Abstract: A data conversion system acquires samples of low frequency signal components of an applied analog signal at a first data conversion rate and samples of high frequency signal components of the applied analog signal at a second data conversion rate that is higher than the first data conversion rate. The data conversion system applies a first correction filter to the acquired samples of the low frequency signal components to provide a first filtered signal and applies a second correction filter to the acquired samples of the high frequency signal components to provide a second filtered signal. The data conversion system interpolates the first filtered signal to provide an interpolated signal, and sums the interpolated signal with the second filtered signal to provide an output signal.

Abstract: A method for calibrating an I Q demodulator includes measuring I, Q, and low frequency data, correcting each set of measured data, combining the corrected I and Q data, interpolating the corrected low frequency data, and combining the corrected low frequency data and the combined corrected I and Q data.

Abstract: A low frequency cross-over network is added to a DC coupled IQ demodulator. The low frequency data can be captured in a very accurate, low cost, low bandwidth DC coupled path with ˜40 MHz of bandwidth. The remaining bandwidth (up to 20 or more GHz) can be captured with the IQ demodulator feeding the high speed ADCs.

Abstract: A data conversion system acquires samples of low frequency signal components of an applied analog signal at a first data conversion rate and samples of high frequency signal components of the applied analog signal at a second data conversion rate that is higher than the first data conversion rate. The data conversion system applies a first correction filter to the acquired samples of the low frequency signal components to provide a first filtered signal and applies a second correction filter to the acquired samples of the high frequency signal components to provide a second filtered signal. The data conversion system interpolates the first filtered signal to provide an interpolated signal, and sums the interpolated signal with the second filtered signal to provide an output signal.

Abstract: A digital-to-analog converting system for producing an interleaved analog signal with enhanced bandwidth includes a first digital-to-analog converter for receiving a first digital data stream and converting the first digital data stream to a first analog signal and a second digital-to-analog converter for receiving a second digital data stream and converting the second digital data stream to a second analog signal. The digital-to-analog converting system is clocked by a clock signal having a clock period, and further includes first timing circuitry for receiving the first analog signal and outputting the first analog signal for a first half of the clock period and second timing circuitry for receiving the second analog signal and outputting the second analog signal for a second half of the clock period to produce the interleaved analog signal.

Abstract: A method and system characterize a random component of the jitter by designating an edge in the repetitive pattern, determining a slope of the designated edge, and acquiring a set of amplitude values at a different occurrences of the designated edge. A frequency domain representation of the set of amplitude values is then obtained, and identified peaks in the frequency domain representation are truncated. An RMS value, or other measure of random variations of the truncated representation is extracted and converted, based on the slope of the designated edge, to a corresponding RMS time jitter that represents the random component of the jitter. A periodic component of the jitter is characterized by determining the peak amplitude deviation of the acquired set of amplitude values, and then determining a periodic amplitude variation based on the RMS value, the peak amplitude deviation and the number of amplitude values in the set of amplitude values.

Abstract: Mask compliance of a digital signal from a reference device is determined. Bit error rates for first sampling points for a low mask region are detected. The bit error rates for the first sampling points are averaged to produce an average low mask region error rate. Bit error rates for second sampling points for a high mask region are detected. The bit error rates for the second sampling points are averaged to produce an average high mask region error rate.

Abstract: An optical sampling method and apparatus use a probe pulse source of a predetermined optical wavelength range, e.g., 1560 nm, to sample incoming optical pulses in approximately the same wavelength range. The probe pulse source is frequency-doubled e.g., using a frequency doubler such as a nonlinear PPLN crystal, to obtain an intermediate second harmonic which may be filtered with a 780 nm bandpass filter to eliminate at least source frequency noise background. The filtered intermediate second harmonic is then mixed with the user input signal using an optional polarizing beam splitter and a dichroic beam splitter. The mixed signal is sent to a sum frequency generating (SFG) nonlinear crystal, e.g., a PPLN crystal, where the resulting frequency is near the third harmonic. The output from the SFG PPLN crystal may be filtered using a bandpass 515 nm filter to remove unwanted wavelengths and processed to measure/sense the near third harmonic content using a photomultiplier tube (PMT).

Abstract: A method and system characterize a random component of the jitter by designating an edge in the repetitive pattern, determining a slope of the designated edge, and acquiring a set of amplitude values at a different occurrences of the designated edge. A frequency domain representation of the set of amplitude values is then obtained, and identified peaks in the frequency domain representation are truncated. An RMS value, or other measure of random variations of the truncated representation is extracted and converted, based on the slope of the designated edge, to a corresponding RMS time jitter that represents the random component of the jitter. A periodic component of the jitter is characterized by determining the peak amplitude deviation of the acquired set of amplitude values, and then determining a periodic amplitude variation based on the RMS value, the peak amplitude deviation and the number of amplitude values in the set of amplitude values.

Abstract: Testing and analysis is performed on an incoming data stream. The incoming data is sampled at a reference voltage threshold and a reference location in a data cycle so as to produce a reference data signal. The incoming data is also sampled so as to produce a data signal. At least one of a voltage threshold and a location in the data cycle for sampling are respectively varied from the reference voltage threshold and the reference location in the data cycle for the sampling to produce the data signal. The reference data signal is compared to the data signal in order to detect bit errors in the data signal. Additional analysis is performed using the reference data signal.

