Offset quadrature phase shift keying modulation method, device and digital signal generator

Abstract

The invention provides a modulation method and device for OQPSK and a digital signal generator. The method comprises converting serial code streams to be modulated into two channels of serial code streams, which comprise a first channel of serial code streams and a second channel of serial code streams; delaying the first channel of serial code streams for half a code element cycle to generate a third channel of serial code streams; combining the second channel of serial code streams with the third channel of serial code streams to form parallel data streams, and converting the parallel data streams into modulation phases; accumulating frequency control words of an N bit to obtain an N-bit phase code under the control of clock pulses; adding the N-bit phase code sent by an N-bit address accumulator to a modulation phase of phase modulation converter to generate a read address of a carrier wavetable storage; and reading out wave shapes according to the read address sent by a phase summator, and outputting digital OQPSK modulation signals. A great number of hardware circuits can be omitted through the method, and the modulation device for OQPSK has the advantages of being small in size, low in power consumption, stable and reliable, settable in parameters and the like.

Description

technical field [0001] The present invention relates to the field of electronic measurement and testing, in particular to an offset quadrature phase shift keying (OQPSK, offsetQuadrature Phase Shift Keying) modulation method, in particular to an offset quadrature phase shift keying modulation method, device and a method for generating Digital signal generator for OQPSK modulated signals. Background technique [0002] In the measurement, verification and maintenance of electronic systems, digital and vector signal generators are widely used. With the development of electronic technology, signal generators are required to be able to generate rich modulation signals. [0003] Offset Quadrature Phase Shift Keying (OQPSK) is a constant envelope digital modulation technology developed on the basis of Quadrature Phase Shift Keying (QPSK). In common QPSK modulation, the data of the two orthogonal branches are completely aligned in time, and when the phases of the two data channels ...

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Problems solved by technology

[0006] 1. Two multipliers are required in the circuit, which will occupy valuable multiplier resources inside the FPGA;

[0007] 2. The multiplier and adder will affect the timing performance of the FPGA, thereby limiting the carrier frequency;

[0008] 3. At present, FPGA mainly uses direct digital signal synthesis technology (DDS, Direct Digital Synthesizer) or CORIDC (Coordinate Rotation Digital Compute) algorithm to generate sine waves. This solution requires FPGA to generate two orthogonal carrier waves, so the consumed FPGA resources, Whether it is programmable logic blocks or internal memory, there will be more;

[0009] 4. In order to increase the carrier frequency, a parallel DDS solution is usually used. At this time figure 1 The multipliers and adders of the

In other words, the above scheme does not scale well

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