A synchronous language by Le Guernic et al of INRIA.

["SIGNAL - A Data Flow-Oriented Language for Signal Processing," P. le Guernic, IEEE Trans Acoustics Speech & Signal Proc, ASSP-34(2):362-1986-04-374].

Last updated: 1996-12-10


<operating system>

A predefined message sent between two Unix processes or from the kernel to a process. Signals communicate the occurrence of unexpected external events such as the forced termination of a process by the user. Each signal has a unique number associated with it and each process has a signal handler set for each signal. Signals can be sent using the kill system call.

Last updated: 1996-12-10

signalling rate


The number of times per second the amplitude, frequency or phase of the signal transmitted down a communications channel changes each second. The signalling rate is measured in baud.

Last updated: 1998-02-14

Signalling System 7


(SS7) A protocol suite used for communication with, and control of, telephone central office switches and their attached processors.

Last updated: 1995-03-01

signal-to-noise ratio


1. (SNR, "s/n ratio", "s:n ratio") "Signal" refers to useful information conveyed by some communications medium, and "noise" to anything else on that medium. The ratio of these is usually expressed logarithmically, in decibels.


2. The term is often applied to Usenet newsgroups though figures are never given. Here it is quite common to have more noise (inappropriate postings which contribute nothing) than signal (relevant, useful or interesting postings). The signal gets lost in the noise when it becomes too much effort to try to find interesting articles among all the crud. Posting "noise" is probably the worst breach of netiquette and is a waste of bandwidth.

[Jargon File]

Last updated: 1996-01-29


1. A set of function symbols with arities.


2. (Or sig) A few lines of information about the sender of an electronic mail message or news posting. Most Unix mail and news software will automagically append a signature from a file called .signature in the user's home directory to outgoing mail and news.

A signature should give your real name and your e-mail address since, though these appear in the headers of your messages, they may be munged by intervening software. It is currently (1994) hip to include the URL of your home page on the web in your sig.

The composition of one's sig can be quite an art form, including an ASCII logo or one's choice of witty sayings (see sig quote, fool file). However, large sigs are a waste of bandwidth, and it has been observed that the size of one's sig block is usually inversely proportional to one's prestige on the net.

See also doubled sig, sig virus.


2. A concept very similar to abstract base classes except that they have their own hierarchy and can be applied to compiled classes. Signatures provide a means of separating subtyping and inheritance. They are implemented in C++ as patches to GCC 2.5.2 by Gerald Baumgartner <[email protected]>.

Last updated: 2001-01-05

Nearby terms:

SIGLASIGMASIGNALsignalsignalling rateSignalling System 7

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