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