NK732

Frequency Counter
Time Interval Analyzer

The NK732 is a high performance time and frequency measurement instrument. Its high resolution and throughput, combined with continuous measurement capability, allow you to make measurements that are not possible with traditional time-interval counters. For example, it can timetag events (edges of an input pulse train) at a rate of 20 million per second continuously to on-board memory, while each of the edges is measured with 2 ps resolution. This provides it with the capability to analyze the dynamic variations in pulse timing, pulse width, or frequency. In other words, the difference between time interval analyzers and traditional counter/timers is analogous to the difference between voltmeters and scopes. Measurements can also be streamed continuously in real-time over the PXIe interface allowing unlimited acquisition at high rates.

Features

• Direct Time Measurement of Pulse Trains
• Measure Jitter, Frequency, Time Interval (Skew), Pulse Width, Risetime, Event Timing, Time Interval Error (TIE), and More
• 2ps Single-Shot Resolution (12 Digits/s Frequency)
• DC to 500MHz Frequency Range for all Measurement Functions Including Pulsewidth, Plus a 6 GHz Prescaler for Frequency and TIE Measurements
• Up to 20 Million Continuous Zero Dead Time Measurements Per Second
• 100ps Minimum Pulse Width
• Highly Sophisticated and Flexible Arming (Triggering)
• PXIe Interface for Super High Throughput (x1, x2, or x4)
• On-board Memory for 128 Million Measurements – Can Be Read While Measurements are Taking Place

Full Specifications

Full-Featured Instrument

The NK732 is a full instrument-on-a-card with all the features and capabilities you would expect in bench-top instruments including high quality inputs, built-in NIST traceable calibration, and software and hardware that deliver fully com-puted results. The instrument has 10 measurement functions such as Frequency, Time Interval and Pulsewidth. All functions work directly on the input signal at frequencies up to 500 MHz without any prescaling. This means that you can measure pulses as narrow as 1 ns, occurring at frequencies up to 500 MHz, or the skew between two signals at 500 MHz. There is also an optional prescaler for each input channel which allows frequency, period, and TIE measurements to 6.0 GHz.

The inputs of the instrument include programmable termina-tion voltages. This feature is seldom found even in the best of the bench-top instruments. The 50 ohm inputs are terminated to an accurately programmable voltage between -2 V and +3 V. This allows you to connect ECL, PECL, or CML sources directly to the instrument with the proper loading. This feature is especially useful in semiconductor ATE and other test systems.

Applications

• PLLs and frequency modulation – measure jitter, time interval error and settling time
• Serial interface timing and characterization
• Ultrasonic and radar pulse timing
• Photon Counting – Measure Time of Arrival to 2 ps
• Optical and magnetic disk drive – measure jitter, risetime, and bit timing directly
• Oscillators and crystals – measure frequency, start-up time and time interval error
• Lidar – Timestamp pulses at up to 20 MHz
• Pulse width modulated signals – measure variations over time
• Time stamping of events in real time
• Nuclear physics

	App note: Clock Chip and Oscillator Testing
	App note: Frequency Reference Comparison

Easy to Use Software

The software for the NK732 is designed for ease of use and extremely high performance. The driver software (Windows and Linux) automatically manages the streaming of measurements at the high rates which are possible with the x4 PXIe interface. The front panel software for Windows allows you to easily set up multiple simultaneous displays of the measurements. This gives multiple views of the same data, or different functions from the same data. For example, you can set up the display to show a graph of the frequency of the signal vs. time, plus a tabulardisplay of the same results, plus a graph of the time deviation of the signal vs. time, all from the same measurement acquisition run. The front panel can also run multiple instruments simultaneously. All instrument models use the same driver for easy migration between models.

The screen images below are from actual measurements of a 62.5 MHz clock. In the first one the instrument was set up to take a measurement every 3 periods of the signal (every 48 ns) for 1 thousand measurements. The second one has 10 measurements taken every 300 periods of the signal (every 4.8 µs). The total acquisition time for both measurement runs is 48 µs.

The display on the top-left is the frequency of the signal. Notice the standard deviation of the frequency measurements. When taken every 4.8 µs the standard deviation is about 20 Hz which is 0.3 ppm.

The display on the top-right is the Continuous Time Interval (CTI), which is the time between sequential measurements. Notice the standard deviation of 1.6 ps.

The display on the bottom-left is a graph of the CTI. The resolution of the graph is 1 ps per division.

The display on the bottom-right is a table of frequency measurements but it also shows the times and event numbers when each measurement was taken. This additional timestamp information can be very powerful tool to analyze detail about your signal.