Measuring device capable of generating pseudo-random sequence quadrature amplitude modulation signal and modulation method thereof

Abstract

The invention discloses a measuring device capable of generating a pseudo random sequence orthogonal amplitude modulation signal and a modulation method. The measuring device includes a system control unit, an orthogonal amplitude modulation unit and an orthogonal amplitude control unit, and when an orthogonal amplitude modulation source is a pseudo sequence modulation source, a baseband rate control module generates a pseudo random sequence baseband clock and a pseudo random sequence modulation clock according to a baseband rate value and a modulation mode; a pseudo random sequence generation module generates pseudo random sequence serial data according to the pseudo random sequence baseband clock and sequence order; a serial-parallel conversion module performs serial-parallel conversion on the pseudo random sequence serial data according to an orthogonal amplitude modulation mode and the pseudo random sequence modulation clock, so as to generate pseudo random sequence to-be-modulated data; and a mapping module generates plural pseudo random sequence modulation signals according to the pseudo random sequence to-be-modulated data and constellation data. When the modulation source is a pseudo random sequence, all modulation modes and a user-defined constellation can be realized.

Description

technical field [0001] The invention relates to the field of test and measurement, in particular to a measuring device capable of generating pseudo-random sequence quadrature amplitude modulation signals and a quadrature amplitude modulation method thereof. Background technique [0002] Quadrature Amplitude Modulation (Quadrature Amplitude Modulation, hereinafter referred to as QAM) is an efficient digital modulation and demodulation method. Compared with other modulation technologies, this modulation technology can make full use of the bandwidth, has a high frequency utilization rate, and is resistant to Noise ability is strong. Therefore, it is widely used in medium and large capacity digital microwave communication systems, high-speed data transmission of cable television networks, and satellite communications. QAM is a kind of vector modulation. The baseband signal to be modulated is first mapped onto a complex plane (constellation diagram) to form 2-way complex modulat...

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Problems solved by technology

Therefore, the above processing flow brings the following problems: the processing time of the central processing unit to read, map, and write is relatively long, which makes the response time slow when modifying the modulation mode or modifying the custom data file, and takes up a lot of central processing time. The resources of the processor unit; and, when mapping a custom data file, such as 8QAM, then the value of the 3-bit custom data file should be mapped to a complex modulation signal with a higher data bit width of 2 channels, in order to ensure that the constellation diagram The accuracy of the above coordinates, usually the data bit width of the complex modulation signal should reach 16 bits, that is, 3 bits must be enlarged to 2 channels of 16 bits, which is nearly 10 times larger, that is to say, the memory of the two channels of complex modulation signals The capacity is 10 times that of the custom data file, obviously, resulting in a great waste of resources

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