Ultrawide-band communication system and method

• US 5,995,534 A
• Filed: 10/10/1997
• Issued: 11/30/1999
• Est. Priority Date: 09/20/1994
• Status: Expired due to Fees

• Current Assignee: Time Domain Corporation (Humatics Corporation)
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Fullerton, Larry W., Cowie, Ivan A.
• Primary Examiner(s): TSE, YOUNG TOI
• Application Number:
  US08/949,144
• Time in Patent Office: 781 Days
• Field of Search: 375/200, 375/208-210, 375/259, 375/367, 370/320, 370/342, 370/441, 370/515
• US Class Current: 375/146
• CPC Class Codes: H04B 1/69 Spread spectrum techniques
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/70753 Partial phase search
• CPC Class Codes: H04B 1/708 Parallel implementation
• CPC Class Codes: H04B 1/71632 Signal aspects H04B1/7172 and H04B1/7176 take precedence
• CPC Class Codes: H04B 1/71635 Transmitter aspects H04B1/7174 takes precedence
• CPC Class Codes: H04B 1/71637 Receiver aspects H04B1/7183 takes precedence
• CPC Class Codes: H04B 1/7176 Data mapping, e.g. modulation
• CPC Class Codes: H04B 1/7183 Synchronisation
• CPC Class Codes: H04B 14/026 using pulse time characteristics modulation, e.g. width, position, interval
• CPC Class Codes: H04B 2001/6908 using time hopping
• CPC Class Codes: H04B 2201/70707 Efficiency-related aspects
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

An impulse radio communications system using one or more subcarriers to communicate information from an impulse radio transmitter to an impulse radio receiver. The impulse radio communication system is an ultrawide-band time domain system. The use of subcarriers provides impulse radio transmissions added channelization, smoothing ad fidelity. Subcarriers of different frequencies or waveforms can be used to add channelization of impulse radio signals. Thus, an impulse radio link can communicate many independent channels simultaneously by employing different subcarriers for each channel. The impulse radio uses modulated subcarrier(s) for time positioning a periodic timing signal or a coded timing signal. Alternatively, the coded timing signal can be summed or mixed with the modulated subcarrier(s) and the resultant signal is used to time modulate the periodic timing signal. Direct digital modulation of data is another form of subcarrier modulation for impulse radio signals. Direct digital modulation can be used alone to time modulate the periodic timing signal or the direct digitally modulated the periodic timing signal can be further modulated with one or more modulated subcarrier signals. Linearization of a time modulator permits the impulse radio transmitter and receiver to generate time delays having the necessary accuracy for impulse radio communications.

Claims

1. An impulse radio transmitter, comprising:

a. a time base to output a periodic timing signal;

b. a code source that uses said periodic timing signal to output a code signal;

c. a code time modulator to time modulate said periodic timing signal using said code signal and output a coded timing signal, wherein the modulation of said periodic timing signal provides channelization and spectral smoothing of an impulse radio signal to be generated;

d. a subcarrier modulator to receive a subcarrier signal and an information signal and modulate said subcarrier signal using said information signal and output a modulated subcarrier signal;

e. a subcarrier time modulator to modulate said coded timing signal using said modulated subcarrier signal and output a modulated, coded timing signal; and

f. an output stage to generate said impulse radio signal using said modulated, coded timing signal, wherein said impulse radio signal comprises monocycle pulses spaced in time.

2. The impulse radio transmitter according to claim 1, wherein said subcarrier modulator frequency modulates said subcarrier signal.

3. The impulse radio transmitter according to claim 1, wherein said output stage transmits monocycle pulses that are broad-band signals.

4. The impulse radio transmitter according to claim 1, wherein said output stage transmits monocycle pulses that are bandlimited signals.

5. The impulse radio transmitter according to claim 1, wherein said code time modulator is responsive to a voltage source.

6. The impulse radio transmitter according to claim 1, wherein said code time modulator is responsive to a current source.

7. The impulse radio transmitter according to claim 1, wherein said code time modulator is responsive to a digital source.

8. The impulse radio transmitter according to claim 1, wherein said subcarrier time modulator is responsive to a voltage source.

