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A DS level and framing specification for synchronous digital streams, over circuits in the North American digital transmission hierarchy, at the T1 transmission rate of 1,544,000 bits per second (baud).

DS1 is commonly used to multiplex 24 DS0 channels. Each DS0 channel, originally a digitised voice-grade telephone signal, carries 8000 bytes per second (64,000 bits per second). A DS1 frame includes one byte from each of the 24 DS0 channels and adds one framing bit, making a total of 193 bits per frame at 8000 frames per second. The result is 193*8000 = 1,544,000 bits per second.

In the original standard, the successive framing bits continuously repeated the 12-bit sequence 110111001000, and such a 12-frame unit is called a super-frame. In voice telephony, errors are acceptable (early standards allowed as much as one frame in six to be missing entirely), so the least significant bit in two of the 24 streams was used for signaling between network equipments. This is called robbed-bit signaling.

To promote error-free transmission, an alternative called the extended super-frame (ESF) of 24 frames was developed. In this standard, six of the 24 framing bits provide a six bit cyclic redundancy check (CRC-6), and six provide the actual framing. The other 12 form a virtual circuit of 4000 bits per second for use by the transmission equipment, for call progress signals such as busy, idle and ringing. DS1 signals using ESF equipment are nearly error-free, because the CRC detects errors and allows automatic re-routing of connections.

Compare T-carrier systems.

[Kenneth Sherman, "Data Communications : a user's guide", third edition (1990), Reston/Prentice-Hall/Simon & Schuster].


(1) See Nintendo DS.

(2) (Digital Signal) A classification of digital circuits. The DS technically refers to the rate and format of the signal, while the T designation refers to the equipment providing the signals. In practice, "DS" and "T" are used synonymously; for example, DS1 and T1, DS3 and T3. See OC.

NORTH AMERICA, JAPAN, KOREA, ETC.VoiceService  Channels     Speed

 DS0         1          64 Kbps
 DS1        24       1.544 Mbps  (T1)
 DS1C       48       3.152 Mbps  (T1C)
 DS2        96       6.312 Mbps  (T2)
 DS3       672      44.736 Mbps  (T3)
 DS4      4032     274.176 Mbps  (T4)

 EUROPE (ITU)Voice        SpeedService  Channels    (Mbps)

 E1         30         2.048
 E2        120         8.448
 E3        480        34.368
 E4       1920       139.264
 E5       7680       565.148

 SONET CIRCUITSOptical  Electrical    SpeedChannel  Channel      (Mbps)

 OC-1      STS-1        51.84
 OC-3      STS-3       155.52
 OC-3c     STS-3c      155.52
 OC-12     STS-12      622.08
 OC-12c    STS-12c     622.08
 OC-48     STS-48     2488.32
 OC-192    STS-192    9953.28
 OC-768    STS-768   39813.12

 OC  = Optical Carrier
 STS = Synchronous Transport Signal
   c = concatenated
References in periodicals archive ?
Atlikus Uarmines korozijos bandymus, nustatyta, kad bandiniu (DS1 ir DS11) santykinis pailgejimas nevirUijo rekomenduojamu reikUmiu ir yra atsparus Uarmines korozijos poveikiui.
Specifically, we randomly sample 150 images of each terrain category from DS1 and record the total encoding time, while, due to the demand of online-training for visual terrain classification applications [60, 61], the training time is also taken into account and illustrated in Figure 7.
The detailed maturity history of Devonian carbonate reservoirs in well DS1 is modeled (Figure 9(a)).
Damage state Total length of the cut [mm] DS0 0 DS1 200 DS2 400 DS3 600 DS4 800 DS5 1000 TABLE 2: Modal frequencies (Hz) at different DS and their variation relative to DS0.
For DS1 and DS2, the fitted results of the K distribution shape parameters in the three channels are shown in Figure 5, where the thermal noise is ignored.
We tabulated the aforementioned evaluation results of our PDE model, G-O model, and white-noise model for DS1, DS2, DS3, and DS4 in Table 3.
Contrary to females, we did not find significant correlations between the duration of male employment at a given institution and the scores of the Desired Changes (DC) Scale and mental well-being (WB2) subscale, and observed significant associations between the duration of male employment and the scores of the Control Scale (SC) and intellectual demands (DS1) subscale.
"We are now focusing our investigation on a metallic blue Citroen -- possibly a DS1 -- seen driving up Nickson Road and onto Bullfield Avenue, towards Gravel Hill, at around 11.30pm with two people in it.
The dataset DS1 contains 11 activity classes, with some of the classes involving actives that are structurally homogeneous and with others involving actives that are structurally heterogeneous (i.e., structurally diverse).
Due to that, the VDSL2 line over ADSL2+ would be able to use only a part of its DS1 frequency band from 2.208 MHz and the rest of US1, DS2, US2 and DS3 channels.