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- Robbed-bit_signaling abstract "In communication systems robbed-bit signaling is a scheme to provide maintenance and line signaling services on many T1 digital carrier circuits using channel-associated signaling (CAS).The T1 carrier circuit is a type of dedicated circuit currently employed in North America and Japan. The T1 circuit is divided into 24 channels, each carrying 8,000 samples per second, each 8 bits long. The Super Frame (SF) consist of 12 frames of 24 channels. The DS1 designation consist of 24 frames called, Extended Super Frame (ESF). In either designation, these channels are multiplexed together and sample at 8000 bit/s. In the DS0 designation, each of the channels induces eight bits into the multiplex output stream, ten are utilized entirely for voice/data and two are utilized partially for voice. Hence, each of the two partial channels yields 7 x 8000 bit/s = 56 kbit/s for voice data and the remaining channels yields 8 x 8000 bit/s = 64 kbit/s.Intuitively, 5 out of 6 frames have 8 bit resolution equal to 64 kbit/s (8 Bits x 8,000 Samples per Second = 64 kbit/s) and 1 out of every 6 frames has a 7 bit resolution (7 Bits x 8,000 Samples per Second = 56 kbit/s) The distortion effect on voice and data signals is negligible when a modem is used for modulation. However, for a 64 kbit/s digital signals the data will render errors when a data signal is transmitted. If such is the case the robbed-bit signaling should be turned off.The robbed-bit signal scheme is used in the super frame circuit (SF). It takes the least significant bit of every sixth channel and utilizes it to convey on or off hook, and busy signal status on telephone lines. The first bit of every six is called A bit, the second bit is called B bit.RBS was developed at the time that AT&T was moving from analog trunks onto digital equipment. This permitted AT&T to run 24 digital phone lines on the same number of wires that 2 analog phone lines would have taken, saving money and improving call quality, without the high cost of frequency-division multiplexing.As in other carrier systems, the physical properties of an actual trunk wire are missing. With analog trunks, to signal the equipment at the far end that a trunk was going to be used, equipment would \"loop\" the line by connecting the wires together at one end or ground start one of the wires (depending on the type of trunk), and do the opposite to return the trunk to idle. With a digital trunk, another method was needed to signal between ends.To do this, signaling equipment \"steals\" the eighth bit of each channel on every sixth frame (see Super Frame and Extended Super Frame) and replaces it with signaling information. This means that the low-order bit on every sixth sample in every DS0 carried on the T1, in either direction, is replaced by signaling information. Simple PCM-encoded voice is not very sensitive to losing these data in a few of its lower-order bits, so it doesn't cause much degradation of voice quality; however, when carrying data, the difference is significant, reducing the available usable data rate by 12.5%. With full 64 kbit/s, a voice channel has a signal-to-noise ratio of 37 decibels (dB). At 56 kbit/s, a voice channel has a signal to noise ratio of 31 dB. As only every sixth least-significant bit is robbed, the signal to noise ratio will be somewhere between 31 and 37 dB. However, since individual T1 links are not in general synchronized to one another, a DS0 passing along several concatenated, unsynchronized, T1 spans may have its lower bit stolen in more than one frame, frequently making real-world performance closer to the lower-bound than the upper bound of signal-to-noise performance.Robbed-bit signaling can have an effect on audio quality under certain circumstances. When a voice call is connected to a quiet termination, as can happen when on hold in a PBX which does not have music on hold or comfort noise enabled, and certain types of framing circuits are used, the noise due to robbed-bit signaling can be heard in the handset as a faint 1333 Hz tone, this frequency being a result of low-bit corruption at a rate of 8000 Hz / 6 = 1333 Hz. This is normally not a very noticeable problem, but if the audio path contains in-line speech compression, such as G.729, the tone can be amplified and modulated by the compression algorithm to the point of annoyance to the user.With Super Frame framing, the robbed bits are named A and B. With Extended Super Frame, the same stream is divided into four bits, named A, B, C, and D. The meanings of these bits depend on what type of signaling is provisioned on the channel. The most common types of signaling are loop start, ground start, and E&M.Unlike T1 systems, most telephone systems in the world use E1 systems that transparently pass all 8 bits of every sample. Those systems use a separate out-of-band channel to carry the signaling information.".
