If you have Onstar and Pikepass

[Conan71]

Im almost certain they deducted from my account when I forgot my Pikepass, by just using Optical Character Recognition of the car tag.  I understand that's how they ultimately plan to do it.

As far as moving the pass from vehicle to vehicle, is there a reason the new stickers cant just be scotch-taped to the windshield instead of using the "permanent" adhesive?

If that were the case I wouldn't have gotten a ticket from OTA via mail one time.  For some reason, my Pikepass didn't scan when I went through the gate.  A couple of weeks later I got a ticket in the mail with a photo of my license plate.  If they deducted from the plate, I would have never gotten the ticket in the first place.

[nathanm]

As far as moving the pass from vehicle to vehicle, is there a reason the new stickers cant just be scotch-taped to the windshield instead of using the "permanent" adhesive?

I think the tag is coupled to the windshield. It doesn't act as an antenna so much (which is how they describe it) as much as a ground plane. It's like those through-the-glass cell phone antennas.

If nothing else, I could probably velcro a piece of safety glass somewhere on the car and stick the tag to that. How well it works would depend on how the antenna is tuned, though.

I just happened across a newsok article from earlier this year that states that the old transponders are no longer being produced. That's not entirely true. Transcore still makes them, but OTA isn't buying. (presumably it costs more money to get the pikepass-specific plastic produced)

[Conan71]

I just happened across a newsok article from earlier this year that states that the old transponders are no longer being produced. That's not entirely true. Transcore still makes them, but OTA isn't buying. (presumably it costs more money to get the pikepass-specific plastic produced)

OTA has never been exactly lauded for being good purveyors of the truth. 

[patric]

For some reason, my Pikepass didn't scan when I went through the gate.  A couple of weeks later I got a ticket in the mail with a photo of my license plate.  If they deducted from the plate, I would have never gotten the ticket in the first place.

I wonder why they didnt just look up the plate number and see that it was a Pikepass customer?  They certainly have the capability.  Maybe they are just waiting on automation.

Also, glass is an insulator and doesnt have the electrical properties to be a ground plane...

[nathanm]

Also, glass is an insulator and doesnt have the electrical properties to be a ground plane...

Well, however it works, the antennas are tuned such that when they're stuck on a windshield in the correct location, they have about 9 meters of range, while without the glass, its range is less than 2 meters. (this according to some papers on the subject I was able to turn up using teh Googles)

[heironymouspasparagus]

Just another Turnpike authority cluster.

[Conan71]

I know people with the transponder who have always kept it in their center console and apparently it reads just fine.  I've been told the only way to keep one from reading in the cockpit of your car was to wrap it in foil.

[Hoss]

I know people with the transponder who have always kept it in their center console and apparently it reads just fine.  I've been told the only way to keep one from reading in the cockpit of your car was to wrap it in foil.

I use mine so little I had reason to use it yesterday.  I forgot and I left it in my center console compartment (Grizz, you're likely familiar with where this is in our model car).  Drove through the initial scanner on the Creek yesterday on my way to Jenks (yes I go there sometimes) and heard an odd beep from my console.  So it does read through glass and a layer of plastic.  Haven't got my new 'sticker' yet; hope I don't because I'm not sticking anything to my windshield that I cannot get off with some semblance of ease and have it not scratch up my glass (*cough*cough*inspectionstickers*cough*cough).

That's just the way I roll, I guess.  Call it caring about the re-sell value of my car.

[nathanm]

Interestingly, someone claims on the City Data forum to have used a sunpass mini (they sell both the passive tag and the active transponder) by holding it up to the windshield while passing through a toll plaza.

Further research shows that a frame on which a sticker tag can be applied that then attaches to the windshield like the old tags has been patented by some company in New York. So obviously the windshield itself isn't actually required, so long as the tag is bonded to something with similar dielectric properties.

My Pikepass will sometimes read when it's not mounted, but sometimes it won't. Had that problem just the other day when going to Wichita, actually.

[Conan71]

Interestingly, someone claims on the City Data forum to have used a sunpass mini (they sell both the passive tag and the active transponder) by holding it up to the windshield while passing through a toll plaza.

Further research shows that a frame on which a sticker tag can be applied that then attaches to the windshield like the old tags has been patented by some company in New York. So obviously the windshield itself isn't actually required, so long as the tag is bonded to something with similar dielectric properties.

My Pikepass will sometimes read when it's not mounted, but sometimes it won't. Had that problem just the other day when going to Wichita, actually.

I don't think you would have dialectric properties between the RFID and windshield since glass is a terrible conductor.  I'm willing to bet you could even hang it on a short string on your rear view mirror and it would read just fine.  I'm sure we will hear more ways to beat sticking it on as they become more prevalent.  I've still not seen one yet, but I've not been looking for it either.

