Patent ID: 8831079
Filing Date: 2014-09-09
Classification: H04L,H04N

Abstract:
1. An apparatus for detecting a symbol rate, comprising: an analog-to-digital converter (ADC), for receiving an analog input signal, and sampling the analog input signal at an original sampling frequency to generate a digital input signal; a coarse detection module, for receiving the digital input signal, and estimating a carrier frequency offset according to the digital input signal; a mixer, coupled to the coarse detection module and the ADC, for adjusting a frequency of the digital input signal according to the carrier frequency offset to generate a frequency-compensated signal; and a fine detection module, for determining a fine symbol rate according to the frequency-compensated signal; wherein the coarse detection module comprises: a spectrum generating unit, for analyzing the digital input signal to generate an input signal spectrum; a threshold determining unit, for determining a maximum energy and a minimum energy in the input signal spectrum, and determining threshold according to the maximum energy and the minimum energy; and a control unit, for determining the carrier frequency offset and the coarse symbol rate according to a plurality of intersections of the input signal spectrum and the threshold; wherein the threshold is an average of the maximum energy and the minimum energy, a difference between an average frequency of two of the intersections and a central frequency is the carrier frequency offset, and a frequency difference of the two intersections is the coarse symbol rate.