A description of telecommunications: AM and FM; use of carrier waves; analog and digital signals; broadcast options; satellite transmission; gain and attenuation; PSTN; mobile/cell phones and networks.
Пікірлер: 98
@DrPhysicsA11 жыл бұрын
All the relevant waves are electromagnetic waves. Sound waves are converted. Carrier waves are generated either in the phone or the transmitter (depending on which way the information is flowing). The carrier wave is an EM wave which has the characteristic of being able to travel sufficient distances (usually in the microwave region). The sound wave which is converted to an EM wave is then embedded in the carrier wave. Once it reaches its destination the carrier wave is stripped off.
@kpbnoc7 жыл бұрын
I am very impressed. This is really free quality education. Thanks.
@jenko70111 жыл бұрын
All your videos are just great , you just nail it every time .
@quantum32803 жыл бұрын
I’m not taking physics but I will soon, in college. I’m so excited and these videos have helped me learn so much and I have taken intense notes on every single video in this series now. Took me a couple of months but I’m now done with the series, thank you sir.
@geoffreyengatkinson8 жыл бұрын
free quality education 😅cant imagine
@kanzaahmedchandio43486 жыл бұрын
yea, but witness it
@tahanikkhah29579 жыл бұрын
Thank you so much for providing this channel for us, helped me a lot !
@gpsinghgajju12 жыл бұрын
thanks very much, after watching your your videos I realize that physics is not difficult to understand if you are taught properly. I learned more physics from your videos in two days than may be in two years in school. Its very exciting.
@aishashar83027 жыл бұрын
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@DrPhysicsA12 жыл бұрын
One way of doing it is Frequency Division Multiple Access (FDMA) : FDMA separates the spectrum into distinct voice channels by splitting it into uniform chunks of bandwidth. Each call sends its signal at a different frequency within the available band per geographical cell. But there are other ways with digital communications. Wikieducator has a good pdf piece on cell phone technology.
@bushraimtiaz37237 жыл бұрын
Really informative. Thank you so much
@manahilkhan25556 жыл бұрын
OMG. NOW I UNDERSTAND THIS WHOLE TOPIC. THANKYOU SO MUCH! LOTS OF LOVE
@LarsBerntzon10 жыл бұрын
Very nice video covering a lot of good information. I detail: the AM modulation you are drawing is not quite like that in normal AM, what you have drawn is side band modulation where no effect is transmitted when the modulation signal is 0 v. With normal AM, the carrier voltage is half its max when modulation signal is at 0 V.
@linkchibi12 жыл бұрын
THANK YOU VERY VERY VERY VERY MUCH , I WILL NEVER FORGET THIS KINDNESS PLEASE KEEP THE VIDEOS COMING . HAVE A NICE DAY SIR
@noctavel8 жыл бұрын
If the power of a mobile is so low, how can be possible for an receiver to get the signal from a mobile phone? can you make a video about it ? Thanks !!
@etiennesilvio8 жыл бұрын
1000 Thanks for this video.!
@krishan10 жыл бұрын
Hi i just don't quite get the bit about bandwidth, how come if you reduce the bandwidth leading to higher frequencies lost, that will reduce the quality of transmitted signal?
@Alfster1810 жыл бұрын
Great video, thank you! What do you mean when you talk about the bandwidth of the AM wave because you say that the amplitude is 20kHz but I thought amplitude was measured as a distance?
@sohaibabbasi33554 жыл бұрын
9:35 i think you mean frequency of the wave
@DrPhysicsA11 жыл бұрын
If you embed a signal within a carrier wave then there is a degree of uncertainty about the precise wavelength of the carrier wave. That uncertainty is really the bandwidth. It is the amount of the spectrum that is taken up to cover all the frequencies needed to be included in the signal such that there will be no interference with the signal embedded in a neighbouring carrier away
@zainabm965011 жыл бұрын
please tell me from where the carrier waves are transmitted??from a radio station?and how does the information signal attatch on the radio carrier waves??and the informaton signal refers to the sound waves??
