METHOD AND DEVICE FOR RECEIVING A DEGRADED RADIONAVIGATION SIGNAL
First Claim
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1. A method of receiving a radionavigation signal comprising the steps of:
- over a first determined time, calculating correlations of the sampled signal received with a locally generated code of period T, the first determined time being equal to the period of the code T, the signal received and the code being shifted with respect to one another from one correlation to the next correlation over the determined time, the signal being shifted from one correlation to the next, the code being fixed, the sampled signal comprising a real component I and an imaginary component Q, the samples of the two components I and Q are placed in series alternately in one and the same memory, the calculations of correlation of the code with I and with Q being performed alternately, the results of the correlation calculations for the same component and having the same shift n between the signal and the code, and obtained over Tc code periods, being added together so as to obtain for each component a coherent integration respectively called ITC(n) and QTC(n), ITC(n)2+QTC(n)2 being calculated, a sum of the amplitudes or of the powers of the coherent integrations having the same shift n being calculated over a time Tnc (Tnc=K×
Tc) so as to obtain for each shift n a noncoherent integration C(n), prior to the correlation calculations step,storing the signal in another memory for a second determined time according to a writing frequency fe, the signal being read according to a reading frequency fl such that fl>
fe with a view to the correlation calculations step,wherein the correlation calculations step is carried out for several codes and in that the signal is read for each code.
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Abstract
The invention relates to a method of receiving a radionavigation signal. Over a first determined time correlations of the sampled signal received are calculated with a locally generated code of period T. The signal is received and the code is shifted with respect to one another from one correlation to the next correlation. Over the determined time, the signal is shifted from one correlation to the next, the code being fixed.
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Citations
24 Claims
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1. A method of receiving a radionavigation signal comprising the steps of:
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over a first determined time, calculating correlations of the sampled signal received with a locally generated code of period T, the first determined time being equal to the period of the code T, the signal received and the code being shifted with respect to one another from one correlation to the next correlation over the determined time, the signal being shifted from one correlation to the next, the code being fixed, the sampled signal comprising a real component I and an imaginary component Q, the samples of the two components I and Q are placed in series alternately in one and the same memory, the calculations of correlation of the code with I and with Q being performed alternately, the results of the correlation calculations for the same component and having the same shift n between the signal and the code, and obtained over Tc code periods, being added together so as to obtain for each component a coherent integration respectively called ITC(n) and QTC(n), ITC(n)2+QTC(n)2 being calculated, a sum of the amplitudes or of the powers of the coherent integrations having the same shift n being calculated over a time Tnc (Tnc=K×
Tc) so as to obtain for each shift n a noncoherent integration C(n), prior to the correlation calculations step,storing the signal in another memory for a second determined time according to a writing frequency fe, the signal being read according to a reading frequency fl such that fl>
fe with a view to the correlation calculations step,wherein the correlation calculations step is carried out for several codes and in that the signal is read for each code. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 17, 18, 19, 20, 21, 22, 23, 24)
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- 2. The method as claimed in claim 2, wherein the correlation calculations step is carried out for several frequency assumptions considered to compensate for the Doppler effect and in that the signal is read for each of these assumptions.
Specification