Circuit for generating RTS signal of a gray code
AssigneeNEC Corporation
InventorKurenai Murakami
Life of this patent
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Abstract
In an RTS generator used in an ATM network where a network reference clock is continuously counted to produce the lower four bits of a counted number, which are, in turn, latched in response to a latching pulse signal produced by frequency dividing a CBR clock by N=3008, the latched number providing the RTS, the lower four bits are formed on the base of the Gray code so as to avoid latching of abnormal number even in racing condition between the change of the counted number and a rising of the latching pulse.
Claims20
An RTS (Residual Time Stamp) generating circuit for use in an ATM (Asynchronous Transfer Mode) network to transfer to a user's signal using a network clock signal of a network clock frequency, the network clock signal being frequency-divided by a predetermined dividing value to form a network reference clock signal of a divided frequency as a network reference frequency, said user's signal having a user's clock signal having a user's clock frequency, which comprises:
- counter means for counting said network reference clock signal to produce a counted number on the base of the Gray code;
- dividing means responsive to said user's clock signal for frequency-dividing said user's clock frequency to produce a divided signal of a divided frequency as a latching pulse signal;
- and
- latching means coupled to said counter means and said dividing means and responsive to said latching signal for latching said counted number to produce a latched number of the Gray code, said latched number providing the RTS signal, wherein a racing condition is substantially prevented by said RTS generating circuit.
An RTS (Residual Time Stamp) generating circuit for use in an ATM (Asynchronous Transfer Mode) network for producing an RTS signal, said RTS generating circuit comprising:
- a first divider responsive to a network clock signal, wherein said first divider divides said frequency of said network clock signal by a first constant to produce a network reference clock signal;
- a Gray code counter, wherein said Gray code counter continuously receives said network reference clock signal and produces a Gray code number based thereon;
- a second divider, wherein said second divider frequency-divides a user signal by a second constant and produces a latching pulse signal at an output therefrom;
- and
- a latching circuit having first and second input terminals, wherein said Gray code counter and said second divider are respectively coupled to said first and second input terminals, wherein said latching circuit latches said Gray code number to produce a latched number of the Gray code.
A method for generating an RTS (Residual Time Stamp) signal for use in an ATM (Asynchronous Transfer Mode) which comprises the steps of:
- dividing a network clock signal to form a network reference clock signal;
- counting said network reference clock signal to produce a counted number based on the Gray code;
- dividing a user clock signal to produce a latching pulse signal;
- and
- latching said counted Gray code number based on said latching pulse signal to produce a latched Grey code number.
Dependencies are inferred from the claim text.