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Amplifier or Booster(Amplification of signals).

  1. Dec 10, 2010 #1
    I have 2 questions:(at least answer on question)
    What is an amplifier? Is amplifier or a booster are same thing? What does an amplification do with signals? If an booster/amplifier is connected in a DSL line so will it amplify DSL connection to get better speed?
    How to make a portable booster that boost DSL speed at least what components I must needed of what values? As phone lines have 9volts in their.
    Actually I have 1mbps of DSL connection while I don't get full speed(1mbps) or even not half(512kbps) not even 150(kbps).
    Sometimes my modem try to catch signals but it fails, sometimes I got 100kbps, sometimes 110kbps..........
    I heard someone that use a booster between your phone line and phone(as my DSL is activated on my phone line) so you could be able to get good signal or speed due to increase an amplitude of signal's waves. Is it true?? Try to help me out.
  2. jcsd
  3. Dec 10, 2010 #2


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    Welcome to the PF.

    It sounds like you need to talk to your DSL provider. Who do you use? What country are you in?

    DSL lines are bidirectional, so building an amplifier would be very non-trivial, and its characteristics would need to match the DSL design. If there is such a thing, you would generally get it through your DSL provider.
  4. Dec 10, 2010 #3
    Thanks for welcoming me.
    I am from Karachi a city of Pakistan.
    Of course you right that I can get such a thing with my DSL provider but I want to make, someone told me that I made a booster that increase the signal of TV cable and this way I get clear channels without any disturbance. So that booster must work on phone line too.
  5. Dec 11, 2010 #4


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    That would be a very difficult project and possibly illegal in most countries.

    The transmit and receive signals are mixed together on a single pair of wires, so what would you regard as the input and output for the amplifier?

    The signals use different frequencies so, theoretically, you could filter them to separate them then amplify them and mix them together again.

    As you can see, this is not a simple job at all and, even if you succeeded, there is a chance that you would produce excessive signals on the line, which may interfere with other users.

    Internet providers have some control of the signal they send you and you could ask to have this checked. That is probably all you can do except move closer to the telephone exchange.
  6. Dec 11, 2010 #5
    Ok I understand what you say. Now tell me what is filtering? What do you mean by "you could filter them to separate them then amplify them and mix them together again."
    And I am not doing anything illegal, I am just try to receiving good signals as I don't get those signals for which I am being payed & I told my ISP too to clear or give me better service, but they didn't pay any attention to my plead.
    So, I decided to do something for me alone. Noe try to help me. I will be very thankful to you for this.
  7. Dec 11, 2010 #6


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    This is the spectrum of what is on your telephone wire in your house.


    The red part is your normal phone voice part.

    The green is the transmit signal from your modem.

    The blue is the receive signal. This will be on the same wires as the green signal and a lot weaker than the green signal.

    So, if you cut the wire and put an amplifier in to amplify the receive signal, what would happen to the transmit signal? It would have to go backwards through the amplifier and it can't do that.

    Your ISP has probably told you that the signal reaching your house is too weak and noisy. If you amplify the signal (even if you could) you will just get a bigger noisy signal.
  8. Dec 11, 2010 #7
    Here is the schematic of a full-duplex telephone hybrid circuit implemented with two op-amps. The transmitted signals and simultaneous received signals share the same 600-ohm line without interfering.

    Bob S

    Attached Files:

    Last edited: Dec 11, 2010
  9. Dec 11, 2010 #8


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    Bob S: Assuming we have to cut the phone line, how would you implement a practical device with that hybrid circuit? The modem is expecting a combined signal again after any amplifiers.

    Do you feel it would have 1 MHz bandwidth? It looks like an audio device with quite large capacitor values.

    You might be better off looking for wireless Internet in Karachi.
    Like this:

    This does not use your phone line
  10. Dec 12, 2010 #9
    Here in thumbnail is the conceptual design of a telephone DAA (data access arrangement). The transmitter does not interfere with the receiver, even though both use the same telephone line simultaneously. I believe the circuit in my previous post uses the two capacitors for a low pass filter on the receiver side..

    Bob S

    Attached Files:

  11. Dec 13, 2010 #10
    Hmmmmm...... You are right that my ISP saying me that signals reaching to my house are too weak or noisy because my house is out of range, But if you see a cable provider, what he does to provide a service?

    He put an amplifier or a booster at pole at the starting of street and then from those booster he provides lines to his costumer, so what we receive noisy or bad channels, answer is no, of course we get good channels.

    So why did you think that if i could amplify my DSL line I would get more noisy signals?
  12. Dec 13, 2010 #11


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    All you have is a noisy signal and you want to amplify it.

    So, if you can amplify it, you will get a louder signal but also a louder noise and the ratio between them will be the same.

    You can only improve the situation if you get to the signal before the noise is introduced and make the signal stronger. Then if the same noise gets on the signal, the ratio between signal and noise will be much greater.

    Unfortunately the cable company can do that, but you can't.

    Incidentally, you said CABLE. I thought we were talking about telephone line ADSL?

    You can buy such boosters on Ebay, but I can't see it helping if your signal is already noisy.
  13. Dec 13, 2010 #12
    You know you are trying to help me, and for this I am very thankful to you, I really appreciate you help.

    Now I want to say, actually my line is clear, no noise, But just due to too distance from telephone exchange I receive weak signal.

    And I am asking you for ADSL not for CABLE, it was just a example that if we can receive better CABLE by boosting signals so why not ADSL?
  14. Dec 13, 2010 #13
    Here is my DSL network file(or a link here "http://s1227.photobucket.com/albums/ee430/Shayaan_Mustafa/?action=view&current=DSLnetwork.jpg"). [Broken] This is my home setup that how I am receiving DSL connection from exchange, so, where should I put or connect booster or an amplifier to amplify signals???

    Attached Files:

    Last edited by a moderator: May 5, 2017
  15. Dec 13, 2010 #14


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    You really don't know if the line is noise-free or not.
    In the previous diagram, you are listening in the red area and this seems OK.
    However the blue area is the place where your incoming data is. If your supplier says it is noisy, it may be noisy unless you can show it isn't.

    I can appreciate your frustration when you are getting such slow speeds, but you need someone to develop an amplifier that will still allow two-way transmission of signals (probably a wideband version of the circuit Bob S posted) and give it to you for free. I doubt if this is going to happen.

    My current speed is 2800 kbps and I find that too slow.
    Try this site for speed testing:
    There is a server in Islamabad you can test with.
  16. Dec 14, 2010 #15
    I tested my speed and my current speed is 192kbps.
    Look at speed, how much slow speed I am getting. I just dunno what I do??? This task seems too difficult.
    Ok I give up. Alone I can't do anything. Thanks every body.
  17. Dec 14, 2010 #16


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    Yes, that is really slow.

    Can you get other providers? Maybe someone else can give you better speed?
  18. Dec 14, 2010 #17
    Yes I can get any other ISP but their service has limited data like some has 5GB/month or some has 10GB/month or 15GB/month.
    But that I am using has unlimited for whole month therefore I still choose it.
  19. Dec 14, 2010 #18


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    I worked out that it would take you about 14 hours to download a Gigabyte at that speed.

    5 Gigabytes would be about 72 hours.

    So, I would prefer to get some extra speed rather than an unlimited download which is almost useless to you at such speeds.

    Most of the speed reduction would be because of the time it takes to repeatedly send the same bytes over and over until they are received correctly.

    Maybe you could check with your neighbours to see if anyone is getting much better speeds than you and, if so, find out who their provider is.
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