GTX2200 Series - Time Interval Counter PXI Card

Time Interval Counter

DC to 225 MHz (GTX2210), DC to 1.3 GHz (GTX2220), DC to 2.0 GHz (GTX2230)
  • 14 measurement functions
  • DC to 225 MHz (GTX2210), DC to 1.3 GHz (GTX2220), DC to 2.0 GHz (GTX2230)
  • 100 ps resolution without averaging (GTX2220 and GTX2230 only)
  • Fast measurement mode: 2300 readings / second
  • External reference clock & arming inputs
  • Gate signal output
  • In-system automatic caibration of time base and trigger levels
  • Software selectable input impedence (1 MOhm or 50 Ohm) and coupling (AC or DC) for each input channel
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The GTX22x0 family of PXI universal time interval counters offer many of the measurement and timing functions of high-end stand-alone frequency counters, including accumulate, auto ratio, frequency, fast frequency (GTX2220 and GTX2230 only), period, ratio, single period, test clock, time interval, time interval delay, totalize, totalize gated, totalize gated once, & pulse width.

There are three models available: the GTX2210, GTX2220 and GTX2230. The GTX2210 frequency range operates to 225 MHz, the GTX2220 covers frequencies up to 1.3 GHz, and the GTX2230 covers frequencies up to 2.0 GHz. The card is also available in PCI format (GC22xx).


The GTX22x0 series counters have two signal input channels via BNC connectors, an external timebase input, arm input, and a gate signal output. The separate input signals can be used for arming and gating the circuitry, and controlling the timing of the analysis (start / stop duration) for maximum measurement flexibilty.

The GTX22x0 series counters use an on-board microprocessor with embedded firmware to off-load processing tasks from the main CPU. The counters use high-density, low-power field programmable gate arrays (FPGA) to perform complex logic tasks. Reciprocal counting techniques are used to achieve high resolution measurements on lower frequency signals without sacrificing measurement time. These techniques provide a fixed number of digits of resolution for all frequencies rather than a fixed resolution in Hz for the same gate time.

The GTX2220 and GTX2230 can measure frequencies to 0.1 parts per million (seven digits) in just 1 ms and resolve each time measurement to 100 ps. This ability to precisely resolve frequency and time allows for increased accuracy as well as reduced measurement time. When combined with 2,300 measurements / second, one of the fastest rates available, more data can be acquired in a single second than a typical GPIB counter can acquire in one minute.

Additionally, the counters include an on-board 10 MHz TCXO timebase for internal frequency reference. As an option, a high precision 10 MHz OCXO is available for the GTX220 and GTX2230 models. An external 10 MHz input is also availble for use with external timebases.

Programming and Software

The board is supplied with the GXCNT software, a software package that includes a virtual instrument panel, and a Windows 32/64-bit DLL driver library and documentation. The virtual panel can be used to interactively program and control the instrument from a window that displays the instrument’s current settings and status. In addition, interface files are provided to support access to programming tools and languages such as ATEasy, LabView, LabView/Real-Time, C/C++, Microsoft Visual Basic®, Delphi, and Pascal. An On-Line help file and PDF User’s Guide provides documentation that includes instructions for installing, using and programming the board.
A separate software package - GtLinux - provides support for Linux 32/64 operating systems.


  • ATE Systems
  • Event timing measurements
  • Frequency measurements
  • Time interval measurements
  • Metrology



GTX2210 225MHz Time Interval Counter with 10MHz TCXO
GTX2220 1.3GHz Time Interval Counter with 10MHz TCXO
GTX2230 2GHz Time Interval Counter with 10MHz TCXO




Input Characteristics
Impedance Below 225 MHz: 1 MΩ or 50 Ω channel independent and software selectable
225 MHz and above: 50 Ω
Coupling DC or AC, channel independent and software selectable
Trigger Positive or Negative edge, channel independent and software programmable, automatic level or hold last
Maximum Signal Input 50 Ω: 5 VRMS
1 MΩ: DC to 1 MHz – 15 VRMS
Above 1 MHz – 5 VRMS
Connectors Front panel BNCs for Channel A & B
Frequency Range
GTX2210 Channels A and B: DC to 225 MHz
Channel A: Programmable, DC to 225 MHz OR
100 MHz to 1.3 GHz (GTX2220)
100 MHz to 2.0 GHz (GTX2230)
Channel B: DC to 225 MHz
Sine 25 mVRMS DC – 20 MHz
50 mVRMS 20 MHz – 50 MHz
200 mVRMS 50 MHz – 225 MHz
250 mVRMS 225 MHz – 1.3 GHz (GTX2220 or GTX2230)
500 mVRMS 1.3 GHz – 2.0 GHz (GTX2230 only)
Pulse 500 mVPP at 5 ns pulse width
Trigger (Threshold) Level
Range ±5.00 V in 1 mV steps (rev C version)
±5.00 V in 40 mV steps (rev A & B versions)
Accuracy ±3% of setting ±0.001 V
Auto Trigger Automatic selection of optimum trigger level Signal repetition rate: 100 Hz to 75 MHz
External Reference Clock Input
Impedance 2 kΩ in series with 47 nF
Maximum Input Voltage 5 VRMS
Coupling AC
Sensitivity 150 mVRMS sine, 450 mVPP pulse
Duty Ratio 40% to 60%
Frequency 10 MHz only
Connector Front panel BNC
External Arm Input
Input Signal Characteristics DC Coupled, TTL compatible (1.4 V threshold), programmable active slope (rising or falling)
Minimum Pulse Width 15 ns
Impedance 2 kΩ
Connector Front panel DIN connector
External Gate Output
Output Signal Characteristics DC Coupled, TTL compatible (1.4 V threshold)
Connector Front panel DIN
Maximum Measurement Rate
GTX2210 200 readings per second for all modes


