Hearing his name called from very close, yet far away, Chargers linebacker Matt Wilhelm turned to put a face with the voice on the sideline at Qualcomm Stadium. He found none.

Matt!! Matt!!

Wilhelm spun the other way. Still nobody.

Matt!!! Matt!!! Matt!!!

Wilhelm whirled again, then threw his arms in the air and yelled, “What??? Where are you?” No answer. Only after scouring the full length of the sideline did he find the Chargers' defensive coordinator, Ted Cottrell, who'd been trying to reach Wilhelm via the helmet-radio system that now connects NFL coaches with the fellow calling plays in the defensive huddle.

Ah, technology. Given the way cell phones and walkie-talkies usually fail at the most important moments, to say nothing of interference and the wonder of who else is listening, you might think the Chargers would be better off using two cans and a string when passing plays from the sideline to the field.

Actually, the first application of the one-way radio worked well, according to personnel at both ends of the line during Saturday's exhibition opener against Dallas. Nary a glitch.

“It's pretty good,” said Wilhelm. “Here and there in training camp it would cut out, but during the game at the stadium it worked just fine, real well. There were a few times when Dallas came out of the huddle quick and didn't allow me time to have my eyes on the sideline, so I just had to listen to the headset.”

The headset is a pair of orange-colored receivers planted just behind the ears in the helmets of Wilhelm and fellow linebacker Tim Dobbins, the latter of whom called the plays for the backup unit and was the only other Chargers defensive player wired Saturday. (Their wired status is denoted to officials with a green dot on the back of the helmet.) According to NFL rules, each team is allowed no more than one headphoned defender on the field.

Players are not equipped with an electronic method of response. Wilhelm said he simply acknowledges getting the verbal call by giving Cottrell a thumbs up, or a thumbs down when failing to receive. The microphone is live only between the start of the play clock and its 15-second mark.

In fact, Wilhelm hadn't even gotten to the huddle from the sideline when the new audio system served its best purpose. Moving in on the San Diego goal line, the Cowboys broke their huddle early.

Instead of having to turn to read Cottrell's hand signals, Wilhelm heard the play in his head and quickly relayed it to the 10 teammates awaiting him.

Not all of the time allotted is needed or used for calling plays, leaving Cottrell an opportunity to alert Wilhelm and the defense to personnel changes that are being made by the opposing offense. Also time to warn what Cottrell suspects the other team may be about to try.

“I love it, absolutely love it,” said Cottrell. “It really helps us quickly to get the information to the field. I'm not totally a technology guy, but I appreciate the advances that have been made available to us. The quarterback's had that tool for a while now. The defense should have it, too, to put us on an even plane.”

The electronic communication system has been in play for NFL offenses for more than a decade, although compared with today, the original equipment might as well have been invented by Alexander Graham Bell. Time ran out or plays were botched – or the wrong plays run – because the radio line went dead or the quarterback simply couldn't hear his orders from the sideline because of crowd noise.

Even with the incredible advances made in communication devices over the past 10 years, though, there likely will be times when the defensive coordinator must resort to the old-fashioned mode. A thumbs down from Wilhelm will elicit a manual signal from the sideline.

“If it does break down, I can look over and get a call,” said Wilhelm. “I do like it as a tool, but I also like knowing we have the backup system in place.”

He likes it more now. At first . . . well, imagine going through your workday with somebody else's voice in your head. Try it on a practice field, let alone with 60,000 people around you, screaming.

“It is weird,” said Wilhelm. “It took a good getting used to throughout the first few days of training camp. I think it's just a matter of understanding between myself and Ted, who is that voice, as far as not overloading me with information. But he does a great job.”

Sometimes, Wilhelm isn't the only one hearing Cottrell's baritone. The linebacker said he's also gotten “some weird looks on the sideline” when teammates hear Cottrell's voice emanating from Wilhelm's helmet.

Incidentally, the communication system is under the strict control of the NFL, which assigns somebody to turn the switch on and off in accordance with the play clock. There is a certain sense of “big brother” to it.

“The guy is somewhere in that stadium,” said Cottrell. “Where exactly, I don't know, but I know he's there.”

Chris Jenkins: (619) 293-1267; chris.jenkins@uniontrib.com