@spdandavate12311 жыл бұрын
very nicly put....i second the comment above...god bless u
@timmytim90545 жыл бұрын
1:18 “coil of WAAAAAH”
@anayparikh31984 жыл бұрын
WAAAAIAAAAA
@gpsinghgajju12 жыл бұрын
Hello, why does signal from one mobile does not interfere with another mobile close by, thanks.
@geoffreyengatkinson8 жыл бұрын
10 million thanks for this video
@saadawan82835 жыл бұрын
Nice work.
@Antropovich11 жыл бұрын
Is it really how ADC works? I mean to represent a wave with a certain amplitude in analog, it takes several waves to represent the same wave in digital... Which is the reason "you loose information density by converting from analog to digital"... Or am I missing something? I am referring to 16:50
@moshecohen-mn9cj7 жыл бұрын
you are the best +DrPhysicsA
@roykharal59788 жыл бұрын
well explained lectures
@Ashique424153211 жыл бұрын
Thank you SO SO SO much!!!
@zatulmutalif323011 жыл бұрын
sir what is bandwidth?? i dont really understand part 09:20...thank u:)
@alexchen25196 жыл бұрын
Im still not sure why the frequency of the signal is added to the frequency of the carrier wave. I thought AM has no effect on the frequency?
@mauthoormotasim63323 жыл бұрын
exactly mate. I don't understand too.
@crossvizannuff7 жыл бұрын
Sir, thankyou very much!
@OMAIMHREEM11 жыл бұрын
Thank you Sir for the wonderful you tube. please give me detail explanation how is Microwave auditory effect this is what I mean microwave hearing, is modulated using satellite.
@Jayce171212 жыл бұрын
Thank you very much sir, you are a-w-e-s-o-m-e :)
@mohamedmahmoud-ze9sx10 жыл бұрын
that was so helpful, thank you :)
@ervinkiller10 жыл бұрын
thank you very much.
@fenghc15 жыл бұрын
The ADC part: x axis should be time other than frequency. Am I right?
@pindiboii72473 жыл бұрын
no its at a particular instant of time so time is constant
@mahmoudm4517 жыл бұрын
at 9:00 what do you mean by "the amplitude is 20KHz" ? how is the amplitude measured in Hz?
@hadiyousef17047 жыл бұрын
He means to say the frequency is 20 kHz, just a silly mistake. well done for catching onto that!
@fareedaappa23277 жыл бұрын
wonderful
@ashazwar67947 жыл бұрын
what to do mean around 14:30 by 200khz=15khz?
@DrPhysicsA7 жыл бұрын
At 13:30 i say that FM equates to (rather than equals)
@zawaideh618 жыл бұрын
hey sir, can you please do video on the attenuation per unit length of the signal??
@learnwithuziharry70354 жыл бұрын
A level physics?
@ArthurZH8 жыл бұрын
The question now is why is there a bandwidth for AM. If I am merely manipulating my carrier wave's amplitude with respect to the signal, it's frequency should remain unchanged, right? Or am I getting something wrong here?
@lazeran7 жыл бұрын
In combining the signal with the carrier you produce two side-bands, one on each side of the carrier.
@alexchen25196 жыл бұрын
Yes but WHYYYY?
@shifamuhammad73665 жыл бұрын
I’m confused about this too! Can someone please please please explain this
@jacobvandijk65259 жыл бұрын
Is the carrier-wave digitalized too (before transmission)? And how does a digital signal move the electrons in the antenna (to create the EM-radiation)?
@DrPhysicsA9 жыл бұрын
No. The carrier wave is just a straightforward Electromagnetic wave in the microwave region or radio wave region. There is no signal in it to digitise until you add the signal itself either in analog or digital form.
@jacobvandijk65259 жыл бұрын
DrPhysicsA Okay, thanks!
