Demodulation is the process of recovering the audio-frequency signal from the modulated wave is known as demodulation or detection.
At the broadcasting radio station, modulation is done to transmit the audio frequency signal over larger distances to a receiver. When the modulated wave is picked up by the radio receiver, it is necessary to recover the audio signal from it. This process is accomplished in the radio receiver and is called demodulation. A demodulation diagram is shown in figure.
- Necessity of demodulation:
The amplitude modulated wave consists of carrier wave and sideband frequencies. The audio signal is contained in the sideband frequencies which are radio frequencies. If the modulated wave after amplification is directly fed to the speaker as shown in figure1 (a), no sound will be heard. It is because diaphragms of the speaker are not at all able to respond to such to such high frequencies. Before the diaphragm is able to move in one direction, the rapid reversal of current tends to move it in the opposite direction i.e. diaphragm will not move at all. Consequently, no sound will be heard.
Fig:1(a)
From the above discussion, it follows the audio signal must be separated from the carrier at a suitable stage in the receiver. The recovered audio signal is then amplified and fed to the speaker for conversion into sound.
- Fundamentals in Demodulate wave:
a)It rectifies the modulated wave:
Demodulation rectifies the modulated wave i.e. negative half pf the modulated wave is eliminated. As shown in fig:1(b),a modulated wave has positive and negative halves exactly equal. Therefore, average current is zero and speaker cannot respond. If the negative half of this modulated wave is eliminated as shown in fig: 1(c), the average value of this wave will not to be zero since the resultant pulses are now all in direction. The average value is shown by dotted line in the fig:1(c).
Fig:1(b)
Fig:1(c)
b) It separates the audio frequency signal from the carrier:
Demodulation separates the audio frequency signal from the carrier wave. The rectified modulated wave contains the audio signal and the carrier. It is desired to recover the audio signal. This is achieved by a filter circuit which removes the carrier frequency and allows the audio signal to reach the speaker.
{ 52 comments… read them below or add one }
You post awsome articles. Bookmarked !
hello it is my first post on this website and to start with I would like to thank for the great quality information, which I were able to find in this and all previous posts , it really helped me a lot. I will definitely add this blog on my google reader
Also, I would like to ask – don’t you mind if I will quate some information from your website since I am writing articles for the Associated Content, Ezine and other articles directories (this is my part time job)? It would really help me with some of mine articles. Of course, I will mention your blog name or URL (not all articles directories allows URL’s , so I can’t 100% promise that you will get a direct link to your blog).
I really treasure this wonderful write up. I really appreciate the information you have provided in this article. Thanks a lot!
I want to subscribe to your site, do you have newsletter ?
I want to start my first blog, what cms do you use and recommend for me ?
Ciekawy artykul, bede wpadal na twoja strone czesciej zapewne
Thought I would comment and say neat theme, did you make it for yourself? It looks superb!
To the point and well written, thanks for the post
You post awsome articles. Bookmarked !
Do you know where to find paid templates for my blog, i got website on the same cms like yours.
well guess this post is a bit old and things have changed since then.but thanks for informing me.
I just added your web page to my favorites. I like reading your posts. Ty!
hello nice article
thanks for this blog
Me too, tyvm for sharing this..
Your site is very interesting. May i write article for you, could you publish it here ? Please mail me
It is always pleasure to read your content, will back here soon
I will steered toward because me personally we give thanks stint you deplete knock croak the result. I’m egotistic furthermore flush unconnected allotment hang about for the supersede dojigger. Your article on the website is very interesting.
Thank you, wonderful job! Just the information I had to have.
I’m having a strange problem I can’t get my reader to pickup your rss feed, I’m using google reader by the way.
Don’t take the bull by the horns, take him by the tail then you can let go when you want to.
A good beginning makes a good ending.
Do you think that this cms is good for my first website ?
Very cool blog, but you must improve your template graphics.
Well, the article is in reality the finest on that worthw hile topic. I harmonise with your conclusions and also definitely will thirstily look forward to your approaching updates. Simply just saying thanks definitely will not simply just be acceptable, for the huge lucidity in your writing. I can immediately grab your rss feed to stay abreast of any updates. Admirable work and much success in your business enterprize!
When I look at your RSS feed it throws up a page of weird text, is the deal on my side?
I agree, tyvm for sharing this..
Can I post part of this on my page if I include a reference to this website?
I also was very pleased to discover such an interesting post. I just want to thank
you for such an informative read. You really did a great job. I’m waiting for
your new post. Very nice even awesome blog. Thanks for sharing this info. Keep
posting, it really worth it.
Thank you, I’ve recently been seeking for information about this subject matter for ages and yours is the best I have located so far.
Thanks for your comment
Thanks a lot
Thanks for comment and bookmarked ! Hopes so you’ll come here again
Most of Premium templates are paid, so you can find this by google searching.Thanks for comment
Thanks for comment here. I’ll try my best to improve my template graphics
Oh yeah you can write article for this site as a guest writer. But no copy paste article wouldn’t be published.And my site’s adsense share feature is currently paused. So if you want to write article for my site as a guest writer i must publish that(Article should be matched with my site’s topic) if you want to write you can contact me with contact us form. Thanks
Thanks for comment, yeah i have newsletter. You can subscribe so easily to my site’s newsletter. To subscribed you will find newsletter subscription form in the bottom left side.
Thanks for comment. hopes you will come back here soon.
If you want to make blog, so i think it’s the best blogging script for your first website.
I am using wordpress for blogging. I recommend you to use wordpress script.You can read this article. Thanks
enormous tally you acquire
Hands down, Apple’s app store wins by a mile. It’s a huge selection of all sorts of apps vs a rather sad selection of a handful for Zune. Microsoft has plans, especially in the realm of games, but I’m not sure I’d want to bet on the future if this aspect is important to you. The iPod is a much better choice in that case.
Concise and well written, thanks for the information
Your post is very good and design are very awesome i really like it. Thanks a lot!!!
People deserve very good life time and or just term loan can make it much better. Because freedom is grounded on money.
thanks for posting this, It?s simply what I used to be researching for on bing. I?d rather a lot relatively hear opinions from an individual, slightly than an organization internet web page, that?s why I like blogs so significantly. Many thanks!
This is really great post. Thanks for sharing.
I’m having a small issue I can’t make my reader pick up your rss feed, I’m using google reader by the way.
but because she remained true to herself and her beliefs, she’ll grow in a very real, very amazing way. The information will never be enough to handle the unexpected issues. You should make greater effort to be able to handle that.
sublime post you’ve receive
Straightforward and written well, thanks for the post
I was really pleased to discover that site.I wanted to thank you for this awesome read!! I surely enjoying every little bit of it and also I have you bookmarked to check on out brand new stuff you post.
{ 1 trackback }