The call that sounds like a robot
A teacher joins a video call. The picture is sharp. But her voice sounds like a robot, and some words are missing.
The internet is "fast". So what went wrong? Five measures can tell you.
By the end of this lesson
Note
I can match a call problem to the measure that causes it.
Key words
| Word | What it means |
|---|---|
| Network | computers joined so they can share data |
| Router | a device that passes data between networks |
| Packet | a small piece of data sent over a network |
| Speed | how fast data seems to move, in megabits a second |
| Bandwidth | the most data a link can carry each second |
| Latency | the delay for a packet to travel, in milliseconds |
| Jitter | how much the delay changes from packet to packet |
| Packet loss | packets that never arrive |
The cells students fill in are left blank in this preview.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Five measures of a network
Speed is how fast your downloads feel.
Bandwidth is the size of the pipe. A big pipe carries more data each second.
Latency is the delay. It is the time one packet takes to arrive.
Jitter is how uneven that delay is.
Packet loss is how many packets never arrive.
Measure, unit and a good value
| Measure | Unit | Good for a call |
|---|---|---|
| Bandwidth | Mbps (megabits per second) | Enough for the call, with room to spare |
| Latency | ms (milliseconds) | Under about 150 ms one way |
| Jitter | ms | Under about 30 ms |
| Packet loss | Out of every 100 packets | Close to none |
The cells students fill in are left blank in this preview.
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.