How Do Modern TVs Normalize Audio Volume Across Channels? Designing a Basic System

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#1 21673013 19 Dec 2014 07:52

Batuhan Batuhan Batuhan Batuhan

Anonymous

Post #1
21673013 19 Dec 2014 07:52

Hi

Forgive me if I can't explain my question clearly i'm not native.

Some of you may remember that the volume level on televisions used to change from channel to channel. This is not a problem anymore audio level is same on every channel now so we don't need to adjust the volume constantly.

I want to learn how this problem was fixed and design a similar maybe more basic system but I don't know where to begin.

All I can think of is that at the input I need to make the system recognize if the input signal is higher or lower than the wanted value and amplify the signal accordingly.

I'd be really glad if someone helps me with where to begin
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#2 21673014 19 Dec 2014 19:24

Neil Mula Neil Mula

Anonymous

Post #2
21673014 19 Dec 2014 19:24

Hi Batuhan,

I think it makes use of bandpass filter circuit and combination of auto-tuner circuit. In more sophisticated application, it uses MCUs.

Hope it helps.

Best,
Neil
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#3 21673015 20 Dec 2014 08:14

Jeff Malcom Jeff Malcom

Anonymous

Post #3
21673015 20 Dec 2014 08:14

I'm not sure if this what is really used, but I think that something similar could be accomplished using an Automatic Gain Control circuit.
#4 21673016 20 Dec 2014 14:46

Richard Gabric Richard Gabric

Anonymous

Post #4
21673016 20 Dec 2014 14:46

You probably want some sort of compressor, search for audio compressors on the net, you are sure to turn something up, and see if that will do what you want,
cheers,
Richard
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#5 21673017 22 Dec 2014 06:22

Constantin Mogos Constantin Mogos

Anonymous

Post #5
21673017 22 Dec 2014 06:22

As Jeff said the AGC circuit is the answer for your problem. Here are some links to look for:
http://www.electronicecircuits.com/electronic...ic-gain-control-pre-amplifier-circuit-diagram
http://www.electroschematics.com/248/automatic-gain-control-agc/
http://www.edn.com/design/analog/4368939/Circuit-provides-70-dB-of-AGC
http://www.engineersgarage.com/tutorials/circuit-design-automatic-gain-control?page=2
Of course you can serch the web, and you will find lots of other circuits to choose from.
Good luck to you.
Costin
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#6 21673018 23 Dec 2014 06:13

WilliamM Brooks WilliamM Brooks

Anonymous

Post #6
21673018 23 Dec 2014 06:13

Every decoder has its own volume settings. When you change the channel the volume increses and decreases , if the channels are of same decoder then it is not happened. This is not the problem of your TV.
#7 21673019 25 Dec 2014 05:34

HVAC Parts Warehouse HVAC Parts Warehouse

Anonymous

Post #7
21673019 25 Dec 2014 05:34

This is a rotary-type wall plate volume control for speaker systems with power ratings of up to 100 watts per channel and impedance ratings of 4 to 16 ohms

https://www.hvacpw.com/hvac-tools
#8 21673020 25 Dec 2014 09:54

Batuhan Batuhan Batuhan Batuhan

Anonymous

Post #8
21673020 25 Dec 2014 09:54

Thank you all for your answers. I'm busy with final exams and homework and lab assignments nowadays. I haven't had the chance to make a detailed research on your answers yet but it looks like AGC is going to solve my problem. Every answer led me learning a new thing so thank you for your answers. Any further info and advice or opinion is very welcome.
#9 21673021 28 Dec 2014 12:02

Sambath Kumar Sambath Kumar

Anonymous

Post #9
21673021 28 Dec 2014 12:02

Hi,Bauthan
AGC is a circuit used in tv to control and balance the gain of the picture ie the light level
of the picture information ie the contrast and brightness level of the picture to a pre setted
viewing level, this is achieved by producing a +ive or _ive voltage from theout put of the same signal and feeding to the in put of the gain controlling amplifier transistor or valve,
when the out put signal is more positive a required amount of _ive voltage is produced and
fed to the in put ,if the out put signal is more _ive a required amount of +ive voltage is produced and is fed to the input amplifier to maintain the pre setted- level.same is the case of the volume level insted of agc we call it as AVC automatic volume control.

Regards Sambath kumar.
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Topic summary

The discussion addresses the issue of inconsistent audio volume levels across TV channels and how modern televisions maintain uniform volume. The primary solution involves the use of Automatic Gain Control (AGC) circuits, which automatically adjust the gain of the audio signal to maintain a consistent output level despite varying input signal strengths. AGC works by detecting the amplitude of the incoming signal and applying a compensating gain to normalize volume. Additionally, Automatic Volume Control (AVC) is mentioned as a related concept specifically for audio volume stabilization. Some responses also suggest the use of audio compressors to achieve similar effects. The implementation may involve bandpass filters, microcontroller units (MCUs), and feedback loops that generate control voltages to regulate amplifier gain. The problem is distinguished from decoder-specific volume settings, which can also affect perceived volume changes between channels.
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How Do Modern TVs Normalize Audio Volume Across Channels? Designing a Basic System

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Topic summary