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C-dub wrote:Within the realm of tracking devices, 100m does sound short range to me. To boost the range further seems like more trouble and expense than most BG will go through.

Grab a map and set a compass to a 100m radius by the scale, then look at how few of those circles it would take to cover a huge area. A car-mounted reader could cover a swath 100m each side of the road it's on, making an area search pretty easy too. With a directional antenna and a calibrated signal strength meter, a fairly accurate location could be had from a single, stationary reader. Failing that, triangulation using a mobile reader with only the directional antenna is trivial.

Even with only a 20-30m range it would be a simple matter for a pedophile to drive around between school-let-out and 5PM looking for a house with no cars in the driveway but an active tag inside. Depending on how tags are issued, it might even be possible to narrow down a range of tags as being issued to a particular range of student ages. Gender is fairly easy to figure out too; how many parents have sports or band signs in the yard with the kid's name on them?

C-dub wrote:

The technology is readily available, and pretty discreet. A few cheap used cars parked around the area with scanners would get you a route mapped in great detail, and since the other kids are tagged, would tell you if and when your target is walking home alone, too.

Wouldn't they have to know which tag belonged to which child?

Pretty easy to do if you have even momentary access to the child, access being defined as getting within range to read the card. Readers aren't very large, so just walking by with a daypack and a directional antenna would be enough.

Because of the extremely short range of RFID it probably would not be used this way due to the cost.

$50-100 for a basic reader. A directional antenna and receive preamplifier is simple stuff you can build from any ham's junk box. Get the range up to even 10ft and it will cover a sidewalk from a car parked on the street. Depending on the tag frequency, a $500 off-the-shelf unit can read some RFIDs at up to 450ft. Keep in mind that TollTags are just RFID tags, and are read by directional antennas from several feet away. If the kids aren't having to scan the badge at every doorway, then it's safe to assume their tags are designed to be read from at least the width of a typical classroom.

Why waste the money when in this case it really would be cheaper to just follow the child.

Well, it would be cheaper to just sit out in my yard and watch for vandals and thieves...if my time had no value at all. Since I have to work for a living, I have about $2k worth of alarm and surveillance gear instead. For a couple hundred to a thousand, our hypothetical kidnapper could put a system in a $200 beater car, park it along a street near the school, and check the data at the end of the day. He could move the car as needed, and within a couple of weeks, he would know the kid's route to and from the school, and a high probability of when the target will be at any given point along that route.

Sure, it's not something a disorganized, opportunistic pedophile would do, but there are plenty of very clever and well-funded criminals out there.

C-dub wrote:

Barbi Q wrote:What's the harm in tracking people without permission?

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Other than being able to get $$$ for the school by saying that the student was there, when they can only prove that their badge was, I don't see too much downside to this.

Because pedophiles and parents without visitation rights could never come up with a way to abuse it, of course.

The technology is readily available, and pretty discreet. A few cheap used cars parked around the area with scanners would get you a route mapped in great detail, and since the other kids are tagged, would tell you if and when your target is walking home alone, too.

C-dub wrote:

KD5NRH wrote:

C-dub wrote:I know it seems like an intrusion, but what really is the difference between this and just following someone around?

Roughly the same as the difference between following someone around to listen to their phone conversations and tapping the line.

Is this apples and oranges? Following someone around still doesn't give them permission to listen to phone conversations. That still requires a warrant, doesn't it?

You can listen to anything you can hear. With good ears, you can easily get both sides of a conversation from the next table.

C-dub wrote:I know it seems like an intrusion, but what really is the difference between this and just following someone around?

Roughly the same as the difference between following someone around to listen to their phone conversations and tapping the line.

jimlongley wrote:With some of my ham equipment I could find it in seconds, and may just start scanning my vehicles routinely.

I'm too lazy to go look up the GPS frequencies, but I'm betting most receivers use the same IF, and leak a bit of it. Easier than looking all over the spectrum for its transmit frequency - especially if it's reporting in only when the vehicle is moving and/or in timed bursts.

It would be even more fun it it uses standard NMEA data between the GPS and the transmitter; haul it in the house, hook it up to the computer, and let your imagination take them wherever you want them to think you're going. Mach 6 through the NYC subway tunnels sounds fun, or follow some submarine patrol routes.