1. Hold-off
Hold-off function allows to insert dead-time into input trigger circuit which effectively acts as a digital lowpass filter. Hold-off can be set to 0 (Hold-off OFF) or in the range [20 ns .. 2.683 s] which correspond to low-pass filter frequency from 100 MHz down to 0.5 Hz.
Setting Hold-off to approx. 75% of the cycle time of the signal allows to inhibit erroneous triggering for noisy signals.
Hold-off is also an effective measure to cope with contact bouncing on the front of the signal under test.
You should be aware of a few limitations to be able to use the Hold-off feature effectively and nambiguously. First you must have a rough idea of the frequency to be measured. A cutoff frequency that is too low might give a perfectly stable reading that is too low. In such a case, triggering occurs only on every 2nd, 3rd or 4th cycle. A cutoff frequency that is too high (>2 times the input frequency) also leads to a stable reading. Here one noise pulse is counted for each half-cycle.
2. Timeout
If stop arming is not used, the Analyzer ends measurement when all requested samples have been collected. However, if signal is absent (or lost) on one of the inputs used for the measurement – timestamps from this channel will never come and Analyzer will wait forever unless measurement is stopped explicitly.
However, in many cases this is undesirable behavior. For example in an automated test system when absence of signal can be a result of a wrong test setup or device under test malfunction, it is would be a waste of time to wait until the expected end of a long measurement to discover that one of the signals is just missing.
This is where Timeout function comes to help. If Timeout is ON, the measurement will end in case there are no samples from one of measurement inputs for the time duration set by Timeout Time.
3. Calibration
3.1. Internal Calibration
The Analyzer has a possibility to compensate for some internal sources of error by the means of internal calibration. This procedure doesn’t require any external signal, the Analyzer can perform it automatically.
Performing internal calibration before the start of measurement helps getting maximum accuracy and best resolution. However, because internal calibration takes up to 2 s it has impact on measurement speed which might be important in automated test systems. Hence, the Analyzer allows to choose the schedule of internal calibration. Summarizes available options.
| Mode | Description |
| Every 30 minutes | The Analyzer performs internal calibration every 30 minutes between successive measurements or when it is idle. This is the default option which provides the best trade-off between accuracy, resolution and average measurement speed. |
| Before every measurement | The analyzer performs internal calibration before each timing measurement to ensure best resolution and accuracy. This results in additional time overhead of around 2 s per measurement session. If such overhead is not critical – this is the recommended choice. |
| Once (after warm-up) | The Analyzer performs internal calibration only once – after the instrument has warmed up. This guarantees no calibration overhead, but resolution will deteriorate over time. |
To provide maximum flexibility, the Analyzer also provides the possibility to perform internal calibration implicitly. This is especially useful when Interpolator Calibration Mode is set to Once.
All above can be configured under Settings → Advanced section (see Figure 39).
3.2. Timebase Calibration
For increasing measurement accuracy, a good reference source can be used for timebase calibration. Connect the source to Input A, select Settings→Timebase Calibration, choose reference frequency and start the procedure. It is possible to interrupt the process midway, re-apply result from previous calibration or reset to factory calibration setting.
3.3. Voltage Calibration
For increasing accuracy of voltage measurements and manual trigger level setting accuracy, a good source of DC voltage can be used for voltage calibration. Open Settings → Voltage menu, select the input to be calibrated and follow the instructions.
Please note: voltage calibration sets inputs to 1 MOhm impedance.
4. Mathematics
The Analyzer can use five mathematical expressions to process the measurement result before it is displayed:
- K×X+L
- K/X+L
- (K×X+L)/M
- (K/X+L)/M
- X/M-1
Select Settings -> Mathematics to enter the mathematics submenu.
The default values of K (Scale factor), L (Offset) and M (Reference value) are chosen to 1, 0 and 1 respectively, so that the measurement result is not affected directly after activating Math. Recalling the default setting will restore these values as well.
It is possible to apply Mathematics function to all measurement series or to selected one.
When Mathematics is turned on, the Analyzer status bart shows MATH indicator.
