"the device must accept any interference received"?

[Adam Funk]

I happened to be looking at the bottom of an electronic game accessory
& noticed the following text:

This device complies with Part 15 of the FCC Rules. Operation is
subject to the following two conditions: (1) this device may not
cause harmful interference, and (2) this device must accept any
interference received, including interference that may cause
undesired operation.

I can understand condition 1 (obviously), but what is the point of
condition 2? Why does a device, even for a relatively trivial
purpose, need to "accept" interference that may cause undesired
operation?


--
XML is like violence: if it doesn't solve the problem,
use more.

[Tim Wescott]

On Wed, 25 Nov 2015 21:32:07 +0000, Adam Funk wrote:

> I happened to be looking at the bottom of an electronic game accessory &
> noticed the following text:
>
> This device complies with Part 15 of the FCC Rules. Operation is
> subject to the following two conditions: (1) this device may not cause
> harmful interference, and (2) this device must accept any interference
> received, including interference that may cause undesired operation.
>
> I can understand condition 1 (obviously), but what is the point of
> condition 2? Why does a device, even for a relatively trivial purpose,
> need to "accept" interference that may cause undesired operation?

Because if you're next to a guy who's transmitting perfectly legally and
your stuff doesn't work, then it is, ipso facto, your stuff's fault. The
FCC just spells that out for you.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

[Michael Black]

On Wed, 25 Nov 2015, Adam Funk wrote:

> I happened to be looking at the bottom of an electronic game accessory
> & noticed the following text:
>
> This device complies with Part 15 of the FCC Rules. Operation is
> subject to the following two conditions: (1) this device may not
> cause harmful interference, and (2) this device must accept any
> interference received, including interference that may cause
> undesired operation.
>
> I can understand condition 1 (obviously), but what is the point of
> condition 2? Why does a device, even for a relatively trivial
> purpose, need to "accept" interference that may cause undesired
> operation?
>

ONce upon a time, one amateur radio operator ended up with all kinds of
trouble because his transmitter caused problems in his neighbor's tv set.
Lots of testing was done, the transmitter was declared clean, but the
problem didn't go away. There was a civil suit (which I think never went
to court) and the ham ended up with modified license preventing him from
using one band. This was in the early sixties.

This clause is to prevent that. Lots of equipment may suffer from a
nearby transmitter, but unless the transmitter is not up to standards,
it's not the fault of the transmitter. The consumer equipment is often not
protected well from nearby transmitters, but people will blame the
transmitter, rather than accept that the consumer equipment is at fault.

This clause merely warns the user about this.

Michael

[Phil Allison]

Adam Funk wrote:
>
> I happened to be looking at the bottom of an electronic game accessory
> & noticed the following text:
>
> This device complies with Part 15 of the FCC Rules. Operation is
> subject to the following two conditions: (1) this device may not
> cause harmful interference, and (2) this device must accept any
> interference received, including interference that may cause
> undesired operation.
>
> I can understand condition 1 (obviously), but what is the point of
> condition 2?

** This kind of wording refers to particular bands that are unlicensed and shared by many users, essentially at their own risk.

What it boils down to is that complaints about interference will not get any attention from the authority.

For example, wireless microphones often share bands used by broadcast TV signals. The mic must not case interference to nearby TV viewers but the other way around is your bad luck.



... Phil

[John Larkin]

I don't think FCC cares about suceptability. CE does.

[Adam Funk]

OK, that makes sense. It seems to me that condition 2 is strangely
written; what it really means is "*you* must suck it up if the device
receives interference".


--
Random numbers should not be generated with a method chosen at random.
--- Donald Knuth

[Ralph Mowery]

"Adam Funk" <a24...@ducksburg.com> wrote in message
news:lftiicx...@news.ducksburg.com...

>>> This clause is to prevent that. Lots of equipment may suffer from a
>> nearby transmitter, but unless the transmitter is not up to standards,
>> it's not the fault of the transmitter. The consumer equipment is often
>> not
>> protected well from nearby transmitters, but people will blame the
>> transmitter, rather than accept that the consumer equipment is at fault.
>>
>> This clause merely warns the user about this.
>
> OK, that makes sense. It seems to me that condition 2 is strangely
> written; what it really means is "*you* must suck it up if the device
> receives interference".
>
>

That is correct. If you buy a device so labled, it is up to you to make
sure it will work if there are other transmitters around. Say you have
several wireless routers in the same house or apartment building. As they
may operate on the same band, they may interfear with each other. If
someone a few blocks away has one, he is probaly far enough away it will not
cause problems.

Years ago the Citizens band radios were licensed and some 100 miliwatt handy
talkies that did not require a license were legal. The HTs had to put up
with the licensed transmitters. When CB became very popular for a few
years, the FCC set aside a few frequencies for them around 49 MHz instead of
around 27. Later they were moved to around 460 MHz .

There was some low powered wireless FM microphones that used the same
frequencies of the FM broadcast band. As they only hada range of around a
few hundred feet, they did not usually cause any problems with the broadcast
station, but if the broadcast station hapened to be on the same frequency
it could wipe out the wireless mic.

[Adam Funk]

It pretty much agrees with common sense. If the label had said "the
user must tolerate interference", I wouldn't have asked the question!


--
We do not debug. Our software does not coddle the weak. Bugs
are good for building character in the user.
--- Klingon Programmer's Guide

[M Philbrook]

In article <nvlhicx...@news.ducksburg.com>, a24...@ducksburg.com
says...

>
> I happened to be looking at the bottom of an electronic game accessory
> & noticed the following text:
>
> This device complies with Part 15 of the FCC Rules. Operation is
> subject to the following two conditions: (1) this device may not
> cause harmful interference, and (2) this device must accept any
> interference received, including interference that may cause
> undesired operation.
>
> I can understand condition 1 (obviously), but what is the point of
> condition 2? Why does a device, even for a relatively trivial
> purpose, need to "accept" interference that may cause undesired
> operation?

It's simply this.

It is not allowed to mess up other equipment but you can't
complain about other equipment bothering it!


In otherwords, to bad if it gets screwed up from the CB'er next door,
but don't you be screwing with his receiver with RF emissions from this
unit.

Short version, don't bother to call anyone about it cause they don't
care.

How do you like description?


Jamie

[Cursitor Doom]

There's also the question of priority. There are signals in what I
believe is called the 'Standard Frequency Service' that are deemed so
important they must not be interfered with (big TV and radio stations for
instance) but THEY can give you grief if you're in their neighbourhood
and there's nothing you can do about it legally.