Redundant word frame synchronization circuit
First Claim
1. A frame synchronization arrangement for use in a data communication system, said communication system arranged to transit data words in a frame format including first and second identical data words having a first bit separation therebetween, said first data word having a second bit separation from a data frame boundaryCHARACTERIZED IN THATsaid frame synchronization arrangement comprises:
- means for serially storing a number of successive data words including the data word immediately following said data frame boundary and said first and second identical data words for a preselected time and then serially outputting all of said stored data words except said second identical data word; and
means for comparing data words in said storing means having both said first bit separation therebetween and said second bit separation to said data frame boundary and generating a valid comparison signal therefrom when the compared data words are the same, which valid comparison signal enables the serial outputting of data words from said storing means and is synchronous with the outputted data word immediately following said data frame boundary.
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Abstract
A frame synchronization arrangement is disclosed for use in a digital data transmission system which utilizes a redundant data word transmission. A selected data word of each frame of data having a fixed location relative to the frame boundary is transmitted twice to provide a framing signal for the receiver circuit. At the receiver circuit the data is shifted through a shift register where a comparator checks predetermined locations of the shift register for redundant data words in the received data stream. Once the redundant data words are detected a valid word received signal is generated. The existence of the valid word received signal together with the known relationship between the location of the redundant word and the frame boundary is used to provide a framing signal.
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Citations
8 Claims
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1. A frame synchronization arrangement for use in a data communication system, said communication system arranged to transit data words in a frame format including first and second identical data words having a first bit separation therebetween, said first data word having a second bit separation from a data frame boundary
CHARACTERIZED IN THAT said frame synchronization arrangement comprises: -
means for serially storing a number of successive data words including the data word immediately following said data frame boundary and said first and second identical data words for a preselected time and then serially outputting all of said stored data words except said second identical data word; and means for comparing data words in said storing means having both said first bit separation therebetween and said second bit separation to said data frame boundary and generating a valid comparison signal therefrom when the compared data words are the same, which valid comparison signal enables the serial outputting of data words from said storing means and is synchronous with the outputted data word immediately following said data frame boundary. - View Dependent Claims (2, 3, 4)
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5. A frame synchronization arrangement of a data communication system which communicates data words in a frame format, said communication system including a transmitter circuit and a receiver circuit, said transmitter circuit comprising:
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means for transmitting data words in a frame format including first and second identical data words having a first bit separation therebetween, said first data word having a second bit separation from a data frame boundary CHARACTERIZED IN THAT said receiver circuit of said communication system comprises a frame synchronization arrangement including means for serially storing a number of successive data words including the data word immediately following said data frame boundary and said first and second identical data words for a preselected time and then serially outputting all of said stored data words except said second identical data word; and means for comparing data words in said storing means having both said first bit separation therebetween and said second bit separation from said data frame boundary and generating a valid comparison signal therefrom when the compared data words are the same, which valid comparison signal enables the serial outputting of data words from said storing means and is synchronous with the outputted stored data word immediately following said data frame boundary. - View Dependent Claims (6)
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7. A method of detecting frame synchronization in a data communication system arranged to transmit data words in a frame format including first and second identical data words having a first bit separation therebetween, said first data word having a second bit separation from a data frame boundary, the method comprising the steps of:
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(a) serially storing a number of successive data words including the data word immediately following said data frame boundary and said first and second identical data words for a preselected time and then serially outputting all of said stored data words except said second identical data word; and (b) comparing stored data words having both said first bit separation therebetween and said second bit separation from said data frame boundary and generating a valid comparison signal therefrom when the compared data words are the same, which valid comparison signal enables the serial outputting of data words from said storing means and is synchronous with the outputted stored data word immediately following said data frame boundary.
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8. A method of providing frame synchronization for a digital communication system arranged to transmit data words in a frame format the method comprising the steps of:
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(a) generating first and second identical data words having a first bit separation therebetween, said first data word having a second bit separation from a data frame boundary; (b) serially storing a number of successive data words including the data word immediately following said data frame boundary and said first and second identical data words for a preselected time and then serially outputting all of said stored data words except said second identical data word; and (c) comparing stored data words having both said first bit separation therebetween and said second bit separation from said data frame boundary and generating a valid comparison signal therefrom when the compared data words are the same, which valid comparison signal enables the serial outputting of data words from said storing means and is synchronous with the outputted stored data word immediately following said data frame boundary.
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Specification