2300 readings per second for Fast Frequency and all time modes,
1400 reading per second typical
1400 readings per second for Frequency and Period modes,
1100 readings per second typical
Actual reading rate depends on system CPU, system configuration, an number of applications executing simultaneously.
Range DC to 225 MHz (GTX2210)
DC to 1.3 GHz (GTX2220)
DC to 2.0 GHz (GTX2230)
Gate Time 250 µs to 3200 s with 0.75 µs resolution (plus up to one signal period)
Number of Significant Digits GTX2210: 8 per second of gate time, e.g., 5 digits in 1 ms
GTX2220 and GTX2230: 10 per second of gate time, e.g., 7 digits in 1 ms
Least Significant Digit (LSD) GTX2210: Freq x (10 ns / Gate Time)
GTX2220: Freq x (100 ps / Gate Time)
GTX2230: Freq x (100 ps / Gate Time)
Resolution (Hz) ±LSD ±(Freq x (300 ps RMS + (1.4 x Trigger Error))) / Gate Time
Accuracy (Hz) ±Resolution ±TimeBaseError
Fast Frequency Mode(GTX2220 and GTX2230)
Range DC to 225 MHz
Gate Time 4 signal periods, fixed
Accuracy (Hz) ((±Freq x (500 ps + 300 ps RMS + (1.4 x trig error))) / gate time) ±timebase error
Time Interval
Range -1 ns to 100,000 sec (> 25 hr)
Least Significant Digit (LSD) GTX2210: 10 ns
GTX2220: 100 ps
GTX2230: 100 ps
Resolution ±LSD ±300 ps RMS ±StartTriggerError ±StopTrigger Error
Accuracy ±Resolution ±TimeBaseError ±TriggerLevelTimingError ± 2 ns
Minimum Pulse Width 8 ns
Delay Recognition of stop events is inhibited for a set time range: 20 µs to 3200 seconds
Totalize and Gated Totalize
Control Count gate can be controlled by software, or by events on the second input channel (Gated Totalize). In Gated Totalize, start and stop event slopes are selectable.
Count Rate DC to 50 MHz, 10 ns minimum pulse width
Modes Software gate: Gate and count reset are controlled by software
Hardware gate: Count is reset before every gate
Accumulative: Count is totalized over multiple gates
Range 0 to 2.8 x 1014 counts
Accuracy ±1 count, reading allowed while counting
Period (Single Period)
Range 25 ns to 100,000 seconds.
See Time Interval for resolution and accuracy
Period (Multiple Period Average)
Range See Frequency
Gate Time See Frequency
Least Significant Digit (LSD) GTX2210: Period x 10 ps / Gate Time
GTX2220: Period x 100 ps / Gate Time
GTX2210: Period x 100 ps / Gate Time
Resolution ±LSD ±(Period x (300 ps + (1.4 x trig error))) / gate time
Accuracy ±Resolution ±TimeBaseError
Ratio A/B or B/A
Gate Time GC2200 / GTX2200: 250 µs to 3200 seconds with 0.75 µs resolution
(plus up to one signal period)
Range DC – 225 MHz on either input.
DC – 25 MHz on second input
Least Significant Digit (LSD) Ratio / (FREQhi x Gate Time)
FREQhi is the higher frequency input
Resolution and Accuracy ±LSD ±(Ratio x FREQlo x Trigger Error) / Gate Time
FREQlo is the lower frequency input
Pulse Width A or B
Accuracy Same as Time Interval, plus 3 ns
Paced Measurement Function
Time Controlled Interval between measurements can be programmed from 0.8 ms to 3200 sec for time interval measurements and 1 ms to 3200 sec for frequency and period measurements.
Accuracy: 200 µs
Available on all modes except Totalize
Source: Internal (alternate channel) or External Input
Arm setup time: Minimum 40 ns before selected event
Time Base
Standard 10 MHz TCXO
Accuracy ±1ppm, 0 °C to +50 °C
Aging: < 1 ppm / year
Supply voltage: < 3 x 10-8 for 1% change
Short term: < 5 x 10-10 RMS with a 1 second averaging time
Source Internal standard
External Reference Input
PXI 10 MHz from backplane
Time Base Output When installed in the PXI Star Trigger  Controller slot (slot 2)
the module’s 10 MHz time base can source the PXI 10 MHz backplane clock
Supplemental Definitions
Trigger Error Error due to noise superimposed on the input signal from both internal and external sources
Trigger Error = ((500 uV * 2 + En * 2) * .5) / (input signal slew rate))
En is RMS noise of input signal (225 MHz bandwidth)
Trigger Level Timing Error Timing error due to threshold uncertainty
Trigger Level Timing Error = (< 250 mV) / (input signal slew rate)
Time Base Error Fractional frequency error of time-base reference, times the measurement result
Power Requirements (Typical) +5 V @ 0.3 A
-3.3 V @ 0.1 A
+12 V @ 0.2 A
-12 V @ 0.05 A
Operating Temperature 0 °C to +50 °C
Storage Temperature -20 °C to +70 °C
Size 3U PXI
Weight 12 oz


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