet using a second synchronization circuit forming part of the second UWB transceiver for synchronizing wireless communications with the first UWB transceiver which comprises at least a second correlator and a second delay-locked loop;
starting a second timer associated with the second UWB transceiver upon determining detection of the predetermined pulse within the last pulse bundle of the plurality of pulse bundles;
transmitting a second packet comprising the plurality of second UWB pulse bundles from the second UWB transceiver when the second timer reaches a predetermined wait time.
16 . The non-transitory computer readable medium storing computer executable instructions according to claim 14 , wherein
the process further comprises repeating the determination of the time of flight a second time with a reduced length of the first packet and second packet.
17 . The non-transitory computer readable medium storing computer executable instructions according to claim 14 , wherein
each first UWB pulse bundle of the plurality of first UWB pulse bundles comprises a plurality N pulses; wherein each pulse of the N pulses is at a first predetermined frequency of a plurality M frequencies, has a first predetermined amplitude, and has a first predetermined pulse length; and
each second UWB pulse bundle of the plurality of second UWB pulse bundles comprises a plurality R pulses; wherein each pulse of the R pulses is at a second predetermined frequency of a plurality S frequencies, has a second predetermined amplitude, and has a second predetermined pulse length.
18 . A non-transitory computer readable medium storing computer executable instructions, the computer executable instructions when executed by a digital signal processing (DSP) circuit cause the DSP circuit to execute a process comprising:
establishing a range between a pair of Ultra-Wideband (UWB) transceivers comprising a first ultra-wideband (UWB) transceiver with a second UWB transceiver using another process in execution upon the first UWB transceiver and the second UWB transceiver; wherein
the another process comprises:
transmitting an ultra-wideband (UWB) impulse with the first UWB transceiver operating with a first clock rate having first integration windows in dependence upon the first clock rate;
receiving from the second UWB transceiver an echo signal generated by the second UWB transceiver in dependence upon receipt of the UWB impulse;
integrating received UWB signals within the first integration windows and determining when the received energy within a first integration window exceeds a predetermined threshold that the echo signal has been received;
passing the integrated energies within the first integration windows to a digital signal processing (DSP) circuit; and
deriving an estimate of elapsed time with the DSP circuit.
19 . The non-transitory computer readable medium storing computer executable instructions according to claim 18 , wherein
the echo signal is generated by the second UWB transceiver through a further process comprising
receiving the UWB impulse at the second UWB transceiver which is operating with a second clock rate having second integration windows in dependence upon the second clock rate;
integrating received UWB signals within the second integration windows and determining when the received energy within a second integration window exceeds a predetermined threshold that the UWB impulse has been received; and
transmitting in the next second integration window after a determination of receipt of the UWB impulse the echo signal.
20 . The non-transitory computer readable medium storing computer executable instructions according to claim 18 , wherein
at least one of:
the UWB impulse comprises a plurality N pulses; wherein each pulse of the N pulses is at a first predetermined frequency of a plurality M frequencies, has a first predetermined amplitude, and has a first predetermined pulse length; and
the echo signal comprises a plurality R pulses; wherein each pulse of the R pulses is at a second predetermined frequency of a plurality S frequencies, has a second predetermined amplitude, and has a second predetermined pulse length.