ShockLog Technical Information
How the ShockLog Works
The ShockLog has been designed to monitor shock and vibration based on acceleration or velocity
measurements. It has several unique features, which make it especially suitable for applications
where the cost of exposure to out-of-specification environmental influences is very high. The
instrument is equally convenient for protecting high-value fixed or mobile installations or
investigating shock and vibration during transportation.
In normal operation, the device checks the output of the sensors (the three built in accelerometers,
the built-in temperature sensor and any external sensors) once every 10 seconds. The information
from the sensors is merged into a record for each recording period and recorded in non-volatile
memory. The length of the recording period can be set between 10 minutes and 24 hours and there
is sufficient memory for 512 periods.
If any of the accelerometer signals or the first external input exceeds the "wake up" threshold, the
processor will be turned on and will check the sensor outputs at a much faster rate (up to 4000
samples per second). If the output of any sensor exceeds the warning or trip thresholds, the
ShockLog will flash its status lamps accordingly. The ShockLog will adjust the sample rate during
the event recording (within parameters set up by the user) to make the most efficient use of memory
and capture the full extent of any events.
The external inputs are intended for use with low bandwidth devices such as pressure or humidity
sensors and, in addition, the first external input can be used to trigger the ShockLog.
The ShockLog also supports peak recording in fixed time slots. In this mode the highest and
lowest signal level present on each input is recorded for each time slot. The time slot length
may be set between 10 seconds and one hour and as many as 262,144 slots may be recorded.
Security
The ShockLog stores all data and status information in high-performance sector erase FLASH memory.
This memory requires no power to retain data and offers special hardware protection against accidental
erasure.
The instrument can be configured by connecting it to a PC running the data analysis and set-up software
supplied free with each ShockLog. During the configuration process, the operator can set the levels for
warnings and alarms, determine the sensor types to be used and set up user passwords for subsequent
access to data.
Before the software will communicate with the ShockLog, the user must supply the factory password
for the individual instrument and any user passwords that may have been set to restrict access to
data, resetting, calibration, or other functions.
The complete electronic and transducer package is enclosed in a robust extruded aluminum case and
encapsulated in polyurethane compound. It is completely impossible to tamper with the hardware
without leaving clear evidence of such action.
Packaging and Environment
The ShockLog has been designed to function reliably in difficult environments. The electronic
components are assembled using surface mount technology and the latest automatic assembly
equipment. The complete electronic and transducer package is enclosed in the metal case and
encapsulated in polyurethane. The securing bolts pass right through the body of the instrument
to guarantee a reliable mechanical installation.
This construction technique, in combination with the absence of cables for power or sensors
(unless additional external sensors are used), results in a very high immunity to electrical
interference and very low levels of RF emission. The ShockLog may safely be used in close
proximity to sensitive instruments or in difficult electrical environments.
The ShockLog is sealed to IP67 (including connectors) and is capable of operating at
temperatures between -4°F/-20°C to +158°F/+70°C (-40°F/-40°C to +185°F/+85°C to special order).
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