Method for creating accurate time-stamped frames sent between computers via a network
First Claim
1. A method for creating accurate time-stamped frames sent between computers via a network, comprising the steps of:
- receiving a universal coordinated time reference signal;
synchronizing clocks electronically connected to universal coordinated time reference signal receivers and associated with sending and receiving computers, but operating independently of operating system clocks of the sending or receiving computers, with the universal coordinated time reference signal by initializing the clocks with the received universal coordinated time reference signal;
using the clocks to create sub-microsecond time values corresponding to a fractionalized universal coordinated time reference signal;
over time, adjusting the clock into synchronization with the universal coordinated time reference signal;
creating a test frame including a tag having reserved fields for transmit and receive time stamps representing the universal coordinated time reference signal and the sub-microsecond time values;
inserting a transmit time stamp into the reserved transmit time stamp field corresponding to the time on the synchronized clock of the sending computer at the instant the test frame is sent onto the network without intervention of the sending computer'"'"'s central processing unit; and
receiving the test frame having the transmit time stamp and inserting a receive time stamp into the reserved receive time stamp field corresponding to the time on the synchronized clock of the receiving computer when the test frame was received by the receiving computer.
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Accused Products
Abstract
A method for creating time-stamped frames sent between computers includes receiving and generating a universal coordinated time reference signal using a global positioning system. Clocks independent of operating systems of the sending and receiving computer are synchronized with the reference signal. A test frame is created including a tag having reserved fields for transmit and receive time stamps. The transmit time stamp is inserted into the reserved transmit time stamp field, without intervention of the sending computers central processing unit, that corresponds to the time on the synchronized clock at the instant the test frame is sent. The test frame having the transmit time stamp is received by the receiving computer, and a receive time stamp is inserted into the reserved receive time stamp field corresponding to the time on the synchronized clock of the receiving computer when the test frame was received.
61 Citations
28 Claims
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1. A method for creating accurate time-stamped frames sent between computers via a network, comprising the steps of:
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receiving a universal coordinated time reference signal; synchronizing clocks electronically connected to universal coordinated time reference signal receivers and associated with sending and receiving computers, but operating independently of operating system clocks of the sending or receiving computers, with the universal coordinated time reference signal by initializing the clocks with the received universal coordinated time reference signal; using the clocks to create sub-microsecond time values corresponding to a fractionalized universal coordinated time reference signal; over time, adjusting the clock into synchronization with the universal coordinated time reference signal; creating a test frame including a tag having reserved fields for transmit and receive time stamps representing the universal coordinated time reference signal and the sub-microsecond time values; inserting a transmit time stamp into the reserved transmit time stamp field corresponding to the time on the synchronized clock of the sending computer at the instant the test frame is sent onto the network without intervention of the sending computer'"'"'s central processing unit; and receiving the test frame having the transmit time stamp and inserting a receive time stamp into the reserved receive time stamp field corresponding to the time on the synchronized clock of the receiving computer when the test frame was received by the receiving computer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 14, 15, 16, 19, 20, 21, 22)
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10. A method for creating accurate time-stamped frames sent between computers via a network, comprising the steps of:
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using a global positioning receiver in communication with sending and receiving computers to generate a universal coordinated time reference signal; synchronizing clocks associated with the sending and receiving computers, but operating independently of operating system clocks of the sending or receiving computers, with the universal coordinated time reference signal by initializing the clocks with the received universal coordinated time reference signal and over time tracking and averaging the periodically received universal coordinated time reference signal and adjusting the clock to correspond to the universal coordinated time reference signal by altering the voltage applied to a voltage controlled crystal oscillator associated with the clock; creating a test frame including a tag having reserved fields for transmit and receive time stamps; creating complimentary time information in the reserved transmit and receive time stamp fields; replacing the complimentary time information in the transmit time stamp field with a transmit time stamp corresponding to the time on the synchronized clock of the sending computer at the instant the test frame is sent onto the network without intervention of the sending computer'"'"'s central processing unit; and automatically attaching a receive time stamp corresponding to the time on the synchronized clock of the receiving computer when the frame was received by the receiving computer to every frame received by the receiving computer. - View Dependent Claims (11, 12, 13)
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17. A method for creating accurate time-stamped frames to be sent between computers via a network, comprising the steps of:
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receiving a universal coordinated time reference signal; creating sub-microsecond time values corresponding to a fractionalized universal coordinated time reference signal using a clock operating independently of a computer clock and in direct electronic communication with a universal coordinated time reference signal receiver, wherein the universal coordinated time reference signal and the sub-microsecond time values together represent an absolute time; over time, comparing the received universal coordinated time reference signal and the created sub-microsecond time values and adjusting the clock into synchronization with the universal coordinated time reference signal; creating a test frame including a tag having reserved fields for transmit and receive time stamps representing the absolute time; and inserting a transmit time stamp into the reserved transmit time stamp field corresponding to the absolute time the test frame is sent onto the network, without intervention of the computer'"'"'s central processing unit. - View Dependent Claims (18, 23, 24, 25, 26, 27, 28)
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Specification