Spatial and time multiplexing of multi-band signals

• US 20060227905A1
• Filed: 04/12/2005
• Published: 10/12/2006
• Est. Priority Date: 04/12/2005
• Status: Active Grant

• Current Assignee: Novatel Incorporated (Hexagon AB)
• Original Assignee: Novatel Incorporated (Hexagon AB)
• Inventors: Fenton, Patrick C., Kunysz, Waldemar
• Granted Patent: US 7,460,615 B2
• Time in Patent Office: Days
• US Class Current: 375/345
• CPC Class Codes: G01S 19/32 Multimode operation in a single same satellite system, e.g. GPS L1/L2
• CPC Class Codes: G01S 19/33 Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS
• CPC Class Codes: G01S 19/36 relating to the receiver frond end
• CPC Class Codes: H04B 7/0822 according to predefined selection scheme
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26

Abstract

A multi-band receiver for use with satellite ranging systems is provided. The receiver has a simplified architecture in which input signals of various frequencies are multiplexed together to form a single composite analog signal. In accordance with one embodiment of the invention, this composite signal only requires a single RF circuit for down conversion to an intermediate frequency. The composite, downconverted signal is sampled, and the digitized samples are demultiplexed to form digital counterparts of the original signals from each frequency band. An embodiment for use with elements of a phased array antenna is also provided.

Claims

1. A receiver for decoding a composite signal consisting of a plurality of frequency bands, the receiver comprising:

a multiplexer coupled with an antenna for receiving as inputs, incoming signals in two or more frequency bands, said multiplexer producing a composite analog multiplexed signal from said incoming signals;

a single RF stage coupled to the output of said multiplexer for receiving said composite analog multiplexed signal said RF channel further comprising a heterodyning mixer for converting the composite signal to an intermediate frequency; and

a sampling circuit having one or more A/D converters and a demultiplexer for obtaining digitized samples and demultiplexing counterparts representing said incoming signals under the direction of an associated sampling clock.

2. The receiver as defined in claim 1 further comprising an associated signal processing device to process the incoming signals.

3. The receiver as defined in claim 1 wherein said frequency bands are the L1 and L2 frequency bands of the United States Global Positioning System.

4. The receiver as defined in claim 1 wherein the frequency bands represent frequencies from one or more different satellite systems including the European Galileo system and the Russian Federation Glonass system.

5. A receiver associated with a controlled reception pattern antenna having a number of antenna elements in a phased array, the receiver comprising:

a plurality of antenna elements each coupled to a multiplexer, said multiplexer producing a multiplexed composite signal which is comprised of information from each individual antenna element;

a single RF channel for down converting said multiplexed signal to an intermediate frequency signal having one or more portions falling within a desired intermediate frequency range;

a sampling circuit including a demultiplexer, said sampling circuit being adapted to produce digitized samples of incoming signals, said sampling circuit having a sampling clock associated therewith, and

a digital beam former and GPS signal processing device coupled to receive the outputs of said sampling circuit and a clocking signal having a timing associated with said sampling clock.

6. The receiver as defined by claim 5 further comprising an automatic gain control circuit associated with the input from each antenna element.

7. A method of processing a signal in a satellite receiver, including the steps of:

A) receiving from an antenna, a signal having a first frequency band portion and a second frequency band portion;

B) multiplexing said first frequency band portion and said second frequency band portion together to form a multiplexed signal;

C) adjusting the strength of each of said first and second frequency band portions;

D) down converting said multiplexed signal using a local oscillator and a mixer to generate a multiplexed intermediate frequency signal;

E) sampling said multiplexed downconverted signal using an A/D converter which samples said multiplexed downconverted signal at the Nyquist rate of the first frequency band portion and in zones between the sampling rate of said first frequency band portion, using the Nyquist rate of the second frequency band portion to sample the multiplexed intermediate frequency signal to generate a digitized multiplexed signal;

F) demultiplexing the digitized multiplexed signal and performing signal processing thereon to generate individual signals for the receiver from said different frequency bands.

8. The method as defined in claim 7 wherein sampling step is at a rate that is N times a rate of said signal processing, where there are N incoming signals multiplexed together.

10. The method as defined in claim 8 including the further step of providing a filter for each demultiplexed signal portion to filter undesired signals prior to passing the signal portion to its dedicated A/D converter.

9. A method of processing signals received by a satellite receiver, including the steps of:

A) receiving from an antenna, multiple incoming signals each having different signal structures;

B) multiplexing said incoming signals to form a multiplexed composite signal;

C) down converting said multiplexed composite signal using a local oscillator and a mixer to generate a multiplexed intermediate frequency signal;

D) demultiplexing the multiplexed intermediate frequency signal;

E) providing a demultiplexed signal representation of each incoming signal of each different signal structure to a dedicated individual A/D converter for that signal structure that produces samples of each said incoming signal; and

F) providing samples of each said incoming signal to an associated digital signal processor.