- Robbed-bit_signaling wikiPageID "962020".
- Robbed-bit_signaling wikiPageLength "5899".
- Robbed-bit_signaling wikiPageOutDegree "25".
- Robbed-bit_signaling wikiPageRevisionID "683418597".
- Robbed-bit_signaling wikiPageWikiLink AT&T_Corporation.
- Robbed-bit_signaling wikiPageWikiLink Analog_signal.
- Robbed-bit_signaling wikiPageWikiLink Carrier_system.
- Robbed-bit_signaling wikiPageWikiLink Category:Telephony_signals.
- Robbed-bit_signaling wikiPageWikiLink Channel-associated_signaling.
- Robbed-bit_signaling wikiPageWikiLink Comfort_noise.
- Robbed-bit_signaling wikiPageWikiLink Decibel.
- Robbed-bit_signaling wikiPageWikiLink Digital_Signal_0.
- Robbed-bit_signaling wikiPageWikiLink Digital_Signal_1.
- Robbed-bit_signaling wikiPageWikiLink Digital_signal.
- Robbed-bit_signaling wikiPageWikiLink E-carrier.
- Robbed-bit_signaling wikiPageWikiLink E_and_M_signaling.
- Robbed-bit_signaling wikiPageWikiLink Extended_superframe.
- Robbed-bit_signaling wikiPageWikiLink Frequency-division_multiplexing.
- Robbed-bit_signaling wikiPageWikiLink G.729.
- Robbed-bit_signaling wikiPageWikiLink Ground_start.
- Robbed-bit_signaling wikiPageWikiLink Line_signaling.
- Robbed-bit_signaling wikiPageWikiLink Loop_start.
- Robbed-bit_signaling wikiPageWikiLink Music_on_hold.
- Robbed-bit_signaling wikiPageWikiLink Out-of-band_data.
- Robbed-bit_signaling wikiPageWikiLink Signal-to-noise_ratio.
- Robbed-bit_signaling wikiPageWikiLink Speech_coding.
- Robbed-bit_signaling wikiPageWikiLink Superframe.
- Robbed-bit_signaling wikiPageWikiLinkText "A- and B-bit signaling".
- Robbed-bit_signaling wikiPageWikiLinkText "RBS".
- Robbed-bit_signaling wikiPageWikiLinkText "Robbed-bit signaling".
- Robbed-bit_signaling wikiPageWikiLinkText "robbed bit".
- Robbed-bit_signaling wikiPageWikiLinkText "robbed bits for signaling".
- Robbed-bit_signaling wikiPageWikiLinkText "robbed bits".
- Robbed-bit_signaling wikiPageWikiLinkText "robbed-bit signaling".
- Robbed-bit_signaling date "February 2013".
- Robbed-bit_signaling reason "needs more structure in article".
- Robbed-bit_signaling wikiPageUsesTemplate Template:Cleanup.
- Robbed-bit_signaling wikiPageUsesTemplate Template:Reflist.
- Robbed-bit_signaling wikiPageUsesTemplate Template:Which.
- Robbed-bit_signaling subject Category:Telephony_signals.
- Robbed-bit_signaling hypernym Scheme.
- Robbed-bit_signaling type Organisation.
- Robbed-bit_signaling type Page.
- Robbed-bit_signaling comment "In communication systems robbed-bit signaling is a scheme to provide maintenance and line signaling services on many T1 digital carrier circuits using channel-associated signaling (CAS).The T1 carrier circuit is a type of dedicated circuit currently employed in North America and Japan. The T1 circuit is divided into 24 channels, each carrying 8,000 samples per second, each 8 bits long. The Super Frame (SF) consist of 12 frames of 24 channels.".
- Robbed-bit_signaling label "Robbed-bit signaling".
- Robbed-bit_signaling sameAs Q7340806.
- Robbed-bit_signaling sameAs m.03tps_.
- Robbed-bit_signaling sameAs Q7340806.
- Robbed-bit_signaling wasDerivedFrom Robbed-bit_signaling?oldid=683418597.
- Robbed-bit_signaling isPrimaryTopicOf Robbed-bit_signaling.