In Networking, Jitter is the variation of the latency of ping times.

Let me clarify that.

To understand jitter, first you must understand ping. When you are trying to check the reliability and availability of a connection, you use a tool called ping. In DOS or a command line (just about any one out there), type in "ping yahoo.com" and your computer will send a short packet over the internet to whatever computer Yahoo is on, and the computer at the other end will send a return packet. The computer calculates the delay it took in milliseconds to get there and back. So a ping is like an echo.

Timing the ping reveals the latency of a connection, or how long it takes for the ping to make a round trip. The variation of this latency is known as the jitter. Imagine if you graphed ping times by pinging every second and showing the change in time. You can see the jitter by changes in this graph.

Jitter is very important to network connections, since certain applications are very sensitive to it. Telemedicine is one example; if you're performing a remote surgery then your patient's life may depend on a reliable connection with very low jitter.

Jitter is relatively difficult to monitor, since just pinging wouldn't be very detailed. One scientist has developed an idea to turn jitter into an audible sound which you can monitor yourself. A ten-millisecond ping would give you a 100Hertz tone by your computer. The longer the time, the lower the pitch. Listening to that would make it extremely easy to diagnose your connection. If the sound started skipping like a CD player, then you can tell there's a problem. If the jitter changes, then you can clearly hear the tone warble.

Read more of this idea at http://www.newscientist.com/news/news.jsp?id=ns99993112


Also, Jitter is also a kind of tremble, a shake, an anxiety, a paranoia. Jitter is usually pluralized as jitters
Kuralt opened the inner door to Harvey’s Hooch House with a grunt. Made from tantalum steel, its mass overshadowed any paltry calculation of local gee as it swung back on hinges squealing from vacuum binding. Willits stepped through, then they both stood on the mat and swung the portal back into place with a solid sound.

Willits took the compressor hose and dusted both their suits down before they racked helmets. The five or six others in the cramped space ignored them as they moved wearily to the bar along the back wall and leaned there, elbow armor clinking on the foamsteel.

“Fuck.” Kuralt addressed the small puddle of liquid on the surface between his arms.

Willits made no reply. There wasn’t much to say.

Harvey came out from the back and set drink pouches in front of them both. They nodded to each other, all three, and the two newcomers popped the integral straws and began to slowly pull on the algaepak alcohol. The stuff was green today, Kuralt noted with not much interest. He wasn’t sure if it was a flavor or a color. After a few minutes of determined sucking, necessary to extract the slash from the spongelike interiors of the algaepaks, Kuralt finally asked. “Any bandwidth?”

“Nope. I’d’ve said.”

“Yeah. I thought.” More silence. Kuralt sighed, looked around the room at the few miners sitting quietly around the small tables before continuing in a quieter voice. “Any visits from Command?”

“Nah.”

“Do they even really know what’s going on?”

Willits snorted. “Who knows? Do we?”

Kuralt scrubbed a hand over his face, hard. “Hell if I know. Is Radiant still in orbit?”

“Sure. She passes over every couple hours, like clockwork. You can see her if you go outside the shack.”

“And there’s still Command personnel up there?”

Willits took another drink. “Yeah, as far as I can tell. There’s whisker laser between her and the top shack, and micro bouncing between her and several spots cislunar. Survey sats, maybe.”

Kuralt turned to look at him. “But what’s the fucking point?”

“How the fuck should I know? I’m just a Comm tech!”

“I know, I know. Sorry.”

Willits waved off the apology and kept drinking, glancing around to see if any of the miners had taken an interest. None of them had. He leaned closer to Kuralt. “Look, you don’t get it yet. This can’t happen. The Net cannot go down. Not unless the core segments all go unstable.”

“I thought it wasn’t down.”

“It’s not down, really. It’s just not stable enough to get an FTL lock.”

“What?”

“Not here. Come on, let’s head back.”

They stacked their pouches. Kuralt placed an insulated container of ammonia on the bar and nodded to Harvey, at the other end; Harvey waved back in thanks. They moved back to the door, slotted helmets. Kuralt checked Willits’ suit indiks, and Willits checked his before they moved into the lock.

Outside, on the rocky surface of the unnamed worldlet, their helmets darkened to protect them from the unblocked flood of radiation from the system primary. Stepping carefully over broken footing using high frequency radar imaging, they made their way across the operations area to a small bunker set into the edge of the ridgeline directly underneath the imposing shape of the ansidish.

Once inside, they settled into the two system console stations. Willits checked readouts by habit. Kuralt didn’t touch anything, and waited for the other to tell him what was happening. At Willets’ headshake, he deflated slightly. “Look, how can the Net be up but not up?”

