Gps, Mobile phones microwaves and radiowaves

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    Gps Microwaves Mobile
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Discussion Overview

The discussion revolves around the differences in signal strength and penetration of GPS signals compared to mobile phone and radio signals, particularly in indoor environments. Participants explore the implications of frequency, power, and signal characteristics in the context of health concerns related to electromagnetic emissions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why GPS satellites and mobile phone communications do not use emissions in the radiowave band, which they suggest is less dangerous for health.
  • Another participant proposes that GPS requires a higher frequency for accuracy, noting that both GPS and cell phone signals fall within the radio wave spectrum.
  • A participant mentions that noise and digital modulation are significant factors affecting signal quality.
  • One contributor argues that the difference in signal strength is due to the power of the signals, with GPS needing to transmit from satellites to Earth, while cell phones and radios transmit shorter distances from towers.
  • Another participant highlights the necessity of national and international agreements to manage frequency use and avoid interference, mentioning specific frequency bands allocated to satellites.
  • A later reply reiterates the initial question and discusses how lower frequencies generally penetrate further, providing examples of AM and FM radio frequencies compared to mobile phone and GPS frequencies.
  • This participant also notes that GPS signals are lower in power compared to mobile phone signals, which can affect their reliability indoors.

Areas of Agreement / Disagreement

Participants express differing views on the reasons for the differences in signal strength and penetration. There is no consensus on the primary factors influencing these differences, with multiple competing explanations presented.

Contextual Notes

Some assumptions regarding the relationship between frequency, power, and signal penetration remain unexamined. The discussion does not resolve the complexities of signal characteristics and their implications for different applications.

SciencePF
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Hello, friends!
I've google about the question below but no success!
The question is:

Gps signals inside buildings are nonexistent or very weak, but mobile phone and am and fm radio signals are good, so the question is: why gps satellites and mobile phone comunications don't use emission on the radiowave band, which is less dangerous for our health.

TIA
 
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I suspect that GPS needs a higher frequency because of the accuracy of the signal, but it is still in the radio wave part of the spectrum. As are cell phone signals.

Also, there really aren't any health issues here.
 
Also, noise and digital modulation are big (related) issues.
 
I donn't think it's a matter of the frequencies used; I think it is a difference in power of the signal. GPS signals have to come all the way from the sattelite to the Earth, cell phones and radios only have to make it from the tower to where you are.
 
National and international agreements are necessary for the use of different frequencies to avoid inteference...and signal characteristics have pros and cons in different applications...
see http://www.mlesat.com/Article9.html

for additional information...note satellites are allocated Ka, Ku, and C bands...and only so much spectrum is available.
 
SciencePF said:
Gps signals inside buildings are nonexistent or very weak, but mobile phone and am and fm radio signals are good, so the question is: why gps satellites and mobile phone comunications don't use emission on the radiowave band, which is less dangerous for our health.

Partly it's the frequency - in general lower frequency (longer wavelengths) penetrate further.
AM radio has the lowest frequency <0.5MHz and penetrates furthest, FM at 100MHz less far.
Mobile phones use 900 or 1800MHz and only go a short distance into a building depending on the construction. But mobile phones are relatively powerful signals.

GPS uses 1500MHz so has similair characteristics to a cell phone but much lower power. It also relies on accurately measuring the signal from a number of satelites to get a position which is difficult if some signals are reflected or blocked.
A phone conversation is intelligible even with very poor signal to noise.

Cell phones, bluetooth, and Wifi are all in the microwave band,
 
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