Method of generating msk modulation signal based on address correction of dds phase accumulator

Abstract

The invention discloses an MSK (minimum shift keying) modulation signal generation method based on DDS (direct digital synthesis) phase accumulator address modification. The method comprises the following steps: (1) setting the values of all phase accumulators generating carrier and data DDS signals; (2) reading in N-bit parallel data and performing serial-parallel conversion to obtain a serial sequence Y; (3) respectively adjusting the Q-path data output address and the I-path data output address; (4) calculating the final values of the DDS data output addresses of the I and Q paths, and updating the final values of the address basic values and carrier output addresses of the I and Q paths; (5) generating the DDS data signals and carrier signals of the I and Q paths by use of the final values of addresses and the final values of carrier output addresses output by the DDS data of the I and Q paths, and outputting the MSK signals of the data cod element; and (6) storing the MSK signal of the data code element, adjusting the data pointer, and outputting the MSK signal of the whole sequence Y. The method disclosed by the invention has the advantages of simple steps and little operational error and error rate, and can be applied to radio communication.

Description

technical field [0001] The invention belongs to the technical field of signal processing, in particular to a method for generating minimum frequency shift keying MSK modulation signals, which can be used in radio communication. Background technique [0002] Minimum frequency shift keying (MSK) modulation is a kind of constant envelope modulation, which can generate modulation signals with constant envelope and continuous phase. Due to the discontinuous phase of the signal processed by the general frequency shift keying FSK modulation form and the large frequency deviation, the spectrum utilization rate is low, while MSK is an FSK modulation form with a modulation index of only 0.5, which has a gap between adjacent symbols. The phase is continuous, the bandwidth is narrow, the spectrum main lobe energy is concentrated, the side lobe energy decays quickly, and the advantages of high frequency band utilization are widely used in the field of radio communication. [0003] The c...

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Problems solved by technology

When this traditional MSK modulation signal generation method is used for MSK signal modulation, five steps must be followed in order: differential encoding, serial-to-parallel conversion, signal baseband quadrature synthesis, signal-carrier quadrature synthesis, and signal subtraction. It is complex and will generate some unnecessary clutter signals that interfere with the generation of MSK modulated signals

[0007] The impulse method based on the surface acoustic wave filter is to solidify the impulse response into the surface acoustic wave filter. As long as the pulse controlled by the baseband signal is used for excitation, the required MSK signal can be output. This method starts from the line equation See, although the circuit design is relatively simple, it is difficult to generate a narrow pulse with a certain amplitude

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