Auto gain control AGC amplifier for 40 kHz ultrasonic transducer

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1

Hi, I'm using a 40 kHz ultrasonic transducer to measure the distance of an object, and I need an AGC amplifier IC for my ultrasonic receiver. However I couldn't find any one.

does any one know such an IC device ? The name of the company and the part number of the IC would be also really helpful for me.

Thanks alot

2

There are a number of amplifier chips whose gain can be controlled by signals on external pins (e.g. by a microprocessor), and it is common practice with ultrasonic distance measuring devices to ramp up the gain with time until an echo is received - or not.

How would you imagine an AGC working "automatically"?

3

bienle:
Hi, I'm using a 40 kHz ultrasonic transducer to measure the distance of an object, and I need an AGC amplifier IC for my ultrasonic receiver. However I couldn't find any one.

does any one know such an IC device ? The name of the company and the part number of the IC would be also really helpful for me.

Thanks alot

Not to say that you can't make an amplifier to work with the transducer to measure distance. But, it's a fairly complex and expensive task. Instead, there's very inexpensive (like $2) sensors that already include the transducers and amplifier so you don't need to re-create anything. Doing it on your own will be more expensive and probably not as good as a $2 already made sensor.

Tim

4

Some time ago there used to be chips called vogad

5

I did it like this

If you don't just trigger on the strongest echo, ie when the 7414 Schmidt trigger goes "off" but capture with an ADC you can tell a lot by the "quality" or slope of the echo.

Don't bother with the Ver 2 circuit, most of the filtering you need is already done by the ultra sonic Rx trancducer itself, it's just a whole lot of hassle to make work and in the end unnecessary.

6

@jremington as far as I understand, TVG can only increase the gain factor respect to the travel time, but it can not suppress the signal if the received signal is too strong.

@Tim unfortunately I have to use a specified ultrasonic sensor !

@Grumpy_Mike Thanks a lot, I checked the VOGAD chip it seems to be acceptable for my case. But somehow it's obsoleted, do you know some other AVG amplifiers for 40kHz ? Thanks