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'[EE] Unlicensed low power FM transmitter (e.g. wir'
2007\06\16@074852 by Peter P.

picon face
I would like to ask the group's wisdom, what (if any) regulations govern this
subject. I know that there exists a plethora of low power FM transmitters for
iPods, baby surveillance, even hands free phone kits (for car use). What is the
allowed maximum input power for these ? I am talking maybe 2 meters of range vs.
a reasonably sensitive state of the art FM receiver. I.e. probably 10uV into 50
ohms at 2 meters (since this is near field one cannot apply the usual equations
I think).

Peter P.


2007\06\16@100322 by Gerhard Fiedler

picon face
Peter P. wrote:

> I would like to ask the group's wisdom, what (if any) regulations govern this
> subject.

You didn't mention the country, what type of device, what frequency range,
whether this is commercial (for sale) or for your own use. (I think this
are the main parameters.)

If you're talking USA, it's the FCC regulations. Harold has a collection
<http://www.hallikainen.com/FccRules/>, specifically part 15
<http://www.hallikainen.com/FccRules/2007/15/>.

> I know that there exists a plethora of low power FM transmitters for
> iPods, baby surveillance, even hands free phone kits (for car use). What
> is the allowed maximum input power for these ?

AFAIK this depends on the frequency and the specific device category. But
AFAIK all intentional radiators (all that you mentioned) need to have
passed FCC certification. (Unless it's a one-off hobby project; I'm not
sure what the regulations are for this.)

Gerhard

2007\06\16@110002 by Peter P.

picon face
Gerhard Fiedler <lists <at> connectionbrazil.com> writes:

> You didn't mention the country, what type of device, what frequency range,
> whether this is commercial (for sale) or for your own use. (I think this
> are the main parameters.)

In general, world wide.

The devices I gave as examples all have CE and some have FCC ratings. I wonder
if this implies testing or just the right stencil at the package
manufacturer's. This is of course not for myself (I will not likely ask for
permission to run a known low power 'unintentional' radiator in my lab - if
I'd have to do that I would have to get written permission every time I turn
on a SMPSU without the shields and filters mounted - and my own radio(s) tell
me already when I'm 'broadcasting').

By this I mean, what chapter should these devices fall under ? I.e. a very low
power device could simply radiate at any frequency it wishes as long as it
stays under the FCC ratings ? That would be too good to be true (and I suspect
that it's true although the lawmakers did not mean it to be like that). As you
know, a couple of uW go a long way with a good receiver.

F.ex. my likely very wrong calculations based on a point isotropic radiator
and a matched lambda/2 dipole at 2 meters distance seem to indicate that I
need 0.5uW radiated RF for 10uV@50Ohms receiving at 100MHz. I don't quite
believe that someone needs a license for a 0.5uW radiator (the LO leakage from
the average FM radio is several times that). (0.5uW radiated corresponds to
100nA at 5V 'input' power at eta=100% - assuming the osc. is 1% efficient and
'transmission' attenuation is 40dB - likely for a LO - this is still only
1mA@5V LO osc input power - so clearly the average FM radio's LO stray
radiation outperforms 'my' transmitter by a wide margin).

thanks,
Peter P.


2007\06\16@122936 by Peter P.

picon face
Gerhard Fiedler <lists <at> connectionbrazil.com> writes:

> If you're talking USA, it's the FCC regulations. Harold has a collection
> <http://www.hallikainen.com/FccRules/>, specifically part 15

Hehe, I feel that my case is covered by FCC part 15.13, but 15.111 contradicts
everything I know about radios I owned and worked on ... Example: Assume LO1 =
1mW  and mixer isolation 40dB from LO1 to input and RF amp reverse gain of 40dB
one has 1mW - 80dB ~= 100nW into the antenna. 2nW into the antenna requires
something like 120 dB isolation from LO1 to antenna. Not likely in any commercial
or consumer receiver (and actual LO1 levels are more like 10mW and higher for
professional receivers). What am I missing ?

Realistic figures figures for a low power FM front end are like LO1 ~= 10mW,
attenuation to ant in ~= -60dB (10uW or 22mV@50Ohms at the antenna - ten times
as much as I intend to radiate).