Abstract: Mask compliance of a digital signal from a reference device is determined. Bit error rates for first sampling points for a low mask region are detected. The bit error rates for the first sampling points are averaged to produce an average low mask region error rate. Bit error rates for second sampling points for a high mask region are detected. The bit error rates for the second sampling points are averaged to produce an average high mask region error rate.

Abstract: A nonlinear crystal has increased spectral acceptance. The nonlinear crystal includes a plurality of domains. The domains are arranged serially across the nonlinear crystal. The domains have alternating polarity. The poling periods of the domains are varied across the nonlinear crystal so as to provide nonuniform chirping of phase matching of focused optical signals propagated through the nonlinear crystal.

Abstract: A method and apparatus for characterizing frequency response of a device under test (DUT) is disclosed. A repeated base bit pattern is received, the base bit pattern including a first transition from a 0-bit to a 1-bit. Then, using bit error rate distribution, multivalue voltage along the first transition is determined. Finally, the multivalued voltages are converted into frequency domain using fast Fourier transform. The apparatus includes a processor and storage with instructions for the processor to perform these operations. Using the present inventive technique, the frequency response of the DUT can be determined using an error performance analyzer such as a BERT.

Abstract: A method and apparatus for displaying a waveform on an error performance analyzer are disclosed. A repeated base bit pattern is received. Then, at a first time and for each incremental time thereafter for a predetermined period of time, multivalued voltage, VM, is determined. The VM is determined by constructing a bit error rate (BER) curve at the each incremental time. Each BER-curve spans a range of voltages from a low slice voltage to a high slice voltage. A derivative of the BER-curve is taken and absolute value of the derivative is used to determine the VM which is the slice voltage where the absolute value of the derivative curve is greatest. The apparatus includes a processor and storage with instructions for the processor to perform these operations.

Abstract: A timebase establishes the timing of samples acquired by a signal sampler relative to a trigger signal that is synchronous with an input signal applied to the signal sampler. The synchronous trigger activates a first pair of samplers included in the timebase to acquire samples of a reference signal and of a shifted version of the reference signal provided within the timebase. A divider receives the reference signal and divides the frequency of the reference signal by a predesignated divisor, and a third sampler included in the timebase acquires samples of this divided reference signal, also according to the synchronous trigger. The samples of the input signal are acquired by the signal sampler according to the divided reference signal. A timing analyzer determines the timing of these acquired samples of the input signal relative to the synchronous trigger, based on the acquired samples of the reference signal, the shifted reference signal and the divided reference signal.

Abstract: Reduction of polarization dependence in optical systems. Polarization dependence is reduced by splitting an input signal into two halves spatially using a split-plate which bisects the optical beam. One half of the split-plate is a waveplate with a retardance of approximately ½ wave which rotates the signal 45 degrees with respect to the polarization axis. The other half of the split-plate is a delay plate which does not rotate the polarization state. Since half the beam is rotated orthogonal to the other half, the average of maximum and minimum polarization state signals will be observed.

Abstract: A timebase establishes the timing of samples acquired by a signal sampler relative to a trigger signal that is synchronous with an input signal applied to the signal sampler. The synchronous trigger activates a first pair of samplers included in the timebase to acquire samples of a reference signal and of a shifted version of the reference signal provided within the timebase. A divider receives the reference signal and divides the frequency of the reference signal by a predesignated divisor, and a third sampler included in the timebase acquires samples of this divided reference signal, also according to the synchronous trigger. The samples of the input signal are acquired by the signal sampler according to the divided reference signal. A timing analyzer determines the timing of these acquired samples of the input signal relative to the synchronous trigger, based on the acquired samples of the reference signal, the shifted reference signal and the divided reference signal.

Abstract: A method and apparatus for displaying an eye diagram on an error performance analyzer are disclosed. A first bit sequence is received and compared with a second bit sequence, the first bit sequence and the second bit sequence being substantially similar. For each delay increment for an entire clock period a bit error rate (BER) curve is constructed. The BER curve is then used to locate the bit voltage or bit voltage spread for the 0-bit and the 1-bit for a particular delay. This is repeated a predetermined number of times to cover an entire period. Then, the bit voltages or bit voltage spreads are displayed as an eye diagram.

Abstract: A timebase establishes the timing of samples acquired by a signal sampler relative to a trigger signal that is synchronous with a signal applied to the signal sampler. A first pair of samplers included in the timebase acquires samples of a reference signal and of a shifted version of the reference signal provided within the timebase, according to a synchronous trigger, to establish a first time position on the reference signal. A second pair of samplers included in the timebase acquires samples of the reference signal and the shifted reference signal according to the synchronous trigger as delayed by a programmed time interval, to establish a second time position on the reference signal. While the programmed time interval is adjusted to designate timing of the sample acquisitions by the signal sampler, the two pairs of samplers in conjunction with a timing analyzer accurately determine the timing of these sample acquisitions based on the established time positions on the reference signal.

Abstract: A nonlinear crystal has increased spectral acceptance. The nonlinear crystal includes a plurality of domains. The domains are arranged serially across the nonlinear crystal. The domains have alternating polarity. The poling periods of the domains are varied across the nonlinear crystal so as to provide nonuniform chirping of phase matching of focused optical signals propagated through the nonlinear crystal.