Phone Call Recorder

baud

In telecommunications and electronics, baud (pronounced /b??d/) is a measure of the "signaling rate" which is the number of distinct symbolic changes made to the transmission medium per second in a modulated signal. It is named after Emile Baudot, the inventor of the Baudot code for telegraphy. For example: 250 baud means that 250 symbols are transmitted in one second. For instance, if 16 different symbols have been defined (each carries 4 bits of information), then in each second 1000 bits of information are transmitted, but with having to send only 250 actual symbols, rather than sending 1000 binary symbols (bits). Note: Baud should not be confused with data rate (also called "bits per second", or bytes per second, etc.). Each signalling event transmitted can carry one or more bits (for example, 8 bits in 256-QAM modulation) of information. When each signalling event transmitted carries one bit the baud rate and the data rate are equal. However, it is more common to make better use of bandwidth by encoding multiple bits in one event. This reduces the time required for sending a given quantity of data. Thus, a 2400 bit/s modem actually transmits at 600 baud (600 symbols/sec), where each quadrature amplitude modulation symbol carries four bits of information. A clear example of the difference between the baud (or signalling rate) and the data rate (or bit rate) is a man using a single semaphore flag. He can move his arm to a new position once each second, so his signalling rate (or baud rate) is 1 per second. However, the flag can be held in one of eight distinct positions: Straight up, 45 degrees left, 90 degrees left, 135 degrees left, straight down (which is the rest state, where he is sending no signal), 135 degrees right, 90 degrees right, and 45 degrees right. This means each signal carries three bits of information, as it takes 3 binary digits to encode 8 distinct states - so the data rate is 3 bits per second. Modems work in the same way - a 2400 bit/s modem will typically have a baud rate of 600 per second - but each signal carries 4 bits of information encoded within it, allowing a data rate of 2400 bit/s.

List of telephony terms:

3gpp - a-law - abbreviated dialing - adsl - ani - answering machine - apn - automatic ring back - b-channel - baud - bell 202 modem - bit rate - bonding - bri - busy signal - cable modem - call-progress tones - call accounting - call capture - call forwarding - call originator - call park - call pick-up - call transfer - call waiting - call waiting deluxe - called party - caller id - caller id spoofing - calling party - carrier wave - cbr - ccitt - cdma - cdma2000 - cellular repeater - celp - channel - clec - clock rate - codec - collect call - conference - conference call - crc - csd - d-channel - data compression - device driver - dial-up - dial - dial tone - direct-inward-dialing - direct distance dialing - distinctive ring - dnis - dsl - dsp - dtmf - dtr - duplex - echo cancellation - edge - extension - fax - fcc - fdma - fidonet - follow-me - g.711 - g.723.1 - g.723 - g.726 - g.lite - gprs - gps - gsm - h.323 - harmonic - headphones - hscsd - hspda - iad - idsn - internet call waiting - isp - ivr - jack plug - local loop - long distance - microcontroller - mobile phone - modem - modulation - mu-law - music-on-hold - night service - off-hook - on-hook - pabx - pager - payphone - pbx - pcm - pots - prank call - precise tone plan - pstn - pulse dialling - push to talk - ring modulation - ring tone - ringback - ringing signal - rj11 - roaming - serial communications - serial port - signal noise - sim - simplex - sit - sms - softmodem - switchboard operator - tapi - tdma - telecommunications - telemarketing - telephone - telephone call - telephone card - telephone company - telephone exchange - telephone line - telephone number - telephone numbering plan - telephone operator - telephone switchboard - telephony - tts - twisted pair - umts - v.32 - v.32bis - v.34 - v.42bis - vbr - vertical service code - voicemail - voip - vox - wap - wav - wi-fi - wimax - wire