CoaXPress Link Validation Tool
Introduction
Short Description
The CoaXPress Link Validation Tool (CXLVT) can be used to validate the operational parameters of a CoaXPress Link.
For a quick test, run the CXLVT until reaching a confidence level of 100% that the probability of single bit error (PER) is 10-10 or better 10-11. This should just take a few minutes.
For an extensive test, run the CXLVT until reaching a confidence level of 100% that the PER is 10-12 or better 10-13. This will take a few hours.
Note: For more information about the theory of bit error rate testing, please refer to http://en.wikipedia.org/wiki/Bit_error_rate.
Host PC requirements
| ● | The Host PC must be equipped with at least one EURESYS Coaxlink board. |
| ● | The Coaxlink Driver version 9.3.2 must be installed on the Host PC. |
Camera requirements
| ● | The camera must be capable to generate a static image pattern. |
Installation
The CXLVT is included in gentl.exe, a command-line tool that is delivered with the Coaxlink Driver since version 9.3.2. No further installation is required.
gentl ber Command
The CXLVT is invoked with the command ber of gentl.exe.
gentl ber --help
gentl ber commands
Test procedure
To setup the CoaxPress Link Validation Tool proceed as follows:
| 1. | With GenICam Browser: |
| □ | Configure the camera as for normal operation and select a fixed test-pattern as video source |
| □ | Configure the frame grabber as for normal operation |
| 2. | Open a command shell and execute gentl ber to start a Read-Eval-Print-Loop |
| 3. | Get intermediate results using the results command |
| □ | Check if the number of acquired images counter increases regularly |
| □ | Check the confidence levels |
| 4. | Run the test until the required confidence levels are reached. This may require several hours. |
Operation
The CoaXPress Link Validation Tool (CXLVT) validates the operational parameters of a CoaXPress Link installation (bit rate, cable type, cable length) resulting in reliable, long-term performance.
CXLVT does this by estimating, with a known confidence level, the probability of single bit errors in a CoaXPress Link setup.
We define:
| ● | PER: Probability of single bit error in a digital connection like a CoaXPress Link; this is an unknown quantity that we want to estimate |
| ● | BER: Bit Error Rate, actually measured by the CXLVT |
It is generally accepted that a CoaXPress Link will operate reliably, if PER < 10-12. This criterion is similar to the one used in other digital serial image transmission schemes. Of course, a better (lower) PER will provide even more assurance that the operation is reliable.
The CXLVT computes the confidence level (CL), or likelihood, that the PER is less than a set of values (10-10, 10-11, 10-12, 10-13, 10-14), based on the measurement of the BER, during a time sufficiently long to accumulate the necessary evidence.
When started, the CXLVT displays these confidence levels, as evidence accumulates with the passing of time, as illustrated in the screenshots hereafter.
Entering the levels command, during the operation of the CXLVT, displays the confidence levels for the 5 PER values.
Confidence levels reported 8 seconds after start
After 8 seconds, we have reached 99.99 % confidence level that the PER is less than 10-10. The PER might very well be much better than that, but at this stage we have insufficient evidence to conclude that this is the case. The CXLVT must be continued.
By entering the results command, during the operation of the CXLVT, additional information can be displayed , after which the CXLVT continues its normal operation, for as long as necessary, to achieve the required confidence level for a predetermined PER.
Intermediate results reported after 16 minutes
From this screenshot, we can already conclude that the confidence level that the PER is less than 10-11 has risen from 64.97 % to 86.28 %, after 16 minutes.
The CXLVT should be continued until the confidence level that the PER is less than 10-12 (at most – a stronger test would be a PER less than 10-13 ) has reached a satisfactory level (at least 95 %, and 99 % for a stronger result). This may require quite some time, because these outcomes require a significant amount of evidence.
Intermediate results reported after 3.5 hours
From this screenshot, we can conclude that the confidence level that the PER is less than 10-12 has risen from 18.01 % to 91.66 %, after 3.5 hours.
To generate a report, execute the report command.
Generate a report command line