Method and device for calculating frequency offset of FM signal
A frequency modulation signal and frequency offset calculation technology, applied in the field of signal processing, can solve the problems of channel noise influence, inaccurate frequency offset results, etc., and achieve the effect of high calculation efficiency and accurate frequency offset results
Active Publication Date: 2020-06-30
上海顺久电子科技有限公司
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Problems solved by technology
However, since the signal carrier of the FM signal has a frequency offset itself, and also has a frequency offset introduced by the modulation content, if the frequency discriminator directly discriminates the frequency, in many cases the sync head is not a piece of unmodulated original carrier, but a modulated signal, then the characteristics of the sync header symbol itself will affect the frequency offset calculated by the frequency discriminator
In addition, there is also the noise effect of the channel itself
Therefore, the frequency offset results obtained by using the existing technology are not accurate
Method used
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[0031] Aiming at the problem that the phase detector obtains the frequency offset directly through phase detection, a large number of statistical samples are required, and the accuracy of the frequency offset result obtained by itself is not high. This application proposes a new method for calculating frequency offset.
[0032] figure 1 The method for calculating the frequency offset of the FM signal provided by an embodiment of the present application, such as figure 1 As shown, the method includes:
[0033] S101. Collect a first phase value corresponding to a start position of a window of a preamble signal and a second phase value corresponding to an end position in phase information of an FM signal.
[0034] Among them, the first phase value can be recorded as φ 1 , the second phase value can be written as φ 2 .
[0035] Here, the preamble signal may refer to an already determined codeword in the FM signal. Optionally, before acquiring the phase information of the FM ...
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The embodiment of the invention provides a frequency offset calculation method and apparatus of a frequency modulated signal. The method comprises the following steps: collecting a first phase value corresponding to a starting position and a second phase value corresponding to an ending position of a window of a preamble signal in phase information of the frequency modulated signal, and calculating a phase change variable in the window of the preamble signal according to the first phase value and the second phase value; determining a phase offset value in the window of the preamble signal according to a total phase offset value of the frequency modulated signal; and calculating the frequency offset of the frequency modulated signal by adopting the phase offset value in the window of the preamble signal and the width of the window of the preamble signal. The phase change in the window of the preamble signal is obtained according to phase information sampling, and the frequency offset is calculated in combination with the width of the window of the preamble signal without counting a large number of samples, therefore the calculation efficiency is high, and the calculated frequency offset result is more accurate.
Description
technical field [0001] The present application relates to signal processing technology, and in particular to a frequency offset calculation method and device for FM signals. Background technique [0002] In the process of studying FM signals, it is often necessary to calculate the frequency offset. Specifically, frequency offset is a unique phenomenon in FM waves, and refers to the shift of a fixed FM wave frequency to both sides, that is, the amplitude of the frequency swing of FM waves. The frequency offset generally referred to refers to the maximum frequency offset, which Affects the spectral bandwidth of FM waves. [0003] In the prior art, to calculate the frequency offset, a phase detector is usually used to directly detect the phase to obtain the frequency offset. However, since the signal carrier of the FM signal has a frequency offset itself, and also has a frequency offset introduced by the modulation content, if the frequency discriminator directly discriminate...
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IPC IPC(8): H04L27/38H04L27/00H04L27/26
CPCH04L27/0014H04L27/2675H04L27/3854H04L2027/0026
Inventor 郑方
Owner 上海顺久电子科技有限公司