Telecommunications – A Level Physics

Telecommunications – A Level Physics
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.

25 thoughts on “Telecommunications – A Level Physics

  1. 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.

  2. 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.


  4. 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??

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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?

  10. 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.

  11. First of all thank you sir for this wonderful explanation of
    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???

  12. 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.

  13. Is the carrier-wave digitalized too (before transmission)? And how does a
    digital signal move the electrons in the antenna (to create the

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