Are we getting any closer to where something small - like an SD
card or smaller - can be hidden in an object and then tracked
with enough precision to apprehend a thief?

I'm thinking more of something that does not need internal power
- like a transponder.

Lo-Jack on the cheap, so-to-speak.
--
PeteCresswell

Am 31.10.2010 23:32, schrieb (PeteCresswell):
> Are we getting any closer to where something small - like an SD
> card or smaller - can be hidden in an object and then tracked
> with enough precision to apprehend a thief?
The size is possible today for the electronics involved.
>
> I'm thinking more of something that does not need internal power
> - like a transponder.
But all devices need power while working actively.
A transponder gets its power from outside while working.

This device would need power
- to gain its position via GPS (not so much power)
- to send this position to you (even more power)
-- via direct link to you (limited area or high power consumption)
-- via GSM or other network (as an SMS or so)

Where to get this power from?

Such a small device does not have enough room for sufficient battery
power to work for a reasonable period of time.

As part of a car or mobile phone you have access to power.

If there is a known source of power near your "object" which you can
access via a wireless connection like a passive transponder, that would
make it. Maybe you can take the power from public TV or radio
transmitters or even better from normal AC power outlets at home via
induction? But you need an (big?) antenna in your device to get access
to this power.

Interesting problem. I do not believe this is already solved.

On Wed, 03 Nov 2010 15:41:00 +0100, Wolfgang Barth wrote:

> Am 31.10.2010 23:32, schrieb (PeteCresswell):
>> Are we getting any closer to where something small - like an SD
>> card or smaller - can be hidden in an object and then tracked
>> with enough precision to apprehend a thief?
> The size is possible today for the electronics involved.
>>
>> I'm thinking more of something that does not need internal power
>> - like a transponder.
> But all devices need power while working actively.
> A transponder gets its power from outside while working.
>
> This device would need power
> - to gain its position via GPS (not so much power)
> - to send this position to you (even more power)
> -- via direct link to you (limited area or high power consumption)
> -- via GSM or other network (as an SMS or so)
>
> Where to get this power from?
>
> Such a small device does not have enough room for sufficient battery
> power to work for a reasonable period of time.
>
> As part of a car or mobile phone you have access to power.
>
> If there is a known source of power near your "object" which you can
> access via a wireless connection like a passive transponder, that would
> make it. Maybe you can take the power from public TV or radio
> transmitters or even better from normal AC power outlets at home via
> induction? But you need an (big?) antenna in your device to get access
> to this power.
>
> Interesting problem. I do not believe this is already solved.

The OP wanted to use a transponder like in a card key, but of course
such things use very little power and must be very close to the lock
even to get that small amount of power.

He said
"I'm thinking more of something that does not need internal power - like
a transponder".

However, there are transponders and there are transponders. The ones in
card keys, as I said, use very little power, but they must be very close
to the door they actuate in order to get that power from the door's
signal. The ones in warplanes (IFF = Identification Friend or Foe, from
WW II) are very far from their interrogator and need to be well-powered
locally. What he wants to do is like the airplane situation, but he
wants to do it like the smart key :-)

--
Gene E. Bloch (Stumbling Bloch)

Per Wolfgang Barth:
>
>Interesting problem. I do not believe this is already solved.

That's kind of what I figured.

Once it is solved, I would hope that theft of things like
bicycles, home appliances, and so-forth would become
significantly more hazardous.

Seems like we are there already for motor vehicles with
Lo-Jack... although, from what I've read, thieves have adapted
somewhat by staging the stolen vehicles somewhere - like on the
street a few miles from where they were stolen - for a few days
before the final move to a chop shop or whatever once it becomes
apparent that nobody is going to locate/recover the vehicle.
--
PeteCresswell

PeteCresswell wrote
> Wolfgang Barth wrote

>> Interesting problem. I do not believe this is already solved.

> That's kind of what I figured.

> Once it is solved,

I dont believe it will be any time soon, particularly with devices
that cant provide any power. Hard to see that a self powered
device can be anything like a SD card in size.

Even mobile/cell phone in size has problems with keeping it charged etc.

> I would hope that theft of things like bicycles, home appliances,
> and so-forth would become significantly more hazardous.

Stuff that is plugged into the mains, sure. Stuff that isnt tho is much harder.

> Seems like we are there already for motor vehicles with Lo-Jack...

Sure, and its obviously not hard to do something similar in something that
is mains powered much of the time, easy enough to have a phone sized
device inside, but SD card sized is much harder for the power/battery.

> although, from what I've read, thieves have adapted somewhat
> by staging the stolen vehicles somewhere - like on the street a
> few miles from where they were stolen - for a few days before
> the final move to a chop shop or whatever once it becomes
> apparent that nobody is going to locate/recover the vehicle.

Sure, but thats harder with an appliance, it isnt likely to last long doing that.

Its also much easier to just put the stolen appliance in a metal box so that it
cant communicate with anything about where it is until the SD card is removed.

And that could easily just be a van etc.