Method and apparatus for impulse radio transceiver calibration

• US 7,230,980 B2
• Filed: 09/17/2002
• Issued: 06/12/2007
• Est. Priority Date: 09/17/2001
• Status: Active Grant

• Current Assignee: Humatics Corporation
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Langford, David W., Troutman, Dennis L.
• Primary Examiner(s): Fan; Chieh M.
• Assistant Examiner(s): ZISKIND, ANNA Y
• Application Number:
  US10/245,222
• Publication Number:
  US 20030076879A1
• Time in Patent Office: 1,729 Days
• Field of Search: 375/219, 375/340, 375/342, 375/349, 375/358, 702/97, 702/94, 702/150, 702/158, 702/159
• US Class Current: 375/219
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/76 wherein pulse-type signals are transmitted

Abstract

A method for calibrating an impulse radio distance measuring system comprising an impulse radio transceiver by conducting a pulse through a transmit receive switch to an antenna, receiving return energy which has been discharged across the transmit receive switch, determining a time of arrival of the return energy. The return energy is comprised of two distinct pulses, one of which represents discharge of the transmit switch as the original pulse travels to the antenna, the second represents energy reflected from the antenna and again discharged across the transmit receive switch while the switch is in the transmit position. The timing of the un-reflected energy is determined then the timing of the reflected energy relative to the un-reflected energy is determined through auto-correlation of the time domain scan of the received composite waveforms.

Claims

1. A method for calibrating an impulse radio distance measuring system, said distance measuring system comprising an impulse radio transceiver, comprising the steps of:

a. switching a transmit/receive switch to a transmit position;

b. transmitting an un-reflected pulse through said switch to an antenna;

c. receiving said un-reflected pulse coupled through said switch as leakage energy while said switch is in said transmit position;

d. receiving a reflected pulse resulting from said un-reflected pulse reflecting from said antenna;

said reflected pulse coupled through said switch as leakage energy while said switch is in said transmit position;

e. determining a difference between times of arrival of said un-reflected pulse and said reflected pulse; and

f. calibrating said distance measuring system based on said difference between times of arrival.

2. The method of claim 1, wherein the step of determining a difference between times of arrival comprises the steps of:

measuring a first time of arrival of said reflected pulse to produce a first measurement;

measuring a second time of arrival of said un-reflected pulse to produce a second measurement; and

determining a difference between said first measurement and said second measurement to yield said difference between times of arrival.

3. The method of claim 1, wherein the calibrating step comprises the step of:

converting said difference between times of arrival to a distance.

4. The method of claim 2, wherein said step of measuring a second time of arrival comprises finding an occurrence of a leading energy excursion of said un-reflected pulse.

5. The method of claim 1, wherein the step of determining a difference between times of arrival comprises the step of:

measuring said difference between times of arrival of said un-reflected pulse and said reflected pulse by using autocorrelation.

6. An impulse radio transceiver apparatus for calibrating an impulse radio distance measuring system comprising:

a. a pulser configured to generate pulses having an ultra wideband frequency characteristic;

b. a transmit/receive switching means coupled to said pulser, said transmit/receive switching means having a transmit position;

c. an antenna means operatively coupled to said switching means;

d. a scanning receiver responsive to said switching means;

e. a control processor having at least one input, said at least one input being coupled to said scanning receiver, said control processor being adapted to determine times of arrival of a leakage energy resulting from an un-reflected pulse being transmitted through said transmit/receive switching means to said antenna means, said leakage energy resulting from said un-reflected pulse being discharged from said transmit position to said receive position along a discharge path as leakage energy while said transmit/receive switching means is in said transmit position and a reflected pulse resulting from said un-reflected pulse reflecting from said antenna means being coupled through said transmit/receive switching means as leakage energy while said transmit/receive switching means is in said transmit position, to convert said times of arrival into a distance, and to use said distance to calibrate said impulse radio distance measuring system.

7. The impulse radio transceiver apparatus of claim 6, wherein said control processor is adapted to determine said times of arrival by finding a leading edge of said un-reflected pulse.

8. The impulse radio transceiver apparatus of claim 7, wherein said control processor is adapted to determine said times of arrival by measuring a time differential between arrival of said reflected pulse and said un-reflected pulse.

9. The impulse radio transceiver apparatus of claim 8, wherein said time differential is measured by auto-correlation.

10. A method for calibrating an impulse radio distance measuring system, said distance measuring system comprising an impulse radio transceiver, comprising the steps of:

a. switching a transmit/receive switch to a transmit position;

b. transmitting an un-reflected pulse through said transmit/receive switch to an antenna; and

c. determining times of arrival of a leakage energy resulting from said un-reflected pulse being coupled through said transmit/receive switch as leakage energy while said transmit/receive switch is in said transmit position and a reflected pulse resulting from said un-reflected pulse reflecting from said antenna being coupled through said transmit/receive switch as leakage energy while said transmit/receive switch is in said transmit position.

11. The method of claim 10, wherein said step of determining said times of arrival comprises determining a first time of arrival, said first time of arrival being the time of arrival of said un-reflected pulse.

12. The method of claim 11, wherein said step of determining said times of arrival comprises determining a second time of arrival of said reflected pulse and determining a differential time, said differential time being the difference in time of the arrivals of said un-reflected pulse and said reflected pulse.

13. The method of claim 12, further comprising the step of:

d. converting said times of arrival into a distance.