RFID: A lot more than I knew!
Rick LaBanca (KA1EZE)
on
December 9, 2002
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Lately there have been lots of ARRL talks about RFID frequency usage.
Well I hadn't kept up on this much, but in an email on privacy I got, it mentioned the Auto-ID system planned.
The big picture for this is to embed passive transmitters with a 96-bit code for just about all-physical items made. This is more than a UPC, also serial numbers.
They envision not just checkout scanners, but market shelves with scanners, ideas about using it for currency, and you can imagine.
Now this application is more troubling to me that use in factories. Isn't there fairly good chance of RFI hell with these small yet numerous scanners all over?
The other view of interest to hams is the effect this might have if you've got some stray RF, and all of your canned goods start talking back!
This isn't too informative... perhaps some of you with real RF engineering skills can look at the white papers and consider the ramifications.
Find the info at:
http://www.autoidcenter.org
Rick
ka1eze
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RFID: A lot more than I knew!
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by WA4PTZ on December 9, 2002
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The prospect does not bother me in the least.
There have been monitoring sites in service for
many years and no one has noticed them so why
should this new RFID change that ? I think it
will sure make the bonehead frequency jammers
think twice and lets not forget the random
tuner upper, who can't keep notes on the
antenna tuner and amp settings so he has to
retune each time. A pink slip or two will
change their attitude.
73 - Tim
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RFID: A lot more than I knew!
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by W1RFI on December 9, 2002
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RFID encompasses a number of possible technologies and frequencies. The ones that ARRL has been battling involve 70 cm. Savi Technology has asked the FCC for permission to use near-continuous transmissions from 425-435 MHz at a peak field strength of 110,000 microvolts/meter.
ARRL has featured this one prominently on the ARRL web page. The following URL will give you a list of stories:
http://www.arrl.org/htdig/?method=and&words=Savi+Technology
ARRL's comments to the FCC on this one can be seen at:
http://gullfoss2.fcc.gov/prod/ecfs/comsrch_v2.cgi
Type in 01-278 as the proceeding and ARRL as the "Filed on behalf of."
If you leave off the proceeding, you can see all of ARRL's comments filed on all recent proceedings.
The RFID devices are legal right now under Part 15. Most would be periodic emitters, as defined in the rules. Periodic emitters are low duty-cycle devices that have not posed much interference potential. (Savi seeks to make them very high duty cycle.)
ARRL's info on Part 15 can be seen at:
http://www.arrl.org/tis/info/part15.html.
73,
Ed Hare, W1RFI
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RE: RFID: A lot more than I knew!
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by KA1EZE on December 9, 2002
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Well this new technology sounds quite different from Savi it seems, since these tags will end up on just about everything purchased. The Savi applications sound like more expensive tags that actually transmit.
How many of the savi tags will actually end up sitting in homes? That's what I am curious about, will all these new tags react to a ham's rf, and become unintentional transmitters?
rick
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RFID: A lot more than I knew!
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by KB5DPE on December 9, 2002
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I'm a lot more concerned about the PRIVACY issues of these things than I am about the TECHNICAL issues! One more giant step in the wrong direction.
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RE: RFID: A lot more than I knew!
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by KA1EZE on December 9, 2002
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Well I got the info from a privacy group actually, and the person in charge is actually looking for some tech help to understand it.
If anyone is so inclined I can forward the info. I would help but I'm really an amateur in the true sense of the word!
rick
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RE: RFID: A lot more than I knew!
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by KJ5O on December 9, 2002
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Here's a brief rundown of how these things work:
There's a small microchip with what amounts to two wires either embedded in them in a coil, or routed elsewhere on or near the chip. These are two antennas.
One antenna is designed to pick up very low frequencies, like in the kilohertz range. The low frequencies are emitted by the reading device. If you've ever used the Mobil or Exxon 'Speedpass', you've used one of these devices. When you put your little tag near the reader, the low antenna in the chip absorbs some of the energy and rectifies it so that you end up with a pulsing DC voltage (small, but nevertheless present) on the chip.
This DC Pulse is what powers the rest of the chip. They don't have any batteries, which is why they're so cheap and low-maintainence. The DC pulse goes into a small capacitor which can hold enough charge for the device to power up, read a unique ID programmed into each one, and then transmit that unique ID on the high-frequency antenna coil.
