On Tue, 24 Jul 2012 09:10:20 -0500, John S
wrote:

On 7/23/2012 4:03 PM, Jeff Liebermann wrote:
(...)
Assuming a 0dBi gain antenna:
Power = 0.3 FS^2
where
FS = field strength in Volts/meter
P = Watts
Plugging in:
Power = 0.3 * (11000 uV/m)^2 = 0.3 * (11000*10^-6 V/m)^2
Power = 0.3 * 0.000121 = 36 milliwatts.

.3 * .000121 = .000036 or 36 MICROwatts.

Oops and thanks (again). I keep fudging the numbers (unintentionally)
to what I think they should be, instead of what they are. Very
embarrassing.

Microwatts doesn't seem to make sense as there are products being sold
that advertise 10mw and 100mw output power levels. Obviously they are
not being certified under Part 15. However, I can't find another US
service on 433MHz that qualifies (except ham radio). FCC frequency
allocations table is of no use:
http://ecfr.gpoaccess.gov/graphics/pdfs/er27ja12.018.pdf
433MHz is an ISM band, but only in region 1 (Europe) and not in region
2 (US).
http://en.wikipedia.org/wiki/ISM_band
My guess(tm) is that the higher power 433MHz devices can only be sold
in Europe. Yet, that's not apparent on any of the sites selling
433MHz data radios.

"FCC Compliance testing Using the MICRF112"
http://www.micrel.com/_PDF/App-Notes/an-55.pdf
Page 9 has the calcs for a typical key fob transmitter.
36 microwatts.

Thanks for catching my mistake and I'll double check the numbers
(again) when I get home from some service calls.

You're welcome again.

I'll do some more reading and checking, hopefully tonite. Paying work
comes first. My appologies (again) for my multiple screwups.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 7/24/2012 12:12 PM, Jeff Liebermann wrote:

Microwatts doesn't seem to make sense as there are products being sold
that advertise 10mw and 100mw output power levels. Obviously they are
not being certified under Part 15. However, I can't find another US
service on 433MHz that qualifies (except ham radio). FCC frequency
allocations table is of no use:
http://ecfr.gpoaccess.gov/graphics/pdfs/er27ja12.018.pdf
433MHz is an ISM band, but only in region 1 (Europe) and not in region
2 (US).
http://en.wikipedia.org/wiki/ISM_band
My guess(tm) is that the higher power 433MHz devices can only be sold
in Europe. Yet, that's not apparent on any of the sites selling
433MHz data radios.

It appears that we have both looked very hard and have come to the same
conclusion. I now wonder if the US suppliers are unaware of the region
1/region 2 thing.

"FCC Compliance testing Using the MICRF112"
http://www.micrel.com/_PDF/App-Notes/an-55.pdf
Page 9 has the calcs for a typical key fob transmitter.
36 microwatts.

I saw that. Lower left corner of page 4 says that continuous operation
is allowed. Where do they get that?

John S wrote:
On 7/24/2012 12:12 PM, Jeff Liebermann wrote:

Microwatts doesn't seem to make sense as there are products being sold
that advertise 10mw and 100mw output power levels. Obviously they are
not being certified under Part 15. However, I can't find another US
service on 433MHz that qualifies (except ham radio). FCC frequency
allocations table is of no use:
http://ecfr.gpoaccess.gov/graphics/pdfs/er27ja12.018.pdf
433MHz is an ISM band, but only in region 1 (Europe) and not in region
2 (US).
http://en.wikipedia.org/wiki/ISM_band
My guess(tm) is that the higher power 433MHz devices can only be sold
in Europe. Yet, that's not apparent on any of the sites selling
433MHz data radios.

It appears that we have both looked very hard and have come to the same
conclusion. I now wonder if the US suppliers are unaware of the region
1/region 2 thing.

