In
digital
Digital usually refers to something using discrete digits, often binary digits.
Technology and computing Hardware
*Digital electronics, electronic circuits which operate using digital signals
**Digital camera, which captures and stores digital i ...
transmission, bit slip is the loss or gain of a
bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented a ...
or bits, caused by
clock drift
Clock drift refers to several related phenomena where a clock does not run at exactly the same rate as a reference clock. That is, after some time the clock "drifts apart" or gradually desynchronizes from the other clock. All clocks are subject to ...
– variations in the respective
clock
A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and t ...
rates of the transmitting and receiving devices.
One cause of bit slippage is
overflow of a receive
buffer that occurs when the transmitter's
clock rate
In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the ...
exceeds that of the receiver. This causes one or more bits to be dropped for lack of
storage capacity.
One way to maintain timing between transmitting and receiving devices is to employ an
asynchronous protocol such as
start-stop. Alternatively, bit slip can be prevented by using a
self-clocking signal
In telecommunications and electronics, a self-clocking signal is one that can be decoded without the need for a separate clock signal or other source of synchronization. This is usually done by including embedded synchronization information with ...
(such as a signal modulated using
OQPSK) or using a
line coding
In telecommunication, a line code is a pattern of voltage, current, or photons used to represent digital data transmitted down a communication channel