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Topic: Cell phone signal repeater or booster (Read 2358 times) previous topic - next topic

siddharthverma

Hey guys i want to make a cell phone signal booster/repeater but i've not found a single DIY related to it. need some help. I have found the operating frequencies of the various network providers in India. Plz help me how to go about this project.

AWOL

Quote
Hey guys i want to make a cell phone signal booster/repeater but i've not found a single DIY related to it.

Don't, unless you want to be very, very unpopular with your neighbours, or you're very rich and can afford the fine.
"Pete, it's a fool looks for logic in the chambers of the human heart." Ulysses Everett McGill.
Do not send technical questions via personal messaging - they will be ignored.

sonnyyu

#2
Jul 04, 2013, 12:13 pm Last Edit: Jul 05, 2013, 01:24 am by sonnyyu Reason: 1

http://forum.arduino.cc/index.php?topic=171404.0

http://forum.arduino.cc/index.php?topic=171746.0


  • Every 6 dBm receiver sensitivity gain will be double the distance.

  • Every 6 dBi antenna gain will be double the distance

  • Every 6 dBm Transmitter power gain will be double the distance.

  • Base on Friis Transmission Equation, for  sub Ghz chipset, if we select 300 Mhz  v.s 900 Mhz  band, the distance  will be 3 times more. same thing if we select 300 Mhz  v.s. 2400 Mhz, the distance will be 8 times more.




Nothing  you can do at receiver sensitivity gain unless you are OEM of handset.

Nothing  you can do at Transmitter power gain unless you don't care fine.

Nothing  you can do at frequency since it is fixed at various network providers.

However you can do antenna gain, [font=Verdana]Every 6 dBi antenna gain will be double the distance[/font].

In urban environments, [font=Verdana]Every 12 dBi antenna gain will be double the distance[/font].


Grumpy_Mike

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Every 6 dBi antenna gain will be double the distance.

Only in an ideal world, or line of sight. Not in practice.

sonnyyu


Quote
Every 6 dBi antenna gain will be double the distance.

Only in an ideal world, or line of sight. Not in practice.


People use it for cell phone reception of basement, subway, elevator... None of them are line of sight.

sbright33

Even the expensive commercial "repeaters" do not work.  The improvement is insignificant, and the results are unreliable.
If you fall... I'll be there for you!
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(262) 696-9619

Grumpy_Mike



Quote
Every 6 dBi antenna gain will be double the distance.

Only in an ideal world, or line of sight. Not in practice.


People use it for cell phone reception of basement, subway, elevator... None of them are line of sight.


Again you have used up three posts to convey practically nothing, are you trying just to increase you post count?

Yes non of those examples are line of sight and in non of those examples does your simplistic rule apply.
Have you ever worked with radio?
Any radio ham will tell you that that rule only applies to line of sight where the transmission losses are due to isotropic radiation losses.

retrolefty

Antenna gain Vs distance does not necessarily correlate to any significant signal strength. Antenna gain relates to antenna pattern, with higher 'gain' meaning narrower pattern of reception so gaining a better signal to noise ratio for a given signal within the favored received pattern of the antenna. While a higher gain cell phone antenna may allow better reception to a specific cell tower, if you turn the phone say 30 degrees you may loss the connection all together.

Antenna 'gain' does not electrically increase the voltage of the received signal, just improves the effective signal to noise ratio of a given signal in the preferred direction of the 'gain antenna' and decreases the signal in the non favored direction. Thus there is a trade-off in gain Vs directive and a high gain antenna would not always be useful for a mobile phone. The highest gain antennas will have a very narrow reception pattern.

Lefty

sonnyyu

#8
Jul 05, 2013, 01:19 am Last Edit: Jul 05, 2013, 01:32 am by sonnyyu Reason: 1
OK, You don't buy in line-of-sight, let's do urban environments.

Friis Transmission Formula with Propagation Law




  • R = Maximum range for communication link

  • N = Propagation Law (N=2 for line-of-sight, N=4 for urban environments)

  • PT= Transmit power

  • GT= Total antenna gain

  • ? = Wavelength

  • PR= Receiver sensitivity

  • FM= Fading margin



if in urban environments;-


  • Every 12 dBm receiver sensitivity gain will be double the distance.

  • Every 12 dBi antenna gain will be double the distance.

  • Every 12 dBm Transmitter power gain will be double the distance.



Electronics is Math.

sonnyyu


Even the expensive commercial "repeaters" do not work.  The improvement is insignificant, and the results are unreliable.


agree 100%, at most case repeaters only hurt S/N ratio.

Grumpy_Mike

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Electronics is Math

True but that formular is not maths. The value N is called a fudge factor. It is not a derived quantity therefor you can not treat it as reality only as an approximation as to the situation.
In reality N will change according to location and will not be a linear constant.

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