D
OCUMENT
301900,
R
EVISION
D
E
PI
S
ENSOR
U
SER
G
UIDE
45
Configure the gain board on the high gain channel with no attenuation and a
gain set according to your desired full-scale range on the high gain channel
– remembering that the 20V differential output already represents an
effective gain of eight.
For example, if you set a gain of 10 on the gain board you would have a
total gain of 80 and the full-scale would be 0.025g. (Gains higher than 30 on
the amplifier will actually tend to reduce the dynamic range and will worsen
the offset problem.) The final concern is the offset of the EpiSensor, which
needs to be adjusted as close to zero as possible for this system to work.
Long Cables
In its low-power configuration (low-power amplifier 2.5V single-ended
output), the EpiSensor can be used with the normal Kinemetrics cable
(P/N 840356 or Belden 9874) for distances up to 1,000 feet with a variety of
instruments.
If the EpiSensor is used with an Altus recorder, this distance can be
extended up to 2,000 feet. For cable runs of this length, we recommend
installation in a grounded metal conduit. If the cable is not installed in its
own conduit and maximum resolution is required, it should not be run
alongside cables carrying heavy AC or transient currents.
For runs longer than 2,000 feet, Kinemetrics P/N 700045 cable is
recommended; it can be used for distances up to 3,000 feet with the low-
power configuration.
When using the low-noise amplifiers and the differential 5V output,
distances are somewhat reduced as shown in the Table 9.
Cable lengths must be reduced considerably for the low-noise and 20V
differential option. The EpiSensor requires a minimum operating voltage of
11.5V to be sure it can supply the +/-10V output with respect to ground. In
the worst case, the standard Altus unit’s power output is only 11.6V.
This limits cable length to 50 feet for the standard Belden cable (P/N 9874)
and 100 feet for the Kinemetrics 700045 cable. Note that this configuration
will seldom be used with standard Altus recorders because the output does
not match the 2.5V input of the recorder.
These calculations for the 2g operating range are provided in the following
tables. These figures are a conservative limit for all other ranges except the
4g range.
