I don't have experience with this device, but I worked as an EE at NovAtel,
in the cellular telecom and GPS arena, for ten years.
The E-911 technology works by either doing time-of-arrival triangulation
between different cellsite towers, or by using GPS technology embedded in
the cellular phone. CDMA cellphone technology requires receivers that
incorporate about 90 percent of the hardware required to do GPS reception,
so some of the current CDMA phones have low-grade GPS capability. Good GPS
performance requires a dedicated receiver, although the phone and GPS
receiver electronics can easily be combined in one package like shown in the
Rover kit.
In any event, GPS signal reception requires a GPS antenna be mounted on the
top side of the vehicle, with line of sight visibility to the sky. In the
Rover kit, the antenna is the rectangular thingy with the 'Trimble' logo on
it. Stealthy GPS systems (such as used for covert vehicle tracking)
sometimes use an antenna mounted under the car, and it measures signals that
reflect off the pavement. This is not technology that's generally available
over the counter at your local Radio Shaft.
No tracking system will report positions when it's off... The E-911 system's
capability of reporting position when it's 'off' really reflects the fact
that it can do quick acquisition so that for all intents and purposes, it
seems instantaneous to the user. Any real tracking system is vulnerable to
loss of battery power and being in a place where there is no GPS and/or
cellular reception.
Having said all that, it is feasible to design a system that could catch the
unwary thief... You can bury the antenna under the dash pad (make a cutout
in the foam and install the antenna under the vinyl), and they are not going
to find anything hidden behind the kickpanels until they disassemble the
car. If a system with its own batteries was installed like that, there is a
chance that it could put out the call for help in time to catch the thief.
However... Custom stuff costs money. $700 for a LoJack system is a good deal
especially when you consider that a lot of folks don't blink about coughing
up $600 for a pristine aircleaner or TBON.
Theo
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