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 method comprising
providing a first Ultra-Wideband (UWB) transceiver which incorporates:
a filter circuit comprising an input port electrically coupled to an antenna for receiving UWB signals and an output port where the filter circuit processes the received UWB signals to generate processed UWB signals;
a clock source; and
an energy detector circuit electrically coupled to the output port of the filter circuit and the clock source; and
a digital signal processing (DSP) circuit coupled to the energy detector circuit; wherein
the first UWB transceiver receives an echo signal generated by a second UWB transceiver in response to a signal transmitted by the first UWB receiver;
the DSP executes a process comprising:
establishing the energy within integration time windows that are established in dependence upon a clock signal generated by the clock source;
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 for two consecutive integration time windows during which the echo signal is received; and
establishing a range between the first UWB transceiver with a second UWB transceiver with another process employing the estimate of the elapsed.
2. The method according to claim 1 , wherein
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.
3. The method according to claim 1 , wherein
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 method according to claim 1 , wherein
the first UWB transceiver and the second UWB transceiver are not synchronized with each other.
5. A method comprising:
providing a first Ultra-Wideband (UWB) transceiver comprising an energy detector circuit and a digital signal processor (DSP) coupled to the energy detector circuit; wherein
the DSP executes a process comprising:
transmitting a signal to a second UWB transceiver, where the signal triggers an echo signal to be generated by the second UWB transceiver which is subsequently received by the first UWB receiver;
establishing the energy within integration time windows that are established in dependence upon a clock signal generated by a clock source forming part of the first UWB transceiver and the output of the energy detector circuit;
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 for two consecutive integration time windows during which the echo signal is received; and
establishing a range between the first UWB transceiver with a second UWB transceiver with another process employing the estimate of the elapsed time.
6. The method according to claim 5 , wherein
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.
7. The method according to claim 5 , wherein
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.
8. The method according to claim 5 , wherein
the first UWB transceiver and the second UWB transceiver are not synchronized with each other.
9. A method comprising:
providing a first Ultra-Wideband (UWB) transceiver comprising a digital signal processor (DSP) coupled to a detector circuit and a synchronization circuit comprising a correlation circuit; wherein
the DSP executes a process comprising:
transmitting a first packet comprising a plurality of UWB pulse bundles;
starting a first timer associated upon transmission of the last pulse bundle of the plurality of UWB pulse bundles;
processing a plurality of other UWB pulse bundles forming a second packet received from the second UWB transceiver;
synchronizing to a predetermined pulse within a last pulse bundle of the plurality of other UWB pulse bundles of the second packet using the synchronization circuit;
stopping the first timer upon determining detection of the predetermined pulse; and
calculating a time of flight in dependence upon the elapsed time of the first timer.
10. The method according to claim 9 , wherein
the second UWB transceiver comprises another digital signal processor (DSP) coupled to another detector circuit and another synchronization circuit comprising another correlation circuit and another delay-locked loop; and
the another DSP executes another process comprising:
processing the plurality of UWB pulse bundles of the first packet;
synchronizing to another predetermined pulse within a last pulse bundle of the plurality of UWB pulse bundles of the first packet using the second synchronization circuit;
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.
11. The method according to claim 9 , wherein
the correlation circuit comprises a delay-locked loop (DLL) comprising a plurality of taps which are spaced at a predetermined time offset relative to one another;
the predetermined time offset of the plurality of taps from one another and the number of taps within the plurality of taps are established in dependence upon at least one of a nominal data rate of the second UWB signal and a duration of a set of other UWB pulse bundles of the plurality of other UWB pulse bundles which comprises a bit of data within the second packet.
12. The method according to claim 10 , wherein
the correlation circuit comprises a delay-locked loop (DLL) comprising a plurality of taps which are spaced at a predetermined time offset relative to one another;
the predetermined time offset of the plurality of taps from one another and the number of taps within the plurality of taps are established in dependence upon at least one of a nominal data rate of the second packet and a duration of a set of other UWB pulse bundles of the plurality of other UWB pulse bundles which comprises a bit of data within the second packet;
the another correlation circuit comprises another DLL comprising another plurality of taps which are spaced at another predetermined time offset relative to one another;
the another predetermined time offset of the another plurality of taps from one another and the another number of taps within the another plurality of taps are established in dependence upon at least one of a nominal data rate of the first packet and a duration of a set of UWB pulse bundles of the plurality of UWB pulse bundles which comprises a bit of data within the first packet.
13. The method according to claim 9 , wherein
the correlation circuit comprises a delay-locked loop (DLL) comprising a plurality of taps which are spaced at a predetermined time offset relative to one another and reference pulse generator which is driven by a signal from a pulse generator for generating a reference pulse sequence where the correlation circuit correlates a portion of a the plurality of UWB pulse bundles received by the first UWB transceiver 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; and
a timing reference process executed by DSP advances which tap of the plurality of taps from the DLL is employed by the pulse generator in driving the reference pulse generator to generate the reference pulse sequence until a correlation peak is established with the correlation circuit.
14. The method according to claim 10 , wherein
the correlation circuit comprises a delay-locked loop (DLL) comprising a plurality of taps which are spaced at a predetermined time offset relative to one another and reference pulse generator which is driven by a signal from a pulse generator for generating a reference pulse sequence where the correlation circuit correlates a portion of the plurality of other UWB pulse bundles received by the first UWB transceiver with the reference pulse sequence generated by the reference pulse generator;
the reference pulse generator is driven by the DLL which itself is driven by a reference clock;
a timing reference process executed by DSP advances which tap of the plurality of taps from the DLL is employed by the reference pulse generator in driving the reference pulse generator to generate the reference pulse sequence until a correlation peak is established with the correlation circuit
the another correlation circuit comprises another DLL comprising another plurality of taps which are spaced at another predetermined time offset relative to one another and another reference pulse generator which is driven by a signal from another pulse generator for generating another reference pulse sequence where the another correlation circuit correlates a portion of the plurality of UWB pulse bundles received by the second UWB transceiver with the another reference pulse sequence generated by the another reference pulse generator;
the another reference pulse generator is driven by the another DLL which itself is driven by another reference clock; and
another timing reference process executed by another DSP advances which tap of the another plurality of taps from the another DLL is employed by the another reference pulse generator in driving the another reference pulse generator to generate the another reference pulse sequence until another correlation peak is established with the another correlation circuit.
15. The method according to claim 9 , wherein
the correlation circuit comprises a delay-locked loop (DLL) comprising a plurality of taps which are spaced at a predetermined time offset relative to one another; and
the DSP executes a timing reference process which employs the correlation circuit in dependence upon processing the plurality of other UWB pulse bundles transmitted by second UWB transceiver.
16. The method according to claim 10 , wherein
the correlation circuit comprises a delay-locked loop (DLL) comprising a plurality of taps which are spaced at a predetermined time offset relative to one another;
the DSP executes a timing reference process which employs the correlation circuit in dependence upon processing the plurality of other UWB pulse bundles transmitted by second UWB transceiver;
the another correlation circuit comprises another DLL comprising another plurality of taps which are spaced at another predetermined time offset relative to one another; and
the another DSP executes another timing reference process which employs the another correlation circuit in dependence upon processing the plurality of UWB pulse bundles transmitted by first UWB transceiver.