Method and apparatus for generating jitter test patterns on a high performance serial bus
First Claim
1. A method of performing a jitter test in a communications system, said communications system comprising a device under test operatively coupled to a second device, the method comprising:
- generating a test pattern, said test pattern comprising an asynchronous packet addressed to an unused node number;
transmitting said asynchronous packet to said device under test, the transmission causing the device under test to recover a clock by analyzing the timing of one or more data edges of the test pattern;
repeating said act of transmitting at least once; and
wherein an error rate due to jitter in said communications system is computed by regularly reading a port error register.
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Accused Products
Abstract
The present invention provides a method for generating random jitter test patterns by generating a sequence of maximum-size asynchronous packets according to the P1394b standard and transmitting the sequence to the device under test. The present invention provides a method for generating jitter test patterns by disabling the transmitter data scrambler of the second device; clearing the port_error register of the device under test; and sending a test pattern to said device under test. The present invention provides for a method for generating supply noise test patterns comprising: transmitting a test pattern to the DUT comprising a maximum length asynchronous packet containing alternate 0016 and FF16 bytes.
169 Citations
27 Claims
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1. A method of performing a jitter test in a communications system, said communications system comprising a device under test operatively coupled to a second device, the method comprising:
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generating a test pattern, said test pattern comprising an asynchronous packet addressed to an unused node number; transmitting said asynchronous packet to said device under test, the transmission causing the device under test to recover a clock by analyzing the timing of one or more data edges of the test pattern; repeating said act of transmitting at least once; and wherein an error rate due to jitter in said communications system is computed by regularly reading a port error register. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device for transmitting a jitter test pattern over a communications bus to a device under test, said device comprising:
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a processing apparatus; a port capable of transmitting said jitter test pattern over said communications bus when said port is operatively coupled to said device under test; a transmit scrambler operatively coupled to said port; and a computer readable medium comprising one or more computer executable instructions that, when executed by said processing apparatus; generate a first jitter test pattern, said first jitter test pattern comprising an asynchronous packet having a length which is equal to a maximum allowed value for said communications bus, and comprising a normal header, a checksum, and a packet payload of all zero values; scramble said first jitter test pattern using said transmit scrambler; transmit said asynchronous packet to said device under test; and repeat said act of transmitting at least once, ignoring a fairness protocol on the port. - View Dependent Claims (12, 13, 14, 15)
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16. A method of testing a device under test in a communications system, said device under test being in data communication with a second device, the method comprising:
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generating a test pattern, said test pattern comprising at least 42 null packets followed by a packet containing at least 50 bytes of consecutive D21.5 symbols; disabling a scrambler once synchronization is achieved between said device under test and said second device; transmitting said test pattern to said device under test; and analyzing said transmitted asynchronous packets to determine an effect of jitter in said communications system. - View Dependent Claims (17, 18, 19, 20, 21, 22, 26, 27)
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23. A device for transmitting a jitter test pattern over a communications bus to a device under test, said device comprising:
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an IEEE 1394b compliant system; a processing apparatus; a port capable of transmitting said jitter test pattern over said communications bus when said port is operatively coupled to said device under test, the transmission causing the device under test to recover a clock by analyzing the timing of one or more data edges of the test pattern; a transmit scrambler operatively coupled to said port; and a computer readable medium comprising one or more computer executable instructions that are configured to, when executed by said processing apparatus; generate a first jitter test pattern, said first jitter test pattern comprising a maximum length asynchronous packet; transmit said maximum length asynchronous packet to said device under test in a scrambled or form based on the operation of the scrambler; and repeat said act of transmitting at least once. - View Dependent Claims (24, 25)
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Specification