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I am not terribly interested in hearing about whether or not EMF/RF is hazardous to ones health (as this is frequently discussed in my house).

What I would like to know is; how much EMF/RF does an average scanner emit?

Edit: I would be using this in my house - near my bed for example.

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  • $\begingroup$ I'm not entirely sure this is on topic here, but will wait and see what the community thinks before closing by mod hammer. As for the question itself, I imagine that the answer is "for all intents and purposes none at all". $\endgroup$ – a CVn Dec 10 '14 at 8:24
  • $\begingroup$ Is there any specific problem you are seeking to solve by asking this question? Knowing the context of your question might help us provide better answers. If there is, please edit your question to describe the context. $\endgroup$ – a CVn Dec 10 '14 at 8:25
  • $\begingroup$ @MichaelKjörling I had done some Googling for it and I wasn't able to find any information about it. I asked because my dad thinks that EMF is dangerous and I wanted to know if I could talk him into letting me purchase one. $\endgroup$ – L.B. Dec 10 '14 at 17:48
  • $\begingroup$ Following up on the answers posted below by Scott, and Phil - I suspect you may get a better answer if you were to include the location at which the scanner is to be used $\endgroup$ – VU2NHW Dec 24 '14 at 19:13
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What I would like to know is; how much EMF/RF does an average scanner emit?

No more than your TV, electric lights, or phone charger. In fact, quite possibly less. Certainly far less than your cell phone, laptop, or Xbox controller, all of which contain intentional transmitters.

A scanner does not emit anything intentionally because it does not transmit. There are, of course, unintended emissions, but then this is true of any electrical device. It is especially true of modern, high speed digital electronics.

Most jurisdictions have some authority which limits the maximum permissible unintended emissions for devices. For example, in the USA this is the FCC. To sell a product, a manufacturer must submit a prototype to an electromagnetic compatibility (EMC) testing facility which measures the very small, unintended emissions of the product. The results are sent to the FCC which must certify the device before it can be sold.

So if you want to know more specifically how much EMF your scanner might emit, check out the regulations in your jurisdiction.

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As mentioned earlier, the answer is along the lines of "not much at all", and "about the same as your TV set".

But remember that in the UK they have TV detector vans (to detect people watching TV without a TV licence. Yes, this is real - see http://en.wikipedia.org/wiki/Television_licensing_in_the_United_Kingdom#Detection_technology) that are rumoured to operate by detecting unintentional emissions by a TV receiver - especially around the local oscillator and IF.

Most common radio receivers are "superhet" receivers that work by mixing a locally-generated signal with a received signal and generating an intermediate frequency from these. This is then optionally mixed down still further to a lower IF, and finally converted to baseband.

Apparently, TV detector vans work by looking for the IF and local oscillator, rather than other electrical signals generated within a TV (such as flyback transformers etc. in a CRT TV), because other signals would also be generated by a computer monitor that does not receive TV signals.

Having said that, there have been reports that TV detector vans are a ruse, to frighten people to buy a TV licence.

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  • $\begingroup$ If I were to attempt to build a TV detector, I would look for emissions from the CRT, not the LO. PAL sweeps vertically at at 50 Hz, and there are 625 scanlines, so the horizontal sweeps happen at 31.25kHz. These emissions are going to be far stronger than the IF. Additionally, the reference you cite says these vans detect "operating (analogue) TV". I wouldn't think the emissions would be different from analog and digital broadcast at the receiver, so I took "analogue" to mean "CRT". $\endgroup$ – Phil Frost - W8II Dec 12 '14 at 14:00
  • $\begingroup$ That would also catch people using their TV to display computer-generated images, for which no TV licence is necessary $\endgroup$ – Scott Earle Jan 26 '15 at 2:56

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