First things first: this is not a conspiracy diary. I think the odds rather disfavor the idea that Sarah Palin will be wearing an earpiece tonight, and getting cues fed to her from someone backstage.
But since that idea's been getting some play here and elsewhere in the blogosphere, and since I have just enough background in engineering to be dangerous, and since I think facts are much more interesting than speculation, perhaps you'd like to follow along as I explore how such a thing could be done, if they wanted to do it, and how we might be able to tell if it's happening.
First, a few bits of background:
1. The RF spectrum is incredibly crowded, especially at a major media event like this one.
In order to get cues into Palin's ear, there has to be some way to get them wirelessly from wherever the cuer is sitting to the stage. The only really practical way of doing that is via a radio link.
Easy, right? Not so much. There's only so much space available on the radio-frequency (RF) spectrum in which you could send such a signal. And at any big event where there's a lot of media coverage, those spaces on the spectrum are in VERY high demand. Consider all the different uses to which radio is being put - wireless mics for TV reporters, wireless "IFB" (earpiece audio) coming back to the reporters, wireless video connections from cameras to live trucks, all the two-way communications going on between security personnel, emergency crews, and on and on.
There's very little spectrum actually available for wireless mics and similar uses. Most of it is shared with UHF TV broadcasts, and there's a constant struggle over whether to free more of this spectrum for other uses. You know that "free the white spaces" ad that sometimes appears at the top of dKos? That's what this is all about - a fight between the companies that make wireless mics and Google, which wants to be able to do wireless data services on those same frequencies. But I digress.
To avoid utter chaos, events like debates use "frequency coordinators" - usually a member of the local Society of Broadcast Engineers - who assign and monitor all the frequencies being used by the media. (Here's a fairly geeky article about frequency coordination at the DNC in Denver this year.)
My point is this - if the McCain/Palin campaign were simply to use an off-the-shelf IFB receiver and earpiece, like the ones TV reporters use, they'd be stepping on someone else's frequency and would be caught pretty quickly.
2. What about using some frequency outside the normal wireless-mic channels?
Not out of the question - but not easy, either. A few factors to consider: the laws of physics dictate that any frequency that's too low (say, under 500 MHz) will require the use of an antenna too big to be easily concealed in a dress. Higher frequencies, above the usual wireless-mic channels, are pretty heavily allocated, and firing up a transmitter without coordination is likely to cause interference that someone, somewhere will notice pretty quickly.
It's worth noting that at the 2004 DNC, the Secret Service, of all agencies, got caught using some uncoordinated frequencies that were causing interference. Here's a link to some pictures showing the frequency-coordination operation in use in Boston - note this caption, in particular:
Three days prior to the start of the DNC, each piece of RF-generating equipment needed to pass RF-purity testing. Peter insured that each piece of RF equipment entering the area possessed an "RF tested-OK" sticker. No sticker, no entry.
Admittedly, nobody's going to be body-searching Sarah Palin for a hidden receiver. But that brings up another question:
3. Where do you put the person doing the cueing?
This one has me stumped, because you have two problems with mutually-exclusive solutions.
Ideally, you'd like the person whispering in Sarah's ear to be somewhere far away from the debate site. You don't want someone pulling back a curtain, Oz-style, and finding Randy Schuenemann hunched over a microphone muttering about the difference between Iran and Iraq.
A hotel room somewhere else, watching on TV? Perfect...except that there's a delay issue to contend with. All the digital links from debate site to satellite uplink to network headquarters to cable company mean that several seconds can elapse between the time the question is asked on stage in St. Louis and the time a viewer sitting somewhere else hears it. And you don't want Palin standing there looking silent while waiting for the cues to come back over her earpiece. (Well, we do, actually, but...)
Then you also have the challenge of getting the whisperer's audio from the hotel room into the arena to be broadcast to Palin's earpiece. Cellphone? Those get overloaded in a busy situation, can drop out, and introduce more delay. Wi-fi? Same problems, to a greater degree. (This is also why you don't just drop a tiny cellphone down Palin's back and connect it to a concealed earpiece - it solves the spectrum issue, but it's just not reliable enough when you need it to be.)
So let's say you put the whisperer right in the arena - say, in a dressing room offstage, or hiding in the men's room, or something? Here, again, we face a dilemma: the more concealed the whisperer is, the more powerful a signal their equipment will need to generate to be able to be clearly received on stage, and thus the more likely they are to cause interference and be found out. And of course they've got to get the equipment in there somehow in the first place, through heavy security.
4. Where do you put the bug on Sarah?
I've read plenty of speculation about her hairstyle being changed to conceal her ears so we don't notice any wires going up there.
I suppose that's not impossible. But here again, the technology isn't quite as super-slick as some might imagine. Remember, these debates are broadcast in HDTV, and press photographers are shooting hi-res images with very sharp long lenses. You'd have to have something very small for it not to show up in a picture somewhere.
The clear earpieces that TV anchors and reporters wear have the transducer (the actual "speaker" that generates the sound they hear) in a little button that clips on to their collar in back; the sound then travels through a clear tube into their ear. You can see one of those if you're looking for it. It's hard to hide.
You could use a much thinner, easily-concealed wire to carry the electrical audio signal to an in-ear transducer...but then you've got something bigger in the ear itself that will be visible.
And you need a receiver somewhere on the body to actually pick up the RF signal being sent to the stage. The tinier the receiver, the more powerful the signal being fed to it will need to be...and thus the more likely to cause interference that will be detected by someone.
(Before someone asks - yes, I do think Bush had something Y-shaped in his back during that debate in 2004; I think it was more likely part of a bulletproof vest than a radio receiver, if only because the "tubes" leading up his shoulder blades were much thicker than earpiece wires would have been, but anything's possible.)
5. Could Sarah manage to be coherent with someone whispering in her ear?
This is not a rhetorical question. Sure, she had some very brief experience as a small-market sports anchor in Anchorage 20 years ago. But if you've seen the clips, you know she was anything but smooth at it.
It takes a real skill to be able to speak smoothly and eloquently while someone's talking in your ear. During the brief part of my career when I had to do it, I sucked at it - and I have a lot more on-air experience than Governor Palin. (Does this mean I'm qualified to run the FCC?)
If the concern is that she's already being over-stage-managed, the worst thing they could do to her is have someone whispering in her ear through the whole debate.
Hmmm...maybe I do wish it were an easier task to accomplish!
UPDATE: About that cast on her hand...
Yes, my inner conspiracy theorist is wondering about that, too. It would certainly be one place where a receiver could be concealed, and then use Bluetooth or something similar to get the audio to a tiny in-ear receiver.
But that still requires either someone in the arena ("behind the curtain") giving the cues through a transmitter that has to be brought in past security, or someone in a hotel room watching the thing on TV, with all the delays that modern TV transmission imparts. Either way creates complications.
And as several commenters below have noted, it takes real skill to be able to perform smoothly while being cued in-ear.
Consider: if they thought Palin could actually handle that task, wouldn't they have cued her that way during her Couric and Gibson interviews? That would have been MUCH easier to accomplish...and if they did in fact try it, well, the results speak for themselves.
And in the end?
I saw no evidence, sitting here at home, that she was wired up in any way.
And if she were...well, whoever was prompting her should be taken somewhere and shot. Oof! What an awful performance.