 All-digital method and apparatus for demodulating an analog signal |
| It is an object of the invention to provide a demodulator that is totally digital in structure, and ... |
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| Test circuit of multiplex equipment |
| An object of the present invention is to provide a test circuit for multiplex equipment to be used ... |
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| Echo canceller |
| OF THE EMBODIMENTS FIG. 1 is a block diagram illustrating an embodiment of an echo canceller of ... |
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| Listener echo cancellation |
| The listener echo cancellation means of the present invention employs a finite impulse response (FIR... |
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| Semiconductor integrated device |
| In the integrated service digital network, the training mode for getting the echo data is carried ... |
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| RF power amplifier linearization |
| OF THE PREFERRED EMBODIMENT Referring now to the drawing, schematically depicted in FIG. 1 is an ... |
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| Waste energy control and management in power amplifier |
| OF THE DRAWINGS These and other features and advantages of the invention will be readily apparent ... |
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| Facility for combining and amplifying two broadband signals |
| It is therefore an object of the invention to provide a facility which is suitable for combining ... |
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| Electronic musical instrument for conducting an arpeggio performance of a stringed instrument |
| In view of the foregoing, it is therefore an object of the present invention to provide an ... |
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Framer circuit for use in a DTDM network
| Details |
Inventors: Beckner, Mark W.; Chao, Hung-Hsiang J.; Robe, Thomas J.; Smoot, Lanny S.;
Assignee: Bell Communications Research, Inc. (Livingston, NJ)
Primary Examiner: Paschall; M. H.
Assistant Examiner:
Attorney, Agent or Firm: Falk; James W.
A framer circuit which may be implemented as a single chip is disclosed. The framer circuit performs a number of functions in a DTDM network including generating trains of empty DTDM frames, enabling the writing of data packets into specific DTDM frames and the examination of header data in specific DTDM frames to generate signals for the control of peripheral circuits. The framer circuit comprises an input serial/parallel converter, a frame detection circuit, an output parallel/serial converter and a control unit comprising one or more finite state machines for generating proper control signals such as read and write strobes for data insertion and extraction. |
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DETAILED DESCRIPTION The digital network transport system, referred to herein as Dynamic Time Division Multiplexing (DTDM), is a flexible network transport system capable of effectively handling both circuit and packet traffic.
By combining conventional time division multiplexing techniques and packet transmission techniques, DTDM enables a flexible transition from the existing circuit type networks to future broadband packet transmission networks.
In a network utilizing DTDM, each transmission bit stream is divided into frames.
These frames are the fundamental unit of data transport in DTDM.
Each such frame comprises two fixed length fields: overhead and payload.
The overhead field includes, for example, a frame alignment word for frame timing and the empty/full status of the frame.
The payload field of each frame may be filled with a data packet including header or a slot from a circuit transmission stream.
Before a slot from a circuit transmission stream can be inserted into the payload field of a DTDM frame, it must first be converted into a packet-like form with a header at its front.
Viewed another way, each occupied DTDM frame comprises a transmission overhead field, a header field, and a data field.
Thus, the DTDM transmission format is a combination of the circuit transmission format and the packet transmission format.
In the DTDM system, packet and circuit traffic can be multiplexed through the same multiplexer.
Thus, such a multiplexer can have continuous circuit type tributaries and bursty packet tributaries.
To multiplex such diverse traffic, a train of DTDM frames with empty payload fields is generated.
This train has a bit rate which defines a basic backbone transmission rate for the DTDM transmission system.
Data in the form of packets or circuit slots with headers attached are inserted into the empty frames to form the DTDM bit stream.
An appropriate analogy is as follows.
The stream of empty DTDM frames may be analogized to a train of empty freight cars.
The empty freight cars are then filled with data from the various tributaries which may have been in circuit or packet format
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Multiplexer-related 