9. The impulse radio transmitter according to claim 1, wherein said subcarrier time modulator is responsive to a current source.

10. The impulse radio transmitter according to claim 1, wherein said subcarrier time modulator is responsive to a digital source.

11. The impulse radio transmitter according to claim 1, further comprising:

a summer to receive and sum a plurality of modulated subcarrier signals and output a resultant signal;

wherein said subcarrier modulator receives a plurality of subcarrier signals, and modulates each of said plurality of subcarrier signals using one of a plurality of information signals to output said plurality of modulated subcarrier signals and said subcarrier time modulator modulates said code timing signal using said resultant signal to output said modulated timing signal.

12. The impulse radio transmitter according to claim 11, wherein said subcarrier modulator direct digitally modulates one of said plurality of subcarrier signals.

13. The impulse radio transmitter according to claim 12, further comprising means for pseudo Manchester coding of said direct digitally modulated subcarrier signal.

14. The impulse radio transmitter according to claim 12, wherein said code signal is binary, and said code time modulator is a binary-to-time delay generator that time positions said periodic timing signal according to said code signal.

15. The impulse radio transmitter according to claim 11, wherein said subcarrer modulator frequency modulates one of said plurality of subcarrier signals.

16. The impulse radio transmitter according to claim 1, wherein said code source comprises means for pseudo noise coding a data signal to produce said code signal.

17. The impulse radio transmitter according to claim 16, wherein said data signal is encoded by a return-to-zero direct digital encoder.

18. The impulse radio transmitter according to claim 17, wherein said return-to-zero encoder comprises one of a pseudo Manchester encoder, a frequency shift keying encoder, an n-ary phase modulation encoder and a phase amplitude modulation encoder.

19. The impulse radio transmitter according to claim 1, wherein said code signal is a pseudo noise code.

20. The impulse radio transmitter according to claim 1, wherein said output stage uses an antenna to transmit said impulse radio signal into a propagation medium.

21. The impulse radio transmitter according to claim 20, further comprising a transmission line coupled between said output stage and said antenna.

22. A method for transmitting impulse radio signals, comprising the steps of:

(1) providing a code signal using a periodic timing signal;

(2) time modulating said periodic timing signal using said code signal to output a coded timing signal, wherein said modulation of said periodic timing signal provides channelization and spectral smoothing of an impulse radio signal to be generated;

(3) modulating a subcarrier signal using an information signal to output a modulated subcarrier signal;

(4) time modulating said coded timing signal using said modulated subcarrier signal to output a modulated, coded timing signal; and

(5) generating maid impulse radio signal using said modulated, coded timing signal, wherein said impulse radio signal comprises monocycle pules spaced in time.

23. The method according to claim 22, further comprising the step of frequency modulating said subcarrier signal.

24. The method according to claim 22, further comprising the step of transmitting monocycle pulses that are broad-band signals.

25. The method according to claim 22, further comprising the step of transmitting monocycle pulses that are bandlimited signals.

26. The method according to claim 22, further comprising the steps of:

modulating each of a plurality of subcarrier signals using one of a plurality of information signals to output a plurality of modulated subcarrier signals;

summing said plurality of modulated subcarrier signals to output a resultant signal; and

modulating said code timing signal using said resultant signal to output said modulated timing signal.

27. The method according to claim 26, further comprising the step of direct digitally modulating one of said plurality of subcarrier signals.

28. The method according to claim 26, further comprising the step of frequency modulating one of said plurality of subcarrier signals.

29. The method according to claim 22, further comprising the step of pseudo noise coding a data signal to produce said code signal.

30. The method according to claim 29, further comprising the step of encoding said data signal as a return-to-zero direct digital signal.

31. The method according to claim 30, further comprising the step of encoding said return-to-zero direct digital signal using one of pseudo Manchester encoding, frequency shift keying encoding, n-ary phase modulation encoding and phase amplitude modulation encoding.

32. The method according to claim 22, further comprising the step of pseudo noise coding said information signal.

33. The method according to claim 22, further comprising the step of linearizing said modulated subcarrier signal.