Method for designing fish finder transmitter signal source

Abstract

The invention discloses a method for designing a fish finder transmitter signal source, and specifically relates to a method for designing a fish finder transmitter sine wave signal source suitable for a D-class power amplifier. The method for designing the fish finder transmitter signal source adopts a Delta-Sigma modulation technology, the generated signal source only needs to connect with a D-class digital power amplifier for amplification, and after high-frequency noise is filtered through a simple low pass filter, the signal source can restore and output sine wave signals, thereby providing for a fish finder transmitter a sin wave signal source which is capable of modulating amplitude and frequency through software and is suitable for a D-class power amplifier. The requirement for bandwidth of a power amplifier tube is substantially lowered, the problem of difficult model selection of the power amplifier tube is solved, the problem that a PWM mode causes output waveform distortion due to power amplifier tube pulse loss is avoided, and the output accuracy of the signal source is substantially improved; the design of the filter is greatly simplified; and amplitude modulation and voltage regulation output of the signal source can be realized without adding of an D/A chip.

Description

technical field [0001] The invention relates to the field of fishing aid equipment, in particular to a method for designing a signal source of a fish finder transmitter. Background technique [0002] The fish finder is a kind of fishing aid equipment that can detect and locate underwater fish schools. Its working principle is the same as that of active sonar. It uses ultrasonic transducers to transmit ultrasonic signals underwater and receive echo signals in all directions to achieve Search, track, identify, locate and range fish. Since the echo signal is formed from the reflection of the transmitted signal by obstacles, the design of the signal source of the transmitter is particularly important. [0003] Existing fish finders mostly use the amplified square wave signal source to directly drive the transducer to transmit signals underwater for detection. However, square waves can be transmitted at short distances due to more harmonic components. With the increase of trans...

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Problems solved by technology

However, this modulation technology has high requirements on the bandwidth of the power amplifier tube, and the selection of the power amplifier tube is difficult. In addition, figure 1 The duration of the narrow pulse width at t1 and t2 cannot be estimated, and it will be shorter than the response time of the optional power amplifier tube. The power amplifier tube loses pulses due to untimely response, resulting in output waveform distortion. With the signal source frequency and sampling The problem will become more serious as the rate increases

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