Frequency deviation capturing method based on pilot signals in a DRM receiver
A pilot signal and frequency offset technology, applied in the field of DRM receivers, can solve problems such as poor performance, large resource consumption, and large amount of calculation, and achieve the effects of reducing computational complexity, saving chip area, and improving performance
Inactive Publication Date: 2009-06-03
宁波中科集成电路设计中心有限公司
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[0023] In the above frequency offset acquisition process, at least 4 OFDM symbols are required to ensure the accuracy of the acquisition. Taking the robust mode A in the DRM receiver as an example, the length of one OFDM symbol in robust mode A is 1280 data, then 4 An OFDM symbol needs to carry out FFT operation of 4×1280=5120 points, which makes the calculation amount of this method very large, and 5120 is not an integral power of 2, which will greatly reduce the speed of FFT operation operation, and if directly use If hardware is used to implement this FFT operation, a large amount of resources will be consumed; in addition, the performance of this method is poor, which is not conducive to the realization of hardware
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[0049] The present invention will be described in further detail below in conjunction with the embodiments of the drawings.
[0050] Such as image 3 As shown, a pilot signal-based frequency offset acquisition method in a DRM receiver includes the following steps:
[0051] 1) Using the feature that the position of the pilot signal in the DRM standard only appears in the low-frequency part, according to the existing Nyquist sampling law, the sub-sampling unit is used to resample the digital signal output from the re-sampling module connected to the sub-sampling unit The sequence is subjected to 1 / 3 sub-sampling processing, and the digital signal sequence after the sub-sampling processing is sent to the Hamming window filter unit. Here, 1 / 3 sub-sampling processing refers to the process of taking every second data from the re-sampled digital signal sequence output from the re-sampling module. The sub-sampling unit is equipped with a shift buffer and a counter. First, save 6 frames of...
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The invention discloses a frequency deviation capturing method based on pilot signals in a DRM receiver and has the advantage that point number of subsequent FFT calculation operation is reduced to 2048 and caused to be a power of 2 by sub-sampling so that not only calculation complexity is reduced, but also performance is improved, and hardware is favorably realized; by quantifying the window coefficient of a hamming window function, the floating-point multiplication operation is altered into fixed-point multiplication operation, and the use of ROM storage space is reduced; by improving a low pass filter, the floating-point multiplication operation and floating-point add operation are altered into shift operation and add operation, thereby improving the performance and saving chip area; in addition, as a divider in an energy normalizing unit occupies a great chip area in a VLSI (very large-scale integration), by utilizing an adder and a comparator to replace the divider in the invention, the hardware is favorably realized.
Description
Technical field [0001] The present invention relates to a DRM (Digital Radio Mondiale, digital amplitude modulation broadcasting) receiver, in particular to a frequency offset acquisition method based on a pilot signal in a DRM receiver. Background technique [0002] AM (Amplitude Modulation, also known as amplitude modulation) broadcasting has been used since the first experimental broadcasting in Reginald Fessenden in 1906. It includes shortwave, medium wave, and long wave below 30Mhz. wave) Three frequency bands. Among them, the medium wave and short wave propagation methods have changed over time. In the daytime, AM signals are transmitted in the form of ground waves through ground diffraction, and a single transmitter can cover a range of hundreds of kilometers; and at night, due to the ionosphere The AM signal propagates in the form of sky waves, which can be transmitted for a longer distance than the daytime AM signal. [0003] Due to the relatively simple modulation and t...
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IPC IPC(8): H04L27/26H04B1/707
Inventor 傅志平黄晁王鸿龙龚国旺许恩
Owner 宁波中科集成电路设计中心有限公司