I guess I'll simply cheat and measure the LO stray radiation from a CE and FCC
approved radio at the antenna, and produce as much power with my thing knowing it
must (?) be reasonable vs. FCC and CE ... incidentally for 10.7MHz IF1 any FM
radio's LO1 stray emissions lie inside the 88-108.5 MHz FM band for at least half
the channels tuned, by design.

Peter P.


2007\06\16@231303 by Gerhard Fiedler

picon face
Peter P. wrote:

>> You didn't mention the country, what type of device, what frequency
>> range, whether this is commercial (for sale) or for your own use. (I
>> think this are the main parameters.)
>
> In general, world wide.

That doesn't exist, as a regulation. It's specific for each country (or
commercial zone that have synced their regulations, like the EU). So you
have to study the regulations for each target market.

> The devices I gave as examples all have CE and some have FCC ratings.

CE and FCC are completely different. I'm not sure how CE deals with
intentional radiators, but at least for non-intentional radiator devices,
you can self-certify CE; just make sure it's within the (non-intentional)
radiation limits (and the other limits, of course).

For an FCC sticker, you need to hire a certified lab to make you a lab
report. (And re-hire them if you change something.)

> By this I mean, what chapter should these devices fall under ? I.e. a
> very low power device could simply radiate at any frequency it wishes as
> long as it stays under the FCC ratings ?

I think this is true -- if it stays below the defined limits. But you have
to hire a certified lab to certify you this for an FCC number if it is an
intentional radiator.

> I don't quite believe that someone needs a license for a 0.5uW radiator
> (the LO leakage from the average FM radio is several times that).

It sounds as if you may confuse whether an operating license is required or
whether the device itself has to be (FCC) certified. At least in the USA,
these two concepts are completely separate. With certain licenses, you may
operate non-certified gear, at rather high powers even. OTOH, there are
many (certified) products that may be operated without license.

AFAIK there is no intentional radiator that doesn't require an FCC
certification, no matter how low the radiation. (The key element here is
not the radiation power, it's the "intention".)

Gerhard

2007\06\17@062056 by Peter P.

picon face
Gerhard Fiedler <lists <at> connectionbrazil.com> writes:

> > In general, world wide.
>
> That doesn't exist, as a regulation. It's specific for each country (or
> commercial zone that have synced their regulations, like the EU). So you
> have to study the regulations for each target market.

Still there are oodles of devices that work anywhere. The ones I have in mind
are the FM transmitters that connect iPods and the like to the car FM radio
without a wire. This is really a small stereo transmitter with 1-2 meters of
range. My easiest option for now is to buy one of these and build with it.

> > I don't quite believe that someone needs a license for a 0.5uW radiator
> > (the LO leakage from the average FM radio is several times that).
>
> It sounds as if you may confuse whether an operating license is required or
> whether the device itself has to be (FCC) certified. At least in the USA,

Thanks for posting that. It sounds like I'll have to make it work 'elsewhere'
first and then deal with FCC if necessary.

> AFAIK there is no intentional radiator that doesn't require an FCC
> certification, no matter how low the radiation. (The key element here is
> not the radiation power, it's the "intention".)

Oh, yes. An engineering standards instiution in the premier technological
nation on the planet defines engineering standards (minimum ERP for licensing)
using legal terms that have no SI units. So, if I happen to built a
Confabulophlogisticoenhancer that mainly consists of a large blue led
that pulses slowly in the rhythm of music and psi wave enhanced bhagra beat
but just so happens to be receivable with any FM receiver from about 2 meters
distance then I should be home free, no ? At last according to radiation
determined by 'intention'. Yes, I am a little sarcastic. Especially because
the same institution (FCC) allows some horrible 'unintentional radiators' to
pollute the radio spectrum at levels that are inconceivable for anything but
jammers imho.

thanks,
Peter P.


2007\06\17@065412 by wouter van ooijen

face picon face
> Still there are oodles of devices that work anywhere.

"work" does not imply "allowed". In my country the use of such devices
is illegal (although posession and sale is not).