This unique ID is heard by the reader/scanner and verified against some database so that the individual RFID device can be identified.
They currently work on various 'output' frequencies and most of them do not interfere with Amateur Radio. It's the proposal by Savi to the FCC to use the low end of the Amateur 70cm band that is a big deal. They have found a way to make the RFID tags transmit their ID in this frequency range very cheaply. Meaning it is easier for Savi to create a chip that has the rf parts and antenna coil tuned for ~430MHz than to create a chip that transmits on any other frequency.
Rather than just deal with the fact that the frequecies that are convenient for them are unavailable for commercial use, they just petition the FCC to change the rules.
Probably, these devices won't cause much intereference to Amateurs, since the output of the RFID tags is very low. However, when you get to the point where every factory and grocery store is full of the things transmitting all over the 430 MHz area, there will likely be a noticeable increase in the average noise-type energy at those frequencies. This is where Amateurs are not happy. The band was reserved for them for experimenting and now it's being taken over by folks looking to make an easier buck than they could if they played by the existing rules.
These RF ID tags exist already and use transmitting frequencies in the 800-900 MHz areas where they don't interfere with Amateur Radio. It's the Savi technology that started the uproar.
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RE: RFID: A lot more than I knew!
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by KJ5O on December 9, 2002
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Also of note is that when these RF ID tags are not near an RFID reader, they are completely dormant and transmit nothing.
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RE: RFID: A lot more than I knew!
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by KA1EZE on December 9, 2002
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If you read the mit site, they are suggesting not being locked down to just one frequency, so I would expect other companies coming in and wanting even more.
I agree that one little transmitter is a low level, but hundreds, who knows? I still keep thinking of low level harmonics triggering all my groceries!
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RE: RFID: A lot more than I knew!
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by W1RFI on December 10, 2002
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> They currently work on various 'output' frequencies
> and most of them do not interfere with Amateur
> Radio. It's the proposal by Savi to the FCC to use
> the low end of the Amateur 70cm band that is a big
> deal. They have found a way to make the RFID tags
> transmit their ID in this frequency range very
> cheaply. Meaning it is easier for Savi to create a
> chip that has the rf parts and antenna coil tuned
> for ~430MHz than to create a chip that transmits on
> any other frequency.
Actually, the Savi tags and readers already transmit on 70 cm, but they are limited by the rules in Sec. 15.231. They transmit data, so they are limited to about 4,000 uV/meter, averaged over 100 milliseconds. Because they pulse inside that 100 milliseconds, they can go to about 40,000 uV/m. Their system, however, can only transmit these pulsed signals for one second, then must be silent for 30 seconds (or any other 30:1 on/off ratio, up to a maximum transmit time of one second). These low-duty cycle signals have not generally caused hams harmful interference, because a burp now and again on an otherwise clear channel would probably be no more than an annoyance.
However, the present rules limit the amount of data that can easily be transmitted. When a cargo container is queried, if it has a large manifest, that cannot be transmitted under the current provisions of 15.231. Savi wants to go to 11,000 uV/m for data, with a permitted 110,000 uV/m peak and transmissions of up to 2 minutes duration, with a 10-second quiet period. There is a BIG difference in the interference potential between the two.
15.231 permits periodic emitter operation on virtually any frequency higher than 70 MHz. IMHO, the reason Savi wants to use the 70 cm band is that in some (not all) parts of the world, 433.92 MHz is an ISM and unlicensed device frequency, so there are lots of cheap oscillators being made for that frequency. ARRL has suggested that Savi operate their devices on 900 MHz, where the existing rules already permit them to do what they are asking the Commission to do.
>Probably, these devices won't cause much >intereference to Amateurs, since the output of the
>RFID tags is very low.
3.3 milliwatts into 0 dBi will create a field of about 110,000 microvolts/meter. If that is close to you, it will be S9+. Some hams have used 3.3 milliwatts for worldwide DX and on 70 cm, it can go for many miles under ideal conditions.
> now it's being taken over by folks looking to make an
> easier buck than they could if they played by the
> existing rules.
Yes, indeed. The existing rules already permit them to do everything they want to do -- on 900 MHz. That, too, is a ham band, but the nature of amateur use of that band has not run afoul of unlicensed devices nearly as often as will happen on 70 cm.