@shockingvideos52259 жыл бұрын
DrPhysicsA how varying voltage is applied?
@jacobvandijk65259 жыл бұрын
Animation The difficulty is that a lot of the time there is talk about waves, where in fact it's just signal-processing. The only real waves are the incoming soundwave and the outgoing radiowave; inbetween there is no wave.
@khizeriftikhar91576 жыл бұрын
Thanks again 😃
@DrPhysicsA10 жыл бұрын
In an AM wave the carrier waves sine wave is itself modulated to carry the signal. The bandwidth is the degree of spread on the carrier wave.
@bmodon688110 жыл бұрын
Thank you very much i have physix=cs exam tomorrow and i think i doing it well!!!!!
@DrPhysicsA10 жыл бұрын
All good wishes for the exam.
@microwavecoffee3 жыл бұрын
THANK YOU
@amroto979 жыл бұрын
In the Cambridge A level endorsed book, it is log(P2/P1), which is opposite to what you have explained can anybody clarify this for me ?
@esaskhan959 жыл бұрын
amr ramadan yep that was a little confusing
@zhen33569 жыл бұрын
amr ramadan you're forgetting the fact that he took P2 as Pin and P1 as Pout
@nriver3810 жыл бұрын
Sir, during your explanation of bandwidth, why did you use kilohertz as the unit of amplitude?
@DrPhysicsA10 жыл бұрын
I was adopting too much of a shorthand. Amplitude is not measured in kilohertz.
@Hammadmk9718 жыл бұрын
+DrPhysicsA what exactly were you referring to? Frequency or amplitude? I'm a little confused .-.
@leonardowilhelmdicaprio9993 жыл бұрын
@@Hammadmk971 Frequency is measured in kilohertz.
@3551Bashir11 жыл бұрын
definely a thumps up.
@leonardowilhelmdicaprio9993 жыл бұрын
Thumbs, you mean?
@adithyarathnayake97976 жыл бұрын
Thank you
@DrPhysicsA10 жыл бұрын
More accurate to say that it will reduce the quality of the embedded signal, that is the actual signal which contains the information about sound etc.
@glaiver4ever10 жыл бұрын
well you basically mean 20KHz Frequency and not Amplitude of the info signal, right?
@maazmunir92135 жыл бұрын
Yes
@adityanalwaya550210 жыл бұрын
First of all thank you sir for this wonderful explanation of Telecommunication I have one doubt here that if you are telling that for sending message to far distance we have to modulate it at higher Frequency But On the other hand FM (Which operates at higher frequency) travels less distance as compared with AM (Which operates at lower frequency) Why is it so can you please clarify that???
@DrPhysicsA10 жыл бұрын
Long wave radio waves will certainly travel further but are subject to greater interference. FM has a better quality.
@madarajkc10 жыл бұрын
thanks :)
@yuanhuilee30827 жыл бұрын
When he said BALLOON at 1.36 i laughed
@Sairam-ky2os3 жыл бұрын
its wrong the bandwidth of AM depends on frequency of signal not amplitude of signal which is volts music consists of many frequiences superposed
@ahmadkathrada602611 жыл бұрын
sir thank u so much could u plz make a video about revision on all application question englobing direct sensing ,medical and telecommunication!!!BTW u are my hero!!!!!!!!
@bilalafzal19148 жыл бұрын
How can we measure amplitude in kilohertz?
@ItsCaydenOG8 жыл бұрын
+Bilal Afzal Its the number of complete cicles per second, and then you divide it by 1000
@lazeran7 жыл бұрын
You can't. Amplitude is loudness, not cycles per second.
@amir-the-great8 жыл бұрын
1 there full !!
@842Mono10 жыл бұрын
Bishoy George Mohamed Yasser
@ujjwalmehrotra31497 жыл бұрын
9:20 you say amplitude is 20kHz . How can amplitude be in hertz> wtf
@DrPhysicsA7 жыл бұрын
I think I probably meant to say frequency.
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