Acquisition of frequency bursts in PCN

• US 5,377,224 A
• Filed: 10/07/1993
• Issued: 12/27/1994
• Est. Priority Date: 10/07/1993
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Hudson, John E.
• Primary Examiner(s): Cain, David C.
• Application Number:
  US08/133,448
• Time in Patent Office: 446 Days
• Field of Search: 375/1
• US Class Current: 375/136
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence

Abstract

A method of acquiring frequency bursts in a PCN broadcast control channel, including the steps of:

i) sampling PCN r.f. signals for successive blocks of time of duration of half the duration of a frequency burst;

ii) determining the first block to have a spectrum level to exceed a threshold value,

iii) comparing the spectrum levels of said first block and an adjacent block during successive occurrences of the frequency burst; and

iv) adjusting the timing of the two blocks until the spectrum levels of the two blocks are substantially equal.

Claims

1. A method of acquiring frequency bursts in a personal communication network (PCN) broadcast control channel including the steps of:

i) sampling PCN radio frequency (r.f.) signals for successive blocks of time of duration of half the duration of a frequency burst;

ii) determining the first block to have a spectrum level to exceed a threshold value,

iii) comparing the spectrum levels of said first block and an adjacent block during successive occurrences of the frequency burst; and

iv) adjusting the timing of the two blocks until the spectrum levels of the two blocks are substantially equal.

2. A method of acquiring frequency bursts in a personal communication network (PCN) broadcast control channel, including the steps of:

i) sampling at a first rate a group of channels having different known frequencies for successive blocks of time of a duration of half the duration of a frequency burst;

ii) performing a digital discrete Fourier transform (DFT) filter operation on the signal samples in each block;

iii) comparing the peak spectrum level of each DFT filtered sample with a predetermined threshold value to determine the first block to have a spectrum level to exceed the threshold value;

iv) comparing the spectrum levels of said first block and an adjacent block repetitively substantially on successive occurrences of the frequency burst to derive a differential of the spectrum levels;

v) generating an error signal representing the differential of the spectrum levels; and

(vi) applying said error signal in a feedback loop to adjust the sampling times of said first and adjacent blocks to drive the differential of the spectrum levels to zero.

3. A method according to claim 2 further including the steps of initially down converting the PCN r.f. signals to baseband, performing a first sampling of the baseband signals at a second rate higher than said first rate and digitally filtering said sampled baseband signals prior to performing said sampling at said first rate.