Synchronization pulse generator in spread spectrum communication system

• US 4,860,307 A
• Filed: 10/09/1987
• Issued: 08/22/1989
• Est. Priority Date: 10/14/1986
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Kenwood (JVC Kenwood Corporation)
• Original Assignee: Kabushiki Kaisha Kenwood (JVC Kenwood Corporation)
• Inventors: Nakayama, Shigeyuki
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/106,420
• Time in Patent Office: 683 Days
• Field of Search: 375/1, 380/34
• US Class Current: 375/145
• CPC Class Codes: H04B 1/70712 with demodulation by means of convolvers, e.g. of the SAW type SAW convolvers in general G06G7/195

Abstract

A synchronization pulse generator in a spectrum spread communication system includes first and second envelope detectors for subjecting a correlation output of a spectrum spread signal to envelope detection; a threshold value generator for generating a threshold value having a level corresponding to an output from the second envelope detector; and a comparator for comparing an output level of the first envelope detector with a threshold value generated by the threshold value generator, and outputting an initial synchronization pulse.

Claims

1. A synchronization pulse generator in a spectrum spread communication system comprising:

first and second envelope detectors for subjecting a correlation output of a spectrum spread signal to envelope detection, a time constant in the second envelope detector being larger than a time constant of the first envelope detector;

threshold value generator means for generating a threshold value having a level corresponding to an output from the second envelope detector; and

a comparator for comparing an output level of the first envelope detector with a threshold value generated by the threshold value generator means, and outputting an initial synchronization pulse.

2. A synchronization pulse generator in a spectrum spread communication system according to claim 1, wherein said threshold value generator means comprises a rheostat for generating a DC output, and an adder for adding a DC output from said rheostat to an output from said second envelope detector.

3. A synchronization pulse generator in a spectrum spread communication system according to claim 1, the time constant of said second envelope detector is 1000 to 10000 times that of said first envelope detector.