Diversity receiver

• US 6,985,544 B2
• Filed: 12/08/2003
• Issued: 01/10/2006
• Est. Priority Date: 09/12/2003
• Status: Expired due to Fees

• Current Assignee: Uniden Corporation (Cornwall Capital Management LP)
• Original Assignee: Uniden Corporation (Cornwall Capital Management LP)
• Inventors: Matsui, Masaki, Sato, Shigeo, Ito, Muneki, Horibe, Akio
• Primary Examiner(s): Ghebretinsae, Temesghen
• Application Number:
  US10/729,372
• Publication Number:
  US 20050059431A1
• Time in Patent Office: 764 Days
• Field of Search: 375/347, 375/267, 375/144, 375/147, 375/148, 455/132, 455/135, 455/277.2, 455/277.1
• US Class Current: 375/347
• CPC Class Codes: H04B 7/0814 based on current reception conditions, e.g. switching to different antenna when signal level is below threshold

Abstract

It is an object of the present invention to improve the diversity gain by conducting linear prediction of fading fluctuations and switching antennas. In order to attain this object, the diversity receiver in accordance with the present invention comprises a plurality of antennas for receiving wireless signals subjected to direct spread modulation, an antenna switch for conducting antenna connection switching thereof, a primary demodulator for demodulating the wireless signals and obtaining a spread spectrum signal, a matched filter for finding a correlation value of the spread spectrum signal and a spread code for demodulation, a mean value computation unit for finding a mean SNR of the received signal by converting the maximum correlation value to a value per 1 frame, an estimation unit for linear prediction of the SNR of the received signal based on the time series data of the mean SNR, and a level comparator for comparing the SNR of the received signal that was predicted by the estimation unit with a threshold value and outputting a control signal for conducting antenna switching to the antenna switch.

Claims

1. A diversity receiver comprising:

a plurality of antennas for diversity receiving wireless signals subjected to direct spread modulation;

an antenna switch for selecting any one of said plurality of antennas and conducting connection switching thereof;

a demodulator for demodulating the wireless signals received via the antenna connected by said antenna switch and obtaining a spread spectrum signal;

correlation value detection means for finding a correlation value of said spread spectrum signal and a spread code for demodulation;

a mean value computation unit for finding a mean SNR (Signal to Noise Ratio) of the received signal by converting a maximum correlation value which is output by said correlation value detection means to a value per 1 frame;

storage means for storing said mean SNR;

an estimation unit for linear/evaluation of the SNR of the received signal based on a time series data of the mean SNR stored in said storage means; and

a level comparator for comparing the SNR of the received signal that was predicted by said estimation unit with a threshold value and outputting a control signal for conducing antenna switching to said antenna switch.

2. The diversity receiver according to claim 1, wherein

said estimation unit estimates the SNR of the received signal by secondary interpolation conducted by curvilinear regression when the number of time series data of the mean SNR stored in said storage is 3 or more.

3. The diversity receiver according to claim 1, wherein

said estimation unit estimates the SNR of the received signal by primary interpolation conducted by linear regression when the number of time series data of the mean SNR stored in said storage means is 2.

4. The diversity receiver according to claim 1, wherein

said level comparator compares the mean SNR stored in said storage means with a threshold value when the time series data number of the mean SNR stored in said storage means is 1 and outputs a control signal for conducting antenna switching to said antenna switch.

5. The diversity receiver according to claim 1, wherein

said estimation unit clears the time series data of said mean SNR stored in said storage means to zero each time the antenna is switched.