Copyright © Sigicom AB 2020
17
The following additional interval channels may also be stored:
•
Frequency
(up to three channels). Frequency is estimated using
a zero-crossing method: the time T between two adjacent zero
crossings is used in the formula:
𝑓 =
1
2∗𝑇
.
The frequency value is
limited within 2Hz – 512Hz. If the signal
2
is continuously low
3
,
no frequency is estimated for that channel, because the value
would not be accurate enough.
The RMS-standards also estimates the frequency for intervals,
and here the estimation is made on the signal
before the RMS-
detector
, using the method described above.
•
Relative values
(three channels). If frequency weighting is
active, weighted interval values will be stored as three relative
channel values (unit: %). They are calculated as the normal
interval value divided by the frequency weighting curve for the
selected standard. Appendix G shows some examples of this.
•
Relative frequencies
(up to three channels). Up to three
corresponding frequency values may be stored.
•
Resultant
(one channel). Calculated by, sample by sample,
finding the maximum resultant of the three processed vibration
signals.
•
VDV
(three channels). Vibration Dose Value accumulated over
each interval [m/s
1.75
]
•
Accumulated VDV
(three channels). Vibration Dose Value
accumulated over one day/night [m/s
1.75
]. Day is defined
between 07:00 – 23:00, and night 23:00 – 07:00.
On questions regarding the different interval channels, please contact
[email protected]
2
The signal here means the one filtered according to the selected standard.
3
The limit here is equal to the lowest possible threshold for the chosen standard
e.g. 0.4 mm/s (0.02 in/s) for standards with level range 250 mm/s, and 0.04 mm/s
(0.002 in/s) for standards with level range 25 mm/s.
