Hardware affected:

• Sentinels with serial 300XXX or lower AND clock module installed

• Sentinels with serial 400XXX or higher AND clock module installed AND no packet module installed

Software affected:

• R13 to R16.0.2

Sentinel allows a user to change the point at which a clock signal is “triggered”, i.e. where it is read - either on the positive/rising edge or on the negative/falling edge. This issue causes the clock signal to trigger Sentinel always on the negative slope.

This will introduce an offset in the time error of a clock measurement equal to the width of the pulse. This would have minimal impact on most clock signal types, but 1PPS pulses have a non-negligible width and so this can significantly affect the measurement result.

To ensure this issue is not encountered, users making 1PPS measurements with ≤300XXX-serial Sentinel units should not upgrade past version 12.0.0.

Please contact Calnex Support (support@calnex.com) or your regional Calnex representative with any questions or concerns.