Here in Europe, 10mW ERP is allowed on 433 MHz. This of course does
not mean that all devices have that much power. I can understand that
a 13dBm transmitter device is allowed with an inefficient antenna and
still result in 10mW ERP or less. 100mW seems to be a bit off the
scale, who would want to waste that much power.

Unfortunately, "allowed" and "in use" are different things. It is
allowed to used 10mW handy talkies on 433 for unlicensed use, but in
reality those users have the wellknown Chinese devices (Wouxun etc)
that output 4 watts. Or they use a 50W standard HAM mobile transceiver.
Without license. On the amateur bands.

On Tue, 24 Jul 2012 12:57:33 -0500, John S
wrote:

On 7/24/2012 12:12 PM, Jeff Liebermann wrote:

Microwatts doesn't seem to make sense as there are products being sold
that advertise 10mw and 100mw output power levels. Obviously they are
not being certified under Part 15. However, I can't find another US
service on 433MHz that qualifies (except ham radio). FCC frequency
allocations table is of no use:
http://ecfr.gpoaccess.gov/graphics/pdfs/er27ja12.018.pdf
433MHz is an ISM band, but only in region 1 (Europe) and not in region
2 (US).
http://en.wikipedia.org/wiki/ISM_band
My guess(tm) is that the higher power 433MHz devices can only be sold
in Europe. Yet, that's not apparent on any of the sites selling
433MHz data radios.

It appears that we have both looked very hard and have come to the same
conclusion. I now wonder if the US suppliers are unaware of the region
1/region 2 thing.

I still have some more reading to do, and ask a few experts. However,
offhand, methinks there's a problem.

"FCC Compliance testing Using the MICRF112"
http://www.micrel.com/_PDF/App-Notes/an-55.pdf
Page 9 has the calcs for a typical key fob transmitter.
36 microwatts.

I saw that. Lower left corner of page 4 says that continuous operation
is allowed. Where do they get that?

It's there, although I had to read it several times before I found it.
http://louise.hallikainen.org/FCC/FccRules/2012/15/231/
See section (e):
Intentional radiators may operate at a periodic rate exceeding
that specified in paragraph ...

The field strength is limited to about 4500 uV/meter. There's also
some notes on the topic on Pg 14 of the TI app note:
http://www.ti.com/lit/an/swra090/swra090.pdf

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 7/24/2012 2:41 PM, Jeff Liebermann wrote:
On Tue, 24 Jul 2012 12:57:33 -0500, John S
wrote:

On 7/24/2012 12:12 PM, Jeff Liebermann wrote:

Microwatts doesn't seem to make sense as there are products being sold
that advertise 10mw and 100mw output power levels. Obviously they are
not being certified under Part 15. However, I can't find another US
service on 433MHz that qualifies (except ham radio). FCC frequency
allocations table is of no use:
http://ecfr.gpoaccess.gov/graphics/pdfs/er27ja12.018.pdf
433MHz is an ISM band, but only in region 1 (Europe) and not in region
2 (US).
http://en.wikipedia.org/wiki/ISM_band
My guess(tm) is that the higher power 433MHz devices can only be sold
in Europe. Yet, that's not apparent on any of the sites selling
433MHz data radios.

It appears that we have both looked very hard and have come to the same
conclusion. I now wonder if the US suppliers are unaware of the region
1/region 2 thing.

I still have some more reading to do, and ask a few experts. However,
offhand, methinks there's a problem.

"FCC Compliance testing Using the MICRF112"
http://www.micrel.com/_PDF/App-Notes/an-55.pdf
Page 9 has the calcs for a typical key fob transmitter.
36 microwatts.

I saw that. Lower left corner of page 4 says that continuous operation
is allowed. Where do they get that?

It's there, although I had to read it several times before I found it.
http://louise.hallikainen.org/FCC/FccRules/2012/15/231/
See section (e):
Intentional radiators may operate at a periodic rate exceeding
that specified in paragraph ...

