Frequency Modulation: Difference between revisions
From Computer History Wiki
Jump to navigationJump to search
Slightly clarify |
m +cat |
||
| (One intermediate revision by the same user not shown) | |||
| Line 7: | Line 7: | ||
It was mostly replaced by [[Modified Frequency Modulation]], which can store twice as many bits in the same maximum reversal rate. | It was mostly replaced by [[Modified Frequency Modulation]], which can store twice as many bits in the same maximum reversal rate. | ||
{{stub}} | {{semi-stub}} | ||
[[Category: Theory]] | |||
Latest revision as of 19:21, 14 December 2018
Frequency Modulation (or FM) is an encoding technique, used in magnetic storage such as disks and floppy drives.
In FM there is a reversal (signal level, or magnetic flux) at the start of every data bit time (i.e. every clock time); for a '1', there is an additional reversal in the middle of the bit time, with no reversal indicating a '0'.
Consecutive zeros show a reversal between data bit times; consecutive ones show two reversals in every bit time (i.e. doubling the frequency of reversals; hence the name).
It was mostly replaced by Modified Frequency Modulation, which can store twice as many bits in the same maximum reversal rate.
