LTC6912-2-based sonar system compensation circuit

Abstract

The utility model relates to a sonar system compensating circuit based on LTC6912-2, which is characterized in that received signals are sequentially processed by an operational amplifier, two groups of filters, two groups of programmable amplifiers, two groups of filters, two groups of programmable amplifiers, two groups of filters, two groups of programmable amplifiers and two groups of filters; after being amplified, the signal is output through an output end B channel, and then is connected with the negative input end of the filter; and then the output end of the filter is connected with the INA pin of the program control amplifier of the second group, the signals are amplified again and then output through the channel B of the output end, then the signals are connected with the negative input end of the filter, and finally clean sonar signals are output and obtained. According to the sonar system compensation circuit, weak signals can be accurately amplified through LTC6912-2, common-mode noise can be effectively restrained through a differential input structure of the LTC6912-2, and the purity and accuracy of the signals are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of circuit signal technology of sonar industry especially is a kind of sonar system compensation circuit based on LTC6912-2. BACKGROUND

[0002] The part sonar system of traditional technology is far, with the increase of action distance, propagation loss also changes, if the same amplification or attenuation coefficient is used, the received signal of system will be lower than detection threshold, thereby the target far away is not observed, sonar image is not complete and other problems. CONTENT OF UTILITY MODEL

[0003] To solve the above technical problem, a kind of sonar system compensation circuit based on LTC6912-2 of the utility model, including operational amplifier, program-controlled amplifier, filter, the signal received by sonar system is handled successively through operational amplifier, filter, program-controlled amplifier, filter, program-controlled amplifier, filter, so that the signal after processing of action distance is higher than detection threshold, and the part of program-controlled amplifier, filter is provided with two groups, and two-stage amplification circuit is formed;

[0004] The program-controlled amplifier adopts LTC6912-2, the amplified signal is output using the output end B channel, and then connected between the negative input end of filter;The output end of filter is connected with the INA pin of the program-controlled amplifier of second group, and the amplified signal is output using the output end B channel again, and then connected between the negative input end of filter, and finally output clean sonar signal.

[0005] In an embodiment of the utility model, the operational amplifier adopts ADA4897-1, and the bandwidth is 230MHz, and the operational amplifier output end is provided with filter, wherein the operational amplifier adjusts input signal, and simultaneously acts as low-impedance buffer between signal source and program-controlled amplifier input end, filter limits out-of-band noise reaching program-controlled amplifier input end, and helps to attenuate the influence of switch capacitor in program-controlled amplifier input end.

[0006] In an embodiment of the utility model, the filter is provided with several groups, and adopts OPA836, and the bandwidth is 205MHz, and the signal-to-noise ratio is-117.6dBc at 1kHz, and the total harmonic distortion is-130dBc, which provides very high linearity and sensitivity.

[0007] In an embodiment of the utility model, the program-controlled amplifier adjusts input signal by inputting different code values, and simultaneously acts as low-impedance buffer, and filter limits out-of-band noise reaching ADC input end.

[0008] The above technical scheme of the utility model has the following advantages compared with prior art: in the sonar system compensation circuit, the LTC6912-2 can be used to accurately amplify weak signals while maintaining low noise and wide bandwidth performance.The differential input structure can effectively suppress common-mode noise and improve signal purity and accuracy.Although the amplification gain gradient of LTC6912-2 is 6db, it can be adjusted by FPGA+ARM, and the sonar image will not appear in steps; the maximum gain of two amplification circuits can reach 192db, which can ensure that the received signal with large action distance is higher than the detection threshold after processing, which is beneficial to imaging. BRIEF DESCRIPTION OF DRAWINGS

[0009] In order to make the content of the utility model more easily understood, the utility model will be further described in detail in the following according to the specific embodiments of the utility model and in conjunction with the drawings.

[0010] Figure 1 It is the principle function block diagram of the sonar system compensation circuit based on LTC6912-2 of the utility model;

[0011] Figure 2 It is the principle schematic diagram of the operational amplifier and filter connection part of the utility model;

[0012] Figure 3 It is the principle schematic diagram of the program-controlled amplifier and filter connection part of the utility model;

[0013] Figure 4 It is the IP core frame of the utility model;

[0014] Figure 5 It is the code value flow chart of the program-controlled amplifier by using FPGA+ARM in the utility model. DETAILED DESCRIPTION

[0015] As shown in Figure 1 The utility model discloses a sonar system compensation circuit based on LTC6912-2, including operational amplifier, program-controlled amplifier, filter, and the signal received by sonar system is handled in turn through operational amplifier, filter, program-controlled amplifier, filter, program-controlled amplifier, filter, so that the signal with large action distance is all higher than detection threshold after processing, and the part of program-controlled amplifier, filter is equipped with two groups, and two-stage amplification circuit is formed;

[0016] The program-controlled amplifier adopts LTC6912-2, and the amplified signal is output through the output channel B of the program-controlled amplifier, and then connected with the negative input end of the filter; the output end of the filter is connected with the INA pin of the second program-controlled amplifier, and the amplified signal is output through the output channel B of the program-controlled amplifier, and then connected with the negative input end of the filter, and finally the clean sonar signal is output.