Yes, but continuing with paragraph (e) includes the last paragraph which
you quoted earlier:

quote you

See the last paragraph of 15.231
http://louise.hallikainen.org/FCC/FccRules/2012/15/231/
In addition, devices operated under the provisions of this
paragraph shall be provided with a means for automatically
limiting operation so that the duration of each transmission
shall not be greater than one second and the silent period
between transmissions shall be at least 30 times the
duration of the transmission but in no case less than 10
seconds.

/quote you

And this last paragraph is part of FCC paragraph (e).

There is nothing in that section which allows continuous transmission.


The field strength is limited to about 4500 uV/meter. There's also
some notes on the topic on Pg 14 of the TI app note:
http://www.ti.com/lit/an/swra090/swra090.pdf

It is parroting paragraph (e). Nothing new nor informative there.

I'm enjoying this, Jeff. Finally, I have someone with which to kick this
around and learn something. I'd really like to get to the bottom of this
whole thing.

On 7/24/2012 3:37 PM, John S wrote:

I'm enjoying this, Jeff. Finally, I have someone with which to kick this
around and learn something. I'd really like to get to the bottom of this
whole thing.


Should we take this somewhere else? I wonder if anyone else is
interested. Maybe Rob? What do you think? If it benefits only three
people, is it worth it?

In article , John S wrote:

Should we take this somewhere else? I wonder if anyone else is
interested. Maybe Rob? What do you think? If it benefits only three
people, is it worth it?

I'm definitely interested, and I think it's sufficiently on-topic for
this newsgroup that it's quite reasonable to continue the discussion
here.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

On 7/24/2012 3:52 PM, John S wrote:
On 7/24/2012 3:37 PM, John S wrote:

I'm enjoying this, Jeff. Finally, I have someone with which to kick this
around and learn something. I'd really like to get to the bottom of this
whole thing.


Should we take this somewhere else? I wonder if anyone else is
interested. Maybe Rob? What do you think? If it benefits only three
people, is it worth it?

I find it very useful since I am interested in the low (weak signal) end
of 70cm.

Don't assume that because we aren't poking our noses in that there
aren't interested people out here. Please carry on where I can see it.

I've always wondered if the imported 433MHz devices were running legally.

tom
K0TAR

On 7/24/2012 6:33 PM, tom wrote:
On 7/24/2012 3:52 PM, John S wrote:
On 7/24/2012 3:37 PM, John S wrote:

I'm enjoying this, Jeff. Finally, I have someone with which to kick this
around and learn something. I'd really like to get to the bottom of this
whole thing.


Should we take this somewhere else? I wonder if anyone else is
interested. Maybe Rob? What do you think? If it benefits only three
people, is it worth it?

I find it very useful since I am interested in the low (weak signal) end
of 70cm.

Don't assume that because we aren't poking our noses in that there
aren't interested people out here. Please carry on where I can see it.

I've always wondered if the imported 433MHz devices were running legally.

tom
K0TAR

Thanks for your inputs, guys. I probably can't do it alone, so I will be
counting on Jeff for some leadership here.

John
KD5YI

In article ,
Jeff Liebermann wrote:

My guess(tm) is that the higher power 433MHz devices can only be sold
in Europe. Yet, that's not apparent on any of the sites selling
433MHz data radios.

"FCC Compliance testing Using the MICRF112"
http://www.micrel.com/_PDF/App-Notes/an-55.pdf
Page 9 has the calcs for a typical key fob transmitter.
36 microwatts.

I've run into interference in a local shopping mall parking lot, which
is sufficient to almost completely block 433 MHz car keyfobs from
working. It comes from a local noodle restaurant, which uses a
wireless order-taking system... from the sound of the transmissions
over the air, I think the central node is polling the hand-held order
entry units 3-4 times per second (well in excess of the Part 15
periodic radiator limit). It's quite audible for about a city block
around the restaurant, in at least some directions.

I got a look at one of the handheld terminals, and did not see any
sort of FCC licensing or type-acceptance sticker.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!