[nathanm]

I don't think you would have dialectric properties between the RFID and windshield since glass is a terrible conductor.  I'm willing to bet you could even hang it on a short string on your rear view mirror and it would read just fine.  I'm sure we will hear more ways to beat sticking it on as they become more prevalent.  I've still not seen one yet, but I've not been looking for it either.

As I mentioned, there are several papers on the subject available on google scholar that claim otherwise.

Intuitively, I agree with you. Obviously RFID tags can work fine without being stuck to anything, given that one often finds them inserted in books and what have you these days. I presume the difficulty has something to do with the antenna being designed to be stuck to a windshield and optimized for that particular condition.

Hmm, this patent seems to give an overview: "The antenna has a characteristic impedance defined in part by a dielectric constant of the flexible circuit substrate and in combination with a dielectric constant of the glass surface. As a result, proper impedance match is achieved only when the sticker is affixed to the glass surface"

So the range issue when it's not stuck to a windshield or something is due to an impedance mismatch in the antenna dissipating power in the antenna instead of transmitting it back to the reader.

Edited to add:

More from the patent (the numbers make sense if you look at the drawings):

Referring now to FIG. 5, an exemplary circuit schematic of the sticker transponder 10 is shown. The antenna is represented within the dotted box 60. The antenna 60 generates an alternating voltage from the signal transmitted from an RFID reader (not shown) represented by a generator 68. The impedance of the antenna 60 is represented by a capacitor 64 in parallel with a resistor 62 and an inductor 67. An impedance matching section 56 connects the antenna 60 to a transponder circuit 50, which includes a modulator 54 and a memory 52. As described above, the tuning stubs (i.e., regions 36,37, and 45, 47) provide the impedance matching section 56.

The exemplary circuit schematic further includes a capacitor 66 coupled in parallel with the impedance defined by the capacitor 64, resistor 62 and inductor 67. The capacitor 66 is a function of the dielectric constant of the glass material 24 (see FIG. 1) having a thickness within a known range. When the sticker transponder 10 is affixed to the glass 24, the capacitor 66 is in parallel with the capacitor 64, resistor 62 and inductor 67. Conversely, when the sticker transponder 10 is not affixed to the glass, such as prior to use or after removal from the glass, the capacitor 66 is uncoupled from the capacitor 64, resistor 62 and inductor 67. Accordingly, the addition of the capacitor 66 directly affects the impedance of the antenna 60. The impedance 55 matching section 56 is therefore intentionally tuned to match the relatively high impedance of the transponder circuit 50 to the relatively low impedance of the antenna 60 when the sticker transponder 10 is affixed to the glass. Conversely, an improper impedance match is formed when the capacitor 64 is uncoupled from the capacitor 64, resistor 62 and inductor 67. As a result, the antenna 60 is only effective in communicating signals with the transponder circuit 50 when the sticker transponder 10 is affixed to the glass.

[Red Arrow]

Has anyone heard how OTA will accomodate trailer towing?  I have both a 2 axle and 3 axle Pike Pass in my car.  I keep the one I'm not using in the anti-static bag they used when they sent the Pike Pass to me through the mail.  The bag is a zip lock type and the material looks like the bag that static sensitive circuit boards come in. Works fine, I have not gotten any double billing.

[OpenYourEyesTulsa]

My old pikepass was only registering 1 out of 3 times so I went to get a new one expecting to get the new sticker but they gave me another old style pikepass (the white plastic shell with the 2 velcro straps).

[Townsend]

My old pikepass was only registering 1 out of 3 times so I went to get a new one expecting to get the new sticker but they gave me another old style pikepass (the white plastic shell with the 2 velcro straps).

They have to mail them or you go to a store like the one at the turnpike gate on 44.

Hmm, this patent seems to give an overview: "The antenna has a characteristic impedance defined in part by a dielectric constant of the flexible circuit substrate and in combination with a dielectric constant of the glass surface. As a result, proper impedance match is achieved only when the sticker is affixed to the glass surface"

The directions state that you must get out as many of the airbubbles as possible or it may not work.

[Hoss]

They have to mail them or you go to a store like the one at the turnpike gate on 44.

The directions state that you must get out as many of the airbubbles as possible or it may not work.

Which likely means they provide you with a cardboard 'edge' to smooth those bubbles out.

Going to their website, they indicate these can be peeled off rather easily.  If so, I don't have as much of a problem affixing it to my windshield.  But I'll reserve judgment until someone can tell me for sure it's easy to peel off.