[0017] The gain range of the two LTC6912-2 is 0-192db dB, and the amplification multiple of the operational amplifier can be designed according to the actual situation.

[0018] Specifically, the operational amplifier and the filter are as follows:

[0019] The operational amplifier adopts ADA4897-1, the bandwidth of which is 230MHz, and has a wide operating voltage range (3V to 10V), which is suitable for systems requiring high dynamic range, precision and high speed.

[0020] The filter adopts OPA836, the bandwidth of which is 205MHz, and has low power consumption and excellent high-frequency characteristics, which is suitable for battery-powered portable applications that focus on power consumption, and the signal-to-noise ratio is-117.6dBc at 1kHz, and the total harmonic distortion is-130dBc, providing extremely high linearity and sensitivity.

[0021] The operational amplifier adjusts the input signal, and also acts as a low-impedance buffer between the signal source and the input end of the program-controlled amplifier, and the filter limits the out-of-band noise reaching the input end of the program-controlled amplifier, and helps to attenuate the influence of the kickback of the switched capacitor in the input end of the program-controlled amplifier. The circuit design principle is as shown in Figure 2 .

[0022] Specifically, the program-controlled amplifier is as follows:

[0023] The program-controlled amplifier adopts LTC6912-2, which is a high-performance, low-noise differential amplifier, and its low-noise design ensures the purity and clarity of the signal, and is suitable for weak signal detection and measurement systems; has a wide bandwidth characteristic, supports amplification and processing of high-frequency signals, and meets the amplification needs of high-frequency signals.

[0024] The program-controlled amplifier adjusts the input signal by inputting different code values, and also acts as a low-impedance buffer, and the filter limits the out-of-band noise reaching the input end of the ADC. This circuit uses a two-stage amplification circuit to increase the gain range. The filter circuit is as shown in Figure 3 .

[0025] LTC6912-2 is composed of two rail-to-rail output matching amplifiers, and a code table composed of 16-bit values, and the code value input can be adjusted according to actual measurement, and the total amplification decibel number meets the requirements, and the currently used code table is as shown in the following table:

[0026] LTC6912-2 code table

[0027]

[0028] At the same time, as shown in Figure 4 , Figure 5 , the code value of the programmable amplifier is controlled by the FPGA+ARM mode, and is fine-tuned. The calculated code value and fine-tuning value are sent to the FPGA by the IO port of the ARM, the FPGA sends the code value to the corresponding hardware pin of the LTC6912-2, and at the same time, the IP core is created in the FPGA, the input is the output value of the ADC and the fine-tuning value sent by the ARM, and the multiplication realizes the function of data smoothing, and the final data is sent to the ARM through the AXI bus, and the ARM sends it to the host computer for image display.

[0029] The sonar system compensation circuit described in the embodiment uses operational amplifiers, filter circuits and programmable amplifiers to process the received signals on the hardware, so that the received signals with a large effective distance are higher than the detection threshold after processing, and the integrity of the image is ensured.

[0030] And the code value of the programmable amplifier is controlled by the FPGA+ARM mode, and is fine-tuned, so that the image is smooth.

[0031] Obviously, the above embodiments are only examples for clear illustration, and are not limited to the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A sonar system compensation circuit based on LTC6912-2, characterized by, The signal received by the sonar system is processed by the operational amplifier, the filter, the programmable amplifier, the filter, the programmable amplifier and the filter in turn, so that the signals with a long action distance are all higher than the detection threshold after processing, and part of the programmable amplifier and the filter is provided with two groups, forming two-stage amplification circuit. The programmable amplifier adopts LTC6912-2, the amplified signal is output through the output B channel, and then connected between the negative input end of the filter; the output end of the filter is connected with the INA pin of the programmable amplifier of the second group, the amplified signal is output through the output B channel again, and then connected between the negative input end of the filter, and finally the clean sonar signal is output.

2. The sonar system compensation circuit of claim 1, wherein: The operational amplifier adopts ADA4897-1, the bandwidth is 230MHz, and the output end of the operational amplifier is provided with a filter, wherein the operational amplifier adjusts the input signal, and simultaneously acts as a low-impedance buffer between the signal source and the input end of the programmable amplifier; the filter limits the out-of-band noise reaching the input end of the programmable amplifier, and helps to attenuate the influence of the backflush of the switch capacitor in the input end of the programmable amplifier.

3. The sonar system compensation circuit of claim 1, wherein: The filter is provided with several groups, adopts OPA836, the bandwidth is 205MHz, the signal-to-noise ratio is-117.6dBc at 1kHz, the total harmonic distortion is-130dBc, and high linearity and sensitivity are provided.

4. The sonar system compensation circuit of claim 1, wherein: The programmable amplifier adjusts the input signal by inputting different code values, and simultaneously acts as a low-impedance buffer; the filter limits the out-of-band noise reaching the input end of the ADC.

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