Modified Frequency Modulation - Revision history

Vaxorcist: Category: Device Basics added

2022-07-14T09:52:31Z

Category: Device Basics added

Jnc: +cat

2018-12-14T19:21:41Z

+cat

Jnc: Proper cat

2018-10-20T00:39:59Z

Proper cat

Jnc: slightly clarify

2017-10-25T15:32:42Z

slightly clarify

Jnc: An OK start

2017-10-25T14:32:20Z

An OK start

New page

'''Modified Frequency Modulation''' is an encoding technique, used in [[magnetic storage]] such as [[disk]]s and [[Disk#Low-cost disks|floppy drive]]s.

It is, as the name says, a modification of the earlier [[Frequency Modulation]] scheme used in the same applications; instead of a clock transition and possibly also an additional data transition in each bit time, in MFM there is at most one transition per bit time. This allows twice as many bits to be encoded with a certain maximum transition rate.

To be exect, in MFM there is a reversal (signal level, or magnetic flux) at the bit time for a '1', and no reversal for a '0'. A reversal ''between'' data bit times occurs with consecutive zeros.

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 It is, as the name says, a modification of the earlier [[Frequency Modulation]] scheme used in the same applications; instead of a clock transition and possibly also an additional data transition in each bit time, in MFM there is at most one transition per bit time. This allows twice as many bits to be encoded for a given maximum transition rate.
-To be exect, in MFM there is a reversal (signal level, or magnetic flux) at the bit time for a '1', and no reversal for a '0'. A reversal ''between'' data bit times occurs with consecutive zeros.
+To be exect, in MFM there is a reversal ([[signal]] level, or [[magnetic flux]]) at the bit time for a '1', and no reversal for a '0'. A reversal ''between'' data bit times occurs with consecutive zeros.
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+{{semi-stub}}

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-'''Modified Frequency Modulation''' is an encoding technique, used in [[magnetic storage]] such as [[disk]]s and [[Disk#Low-cost disks|floppy drive]]s.
+'''Modified Frequency Modulation''' (also '''MFM''') is an encoding technique, used in [[magnetic storage]] such as [[disk]]s and [[Disk#Low-cost disks|floppy drive]]s.
-It is, as the name says, a modification of the earlier [[Frequency Modulation]] scheme used in the same applications; instead of a clock transition and possibly also an additional data transition in each bit time, in MFM there is at most one transition per bit time. This allows twice as many bits to be encoded with a certain maximum transition rate.
+It is, as the name says, a modification of the earlier [[Frequency Modulation]] scheme used in the same applications; instead of a clock transition and possibly also an additional data transition in each bit time, in MFM there is at most one transition per bit time. This allows twice as many bits to be encoded for a given maximum transition rate.
 To be exect, in MFM there is a reversal (signal level, or magnetic flux) at the bit time for a '1', and no reversal for a '0'. A reversal ''between'' data bit times occurs with consecutive zeros.
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