Jitter measurement apparatus, jitter measurement method, and recording medium
A jitter measurement apparatus measures a jitter of a data signal having a substantially constant data rate. The jitter measurement apparatus includes therein a signal converting section that generates a clock signal based on the data signal, where the clock signal retains timings of data transition edges of the data signal at which a data value of the data signal transits and has edges whose cycle is substantially equal to the data rate, an analytic signal generating section that generates an analytic signal represented by a complex number based on the clock signal, and a jitter measuring section that measures the jitter of the data signal based on the analytic signal.
1. A jitter measurement apparatus for measuring a jitter of a data signal having a substantially constant data rate, the jitter measurement apparatus comprising:
a signal converting section that generates a clock signal based on the data signal, the clock signal retaining timings of data transition edges of the data signal at which a data value of the data signal transits and having edges whose cycle is substantially equal to the data rate;
an analytic signal generating section that generates an analytic signal represented by a complex number from the clock signal; and
a jitter measuring section that measures the jitter of the data signal based on the analytic signal.
2. The jitter measurement apparatus as set forth in claim 1 , wherein
the signal converting section is constructed and arranged such that when an interval between the data transition edges of the data signal is larger than a predetermined value determined in accordance with the data rate, the signal converting section generates the clock signal having therein one or more virtual edges provided in accordance with the timings of the data transition edges for interpolating the data transition edges.
3. The jitter measurement apparatus as set forth in claim 2 , wherein
the signal converting section generates the clock signal having therein the virtual edges provided at a substantially constant interval determined in accordance with the data rate in the interval between the data transition edges whose interval is larger than the predetermined value.
4. The jitter measurement apparatus as set forth in claim 1 , further comprising
an AD converter that inputs a digitized signal generated by digitizing a level of the data signal at a predetermined sampling rate into the signal converting section.
5. The jitter measurement apparatus as set forth in claim 2 , wherein the signal converting section includes:
a virtual edge calculating section that calculates timings of the virtual edges; and
a virtual edge generating section that generates the virtual edges in accordance with the timings of the virtual edges, by inverting the data value of the data signal with respect to a substantially 50% level of the data signal.
6. The jitter measurement apparatus as set forth in claim 1 , wherein the jitter measuring section includes:
an instantaneous phase calculating section that calculates instantaneous phases of the clock signal based on the analytic signal;
a phase noise calculating section that calculates an instantaneous phase noise of the clock signal by removing a linear component from the instantaneous phases of the clock signal; and
a jitter calculating section that calculates the jitter of the data signal based on the instantaneous phase noise of the clock signal.
7. The jitter measurement apparatus as set forth in claim 6 , wherein the jitter calculating section calculates the jitter of the data signal based on the instantaneous phase noise of the clock signal which corresponds to the timings of the data transition edges of the data signal.
8. A jitter measurement apparatus for measuring a jitter of a data signal having a substantially constant data rate, the jitter measurement apparatus comprising:
a signal convening section that generates a clock signal based on the data signal, the clock signal retaining timings of data transition edges of the data signal at which a data value of the data signal transits and having edges whose cycle is substantially equal to the data rate;
a Fourier transforming section that transforms the clock signal into a frequency-domain spectrum; and
a jitter measuring section that measures the jitter of the data signal based on a ratio of a signal component to noise components of the clock signal in the frequency domain spectrum.
9. A jitter measurement method for measuring a jitter of a data signal having a substantially constant data rate, the jitter measurement method comprising:
receiving the data signal from an electronic device;
generating a clock signal based on the data signal, the clock signal retaining timings of data transition edges of the data signal at which a data value of the data signal transits and having edges whose cycle is substantially equal to the data rate;
generating, based on the clock signal, an analytic signal represented by a complex number; and
measuring the jitter of the data signal based on the analytic signal.
10. A jitter measurement method for measuring a jitter of a data signal having a substantially constant data rate, the jitter measurement method comprising:
receiving the data signal from an electronic device;
generating, based on the data signal, a clock signal, the clock signal maintaining timings of data transition edges of the data signal at which a data value of the data signal transits and having edges whose cycle is substantially equal to the data rate;
transforming the clock signal into a frequency-domain spectrum; and
measuring the jitter of the data signal based on a ratio of a signal component to a noise component of the clock signal in the frequency domain spectrum.
11. A tangible article of manufacture including a computer-readable medium storing thereon program code that if executed by a computing device causes the computing device to function as a jitter measurement apparatus for measuring a jitter of a data signal having a substantially constant data rate, the program causing the computer to function as:
a signal convening section that generates a clock signal based on the data signal, the clock signal retaining timings of data transition edges of the data signal at which a data value of the data signal transits and having edges whose cycle is substantially equal to the data rate;
an analytic signal generating section that generates an analytic signal represented by a complex number from the clock signal; and
a jitter measuring section that measures the jitter of the data signal based on the analytic signal.
12. A tangible article of manufacture including a computer-readable medium storing thereon program code that if executed by a computing device causes the computing device to function as a jitter measurement apparatus for measuring a jitter of a data signal having a substantially constant data rate, the program causing the computing device to function as:
a signal converting section that generates a clock signal based on the data signal the data signal into a clock signal, the clock signal retaining timings of data transition edges of the data signal at which a data value of the data signal transits and having edges whose cycle is substantially equal to the data rate;
a Fourier transforming section that transforms the clock signal into a frequency-domain spectrum; and
a jitter measuring section that measures the jitter of the data signal based on a ratio of a signal component to noise components of the clock signal in the frequency domain spectrum.