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products
docent Hogeschool van Utrecht: http://www.voti.nl/hvu



2007\06\17@071459 by Roger, in Bangkok

face
flavicon
face
Many countries' governments consider anything "wireless" as war devices ...
especially if/when under martial law.  Possession or even innocent
importation can get you serious jail time here.

Regards/Roger, in Bangkok


On 6/17/07, wouter van ooijen <spam_OUTwouterTakeThisOuTspamvoti.nl> wrote:
{Quote hidden}

> -

2007\06\17@115703 by Peter P.

picon face
Roger, in Bangkok <mercies <at> cscoms.com> writes:
> Many countries' governments consider anything "wireless" as war devices ...
> especially if/when under martial law.  Possession or even innocent
> importation can get you serious jail time here.

You are right Roger, excepting that by certain definitions of 'intended radiator'
all the crystals in the holistic/wicca shop are illegal, as they are intended
radiators (it says so on the boxes), but then there are countries where just
playing certain kinds of music or showing your hair or ankle can get you jailed
and worse. Some of them even call themselves 'republics' and 'democracies'. The
latter means that a lot of people will participate in any lapidation that may
take place. One could call that 'voting with stones' I think. (this is going way
off topic, and it's my fault as usual).

Peter P.


2007\06\17@121057 by Gerhard Fiedler

picon face
Peter P. wrote:

>>> In general, world wide.
>>
>> That doesn't exist, as a regulation. It's specific for each country (or
>> commercial zone that have synced their regulations, like the EU). So you
>> have to study the regulations for each target market.
>
> Still there are oodles of devices that work anywhere.

As others have said, it is a bit more complex :)

In general, I think you have to distinguish for commercial devices (and I
may miss a few):

- operator license (like ham radio operators, telecom companies)

- product certification (like FCC, with certified lab reports)

- product self certification (like CE, no official lab reports required but
the product is required to have the sticker)

- no certification required but existing regulations need to be met
(probably in practice pretty much the same as self certification; at least
I don't see a real difference)

- the difference between possessing, selling commercially, selling
privately, operating commercially and operating privately which may affect
any of the above and also the consequences of non-compliance (like a
private user operating an illegal device may face simply confiscation of
the device while the company that sold it may face confiscation of all
related stock plus a stiff fine)

- regulations of any of the above kinds exist but are not or rarely
enforced or can be circumvented by payments of bribes (the required
know-how in this case is how to avoid being caught, or how to avoid being
affected when caught, or how and to whom to pay the bribes)

- no regulations at all (not sure this exists)


All but the last imply that some regulations (official or unofficial) exist
-- and these will always be specific to a certain administrative entity. So
for each country or entity where you want to sell, you have to check the
specific situation. It also depends whether you are in the country under
consideration or have assets there (I think often devices illegal in a
certain country are sold there online by companies that are not located in
that country, and leave these "details" of operation up to the user).

Even if others seem to be able to sell something without getting bothered
by the authorities, you don't know what exactly they did or do to be able
to do so. Met some specs? Bribed the right guy? Just know that they can't
be bothered by the authorities of the country where they sell?


> Especially because the same institution (FCC) allows some horrible
> 'unintentional radiators' to pollute the radio spectrum at levels that
> are inconceivable for anything but jammers imho.

Well, and if you sell an unintentional radiator for use in cars, it doesn't
even have to pass any FCC certification. You could sell your little
transmitter as a psychedelic LED blinker for use in a car that happens to
have a non-intentional radiation that by coincidence can be received in a
nearby FM radio... Don't quote me on this, though :)

Gerhard

2007\06\18@040829 by Alan B. Pearce

face picon face
>> I would like to ask the group's wisdom, what (if any)
>> regulations govern this subject.
>
>You didn't mention the country, what type of device, what
>frequency range, whether this is commercial (for sale) or
>for your own use. (I think this are the main parameters.)

If looking to do something for international markets have a look at the
datasheet for Analog Devices ADF7021 transceiver chip. They list a whole
host of regulations that their chip is designed to meet, and this list
should give suitable pointers to what you want (including multiple FCC
ones).

