256/512 CHANNEL OPERATION
- For most geophysical applications, the 256 channel operation is fully adequate. However, the extra precision provided by the 512 channel capability, especially in the lower regions of the spectrum, offers significant improvements in data resolution for the environmental sector. This 256/512 channel option is software selectable from the GR-320 keyboard.

TWO DETECTOR CAPABILITY
- In most portable applications a single 21 cubic inch sodium-iodide detector is adequate. However, in surface vehicle, helicopter and aircraft applications, larger crystals are required. The GR-320 can support detector packs of up to 512 cubic inch size.

AUTOMATIC SPECTRUM STABILISATION
- The operator may select to stabilise the system using an internal Cesium source, or choose a naturally occurring isotope at the site of operation. In the local isotope mode, the system automatically accumulates until the isotope data is useable for gain control. This feature is especially important for environmental applications.

CALIBRATION
- Exploranium calibrates each spectrometer on test pads traceable to GSC standards to assure the accuracy of each instrument.

ASSAY MODE
- Using internal calibration constants, the GR-320 measures concentrations in %K or ppm of U and Th.

REGIONS-OF-INTERESTbr> - Up to 8 ROIs may be set from the system keyboard.br>
EXPOSURE RATE
- For environmental applications, the GR-320 does automatic natural isotope spectrum stripping, and then carries out a full peak analysis to identify any isotopes in the stripped spectrum. The individual isotope exposure rate is then computed by using internal calibration data.

HIGH LINEARITY ADC
- The GR-320 uses a unique technique to achieve fast, zero dead time analog-to-digital conversion with excellent differential linearity. This capability is important in large detector/high count rate applications.

COINCIDENCE
- Either coincidence or anti-coincidence operation is possible when two detectors are used with the GR-320.

GPS DATA
- The GR-320 has the capability to accept the location data from a portable GPS receiver. This location data is then stored with the spectrometer data in internal memory. This feature gives users the capability of fully portable field measurements with a minimum amount of equipment.

REAL TIME CLOCK
- A real time clock is built into the system.

DATA STORAGE
- The GR-320 enables the operator to select combinations of ROI, spectra and GPS data to be stored in an internal memory (capacity 384 kbytes) or put out via an RS-232 port. For example, if ROI alone is selected, a maximum of 4468 sets of ROI data may be stored. If spectrum and GPS are selected, up to 335 spectra data points and location data can be stored in the 512 channel mode.

DISPLAY
- An LCD graphics display is used to display computed data as well as full spectra data.

DIGITAL OUTPUT
- Bidirectional serial (RS-232) output port with operation up to 19200 Baud is provided. Data is fully buffered so that 1/sec data transfer of full spectrum data does not interfere with data acquisition.

POWER
- The GR-320 is powered by a rechargeable battery pack with built-in charger, or by 9-15V DC external power. The following power options are also available: a battery pack for operation with 6 x "D" type alkaline batteries, and a power attachment permitting operation from 14-40V DC.

DETECTOR SPECIFICATIONS

GPS-21
-Hand carry detector: 0.35 litres (21 cu. ins.), (114 mm diameter x 394 mm length (4.5"x 15.5") , 3.6 kg (8 lbs)

GPS-112
- Portable detector: 1.8 litres (112 cu. ins.), 152 x 152 x 457 mm (6" x 6" x 18"), 12.7 kg (28 lbs)

GPS-256
- Vehicle borne: 4.2 litres (256 cu. ins.), 216 x 178 x 787 mm (8.5" x 7" x 31") , 24 kg (53 lbs)

GPS-512
- Vehicle/airborne: 8.4 litres (512 cu. ins.) , 330 x 178 x 787 mm (13" x 7" x 31"), 44 kg (98 lbs)