Ultra-wideband receiver and transmitter

• US 20060039449A1
• Filed: 10/13/2005
• Published: 02/23/2006
• Est. Priority Date: 05/16/1997
• Status: Active Grant

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Larrick J. Frederick Jr, Robert J. Fontana
• Inventors: Fontana, Robert J., Larrick, J. Frederick Jr.
• Granted Patent: US 7,369,598 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• 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 1/7172 Pulse shape in general H04L25/03834
• CPC Class Codes: H04B 1/7174 Pulse generation in general H04L25/03834
• CPC Class Codes: H04B 2001/6908 using time hopping

Abstract

A waveform-adaptive ultra-wideband (UWB) transmitter and noise-tracking UWB receiver for use in communications, object detection and radar applications. In one embodiment, the output of an oscillator is gated by a low-level impulse generator either directly or through an optional filter. In a special case of that embodiment wherein the oscillator is zero frequency and outputs a DC bias, a low-level impulse generator impulse-excites a bandpass filter to produce an UWB signal having an adjustable center frequency and desired bandwidth based on a characteristic of the filter. In another embodiment, the low-level impulse signal is approximated by a time-gated continuous-wave oscillator to produce an extremely wide bandwidth pulse with deterministic center frequency and bandwidth characteristics. The low-level impulse signal can be generated digitally. The UWB signal may be modulated to carry data, or may be used in object detection or ranging applications. The power amplifier may be gated to provide a power-efficient UWB transmitter. The UWB transmitter exhibits well defined and controllable spectral characteristics. The UWB transmitter is capable of extremely high pulse repetition frequencies (PRFs) and data rates in the hundreds of megabits per second or more, frequency agility on a pulse-to-pulse basis allowing frequency hopping if desired, and extensibility from below HF to millimeter wave frequencies.

Claims

1. A communication system utilizing an ultra-wideband transmitter, said system comprising:

a switched impulse generator to generate a low-level ultra-wideband signal characterized by a series of UWB pulses, said switched impulse generator including one of an on-off switched oscillator, an oscillator having a time-gated dc bias that alternately biases the oscillator on and off, and an impulse-gated mixer that mixes an oscillator output;

a filter responsive to said switched impulse generator to filter said UWB pulses;

an antenna responsive to said filter to radiate a representation of said UWB pulses; and

a receiver that detects data from individual ones of radiated UWB pulses.

3. The communication system as recited in claim 1, further comprising an amplifier interposed between said filter and antenna to amplify said ultra-wideband signal.

4. The communication system as recited in claim 3, wherein said filter comprises one of a band-pass filter and a pulse shaper that substantially confines radiated emissions of said antenna within a given passband.

5. The communication system as recited in claim 1, wherein the receiver includes:

a variable attenuator coupled to a receiving antenna to adjust attenuation levels thereof based on a rate of error detection of said radiated ultra-wideband signal received at said receiver; and

a detector to detect an output of said variable attenuator.

6. The communication system as recited in claim 5, wherein said detector comprises a tunnel diode and said variable attenuator adjusts said attenuation by alternately applying noise and received information signals to said tunnel diode.

7. The communication system as recited in claim 6, further including a controller that digitally controls the variable attenuator according to signals received during respective noise dwells and data dwells to enable the detector to discriminate between said noise and received information signals.

8. The communication system as recited in claim 7, wherein said controller utilizes a bit error rate to discriminate between noise and information signals.

2. A method of detecting an object utilizing ultra-wideband transmitting techniques, said method comprising:

impulse-switching an oscillator to generate a low-level ultra-wideband signal;

wave filtering said low-level ultra-wideband signal;

after said filtering step, transmitting a signal representing said low-level ultra-wideband signal; and

after said transmitting step, receiving from said object a reflected pulse of said ultra-wideband signal thereby to detect said object.

9. The method of claim 2, further comprising the step of providing a tunnel diode to receive the reflected pulse.

10. The method of claim 2, further comprising, after generating said low-level ultra-wideband signal, amplifying said low-level ultra-wideband signal.

11. The method of claim 10, wherein said filtering comprises one of bandpass filtering and pulse shaping of said low-level ultra-wideband signal in order to substantially confine radiated emissions of said antenna within a given passband.

12. The method of claim 11, further comprising the step of defining a bandwidth of the signal radiated upon the object.

14. The method of claim 2, further comprising, in the receiving step:

variably attenuating the reflected pulse to adjust an attenuation level thereof according detected error in the reflected pulse received at said receiver; and

detecting a signal produced by the reflected pulse after said variably attenuating.

15. The method of claim 14, further including providing a tunnel diode to detect the reflected pulse and adjusting said variably attenuating by alternately applying noise and received information signals to said tunnel diode.

16. The method of claim 15, further including digitally controlling said variably attenuating of the reflected pulse according to signal received during respective noise dwells and data dwells to enable discrimination between noise and signals representing the reflected pulse.

17. The method of claim 16, including utilizing bit error rate to discriminate between noise and signals representing the reflected pulse.

18. A method of transmitting an ultra wideband pulse, said method comprising:

generating a low-level UWB pulse that includes an energy burst having a few cycles of RF energy at a defined carrier frequency,

wave filtering the energy burst to reject out-of-band emissions, and

radiating a filtered representation of said energy burst.

19. The method of claim 18, further comprising amplifying said energy burst prior to said radiating.