SC11 Sensor Interface Product Description

The SC11/SI/USB is the latest version of our comprehensive site survey equipment. It features data acquisition and pre-processing by an embedded microcomputer in the Sensor Interface for enhanced performance. The separate data acquisition card (DaqCard) used by our earlier systems is not required. The data interface to the computer is through an industry standard USB connection, which enables the system to be used with most modern laptops running Microsoft Windows.

The system is designed to be flexible and adaptable to suit customer requirements. A typical system includes the Sensor Interface, a DC-10 kHz three axis magnetic field sensor, an accelerometer and a precision microphone all supplied in a rugged custom carrying case.

The software suite consists of three virtual instruments, an oscilloscope, a spectrum analyser and a chart recorder plus a comprehensive results plotting program “SCplot”. During measurements, all results are displayed graphically on the laptop screen.

Hardware

Laptop computer
The laptop computer is optionally supplied by Spicer Consulting with all the software pre-installed. Alternatively you may install the software on your own laptop PC. If desired, Spicer Consulting can install the system on your own computer.

Sensor Interface
The Sensor Interface operates from universal AC power (100-240 V ~ 50/60 Hz) which is used to power all the sensors. For long term monitoring applications, where loss of data would not be acceptable, the sensor interface can be powered from an un-interruptible power supply. Our tests with a fully charged 350W UPS from APT provided up to four hours of operation.

There are inputs for two Spicer Consulting 3-axis magnetic field sensors. Sensor SC20/DCMR, Sensor SC20/AC and Sensor SC20Fast/AC are all compatible. If two sensors are used we recommend they are the same type to avoid confusion.

There are inputs for three Wilcoxon 731A accelerometers. The inputs provide the constant current load and power supply for each Wilcoxon 731A and are suitable for most other types of piezo accelerometers when using the spectrum program.

There is an input for a Brüel & Kjær 4190/2669L precision microphone. The Interface provides the special power supplies for the 2669L microphone pre-amplifier to enable the microphone to operate to its full specification.

There is a general purpose DC coupled auxiliary input via a BNC connector at the back of the interface.

Sensor SC20/DCMR
This is the 3-axis magnetic field sensor most commonly used with the SC11/SI/USB system. It can measure DC and AC fields, e.g. changing DC fields from trams and elevators and AC power line fields. It has internal bias coils that are used to null the Earth’s field. The bias coil currents are reset by clicking an icon on the program screen, each time the sensor is moved. The measurement range is ± 20 mG. The sensor has low noise and when fully warmed up the DC drift is below 20µG/day. It is not recommended for measuring higher frequency fields (e.g. 9kHz from wafer transport robots). Sensor SC20/AC or Sensor SC20Fast/AC should be used for this purpose. (The MEDA uMAG-01N is also supported).

Sensor SC20/AC
This is the standard Spicer Consulting low noise AC sensor used with our magnetic field cancelling systems. Its measurement range is 40 mG Pk-Pk. Its frequency range is 5Hz –20kHz. It can be used to measure the 9kHz field from wafer transport robots.

Sensor SC20Fast/AC
This is the AC sensor used with Spicer Consulting SC20Fast field cancelling systems. Though not generally sold with the SC11/SI/USB if the sensor is available it can be used with the oscilloscope and spectrum programs. Its measurement range is 40 mG Pk-Pk. Its frequency range is 25Hz –20kHz. It can be used to measure the 9kHz field from wafer transport robots.

Precision Microphone
The Brüel & Kjær 4190 microphone with 2669L preamplifier connects directly to the sensor interface. It measures sound levels from 20dB to 103dB and 1.5 Hz to 20 kHz.It measures infrasound levels (i.e. frequencies below 20Hz) which can limit the performance of transmission electron microscopes by vibrating the sample. (The Sound Level Meter supplied with the SC11/Basic is also supported).

Accelerometer
The accelerometer is a Wilcoxon Research model 731A, with a bandwidth of 0.1 Hz to 500 Hz in this system. It is suitable for the measurement of extremely low level vibrations. Each accelerometer measures vibration along its axis. Up to three can be connected to measure the three orthogonal X, Y and Z axes at once, or one can be rotated to measure them one at a time.