Echo sensitivity as a function of target range: Automatic gain control in echolocating bats

S. A. Kick

doi:10.1121/1.2019886

Keeping returns optimal: gain control exerted through sensitivity adjustments in the harbour porpoise auditory system

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2011.2465 ◽

2012 ◽

Vol 279 (1736) ◽

pp. 2237-2245 ◽

Cited By ~ 21

Author(s):

Meike Linnenschmidt ◽

Kristian Beedholm ◽

Magnus Wahlberg ◽

Jakob Højer-Kristensen ◽

Paul E. Nachtigall

Keyword(s):

Dynamic Range ◽

Automatic Gain Control ◽

Energy Levels ◽

Gain Control ◽

Auditory Brainstem ◽

Sound Level ◽

Harbour Porpoise ◽

Fourth Power ◽

Target Range ◽

Brainstem Response

Animals that use echolocation (biosonar) listen to acoustic signals with a large range of intensities, because echo levels vary with the fourth power of the animal's distance to the target. In man-made sonar, engineers apply automatic gain control to stabilize the echo energy levels, thereby rendering them independent of distance to the target. Both toothed whales and bats vary the level of their echolocation clicks to compensate for the distance-related energy loss. By monitoring the auditory brainstem response (ABR) during a psychophysical task, we found that a harbour porpoise ( Phocoena phocoena ), in addition to adjusting the sound level of the outgoing signals up to 5.4 dB, also reduces its ABR threshold by 6 dB when the target distance doubles. This self-induced threshold shift increases the dynamic range of the biosonar system and compensates for half of the variation of energy that is caused by changes in the distance to the target. In combination with an increased source level as a function of target range, this helps the porpoise to maintain a stable echo-evoked ABR amplitude irrespective of target range, and is therefore probably an important tool enabling porpoises to efficiently analyse and classify received echoes.

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Research on Measurement Method of Ultrasonic Transit Time based on Automatic Gain Control

2020 39th Chinese Control Conference (CCC) ◽

10.23919/ccc50068.2020.9188416 ◽

2020 ◽

Author(s):

Qinyong Ma ◽

Yuanzheng Zhang

Keyword(s):

Transit Time ◽

Measurement Method ◽

Automatic Gain Control ◽

Gain Control

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Measuring Current in a Power Converter Using Fuzzy Automatic Gain Control

Applied Sciences ◽

10.3390/app11135793 ◽

2021 ◽

Vol 11 (13) ◽

pp. 5793

Author(s):

Bartosz Dominikowski

Keyword(s):

High Resolution ◽

Fuzzy Controller ◽

Automatic Gain Control ◽

Gain Control ◽

Measurement Range ◽

Power Converter ◽

Current Measurement ◽

Dc Power ◽

Programmable Gain ◽

Electric Loads

The accuracy of current measurements can be increased by appropriate amplification of the signal to within the measurement range. Accurate current measurement is important for energy monitoring and in power converter control systems. Resistance and inductive current transducers are used to measure the major current in AC/DC power converters. The output value of the current transducer depends on the load motor, and changes across the whole measurement range. Modern current measurement circuits are equipped with operational amplifiers with constant or programmable gain. These circuits are not able to measure small input currents with high resolution. This article proposes a precise loop gain system that can be implemented with various algorithms. Computer analysis of various automatic gain control (AGC) systems proved the effectiveness of the Mamdani controller, which was implemented in an MCU (microprocessor). The proposed fuzzy controller continuously determines the value of the conversion factor. The system also enables high resolution measurements of the current emitted from small electric loads (≥1 A) when the electric motor is stationary.

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