Method and apparatus for modulation differentiation

• US 5,912,922 A
• Filed: 06/26/1998
• Issued: 06/15/1999
• Est. Priority Date: 06/04/1997
• Status: Expired due to Term

• Current Assignee: Blackberry Limited
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Nowak, Michael, Koszarsky, Christopher, Northcutt, John
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US09/105,809
• Time in Patent Office: 354 Days
• Field of Search: 375/224, 375/228, 375/216, 375/227, 455/226.1, 455/226.2, 455/142, 455/422
• US Class Current: 375/224
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation

Abstract

To differentiate between different types of modulation, a fast RSSI detector performs a RSSI measurement on a received signal. The output of the RSSI detector is sampled over a sampling window and generates sampled values. A processor calculates absolute values of piecewise first derivatives of the sampled values and sums the result to create a summation constant. A modulation detector determines the type of modulation based on the value of the summation constant and an RSSI compensation calculates a compensation factor to correct the RSSI measurement.

Claims

1. An apparatus for calculating a compensation factor for incorporating into a received signal strength indicator measurement to compensate for measurement errors comprising:

a received signal strength indicator detector for generating a received signal strength indicator waveform whose value is logarithmically proportional to the amplitude of a received signal;

a sampler for sampling the generated received signal strength indicator waveform, the sampler sampling the received signal strength indicator waveform over a sampling window and generating sampled values;

a processor for calculating absolute values of piecewise first derivatives of the generated sampled values and further for calculating a summation constant equal to the sum of the absolute values of the piecewise first derivatives; and

a received signal strength indicator compensator for calculating a received signal strength indicator compensation factor according to the expression CF=(4.290×

10^-3)C-0.334 where CF is the compensation factor and C is the summation constant calculated by processor.

2. A method for calculating a compensation factor for incorporating into a received signal strength indicator measurement to compensate for measurement errors comprising:

generating a received signal strength indicator waveform whose value is logarithmically proportional to the amplitude of a received signal;

sampling the received signal strength indicator waveform over a sampling window and generating sampled values;

calculating absolute values of piecewise first derivatives of the sampled values;

calculating a summation constant equal to the sum of the absolute values of the piecewise first derivatives; and

calculating a received signal strength indicator compensation factor according to the expression CF=(4.290×

10^-3)C+0.334 where CF is the compensation factor and C is the summation constant calculated by processor.