Want To Be Happy With GPS Tracking? Read The Spec
Here’s a news item that caught my attention last week:
Sex offender faces new charge
Pollitt accused of violating conditions of probation; he says his tracking device simply malfunctioned
SOUTHBURY — Convicted rapist David Pollitt has again found himself at odds with the law.
Pollitt, who was released from prison last fall after serving 25 years on multiple sexual assault convictions, was charged this week for allegedly violating the conditions of his probation.
Gov. M. Jodi Rell, who opposed Pollitt’s release into the community last October, is urging court officials to send him back to prison.
According to the arrest warrant affidavit issued Wednesday for the alleged probation violation, Pollitt left the yard of his sister’s house, where he has been living since his release, for about 15 minutes Sept. 3.
"His GPS tracking device recorded his movement as he left his yard and walked through a wooded and residential neighborhood behind his residence," the affidavit says… read the rest of the GPS Failure article here.
I guess this David Pollitt individual is one bad dude. He’s a convicted rapist but he has served his time and is now on parole. Apparently, no less than the governor of the state is watching his every move, and of course there’s some justification in that because he is what he is and he did what he did,
But I think this is an excellent place to point out that those who watch need to be aware of what exactly they are watching. The also need to look closely at the contracts they have in place with firms that monitor subjects for government agencies. All the good intentions and righteous indignation in the world can not make GPS what it is not. It’s a tool and a technology and like any technology it can only operate within the specifications of the system and within the laws of physics. We here ay the GPS Tracking ROI blog are unabashed GPS supporters,“
Normally, commercial GPS tracking devices operate on the Standard Positioning Service (SPS) of the GPS. The specifications for that service state the desired accuracy to be 10 meters CEP 95% … this means the positron reported by the unit will be within a circle of 10 meters radius (that’s 65.61 feet across for the metrically challenged). 65 feet is wider than some people’s residential lots, if you take a look at it. That is 95% of the time, or 1368 minutes per day. the other 5% (or 72 minutes of the standard 1440 minute day)? Undefined. That’s right. The standard specification which the operators of the system attempt to meet or exceed allows up to 72 minutes per day to be totally ‘off’ and still fall within the specs. Did you know GPS was allowed to have that many minutes unaccounted for? This furor over Mr. Pollitt’s location or uncertainty of same all blew up over what is reported as a gap of 11 minutes … seems well within specs to me.
The case referenced here has since quieted down somewhat as the tracking company involved has been forthright enough to notify the state that they have proof that the position originally reported was in error .. so probably the subject will not have to return to prison over a system error that was really not an error at all.
Life critical GPS applications, such as aircraft using GPS to make instrument weather landings as one example use other systems, such as the FAA’s Wide Area Augmentation System (WAAS) to insure safety during those system gaps that are pert of the inbuilt level of accuracy … or lack of same … in the GPS Standard Positioning Service.
Again, I’m a supporter, but don’t try to use the system for something it was not designed for and is not capable, on its own, of attaining. GPS tracking only does the amazing, it can not perform the impossible.