Despite how you see on TV, criminal charges don't always result in the police barging in and catching you red handed, reading you your rights, and hauling you off to the slammer. When they know who and where you are, the wheels of justice can be pretty slow in PA. Typically it can be three months or more before misdemeanor charges are filed and yes, you'll get them in the mail. If you are charged, you should consult a lawyer.
Eh? You're whether they look at your GPS or not has no bearing on your innocence. You mean you think they only PROOF they have of your crimes is your GPS. That may not be the case, but your lawyer can find out once you are charged.
Here's what you can expect if they proceed on this.
You'll get a summons for the Preliminary Arraignment/Preliminary Hearing. This is the best time for you to have an attorney who can find out what exactly they have against you and negotiate things down (perhaps to a summary offense which other than a small fine has no long term effects). The other thing that would avoid a conviction is ARD where you serve a period of probation and if you don't screw that up, everything gets dismissed. Note ARD is by and large entirely at the discretion of the prosecutor, so best to have a lawyer see about getting that (this is not cut and dry like a DUI).
Unless you get this dismissed or knocked down to a summary offense at the Prelim, you'll be formally charged and given a date for your arraignment. Depending on what sort of trial you want (plead guilty, bench trial, jury trial) the date will be scheduled for the trial.