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Gavinmc42
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Legally extending Zero WiFi?

Mon Jul 31, 2017 12:05 pm

jamesh locked this thread, but can we get some more clarification please?
viewtopic.php?f=29&t=189475

I understand modifying the Zero W PCB will break WiFi certification.
Don't even talk about that connector footprint :shock:

But what are the legal ramification of using unmodified Zero's at the focal points of dishes or Woks? How much gain would that give?
Solar powered Zero WiFi repeaters could be useful for rural areas, over the hill connections, village to village, disaster networks etc.

For disaster scenes the dishes could be alum foil coated cardboard or corflute made on site. Never really thought about this before but $10 programmable WiFi transceivers never used to be so common.

Local to directional units = Zero W with a USB extension cabled WiFi USB dongle/dish on different channel.
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mattmiller
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 1:40 pm

EIRP varies from country to country and its a matter of debate whether anyone classes the reflector as part of the device antenna

WiFi is intended for local area use not long range and regulations were designed to try and limit it to such use

But loads of companies sell point-point wifi links so.....

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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 2:24 pm

Putting the Pi in a parabolic reflector (ie satellite dish) WILL exceed the radiation level per some figure (cannot remember the exact name), which is 100mw, so will break certification - Wifi is deliberately limited to this value. Those limits are there for a reason, so I'm afraid this thread is going the same way as the other. I'm sure you can find other websites that are less concerned with telling people how to break the law.
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rurwin
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 2:51 pm

If the legal limit is Effective Isotropically Radiated Power (EIRP), then you cannot increase it using an antenna of any sort. The antenna is included in the calculation; if you use more gain then you must use less power. It's not a matter of debate, merely rumour, misinformation and how proactive your enforcement officers are.

If the legal limit is transmitter power, then you can use an antenna that has directional gain.

Which case pertains may depend on the country that you are in but a swift Google seems to say that using EIRP is fairly universal.

MarkTF
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 2:59 pm

Parabolic dish antenna systems use a moderately directional feed antenna that directs it's energy at the dish which focuses it into a tighter beam. The technical issue with simply putting a Zero at the feed point of a dish is that with its nominally omnidirectional antenna, most of the energy misses the dish. One would get gain in the direction of the dish, but not very efficiently.

mikerr
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 3:21 pm

There is a hack to add a ufl connector to the pi zero:
http://www.briandorey.com/post/Raspberr ... ntenna-mod

Use that, and then a directional antenna (at both ends of the link).
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rurwin
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 3:50 pm

The subject is "Legally extending Zero WiFi".

Whatever hack you do will break certification. It is illegal to transmit on an uncertified device, even if your hack does not result in illegal EIRP.

If, and only if, the Zero is not capable of transmitting at full legal EIRP in the country you are using it in. (I believe some countries allow 1W EIRP, and maybe the Zero is not capable of that) then you could consider a directional aerial, but you would have to get it certified yourself. Similarly, a parabolic dish will probably work reasonably well, but would still break the certification.

I am a licensed radio amateur and I am required to know about power limits and equipment certification as a condition of my license. I'm not guessing here.

Pithagoros
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 3:56 pm

mikerr wrote:
Mon Jul 31, 2017 3:21 pm
There is a hack to add a ufl connector to the pi zero:
http://www.briandorey.com/post/Raspberr ... ntenna-mod

Use that, and then a directional antenna (at both ends of the link).
Superb, thank you.

I've increased my range by enhancing my access point, but this is another option.

hippy
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 6:55 pm

rurwin wrote:
Mon Jul 31, 2017 3:50 pm
Whatever hack you do will break certification. It is illegal to transmit on an uncertified device, even if your hack does not result in illegal EIRP.

I am a licensed radio amateur and I am required to know about power limits and equipment certification as a condition of my license. I'm not guessing here.
I am not a licensed radio amateur so don't know but; would breaking certification, using an uncertified device, or exceeding EIRP, be illegal if it were done under laboratory conditions, inside a suitable Faraday cage or similar where the effects of that would be entirely contained within the testing area ?

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mahjongg
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Re: Legally extending Zero WiFi?

Mon Jul 31, 2017 10:05 pm

no, because people doing these kinds of tests do have a legal permit of testing devices that probably/possibly are NOT legal.
But any attempt/device to increase transmission strength of a legally tested device makes the testing invalid and turns the device back into an untested and thus potentially (and practically ) illegal device.

There is a *reason* transmission strengths are limited by law!

locking this thread, as its about attempting to circumvent the law.

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rurwin
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Re: Legally extending Zero WiFi?

Tue Aug 01, 2017 6:02 am

http://www.legislation.gov.uk/uksi/2000 ... 730_en.pdf

See in particular, sections 5, 19 and 20.
5.
—(1) Subject to regulations 6, 7 and 8, no person shall place on the market or put into service any apparatus unless the requirements of paragraph (2) and (in the case of radio equipment) the requirements of paragraph (3) have been complied with in relation to it.

Conformity assessment procedures for apparatus
9.
—(1) For the purposes of regulation 5(2)(c), the appropriate conformity assessment
procedure for apparatus shall, subject to paragraph (2), be chosen from the procedures set out
in Schedules 2, 3, 4 and 5 as follows: ...

Offences
19.
Any person who—
(a) contravenes or fails to comply with regulation 5(1) or 12; or
(b) fails to supply or retain a copy of the appropriate documentation as required by
regulation 9(3),
shall be guilty of an offence.

Penalties
20.
—(1) A person guilty of an offence under regulation 19(a) shall be liable on summary conviction—
(a) to imprisonment for a term not exceeding 3 months; or
(b) to a fine not exceeding level 5 on the standard scale,
or to both.
(2) A person guilty of an offence under regulation 19(b) shall be liable on summary
conviction to a fine not exceeding level 5 on the standard scale.
A level 5 fine appears to be up to £5,000.

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