At 08:39 PM 8/28/2000 -0700, you wrote:
>At 08:56 PM 8/28/00 -0500, you wrote:
>>At 01:27 PM 8/27/2000 -0700, you wrote:
>>>At 12:06 PM 8/25/00 -0400, you wrote:
>>With only one repeater, wouldn't it be possible to "ping" the phone, and
>>determine the distance? From that, and if the tower can get a heading,
>>it should be possible to locate a phone with only one repeater. If
>>nothing else, monitor the outgoing signal, compare to the echo of the
>>outgoing signal that is present in the incoming signal, find the closest
>>match within half a second, and figure distance from that.
>
>I just thought of another ruse. If one can create a custom subscriber
>unit you might be able to thwart pings by varying the response delay and
>buffering outgoing data to fit within the designated time slots but not
>actually lie along the arc at the assumed distance from the tower that the
>delays imply.
>
>steve
From the last e-mail. I use repeater to describe a radio tranceiver tower
used to extend the range of two-way radios. Not quite a cell-phone tower,
but what I intended.
If you're dealing with data, you might be able to clean the signal better,
and isolate more fully the input from the output. This would definately
have to be attempted, and tested, before people started relying on it. A
test might be workable if someone had a phone with remarkably little of
that echo effect that cell-phones are prone to, and a modem for
same. Although I suspect part of the echo may be inherent in the
technology, and thus likely to persist, even if you added an echo box of
some sort the first echo would still provide the true distance in this
case, if it's in the circuitry, it may be fixable.
Naturally, a non-echoing phone would be a popular thing with the community
at large as well.
The trick may be to pre-empt the tower. Get a range on it in the same
manner, then add a delay to the sound so that it adds up to being 100 miles
from the repeater. Since no one would be using a phone at that range, this
number should always be positive. For this to work, which is essentially
an expensive addition to your idea, the phone can not have any inherent
echo in the circuitry that can't be isolated, and given your delay.
Do the new digital phones have an echo?
Good luck,
Sean