4.1. Example use cases
If you want to observe the deviation from a nominal frequency, for example 10 MHz, instead of the absolute frequency itself, you can do like this:
- Select Math
- Select the expression K×X+L
- Select K = 1 (if not already set)
- Select L = -10 MHz
- Now the display will show the deviation from the value you have just entered.
By changing the constant K you can scale the result instead. Set for example K = 60 to convert Frequency in Hz to RPM (revolutions per minute) from rotation transducers.
Use the expression X/M-1 if you want the result to be displayed as a relative deviation. The result will be displayed as
%, ppm, ppb, or as a dimensionless number like +1.2345E-12
5. Limits
Limits feature is used for setting numerical limits and selecting the way the instrument will report the measurement results in relation to them.
Limit Behavior setting defines how the device will react on limits:
- Off – limits are not checked.
- Capture – only samples meeting the limit criterion are captured, the rest are discarded. Limit status is displayed.
- Alarm – all samples are captured; limit status is displayed.
- Alarm Stop – measurement session stops if measured value doesn’t meet the limit criterion.
Limit Type:
- Above – results above set Lower Limit will pass.
- Below – results below set Upper Limit will pass.
- Range – results within the set limits will pass.
Limits can be applied to all measurement series or to selected one, depending on user’s choice.
When Limit Behavior is not Off, Analyzer status bar shows LIM. It will change to LIM! if at least one sample didn’t meet set Limit criterion during measurement session.
Numeric, Graph and Distribution screens will also have additional Limit indicators displayed.
6. Pulse Output (option)
Please note: license is needed to unlock Pulse Output functionality in the Analyzer
Pulse Output is located on rear panel of the Analyzer and can be used for one of the following purposes:
- Pulse Generator. Pulse period can be selected from the range [10 ns .. 2.147 s] in 2 ns steps, pulse width – in the range [6 ns .. 2.147 s] in 2 ns steps.
- Gate Open. Indicates if measurement is in progress.
- Alarm Out. Indicates when Limits Alarm is active. Can be selected between Active High and Active Low
Irrespective to the selected mode, the amplitude of Pulse Output signal is set to TTL levels into 50 Ohm termination
7. Network
The Analyzer supports wired 10/100/1000 Mbps connection as well as wireless (via external USB Wi-Fi adapter).
It has IPv4 support and can be configured in either Static or Dynamic (DHCP) mode. If Static mode is selected, user is expected to manually enter IP address, Network mask and Gateway. For Dynamic mode, these fields are read-only and display IP address, network mask and gateway that are currently in use.
7.1. Web Interface
The Analyzer has built in web server that provides Web Interface allowing to see the instrument screen and control it remotely, download files and upgrade firmware.
7.2. VNC
The Analyzer also exposes VNC server on port 5901 which allows remote access and control. One can use any VNC client software on PC, mobile phone or tablet.
8. Front USB ports
Front panel USB ports can be used for connecting:
- Peripherals (PC keyboard and mouse) which complement the touch screen interface.
- USB storage for saving measurement results, presets or upgrading firmware.
- Wi-Fi adapter for enabling wireless networking.
9. File Manager
The Analyzer has built-in File Manager accessible via Settings → User Options → File Manager or dedicated icon on measurement screen.
10. Firmware Update
There are 2 ways of updating firmware of the Analyzer:
Update via Web Interface (preferred):
- Download SW update file (it has .swu extension) to your PC
- Connect CNT-104S to LAN: either via ethernet cable or use supported Wi-Fi dongle to connect via Wi-Fi
- On CNT-104S open Settings -> User Options -> Network to check or set current IP address
- On PC, open web browser and put CNT-104S address to adress field. CNT-104S Web Interface will open
- Click Software Update link on top right and follow the instructions
Update via USB stick:
- Copy SW update file (it has .swu extension) to USB stick
- Insert USB stick to one of the CNT-104S front panel USB ports
- On CNT-104S Open Settings -> User Options -> Firmware Update to open Firmware Update screen
- On CNT-104S Firmware Update screen tap/click on SW update file. SW update will start. No progress indication will be displayed – wait until CNT-104S reboots
11. Installing license
- Put License File on USB stick
- Plug it to one of front USB ports
- Navigate to Settings → User Options → Import License
- Select License to be imported