It remains to be seen if they will "take over." ARRL's case to the FCC has been extensive and compelling. If I don't have 100+ staff hours into this one, I would be surprised, having prepared a number of pages of Ex Parte filings that can be seen on the FCC web site (see my earlier post for the URL). If amateur radio doesn't win, it would appear that the fix was in! :-)
73,
Ed Hare, W1RFI
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RE: RFID: A lot more than I knew!
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by W1RFI on December 10, 2002
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>How many of the savi tags will actually end up >sitting in homes? That's what I am curious about,
>will all these new tags react to a ham's rf, and >become unintentional transmitters?
Don't fall into the trap of thinking of this rulemaking proceeding in terms of Savi's equipment. Savi's equipment will be used in warehouses and similar environments. (Although I know of a number of shipping companies that have facilities near or in residential areas.)
But the rules change would not authorize only Savi's equipment -- they would all any type of RFID device to operate at peak fields of 110,000 microvolts/meter from 425-435 MHz with two-minute long transmissions. If you build a highway, it will soon be filled with all sorts of vehicles.
73,
Ed Hare, W1RFI
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RE: RFID: A lot more than I knew!
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by N8FVJ on December 11, 2002
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These tags operate for the most part on an international agreed upon frequency around 13.5mHz. The output is so low that the read/write is limited to a range of 12 inches. I do not believe interference will be noticable compared to other future electronics. I also suspect analog communications will go the way of the 'buggy whip'.
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RE: RFID: A lot more than I knew!
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by KA1EZE on December 12, 2002
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Everyone seems to be pretty familiar with the current tags and savi. But my fear is the new auto id. Read the info on the site.
It's speculation as to how far it will go, but they are proponents of much more widespread and frequency free application of rf tags.
Here's a blurb from a new product being developed already:
"In collaboration with the Auto-ID Center, ThingMagic LLC has developed a unique multi-band RFID tag reader reference platform. This reader has been designed to read tags conforming to the Auto-ID Center’s emerging EPC specifications at both the 13.56MHz (HF) and 902 – 928MHz (UHF) frequency bands. The hardware architecture consists of a general purpose analog front end up/downconverter for each band, followed by a software radio architecture allowing easy adaptation to new frequencies and protocols."
HF, and note the mention of easy use of other freqs.
rick
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RE: RFID: A lot more than I knew!
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by WA5SWD on December 19, 2002
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There are some good comments here, and some unfounded concerns. The privacy issue is no big deal, since "RFID tag killers" will be in place at checkout stands, just as they are for the anti-theft sensors.
Who am I? Ed Lawrence. I work at RFSAW, Inc, in the Dallas area. We are using SAW tags at 2.44 GHz. We use milliwatts, not watts, and have ranges of many, many meters. Go look us up at www.rfsaw.com. I'm not one of the managment, I'm lower down the food chain.
Those of you who have either RF exposure or interference concerns should be backing the type of passive tag that does NOT require being blasted with extremely high levels of RF to power it.
There are many tags in work now, not just a few. They are operating on lots of frequencies with a wide range of systems. All have limitations. All have strong points. The benefits will be enormous to the consumer. First, tracking items from raw material to consumer will reduce storage costs. It will reduce labor costs for inventory control. It will minimize "shrinkage", which is a polite term for employee theft. These are two big factors which wind up increasing the cost of goods.
There are a lot of other areas, such as goods recall, where this is a valuable technology. Don't fight it. Get on board and make it happen. I can be reached by email at elawrence@rfsaw.com
Ed WA5SWD
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RE: RFID: A lot more than I knew!
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by KA1EZE on December 20, 2002
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Just a comment on the killers, these particular tags I've read about aren't intended to be killed, but still be pollable after purchase. The idea is having a fridge that knows its contents etc.
rick
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RE: RFID: A lot more than I knew!
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by W6NYX on July 14, 2003
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I am interested in learning more about how these RFID devices work. For example, the EZ Pass/FastTrak transponders that allow people to breeze through toll booths. Do they work basically the same was as the RFID devices used to tag merchandise? I know I've heard that the toll-collection devices transmit on the 33cm band, but I'm curious about what modes they use and how they work. I doubt they use anything as sophisticated as, say, packet radio...
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