315mhz/433mhz transmitter
 

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!

315mhz/433mhz transmitter
 

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

315mhz/433mhz transmitter
 

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

315mhz/433mhz transmitter
 

In message , Jeff Liebermann
writes




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's unlikely that any high power short-range devices are legally on
sale in Europe. The UK spec is 10mW erp (which is probably the norm).
http://stakeholders.ofcom.org.uk/bin...m-policy-area/
spectrum-management/research-guidelines-tech-info/interface-requirements/
IR_2030.pdf
page 17.

Of course, over here, 70cm is only 430 to 440MHz, and (for various
reasons) most of the simplex activity is 432 to 434MHz. An SRD
allocation at 433MHz can cause some interesting problems - especially to
car key systems which, in the past, have often had fairly 'elementary'
and unselective receivers. It is said that great fun can be had when
you're sitting in your car in the shopping mall carpark, waiting for
your wife to emerge from the shops.





--
Ian

315mhz/433mhz transmitter
 

On 7/23/2012 11:21 AM, Jeff Liebermann wrote:
On Mon, 23 Jul 2012 08:56:41 -0500, John S
wrote:

On 7/23/2012 1:28 AM, Jeff Liebermann wrote:
On Sun, 22 Jul 2012 23:21:12 -0700, Jeff Liebermann
wrote:

FCC 15.209
http://louise.hallikainen.org/FCC/FccRules/2012/15/209/
200 uv/meter maximum, measured at 3 meters. That works out to about
-46dBm ERP or about 12 milliwatts into a unity gain antenna.

Sorry, brain damage.
The -46dBm should be 10.8dBm ERP

Hmmm... my calculator says P = 12 nanowatts.

Your calculator is correct. My -46dBm is wrong. It was late, I was
multitasking, the phone range, I was tired, etc. Sorry for the
muddle.
+10.8dBm converts to 12 mw.
http://www.rapidtables.com/convert/power/dBm_to_mW.htm

Then... I find a 433MHz radio that delivers +20dBm (100mw).
http://www.sparkfun.com/products/10153
By my reading of 15.209, that's overpowered unless operating with a
miserable -9dB gain antenna. From the manufacturers web pile at:
http://www.hoperf.com/rf_fsk/
they offer +10, +13, and +20dBm outputs and claim they all meet ETSI
and FCC regs. I dunno about that.


I looked at one of the Hoperf parts and found this:

"The RFM69H is intended for applications over a wide frequency range,
including the 433 MHz and 868 MHz European
and the 902-928 MHz North American ISM bands."

That's the catch. Although it is capable of operating at 10dBm on 433,
you are responsible for only doing that in Europe where it is legal.
Otherwise, you may operate it at its maximum power capability here in
the US on 915MHz. Under those conditions, it complies with FCC regs.

315mhz/433mhz transmitter
 

On Tue, 24 Jul 2012 18:40:42 -0500, John S
wrote:

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

I'll try, but I'm a bit busy with work right now. I'll get back to
this in the next day or two, and when I get some replies to several
emails.

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

315mhz/433mhz transmitter
 

On Tue, 24 Jul 2012 11:16:19 -0700, (Dave Platt)
wrote:

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...

One of these?
http://www.alibaba.com/product-gs/310363481/315_433Mhz_wireless_pager_system_for.html
http://www.alibaba.com/product-gs/541027413/Wireless_service_calling_system_for_restaurant.htm l
http://www.alibaba.com/product-gs/496387830/Restaurant_paging_system_table_button_with.html
http://factory.dhgate.com/pos-terminal-cash-register/433mhz-restaurant-ordering-terminal/-wireless-restaurant-ordering-device/-wireless-ordering-device-p39229505.html
http://www.aclas.tw/Products/Application-Restaurant/Restaurants-ordering-system.html
http://www.aclas.tw/PDF/Restaurants-Ordering-System.pdf
etc... ALL (and I do mean all) of the ones listed under "wireless
order system restaurant" on Alibaba run on 315 - 433MHz.

Remind me to lookup the rules for 433MHz in China.

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.

Lovely. Remind me to rant on the topic of wireless systems that belch
RF when there's no data to transfer.

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

Here's the FCC interference complaint form:
https://esupport.fcc.gov/ccmsforms/form2000.action?form_type=2000F
It's an election year, so the FCC EB may actually be interested in
doing something. At the least, the restaurant owner will get a
warning letter in the mail.

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

315mhz/433mhz transmitter
 

On 7/25/2012 8:47 AM, John S wrote:
On 7/23/2012 11:21 AM, Jeff Liebermann wrote:

Then... I find a 433MHz radio that delivers +20dBm (100mw).
http://www.sparkfun.com/products/10153
By my reading of 15.209, that's overpowered unless operating with a
miserable -9dB gain antenna. From the manufacturers web pile at:
http://www.hoperf.com/rf_fsk/
they offer +10, +13, and +20dBm outputs and claim they all meet ETSI
and FCC regs. I dunno about that.


I looked at one of the Hoperf parts and found this:

"The RFM69H is intended for applications over a wide frequency range,
including the 433 MHz and 868 MHz European
and the 902-928 MHz North American ISM bands."

That's the catch. Although it is capable of operating at 10dBm on 433,
you are responsible for only doing that in Europe where it is legal.
Otherwise, you may operate it at its maximum power capability here in
the US on 915MHz. Under those conditions, it complies with FCC regs.


Continuing the investigation, I find that the US has no ISM band
anywhere near 433MHz. The closest is 915MHz.

Interestingly, on that band, the FCC says:

"§ 18.305 Field strength limits.
(a) ISM equipment operating on a fre-
quency specified in § 18.301 is permitted
unlimited radiated energy in the band
specified for that frequency."

Wow! Unlimited!

The catch is that you may have no emissions outside the ISM bands
exceeding 25uV/m at 300m. That would be equivalent of less than 2
microwatts of 2nd, 3rd,.... etc, harmonics and other stuff being
radiated by the antenna. That, I think, would be about -37dBc when
running 10mW. The more power you run, the harder it gets to filter.

In addition, I still have some questions in my mind about certification.
Just because a manufacturer says it will meet the requirements, doesn't
necessarily mean it is certificated. Part 15 (not ISM) allows us to
build our own transmitters which are not for sale. But, I can find no
mention of that in part 18 (ISM).

Still lots of questions out there.

315mhz/433mhz transmitter
 

On 7/25/2012 12:03 PM, Jeff Liebermann wrote:
On Tue, 24 Jul 2012 18:40:42 -0500, John S
wrote:

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

I'll try, but I'm a bit busy with work right now. I'll get back to
this in the next day or two, and when I get some replies to several
emails.


Of course. Work comes first.

315mhz/433mhz transmitter
 

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