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30pW ???
- 09-11-2007
- Phil Allison
September 11, 2007, 3:50 am

Hi to all,
the LIPD ( Low Potential Interference Device ) class licence 2000 allows
the use of deliberate transmitters on a host of bands and at various EIRPs
( radiated powers).
One has me intrigued, for the band between 3.5 MHz and 3.7 MHz - see
page 6 of the PDF.
http://www.comlaw.gov.au/ComLaw/Legislation/LegislativeInstrumentCompilation1.nsf/0/71D36E0C17A40CB3CA2571B80018AF7A /$file/RadcomLIPDClassLic2000.pdf
WTF is 30pW at 3.6 MHz any good for ???
....... Phil

Re: 30pW ???

http://www.comlaw.gov.au/ComLaw/Legislation/LegislativeInstrumentCompilation1.nsf/0/71D36E0C17A40CB3CA2571B80018AF7A /$file/RadcomLIPDClassLic2000.pdf

I wonder how they derive these numbers?
Even RFID transmitters operating at similarly low frequencies have a maximum
100pW EIRP (item 30).

Re: 30pW ???
"swanny"

http://www.comlaw.gov.au/ComLaw/Legislation/LegislativeInstrumentCompilation1.nsf/0/71D36E0C17A40CB3CA2571B80018AF7A /$file/RadcomLIPDClassLic2000.pdf

** That might be the application - RFID badges.
Most are just a coil and a tiny diode used to generate harmonics of the
drive signal.
Makes them technically transmitters with a few pWs power level.
....... Phil

Re: 30pW ???

http://www.comlaw.gov.au/ComLaw/Legislation/LegislativeInstrumentCompilation1.nsf/0/71D36E0C17A40CB3CA2571B80018AF7A /$file/RadcomLIPDClassLic2000.pdf

Good point. Those anti-shoplifting and library book passive stick-on RFID tags
would fit your description.
I'm not sure what frequency they operate at, but the detector coils you walk
through at the entrance/exit seem to be quite large.

Re: 30pW ???

From http://www.easitag.com.au/whatIsSourceTagging.aspx ....
What is RF EAS?
Radio Frequency (RF) Electronic Article Surveillance (EAS) is a proven
and successful concept where electronic sensors alarm when unauthorized
RF tagged merchandise is being removed from EAS retail environment.
What is RF EAS Source Tagging?
When merchandise is secured using RF EAS security tags (usually in the
form of a label) at the point of manufacture. The RF EAS tag can be
positioned directly onto the merchandise or concealed within or on the
packaging.
How does RF EAS work?
RF EAS sensors are located at all the customer exit points. The sensors
contain either a transmitter or a receiver. The transmitter and
receivers are tuned to 8.2 MHz as are the RF EAS tags and labels. When
a live tag passes through the sensors it activates a signal to the
receiver, which in turn alarms the system.
A selection of tags are at: http://www.bestsecurity.com.au/eas.html
It looks like one of the more common frequencies used in Aust is
8.2MHz. The printed coil/antenna in paper tags I've removed and examined
(after leaving the store, in case you were wondering!) look like they'd
have enough turns to resonate in that part of the band.
Bob

Re: 30pW ???
On Tue, 11 Sep 2007 21:14:54 +1000, Bob Parker

The most common systems use 58khz and 8.2mhz as suggested. I have also
played with some 125khz systems. The lower frequencies are supposed to
be less susceptible to being fooled with metallic foil, but I can
guarantee you that the quickest way to destroy the tags is to drag
your feet around a store and hit them with a static discharge.

Re: 30pW ???
Probably EAS tags
Check here
http://en.wikipedia.org/wiki/Electronic_article_surveillance
It's a Tx Rx system where a tag in the field helps the Tx reach the Rx and
sound an alarm
My understanding is - if an emitter is only transmitting in the near field
(more magnetic than electro-magnetic field) then it is not classes and an
intentional radiator and not really a transmitter.
Joe

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