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Thread: using walkie talkie on SMRT trains

  1. #1

    Default using walkie talkie on SMRT trains

    I have been using Motorola T4503 walkie talkie (3km range) when out shopping with my buddies. In general, they work well in most part of Singapore. Even on the SMRT train platform, as in from one end to the other end of the platform.

    However, when we board the same train, first and last carriage, the walkie talkie set would not be able to establish the radio link. Do not think it is an issue with the range, since the moment both of us step out of the train carriage, radio link is reestablished.

    We had tried using other more powerful walkie talkie sets with the same results.

    Anyone had this experience or know what is the cause ?

    Please advise. Thanks.

  2. #2
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    Default Re: using walkie talkie on SMRT trains

    Why would u want to talk to yr friend walkie talkie in the same SMRT train ?

  3. #3
    Senior Member Canew's Avatar
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    Default Re: using walkie talkie on SMRT trains

    Probably because there are more obstacles (train carriage, people, etc.) in between the 2 sets when you guys are inside the train. When the sets are at the platform, the path between the 2 sets has less obstacles.

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    Default Re: using walkie talkie on SMRT trains

    you and your friend don't like each other?
    sit together lor

  5. #5
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    Default Re: using walkie talkie on SMRT trains

    Quote Originally Posted by Canew View Post
    Probably because there are more obstacles (train carriage, people, etc.) in between the 2 sets when you guys are inside the train. When the sets are at the platform, the path between the 2 sets has less obstacles.
    Radio frequency, no need line of sight.

  6. #6
    Senior Member Canew's Avatar
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    Default Re: using walkie talkie on SMRT trains

    Quote Originally Posted by Astin View Post
    Radio frequency, no need line of sight.
    Bro Astin, I am no expert, but what I've read, there is a line of sight consideration even for radio frequency.

    Here is an explanation from Wikipedia: http://en.wikipedia.org/wiki/Line_of_sight
    "Radio signals, like all electromagnetic radiation, travel in straight lines."

    Another statement: http://en.wikipedia.org/wiki/Non-lin...ht_propagation
    "Many types of radio transmissions depend, to varying degrees, on line of sight between the transmitter and receiver. Obstacles that commonly cause Non Line Of Sight conditions include buildings, trees, hills, mountains, and, in some cases, high voltage electric power lines. Some of these obstructions reflect certain radio frequencies, while some simply absorb or garble the signals; but, in either case, they limit the use of many types of radio transmissions."
    Last edited by Canew; 26th September 2007 at 04:18 PM. Reason: Added note.

  7. #7
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    Default Re: using walkie talkie on SMRT trains

    Quote Originally Posted by Canew View Post
    Bro Astin, I am no expert, but what I've read, there is a line of sight consideration even for radio frequency.

    Here is an explanation from Wikipedia: http://en.wikipedia.org/wiki/Line_of_sight
    "Radio signals, like all electromagnetic radiation, travel in straight lines."
    Maybe we can ask those security officers in shopping centres, they should know better...

  8. #8

    Default Re: using walkie talkie on SMRT trains

    We are want to test the range of walkie talkie and determine if we can depend more on walkie talkie and avoid the airtime charges of mobile phone.

    Very often when out and about with buddies, there are lots of unnecessary phone calls as in
    a) are you here yet
    b) I am here, what is your exact location
    c) etc...

    In theory, the range is determine the line of sight. If both walkie talkie are not in line of sight, the signal would either be distorted or very weak. But this is not the case when inside the train carriage because the link is totally silence. Both party cannot hear each other at all, which is very weird.
    Last edited by firefly99; 26th September 2007 at 04:20 PM. Reason: additions

  9. #9

    Default Re: using walkie talkie on SMRT trains

    got a theory of my own, maybe the high voltage rails that power the train caused some interference of some kind?

  10. #10
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    Default Re: using walkie talkie on SMRT trains

    There is line of sight considerations for radio signals too. The reason why radio signals appears not to require line of sight is that radio waves can bounce off surfaces. Everytime it bounces off something, the signal becomes weaker.

    My guess is that it could be the material that the train carriages are made off? Maybe there's some radio insulation or something to prevent interference with the electric components on the train?
    (Though I think I've seen those SBSTransit guys carrying walkie talkies on the NE line.)

  11. #11
    Senior Member Canew's Avatar
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    Default Re: using walkie talkie on SMRT trains

    Quote Originally Posted by Astin View Post
    Maybe we can ask those security officers in shopping centres, they should know better...
    I myself is using a walkie talkie (using the GRID network). When I am at certain areas (eg. middle of the a building) where I am unable to get a signal. I need to walk to the edge of the building in order to re-acquire the signal.

  12. #12

    Default Re: using walkie talkie on SMRT trains

    This set of talkies has a low transmission range at lower power and agreed it will never work. Try another high power version maybe more than 1Watts, you will receive the transmission. Nothing to do with interference but the quality of the set itself.


    Quote Originally Posted by firefly99 View Post
    I have been using Motorola T4503 walkie talkie (3km range) when out shopping with my buddies. In general, they work well in most part of Singapore. Even on the SMRT train platform, as in from one end to the other end of the platform.

    However, when we board the same train, first and last carriage, the walkie talkie set would not be able to establish the radio link. Do not think it is an issue with the range, since the moment both of us step out of the train carriage, radio link is reestablished.

    We had tried using other more powerful walkie talkie sets with the same results.

    Anyone had this experience or know what is the cause ?

    Please advise. Thanks.

  13. #13

    Default Re: using walkie talkie on SMRT trains

    Could it be the electromagnet that came out from the train?

    I used to worked very near MRT track (below it) and everytime when the train pass by, my monitor color will start changing (slightly), due to the electromagnet (cause by train movement on the track).

  14. #14

    Default Re: using walkie talkie on SMRT trains

    yes, monitor will be affected. shield it with alu-alloy or switch to LCD


    Quote Originally Posted by yk200 View Post
    Could it be the electromagnet that came out from the train?

    I used to worked very near MRT track (below it) and everytime when the train pass by, my monitor color will start changing (slightly), due to the electromagnet (cause by train movement on the track).

  15. #15
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    Default Re: using walkie talkie on SMRT trains

    so cute.. so many interesting interpretations of how walkie talkies work.
    “How fortunate for leaders that men do not think.” - Adolf Hitler

  16. #16
    Senior Member zac08's Avatar
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    Default Re: using walkie talkie on SMRT trains

    Walkie talkies uses radio frequency, normally shortwave.

    They travel in a sine curve and will be affected by electronics, barriers and also by large groups of humans. It normally works better in open ground/
    Michael Lim
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  17. #17

    Default Re: using walkie talkie on SMRT trains

    Handphone bill too expensive?
    I am NOT a PROfessional photographer and photography is NOT my hobby

  18. #18

    Default Re: using walkie talkie on SMRT trains

    The quoted range for walkie talkies are optimistic, and are valid only in open terrain. In an urban environment, the range is reduced signficantly. Google to understand more.

  19. #19
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    Default Re: using walkie talkie on SMRT trains

    Those walkie talkies arnt cheap. Put it towards the phone bill! My phone works on MRT

  20. #20

    Default Re: using walkie talkie on SMRT trains

    Metals, re-inforced concretes, etc, greatly reduce the range of radio signals. It is not surprising that the metal MRT carriages blocked the transmission.

    BC

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