# US 6,721,354 B1 · Method of searching the point which is the nearest from a characteristic of a received signal in an assembly of non-uniformly distributed points

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- Number: US 6,721,354 B1
- Document ID: US6721354B1
- Status: Granted
- Kind: B1
- Application number: 09/390,852
- Filed: 1999-09-07
- Granted: 2004-04-13
- Earliest claimed: 1998-09-08
- Assignees: Koninklijke Philips Electronics N.V.
- Inventors: Antoine Chouly; Véronique Brun
- Web page: https://patentgrep.com/patent/US6721354B1

## CPC

- H03M 1/1235: {Non-linear conversion not otherwise provided for in subgroups of H03M1/12}
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)

## Abstract

The invention proposes an efficient method of determining, in an arbitrary assembly of non-uniformly distributed points, the point which is nearest from a characteristic of a given analog signal. It is particularly applicable to the detection of symbols in a PCM modem. The method comprises the step of considering successive search intervals, each search interval being obtained by splitting up a preceding search interval into two intervals, each interval comprising a number of points, the numbers being equal or different by one, such that one of these two intervals which comprises the received point constitutes the next search interval.

## Claims

### Claim 1

A method of searching, in an assembly of non-uniformly distributed points (C(i), i=0, . . . , k−1), the point which is the nearest from a characteristic (|S|) of a given analog signal, comprising the steps of:
considering successive search intervals (Ij) in the assembly, and wherein a first interval is determined using a lowest and highest amplitude points, and in successive search intervals, splitting up a previous search interval into two intervals, each of the two intervals including a respective number of points, the respective number of points being equal or different by one.

### Claim 2

A receiver comprising:
means for receiving an analog signal; and
a decoder arranged to select, in an assembly of non-uniformly distributed points, the point which is the nearest from a characteristic of the received analog signal, said decoder being configured for elaborating successive search intervals (Ij) in the assembly, wherein a first interval is determined using a lowest and highest amplitude points, and the successive search intervals being obtained by splitting up a previous search interval into two intervals, each of the two intervals including a respective number of points, the respective number of points being equal or different by one.

### Claim 3 (depends on 2)

A receiver as claimed in claim 2, further comprising means for determining a point, referred to as central point of a search interval, from the entire part of half the number of points comprised in the interval.

### Claim 4

A modem comprising:
means for receiving analog signals; and
means for decoding the received analog signals, said decoding means comprising means for selecting, in an assembly of non-uniformly distributed points, the point which is the nearest from the amplitude of the received analog signal,
wherein a first interval is determined using a lowest and highest amplitude points, and wherein said selection means includes means for elaborating successive search intervals in the assembly, the successive search intervals being obtained by splitting up a previous search interval into two intervals, each interval including a respective number of points, the respective number of points being equal or different by one.

### Claim 5

A transmission system comprising:
at least a transmitter: and
a receiver for receiving analog signals, the receiver including decoding means for selecting, in an assembly of non-uniformly distributed points, the point which is the nearest from a characteristic of the received signal,
wherein a first interval is determined using a lowest and highest amplitude points, and wherein said decoding means includes means for elaborating successive search intervals in the assembly, the successive search intervals being obtained by splitting up a previous search interval into two intervals, each interval including a respective number of points, the respective number of points being equal or different by one.