Abstract:
Processing method for modulated data transmitted in the form of multiplexed frames (Frame 1, . . . Frame 10) containing symbols that have a symbol frequency. The method comprises a frame selection processing operation performed at least partly at a working frequency below the symbol frequency, and a demodulation processing operation comprising at least a part performed at the working frequency on the selected frames.
Abstract:
Processing method for modulated data transmitted in the form of multiplexed frames (Frame 1, . . . Frame 10) containing symbols that have a symbol frequency. The method comprises a frame selection processing operation performed at least partly at a working frequency below the symbol frequency, and a demodulation processing operation comprising at least a part performed at the working frequency on the selected frames.
Abstract:
A method and a circuit for decoding a coded signal including a first decoding system capable of receiving the coded signal and of providing a first signal comprising portions considered correct and a second decoding system capable of providing a second signal from the coded signal and from portions considered correct of the first signal.
Abstract:
A method and a device for determining, in a signal, a value of the frequency of a carrier and a value of the frequency of symbols carried by the carrier. A band of the signal is analyzed at three points and the relations between the powers at these points enable determining values of the carrier frequency and of the symbol frequency.
Abstract:
A method and a circuit for decoding a coded signal including a first decoding system capable of receiving the coded signal and of providing a first signal comprising portions considered correct and a second decoding system capable of providing a second signal from the coded signal and from portions considered correct of the first signal.
Abstract:
A device for providing a digital error signal, for a timing correction loop of a digital demodulator for digital transmission by phase modulation or amplitude and phase modulation, the device successively receiving pairs of digital signals representative of the components of complex signals, and having circuitry for providing a difference signal representative of the difference between the modulus of the complex signal corresponding to the last received pair of digital signals and the modulus of the complex signal corresponding to the previously-received pair of digital signals; circuitry for providing a weighting factor which depends on the angle between the complex signal corresponding to the last received pair of digital signals and the complex signal corresponding to the previously-received pair of digital signals; and circuitry for providing the error signal proportional to the product of the difference signal and of the weighting factor.
Abstract:
A method and a device for determining, in a signal, a value of the frequency of a carrier and a value of the frequency of symbols carried by the carrier. A band of the signal is analyzed at three points and the relations between the powers at these points enable determining values of the carrier frequency and of the symbol frequency.
Abstract:
A method for detecting the lock-in of a loop that synchronizes an internal clock on the transmission of value pairs provided by a demodulator. According to the method, a module of a vector that has as components the values of one of the value pairs is calculated, and the module is compared with a threshold that is smaller than a theoretical module. The locked-in condition is determined according to the ratio of the number of modules found to be greater than or smaller than the threshold to the total number of modules. In one preferred method, the threshold is incremented by a first value if the module is greater than the threshold and is decremented by a second value if the module is less than the threshold. A lock-in detection circuit for detecting the lock-in of a loop is also provided. A calculation circuit calculates a module of a vector that has as components the values of one of the value pairs. A register stores a threshold and a comparator compares the stored threshold with the calculated module. A modification circuit modifies the stored threshold based on the comparison result, and an analysis circuit analyzes the stored threshold to determine the locked-in condition.
Abstract:
The present invention relates to a demodulator provided to extract two signals modulated in phase quadrature from an intermediary frequency signal, including two analog-to-digital converters receiving the intermediary frequency signal and clocked in phase opposition by a clock at a frequency smaller than the intermediary frequency, at least equal to the bandwidth of the modulated signals, and such that the central frequency of one of the aliased spectrums of the signal converted into digital is substantially equal to half the clock frequency; and two multipliers respectively receiving the outputs of the analog-to-digital converters and receiving at the same time a sequence of values 1, −1, 1, −1, 1 . . . at the clock rate.