Huntleigh SonicaidTeam, Operator'S Manual, Page: 88 / 113

Sonicaid Team Operator’s Manual
88
9 Troubleshooting
9.1 General questions
Question Answer
Why when Team is turned
on do you initially get a
rate with the transducers
in air? Team has a software version of Automatic Gain
Control (AGC). This enables it to detect a wider range
of input signals and extract the best FHR. When first
switched on the algorithm selects a high gain and
low threshold., and attempts to count any signal it
can find amongst the noise until the average level of
the noise pushes the threshold up.
As soon as a recognizable periodic signal is present
the gain and threshold are set above the noise floor
and the spurious signals are less likely to be detected.
Question Answer
Why is STV measured only
over a 60-minute period,
when the other
parameters on the Team
IP Trend analysis are also
measured over a 15-
minute period? STV is measured using the valid one-minute sections
of the heart rate trace. A valid section does not
contain any decelerations, or parts of decelerations,
or high signal loss or artifact.
An intrapartum trace is quite likely to have
decelerations and signal loss and artifacts, and many
one-minute sections of the trace will be discarded as
not valid by the analysis when calculating the STV.
A15-minute section might contain only a small
amount of valid data, and STV measurement would
not be reliable.
A 60-minute period provides a more significant
amount of ‘valid’ data for the measurement of STV,
and therefore produces a more reliable measurement
of heart rate variability