Abstract: An apparatus is operable to receive a digital video signal transmitted over a channel and comprises an operational module configured to operate in a first mode of operation and in a second mode. The apparatus is configured to switch operation of the operational module from the first mode to the second mode in dependence of an estimate of an environment (condition) of the channel.

Abstract: An apparatus for demodulating an analogue input signal comprises a hard limiter stage (4) for converting the signal to a two level signal. A digital down converter/low pass filter stage (6) converts the signal to a base band signal, and a symbol synchronization stage (8) extracts symbol timing. An instantaneous phase detector (10) calculates the instantaneous phase of the one or more symbols associated with the input signal. If the input signal has been modulated according to a pi/4DQPSK, pi/2DBPSK, GMSK, or a GFSK modulation scheme, a differential detector (12) determines a difference in the phase between adjacent symbols, a coarse frequency offset compensation stage (14) applies a compensation signal to compensate for frequency offset, and a frequency offset estimation stage (16) updates this compensation signal. A demapper (18) generates a demodulated output signal after compensation by the frequency offset compensation stage.

Abstract: An apparatus for timing recovery in an OFDM system comprises a third order phase lock loop comprising a Fast Fourier Transform stage for receiving a number of input signals in the time domain and transforming the signals to the frequency domain. A phase rotation stage adjusts the phase of one or more of the transformed signals. A frequency offset estimation stage estimates frequency offset between sampled signals and a first accumulator accumulates the frequency offset estimates. A low pass filter couplable to an output of the first accumulator stabilizes the phase lock loop. A second accumulator accumulates outputs of the low pass filter and controls phase rotation in the phase rotation stage. A controller controls timing associated with the window of operation of the Fast Fourier Transform process and is itself controlled by the second accumulator. There is also disclosed a receiver comprising the above apparatus and a method for timing recovery in an OFDM system.

Abstract: An apparatus for demodulating a modulated signal comprises an analog to digital converter (2, 12) for converting an analog modulated input signal to a digital signal. The analog to digital converter is arranged to sample the input signal at a predetermined sampling rate. A digital down converter (4, 14) then receives the digital signal at the sampling rate. The digital down converter has an associated digital intermediate frequency and reduces the frequency of the digital signal to one quarter of the sampling rate. A low pass filter (6, 16) filters selected frequencies from the digital signal. A frequency offset stage (8, 18) applies a modification to the frequency of the filtered signal to reduce frequency offset therein, and a differential demodulator (10, 20) demodulates the signal after modifying the frequency to reduce the frequency offset. There is also disclosed a method for demodulating a signal.

Abstract: An apparatus for demodulating a modulated signal comprises an analog to digital converter (2, 12) for converting an analog modulated input signal to a digital signal. The analog to digital converter is arranged to sample the input signal at a predetermined sampling rate. A digital down converter (4, 14) then receives the digital signal at the sampling rate. The digital down converter has an associated digital intermediate frequency and reduces the frequency of the digital signal to one quarter of the sampling rate. A low pass filter (6, 16) filters selected frequencies from the digital signal. A frequency offset stage (8, 18) applies a modification to the frequency of the filtered signal to reduce frequency offset therein, and a differential demodulator (10, 20) demodulates the signal after modifying the frequency to reduce the frequency offset. There is also disclosed a method for demodulating a signal.

Abstract: An apparatus is operable to receive a digital video signal transmitted over a channel and comprises an operational module configured to operate in a first mode of operation and in a second mode. The apparatus is configured to switch operation of the operational module from the first mode to the second mode in dependence of an estimate of an environment (condition) of the channel.

Abstract: An apparatus for demodulating an analogue input signal comprises a hard limiter stage (4) for converting the signal to a two level signal, A digital down converter/low pass filter stage (6) converts the signal to a base band signal, and a symbol synchronization stage (8) extracts symbol timing. An instantaneous phase detector (10) calculates the instantaneous phase of the one or more symbols associated with the input signal. If the input signal has been modulated according to a pi/4DQPSK, pi/2DBPSK, GMSK, or a GFSK modulation scheme, a differential detector (12) determines a difference in the phase between adjacent symbols, a coarse frequency offset compensation stage (14) applies a compensation signal to compensate for frequency offset, and a frequency offset estimation stage (16) updates this compensation signal. A demapper (18) generates a demodulated output signal after compensation by the frequency offset compensation stage.

Abstract: A digital receiver, comprising: a frequency converter (100, 101, 102, 103, 104, 105) arranged to convert a received signal into baseband signals; delay units (106, 107) arranged to delay the baseband signals to provide delayed signals; normalizing means (108) arranged to truncate the baseband signals and the delayed signals to a predetermined length and provide normalized signals; a demodulator (109) arranged to demodulate the normalized signals and provide a demodulated signal; and frequency offset sensing means (110) arranged to sense an envelope of the demodulated signal to provide an offset signal indicative of a frequency offset of the received signal.