Virgin American In-Flight Internet Review, From In-Flight 198
wintersynth writes "I've posted a review of Virgin America's in-flight internet provided by Gogo. Here's the scoop: Avg. .90 megabits/sec DL, .283 megabits/sec UL, ping: 130.6 msecs, $12.95 for the duration of the flight. Verdict: AWESOME. In fact, I'm posting this from 36,000 feet right now. Skype did not work for voice, even though I'm pretty sure those stats are over the minimums. Any ideas from the slashdotters on what might be going on?"
Skype (Score:5, Informative)
Another possibility is that Gogo is demoting UDP traffic in some sort of QoS scheme to ensure that things like e-mail and regular HTTP traffic aren't slow or interrupted because 4 people are using Skype.
Re:Skype (Score:5, Informative)
Skype uses UDP rather than TCP (like normal web traffic). If I remember correctly, UDP packets are many small packets which may perform badly over connections of very high latency.
UDP shouldn't have anything to do with latency, nor is it limited to "many small packets". UDP is just a transport protocol that lacks the error checking/data integrity and ordering mechanism of TCP. If such features are important to you then you need to use TCP or build them into your application that uses UDP.
The advantage of UDP comes in time critical applications where it's probably better to lose a few packets (i.e: have a second or two of dead air during a phone call) than delay the transmission (conversation stops while it waits for the lost packets to be retransmitted). Latency really doesn't have anything to do with it, although latency is bad for VoIP for other reasons.
Skype is Not Blocked (Score:3, Informative)
Probably blocked everything VoIP related to force airphones on you.
From the article:
I'm trying to get some critical production tasks done, and the rep I work with emailed me to call her. Thinking I was so tricky and cool, I fired up Skype and dialed out. Massive failure. For some reason the sound is horrendously choppy and thin sounding. It was completely unusable. I didn't get a chance to speak and see how I sounded on the other end. I tried dialing the Skype test call, but I only caught every other word.
Sounds like he could connect, it was just choppy.
Banned VOIP (Score:2, Informative)
Re:Srsly? (Score:1, Informative)
maybe... (Score:1, Informative)
you couldn't use skype because the connection was likely via satellite and that usually means you get to download really big packets really fast, but a lot of small packets could be highly inefficient I THINK
Re:Skype is Not Blocked (Score:2, Informative)
Re:Skype (Score:5, Informative)
I fired up Skype and dialed out. Massive failure. For some reason the sound is horrendously choppy and thin sounding. It was completely unusable.
You're experiencing high "jitter." Jitter is the change in delay from packet to packet. If odd numbered packets take 100 ms and even numbered packets take 150 ms then you have 50ms of jitter.
Certain protocols like VoIP and NTP require connections with low jitter in order to perform acceptably.
Re:May I be the first to say (Score:3, Informative)
They talk louder because they judge how well they are being heard by how well they hear themselves. Over the constant drone of jet engines, people have to talk louder to hear themselves. Thus, they assume they need to be that loud so the microphone just an inch away from their face can hear them.
plus it is pressurized to reduce the need to scream further.
"Pressurized" is a relative term. Standard cabin air pressure is around 8000 feet altitude. Less than sea level. The pressure is lower than normal, even though the cabin is "pressurized".
If everyone has small chatter it actually creates a bit of a whitenoise effect = sleep.
I don't know what airplanes you fly on, but on the ones here on earth, lots of people chatting isn't "white noise" by any stretch of the imagination. The people ahead/behind you are always louder and prevent any realistic averaging. HA HA HA YOU DIDN'T...
Southwest airlines testing now (Score:5, Informative)
Southwest is testing Wi-Fi on four of its planes now. I was on one on a flight from Las Vegas to Baltimore. They sent me an email the day before telling me that the plane would have wi-fi and that it would be free during this test period.
The speed was fantastic, but I didn't benchmark it. However, I was able to do a video iChat with my wife at home. Didn't try to do any audio, just video.
The big drawback about Southwest is that their planes have no power outlets. Not sure if they're going to add them. But they're aware of the issue.
Re:Skype (Score:3, Informative)
http://www.networksorcery.com/enp/protocol/udp.htm [networksorcery.com]
http://www.networksorcery.com/enp/protocol/tcp.htm [networksorcery.com]
Jitter Buffer (Score:4, Informative)
Asterisk 1.4+ has a jitter buffer for at least IAX and SIP which helps to work around jitter in most cases. Given that they know what they're doing, I assume Skype does too.
Jitter is (relatively) okay, it's packet loss that VoIP is particularly sensitive to. Packet loss at levels that will only mildly inconvenience most other traffic will screw up VoIP quite badly... there's no mention of packet loss in the article that I see, but I suspect that's what's causing the poor quality.
If you can ask me to not take up extra seatage (Score:1, Informative)
Can I get you to stop reclining into my knees?
Im 6'4, my body frame will be large no matter how skinny I am, and yes I can wear a seatbelt without an extension.
Do you think I can shrink by not eating?
Re:Jitter Buffer (Score:2, Informative)
The GSM codec popularized by mobile phones, and commonly used by VoIP packages actually tolerates bit and packet loss quite well.
It uses a progressive refining encoding, and a probabilistic packet layout to keep the core 'shape' of the sound through all but the most severe conditions, so that losses are likely to only affect the details.
It also specifies protocols for 'looping' previous datagrams in a way that makes it easier to understand what was being said through such losses.
Keeping in mind that there's actually extremely little temporal detail in human speech, it's possible (and in my mind, hopeful) that what you were experiencing is the result of the airline deliberately choking known VoIP providers, in order to not end up with a plane full of jerks yelling into their laptop for a six hour flight.