Willits was fitting the headset onto his skull. “The base net is up. But I can’t get a stable signal through the network to the core systems. I can get packets through, but they’re not going through in a predictable manner. They’re coming back unpredictably out of phase and sequence. That means I can’t get the system here to lock onto the system there, and we can’t get a Comm link established. There’s some kind of halfway link, but nothing you can transmit information over.”

Kuralt glared at him. “How can you have a communications link that can’t transmit information?”

Willits groaned. “Look, I’m just a tech, okay? This is FTL physics. Unless everything is working, and the equations balance, you can’t pass information through foldspace. You can do a lot of things that look like you’re passing information, but you’re not, really. Until the foldspace link comes up, you’re sort of looking into a mirror box. That’s the best I can explain it.”

“Then what are you doing now?”

“Now?” Willits laughed, but it was a bleak sound. “Now I have to go back into that mirror box.”

“Why?”

“Because the fucking thing doesn’t synchronize automatically. That’s another rule. There has to be intelligence of some form to make that connection. Volition, or something. In order to make that sync, the operator has to ride the foldspace signal up the link and hope the other end is synced up. If it is, great; the link comes up, and it’s just like I’m dialed into the VR-Comm system at Lalande, or Halfway station or wherever.”

“What if it’s not up?”

Willits grunted as the headset touched his shaved scalp and his expert fingers twitched it gently into optimal position. “I told you. Mirrors on the inside of the box. Silence. Forever.”

init
init
uplink
base::link::45::978:489:151:980:449:386:205
initiating foldlink::

Willets grunted softly without moving. Kuralt looked at his closed eyes expressionlessly, his left hand turning over a gleaming piece of machined alloy.

foldlink open::
Fomalhaut XVII::link::transfer-routing-intrstlr-indstrl-ttrnk-113:677:789:439:023:308:887
initiating foldlink::

Outside, the shift change was underway. Kuralt could tell from the regular vibration in the floor as the crawlers ferried miners in from the works to the barracks. Willets was still sitting unmoving in the station chair.

foldlink open::
Lalande VIII::link::lcl-access-routing-interstlr-indstrl-ttrnk2
checking link quality
packet spectra sigma 9.559, sigma 10.559, sigma 17.5
* * VARIANCE UNACCEPTABLE * * *
initiating foldlink::

Willits’ lips twisted slightly. He made no sound, but that small expression was enough to send a chill through Kuralt, who had seen his friend make Contact hundreds of times in their last few Tours. Forcing himself to sit still, he looked down at the alloy part he was twiddling and waited.

foldlink open::
Proxima Centauri II::link::lcl-access-routing-interstlr-indstrl-ttrnk3
checking link quality
packet spectra eta 15.3 eta 16.6 eta 14.9
* * * VARIANCE UNACCEPTABLE * * *
initiating foldlink::

This time a small spitting sound did escape, and Kuralt sagged into his chair, shoving the part into a pouch in his suit. Willits was still sitting calmly, but that was as much a function of the alphablockers in the headset as his own state of mind. Which, given the sound that had just escaped, wasn’t good.

Sol Halfway::link::lcl-access-final-intrstlr-indstrl-ttrunkfin
linking::linking::linking::linking::linking::linking::linking::linking::linking::linking::
packet spectra zeta 4.1 zeta 20.4 zeta 18.1
linking::linking::linking::linking::linking-

Willits slid the headset up and jerked to one side as the artificial calm was released. “Fuck.”

“Nothing?”

“Nothing. Worse.”

“What’s worse than nothing?”

“I can get to Sol, man. I can get there. I just can’t get out of the fucking system. Don’t you understand? The machines are still running. The machines are STILL RUNNING!” Willits clapped his hands to his face, Kuralt suspected to hide tears, and slumped in his seat.

“But if the machines are still running, then they’ll get it fixed, right?”

There was no answer for a moment.

“Will? Hey, man...”

Willits pulled his hands down and leaned forward to put his face down onto the console desk. “No.”

“What do you mean, no?”

“There’s no way the machines could still be running after two months and the link not be Comm quality, unless there wasn’t anyone on Halfway to make contact with.”

“How the hell can there not be anyone on Halfway? Shit, what about the relays in beween, for that matter? Didn’t you tell me you had to go through like four different systems to get there?”

Willits gave him another death’s head grin. “Yep.”

“Then...”

“That’s my point. Nobody’s online. Fomalhaut, Lalande, Proxima, Sol. Nobody’s online. The machines are running. But nobody’s answering. For two months. Since we came out of jumphibe and set up shop, nothing. It’s been, what, eighteen months objective since we left Lalande.”

“But....but what the hell could have happened to everybody?” Kuralt asked quietly.

Willits looked at him for a time. Then, like he’d done every day, for the past two months, he put the headset back on, and Kuralt shivered to see the mirrors in his eyes.

Log in or registerto write something here or to contact authors.