Diversity receiver and method by detecting signal strengths in successive stages

• US 6,415,141 B1
• Filed: 12/17/1999
• Issued: 07/02/2002
• Est. Priority Date: 12/17/1998
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kakura, Yoshikazu, Osawa, Tomoki
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Nguyen, Simon
• Application Number:
  US09/465,632
• Time in Patent Office: 928 Days
• Field of Search: 455/269, 455/270, 455/272, 455/275, 455/276.1, 455/277.1, 455/277.2, 455/562, 455/67.1, 455/101, 455/278.1, 342/422-437, 375/347
• US Class Current: 455/277.1
• CPC Class Codes: H04B 7/0805 with single receiver and antenna switching H04B7/0822 takes precedence

Abstract

A diversify receiver comprises an antenna selector for selecting signals received by diversity antennas. Detection circuitry detects respective strengths of the selected signals and produces first and second strength indication signals. A mode selector is provided for selecting a reference threshold or the second strength indication signal. A comparator compares the output of the mode selector with the first strength indication signal. The mode selector is controlled to select the reference threshold so that the first strength indication signal is compared with the reference threshold and then to select the second strength indication signal in response to a first output signal of the comparator indicating that the first strength indication signal is higher than the reference threshold, so that the first strength indication signal is compared with the second strength indication signal. The antenna selector is then controlled according to a second output signal of the comparator indicating the result of the comparison between the first and second strength indication signals.

Claims

1. A diversity receiver having a plurality of diversity antennas for producing antenna signals, comprising:

a first selector for selecting said antenna signals;

detection circuitry for detecting respective strengths of the selected antenna signals and producing Therefrom first and second strength indication signals;

a second selector for selecting a reference threshold or said second strength indication signal;

comparator circuitry for comparing in output signal of the second selector with said first strength indication signal; and

a control circuit for controlling said second selector to select said reference threshold so that said first strength indication signal is compared with said reference threshold and controlling said second selector to select said second strength indication signal in response to a first output signal of the comparator circuitry indicating that said first strength indication signal is higher than said reference threshold, so that said first strength indication signal is compared with said second strength indication signal,

said control circuit controlling said first selector according to a second output signal of the comparator circuitry indicating a result of comparison between said first and second strength indication signals.

2. A diversity receiver as claimed in claim 1, wherein said detection circuitry comprises:

a signal strength detector connected to receive said selected antenna signals; and

a sampling circuit for sampling in output signal of the signal strength detector.

3. A diversity receiver having a plurality of diversity antennas for producing antenna signals, comprising:

a first selector for selecting said antenna signals;

detection circuitry for detecting respective strengths of the selected interim, signals and producing therefrom a plurality of strength indication signals;

a second selector for selecting a reference threshold during a first mode and selecting one of said strength indication signals during a second mode;

comparator circuitry for comparing, during said first mode, the reference threshold selected by the second selector with one of said strength indication signals and determining, during said second mode, a maximum value of said plurality of strength indication signals including said one strength indication signal selected by the second selector; and

a control circuit for controlling said second selector to operate in said first mode and subsequently controlling said second selector to operate in said second mode in response to a first output signal of the comparator circuitry indication that said one strength indication signal is higher, than said reference threshold, and controlling said first selector according to a second output signal of the comparator circuitry identifying one of said antenna signals corresponding to the strength indication signal of said maximum value.

4. A diversity receiver as claimed in claim 3, wherein said comparator circuitry comprises:

a plurality of comparators, each comparator comparing between a pair of said strength indication signals; and

a maximum detector for determining said maximum value from output signals of said comparators and identifying one of said strength indication signals corresponding to said maximum value.

5. A diversity receiver as claimed in claim 3, wherein said detection circuitry comprises:

a signal strength detector connected to receive said selected antenna signals for detecting the strengths of the selected antenna signals; and

a sampling circuit for sampling the detected strengths to produce said plurality of strength indication signals.

6. A method of selecting antenna signals or a plurality of diversity antennas, comprising the steps of:

a) selecting one of said antenna signals;

b) detecting a strength of the selected antenna signal and producing therefrom a first strength indication signal;

c) comparing said first strength indication signal with a reference threshold;

d) repeating the steps (a) and (b) to produce second and third strength indication signals if said first strength indication signal is higher than said reference threshold;

e) performing a comparison between said second and third strength indication signals; and

f) selecting uric of said antenna signals according to a result of the comparison by the step (e).

7. A method of selecting antenna signals of a plurality of diversity antennas, comprising the steps of:

a) selecting one of said antenna signals;

b) detecting a strength of the selecting antenna signal and producing therefrom a strength indication signal;

c) comparing said strength indication signal with a reference threshold;

d) repeating the steps (a) and (b) to produce a plurality of strength indication signals if said strength indication signal is higher than said reference threshold;

e) determining a maximum value of said plurality of strength indication signals and identifying one of said antenna signals

corresponding to the strength indication signal of the maximum value; and

f) selecting said identified antenna signal.