Eduqas A500QS 2.8: Data security and integrity processes
The free BugBot lessons that teach this point, a robot to try it on, and the past-paper questions that test it.
What it covers
Bits get corrupted. Radio interference flips a bit in a message, a scratch damages a disc, a person mistypes a code. A robot that obeys LEFT 90 when it was sent LEFT 10 is a hazard. The methods in this lesson add a little extra data, calculated from the real data, so the receiver can detect that something went wrong, and in some cases correct it.
- Parity bits
- Majority voting
- Checksums
- Check digits
- Comparing the methods
Or do it in the simulator, with tasks that mark themselves
Lessons that teach it
- A7.6 Error checking and correction Data representation
Parity bits, majority voting, checksums and check digits, with checksums on the robot's radio messages. - A7.10 Project: a secure sensor packet Data representation
Pack a distance reading into fixed point bytes with flags and a checksum, encrypt it with a one-time pad and send it by radio.
Try it on a robot
The task from A7.6 Error checking and correction, running here. Change the program and press Run.
The specification is Eduqas's own document; this page says which of our lessons teach point 2.8 and is not endorsed by the board.