Pulse or digital communications – Transmitters
Reexamination Certificate
1997-11-26
2001-01-09
Vo, Don N. (Department: 2734)
Pulse or digital communications
Transmitters
C375S272000
Reexamination Certificate
active
06173017
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a transit modulator for jittering (adding jitter to) a signal, said modulator comprising a memory, a clock generator connected to said memory and generating a jitter free input clock as well as a further clock generator connected to said memory and generating a jittered output clock.
BACKGROUND OF THE INVENTION
A transit modulator of this type is for example disclosed in the service manual for the K4312 SDH/PDH analyser of Siemens AG (pages 5-5 and 9-36). In this prior art transit modulator, a memory as well as associated electronic components for storage and output is integrated in an ASIC (application specific IC) module. Using the prior art transit modulator, binary digital signals may be jittered.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a transit modulator which can be used to jitter any kind of signal.
This object is accomplished by a transit modulator according to the invention in which an A/D converter is pre-connected and a D/A converter is post-connected to said memory.
The advantage of the transit modulator according to the invention is that the presence of the A/D and D/A converters also allows the jittering of non-binary digital signals such as 2B1Q or 4B3T signals as well as analog signals.
The above-mentioned reference also discloses a method for jittering a signal in which binary values characterizing said signal are stored in a memory using a jitter free input clock and subsequently read out using a jittered output clock, and a jittered signal is generated from the binary output values.
For jittering any kind of signals, the invention suggests a method in which the signal is sampled to give samples, the binary values characterizing said signal are obtained from said samples by A/D conversion and the jittered signal is generated by D/A conversion of the binary values read out.
The advantage of the method according to the invention is that the A/D and D/A conversions allow the jittering not only of binary digital signals, but also of non-binary digital signals such as 2B1Q or 4B3T signals as well as analog signals.
REFERENCES:
patent: 5245341 (1993-09-01), Maeder
patent: 5252973 (1993-10-01), Masuda
patent: 5311180 (1994-05-01), Borgen
Robert C. Dixon, Spread Spectrum Systems with Commercial Applications, 1994, John Wiley & Sons, p. 436.
Marvin E. Frerking, Digital Processing in Communication Systems, 1994, Kluwer Academic Publishers, pp. 95, 96, 326, 342, and 346.*
Gray Francis I.
Lenihan Thomas F.
Tektronix Inc.
Vo Don N.
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