2007\06\18@062407 by Michael Rigby-Jones

picon face


>-----Original Message-----
>From: .....piclist-bouncesKILLspamspam@spam@mit.edu [piclist-bouncesspamKILLspammit.edu]
>On Behalf Of Gerhard Fiedler
>Sent: 16 June 2007 15:02
>To: .....piclistKILLspamspam.....mit.edu
>Subject: Re: [EE] Unlicensed low power FM transmitter (e.g.
>wireless iPod toFM etc)
>
>
>Peter P. wrote:
>
>> I would like to ask the group's wisdom, what (if any) regulations
>> govern this subject.
>
>You didn't mention the country, what type of device, what
>frequency range, whether this is commercial (for sale) or for
>your own use. (I think this are the main parameters.)


For anyone interested the UK finaly legalised low power "micro transmitters" in the FM broadcast band (88-108MHz) late last year.  But they really mean LOW power, the regulations are available at http://www.ofcom.org.uk/radiocomms/ifi/tech/interface_req/uk2030.pdf and allow a maximum e.r.p. of just 50nW in this band.  FWIW, the Griffin iTrip meets this requirement.

Regards

Mike

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2007\06\18@072523 by Tony Smith

picon face
> Roger, in Bangkok <mercies <at> cscoms.com> writes:
> > Many countries' governments consider anything "wireless" as
> war devices ...
> > especially if/when under martial law.  Possession or even innocent
> > importation can get you serious jail time here.
>
> You are right Roger, excepting that by certain definitions of
> 'intended radiator'
> all the crystals in the holistic/wicca shop are illegal, as
> they are intended radiators (it says so on the boxes), but


Hmmm, get the new-age flakes arrested for illegal broadcasting...
Interesting...

The iPod transmitter (and similar) have only recently been made legal in the
UK.

Tony

2007\06\18@074535 by Peter P.

picon face
Alan B. Pearce <A.B.Pearce <at> rl.ac.uk> writes:

> If looking to do something for international markets have a look at the
> datasheet for Analog Devices ADF7021 transceiver chip. They list a whole

Ok, thanks for that, I'll foloow up on it.

Peter P.




2007\06\18@100049 by Peter P.

picon face
Michael Rigby-Jones <Michael.Rigby-Jones <at> bookham.com> writes:

> For anyone interested the UK finaly legalised low power "micro transmitters"
> in
> the FM broadcast band
> (88-108MHz) late last year.  But they really mean LOW power, the regulations
> are available at
> http://www.ofcom.org.uk/radiocomms/ifi/tech/interface_req/uk2030.pdf and allow
> a maximum
> e.r.p. of just 50nW in this band.  FWIW, the Griffin iTrip meets this
> requirement.

50 nW is low by any standards (but higher than 'intention' units). Thanks.

Speaking of iTrip etc, I was just reading on the net about it and it seems to be
the first time when the RFI-proofing qualities of a CE (paper) label are proven.
Several authors confirmed that removing the paper label from an iTrip and
erecting the tiny antenna that hides under it improves reception ...

link:

 http://www.macintouch.com/ipod26.html

(see 'The Mobile iPod' therein, Jul. 8 2004, article)

thanks for posting,

Peter P.


2007\06\18@155633 by Peter P.

picon face
Peter P. <plpeter2006 <at> yahoo.com> writes:

> 50 nW is low by any standards (but higher than 'intention' units). Thanks.

In continuation, it's pretty clear that whatever units the FCC uses for these
'intentional' radiators they are legal in the US, and specifically require no
broadcast license to use (as opposed to more powerful transmitters, which do).
So there must be a way to specify them. Unfortunately none of the (many) units
I saw on sale has a relevant datasheet. I wonder why ? Anyway good brand units
have a FCC ID (and indicate range: 10-30 ft - I need a fifth of that). Example:

 http://www.griffintechnology.com/products/itripdock/

So the question of FCC ID is settled. But I wonder if it's needed because of the
microprocessor and PLL inside or the FM output ... i.e. is it an intended PLL
with microprocessor control, or an intended 'radiator' <g>

Peter P.


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