Congratulations on your choice of instrument. It will serve you well and stay ahead of most competition for many years to come, whether in bench-top or rack system use. It gives significantly increased performance compared to traditional Timer/Counters. The ‘9X’ offers the following advantages:
- 12 digits of frequency resolution per second and 50 or 100 ps resolution, as a result of high-resolution interpolating reciprocal counting.
- A high measurement rate of up to 250k readings/s to internal memory.
- Optional oven-controlled timebase oscillators, except the CNT-91R & CNT-91R/AF, which have an ultra-stable rubidium oscillator.
- CNT-90, CNT-91(R): A variety of RF prescaler options with upper frequency limits ranging from 3 GHz to 20 GHz.
- CNT-91R/AF: Special version of CNT-91R with selected Rubidium oscillator, plus 5 Reference frequency outputs covering 100 kHz, 1 MHz, 5 MHz, and 10 MHz. Model CNT-91R/AF has a 3 GHz input C and CNT-91R/AF/20G has a 20 GHz input C as standard
- CNT-90XL: A number of microwave inputs with upper frequency limits ranging from 27 to 60 GHz.
- CNT-90(XL): Optional Pulsed RF for RF pulse characterization up to 60 GHz carrier frequency and down to 30 ns pulse width.
- Optional built-in Li-Ion battery supply realizes instant high-precision measurements in the field and true UPS operation.
- Integrated high performance GPIB interface using SCPI commands.
- A fast USB interface that replaces the traditional but slower RS-232 serial interface
- Optional external GPIB-to Ethernet controller that allows connection to LAN .
A unique performance feature in your new instrument is the comprehensive arming possibilities, which allow you to characterize virtually any type of complex signal concerning frequency and time.
For instance, you can insert a delay between the external arming condition and the actual arming of the counter. Read more about Arming in Chapter 5, “Measurement Control”.
In addition to the traditional measurement functions of a timer/counter, these instruments have a multitude of other functions such as phase, duty factor, rise/fall-time and peak voltage. The counter can perform all measurement functions on both main inputs (A & B). Most measurement functions can be armed, either via one of the main inputs or via a separate arming channel (E).
By using the built-in mathematics and statistics functions, the instrument can process the measurement results on your benchtop, without the need for a controller. Math functions include inversion, scaling and offset. Statistics functions include Max, Min and Mean as well as Standard and Allan Deviation on sample sizes up to 2*109.
You will soon find that your instrument is more or less self-explanatory with an intuitive user interface. A menu tree with few levels makes the timer/counter easy to operate. The large backlit graphic LCD is the center of information and can show you several signal parameters at the same time as well as setting status and operator messages.
Statistics based on measurement samples can easily be presented as histograms or trend plots in addition to standard numerical measurement results like max, min, mean and standard deviation.
The AUTO function triggers automatically on any input waveform. A bus-learn mode simplifies GPIB programming. With bus-learn mode, manual counter settings can be transferred to the controller for later reprogramming. There is no need to learn code and syntax for each individual counter setting if you are an occasional GPIB bus user.
These counters are designed for quality and durability. The design is highly integrated. The digital counting circuitry consists of just one custom-developed FPGA and a 32-bit microcontroller. The high integration and low component count reduces power consumption and results in an MTBF of 30,000 hours. Modern surface-mount technology ensures high production quality. A rugged mechanical construction, including a metal cabinet that withstands mechanical shocks and protects against EMI, is also a valuable feature.
The use of reciprocal interpolating counting in this new counter results in excellent relative resolution: 12 digits/s for all frequencies.
The measurement is synchronized with the input cycles instead of the timebase. Simultaneously with the normal “digital” counting, the counter makes analog measurements of the time between the start/stop trigger events and the next following clock pulse. This is done in four identical circuits by charging an integrating capacitor with a constant current, starting at the trigger event. Charging is stopped at the leading edge of the first following clock pulse. The stored charge in the integrating capacitor represents the time difference between the start trigger event and the leading edge of the first following clock pulse. A similar charge integration is made for the stop trigger event.
When the “digital” part of the measurement is ready, the stored charges in the capacitors are measured by means of Analog/Digital Converters.
The counter’s microprocessor calculates the result after completing all measurements, i.e. the digital time measurement and the analog interpolation measurements.
The result is that the basic “digital resolution” of + 1 clock pulse (10 ns) is reduced to 100 ps for the CNT-90 and 50 ps for the CNT-91(R).
Since the measurement is synchronized with the input signal, the resolution for frequency measurements is very high and independent of frequency.
CNT-91/91R features gap-free back-to-back frequency measurements, ensuring no missing periods The counters have 14 display digits to ensure that the display itself does not restrict the resolution.
This instrument is programmable via two interfaces, GPIB and USB.
The GPIB interface offers full general functionality and compliance with the latest standards in use, the IEEE 488.2 1987 for HW and the SCPI 1999 for SW.
In addition to this ‘native’ mode of operation there is also a second mode that emulates the Agilent 53131/132 command set for easy exchange of instruments in operational ATE systems. The USB interface is mainly intended for the lab environment in conjunction with the optional TimeView™ analysis software. The communication protocol is a proprietary version of SCPI.
These counters are not only extremely powerful and versatile bench-top instruments, they also feature extraordinary bus properties.
The bus transfer rate is up to 4000 triggered measurements/s in CNT-91(R). Array measurements to the internal memory can reach 250 k measurements/s.
This very high measurement rate makes new measurements possible. For example, you can perform jitter analysis on several tens of thousands of pulse width measurements and capture them in less than a second.
An extensive Programmer’s Handbook helps you understand SCPI and counter programming.
The counter is easy to use in GPIB environments. A built-in bus-learn mode enables you to make all counter settings manually and transfer them to the controller. The response can later be used to reprogram the counter to the same settings. This eliminates the need for the occasional user to learn all individual programming codes.
Complete (manually set) counter settings can also be stored in 20 internal memory locations and can easily be recalled on a later occasion. Ten of them can be user protected.