Is it possible to construct such a computer peripheral device?

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Discussion Overview

The discussion revolves around the feasibility of constructing a computer peripheral device, such as a USB stick, that can measure electromagnetic amplitude across various wireless communication standards without filtering for frequency. The scope includes theoretical considerations, technical challenges, and practical implications of such a device.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that a device could measure the electromagnetic amplitude of various wireless standards, proposing that a computer program could filter the signals for specific frequencies.
  • Another participant points out that efficient antennas are typically sized according to the wavelength of the electromagnetic waves, making it challenging to use a single antenna for broadband reception.
  • Concerns are raised regarding the signal-to-noise ratio (SNR) when attempting to create a broadband RF receiver, emphasizing the importance of narrow band filtering for better sensitivity.
  • Software Defined Radios (SDRs) are mentioned as existing technology that somewhat aligns with the proposed concept, although they may not be fully broadband.
  • It is noted that interacting with networks like WiFi or LTE requires both transmission and reception capabilities, complicating the design compared to one-way communication systems like FM radio.
  • Another participant questions the processing power and memory bandwidth requirements for continuous operation of such a device, suggesting that the demands may exceed practical limits for a USB stick.

Areas of Agreement / Disagreement

Participants express a range of views on the feasibility and practicality of the proposed device, with no consensus reached on whether it can be effectively constructed. Multiple technical challenges and considerations are highlighted, indicating ongoing debate.

Contextual Notes

Participants mention limitations related to antenna design, signal processing requirements, and the inherent challenges of broadband reception versus narrow band filtering. The discussion also touches on the mathematical considerations involved in signal processing.

somega
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There are many wireless communication standards like:
- WiFi
- DVB-T /DVB-A
- LTE
- FM broadcasting

As far as I know they are all using electromagnetic waves.
And if they are all sending then the electromagnetic field amplitude is the combination of them all.
Is it possible to construct a computer device (e.g. USB stick) which measures the electromagnetic amplitude (without filtering for a frequency)?
A computer program could then filter the signal for a specific frequency/standard.
This would mean you have 1 USB stick which can receive any kind of wireless communication standard.
 
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Good question -- keep on thinking like this!

Several issues:
  • Efficient antennas are about the size of the wavelength of the EM. So it's hard to use a single antenna for broadband reception
  • The broader your initial RF receive preamp's bandwidth, the more noise you also pick up. It's generally best for obtaining a good signal/noise ratio (SNR) to do narrow band filtering of the input signal (often with a passive resonant circuit right after the receive antenna), and then do your mixing and processing after that. It's very hard to make an RF receiver with good sensitivity if you try to make it too broadband.
  • There are "software defined radios" (SDRs) that are pretty interesting. They aren't necessarily broadband, but they are generally pretty flexible. Do a search and some reading about them to learn more.
:smile:
 
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The other issue is to interact with something like a wifi or LTE network you need both transmit and receive, and generally you need to register on the network, so fundamentally quite different from FM radio and digital TV which are one way (large transmitter, lots of little receivers).
 
somega said:
Is it possible to construct a computer device (e.g. USB stick) which measures the electromagnetic amplitude (without filtering for a frequency)?
A computer program could then filter the signal for a specific frequency/standard.
Just think about the requirements for processing power and IO/memory bandwidth for continuous operation. I did not delve too deep into the math but just a single upper limit check said that a barely adequate sampling for LTE g4 would consume a whole PCIe3.0 X8 slot. Just forget about any sticks here 😄

BTW the math exists and for audio or low frequency (the 'low' here is subject of relativity) signals the method works.
 

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