# US 8,787,435 B2 · Narrow band interference determined by second and fourth order norms

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- Number: US 8,787,435 B2
- Document ID: US8787435B2
- Status: Granted
- Kind: B2
- Application number: 14/047,204
- Filed: 2013-10-07
- Published: 2014-02-06
- Granted: 2014-07-22
- Earliest claimed: 2009-07-30
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Bijoy Bhukania; Jawaharlal Tangudu; Karthik Ramasubramanian
- Web page: https://patentgrep.com/patent/US8787435B2

## CPC

- H03G 3/3036: {in high-frequency amplifiers or in frequency-changers (H03G3/3052, H03G3/32, H03G3/34 take precedence)}
- H03M 1/185: {the determination of the range being based on more than one digital output value, e.g. on a running average, a power estimation or the rate of change}
- H04B 1/1036: {with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters (H04B1/123 takes precedence; filter circuits H03H)}
- H04B 17/309: Measuring or estimating channel quality parameters
- H04B 17/345: Interference values ({signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]} H04B17/336)
- H04L 27/08: Amplitude regulation arrangements
- H03G: CONTROL OF AMPLIFICATION
- 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)
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Automatic gain control in a receiver. A method for controlling operating range of an analog-to-digital converter (ADC) by an automatic gain control circuit includes estimating a peak-to-average ratio corresponding to an analog signal from digital samples of the analog signal. The method includes determining a peak value corresponding to the analog signal based on the peak-to-average ratio. Further, the method includes maintaining magnitude of the analog signal at an input of the ADC and gain of the receiver based on the peak value.

## Claims

### Claim 1

A method for detecting narrow band interference by an automatic gain control circuit in a receiver, comprising:
A. estimating a peak-to-average ratio corresponding to an analog signal from digital samples of the analog signal, the estimating a peak-to-average ratio includes determining a second order norm of the digital samples, the second order norm representing a root-mean-square voltage of the digital samples, and determining a fourth order norm of the digital samples, the fourth order norm being a statistical representation of peak amplitude characteristics of the digital samples;
B. comparing the peak-to-average ratio with a threshold; and
C. detecting the narrow band interference if the peak-to-average ratio is below the threshold.

### Claim 2 (depends on 1)

The method as claimed in claim 1 including controlling an operating range of an analog-to-digital converter based on the narrow band interference by providing the peak-to-average ratio as a metric to be used by the analog-to-digital converter.