Geotech Instruments, LLC

16-Bit Remote Digitizer

Model 49.65

  • 16-bit digital resolution
  • 50 or 100 samples per second
  • 1 to 3 channel inputs

Geotech's model 49.65 remote digitizer is a 16-bit analog-to-digital converter designed to operate with Geotech preamplifier/filter module PF.70 in our Compact Remote Station system. The Model 49.65 remote digitizer features an RS-232 compatible output with jumper-selectable sample rates of 50 and 100 samples per second for 1 to 3 channel operation.

The 49.65 provides three 7-pole, low-pass filters and oversampling techniques for additional digital filtering. Additional anti-alias filtering is provided by the selectable filters in our preamplifier/filter modules. Their cut-off frequencies are 12.5 Hz and 25 Hz for sampling rates of 50 and 100 samples per second, respectively.

System testing and calibration are simplified by Geotech software that operates on any IBM-compatible PC system. At a central station, the 49.65 signals are received by Geotech's Intelligent Communications Processor system. 



TECHNICAL SPECIFICATIONS
                                  
INPUT

Number

Voltage Range
Impedance
Noise Level

 - 1 or 3 data channels, jumper selectable. One Auxiliary channel, jumper selectable
- 4.5 V
- Greater than 10 MOhms (at dc)
- Less than 0.14 mV rms
 
OUTPUT

Type
Baud Rates
Transmission Rate

 - RS-232 levels, asynchronous
- 2400, 4800, 7200, or 9600, selectable
- One second of data is transmitted once per second		 
DIGITIZER

Resolution
Multiplexer
Rate

Track Period
Hold Period

 - 16-bit ±½ LSB
- 8 channels, 3 data plus 5 test data
- 1600 samples per second (the data channels are later re-sampled 200 times per second)
- 555 microseconds
- 70 microseconds		 
POWER REQUIREMENTS

Voltage
Current
Voltage Sensitivity

 - 8.5 to 14 V dc
- 95 mA (+), 40 mA (-)
- At 12 V input a 2 V change will affect full scale calibration by less than ±½ LSB		 
 HARDWARE FILTER

Type
Damping Factor
Gain
Cutoff Frequency

 - 7 pole low pass
- 0.70 (Q = 1.4)
- 1.0 ± 0.1%
- 12.5 Hz @ 50 sps or 25.0 Hz @ 100 sps, jumper selectable		 
SOFTWARE FILTER
The basic sample rate of 200 sps is reduced to 100 or 50 sps by simple averaging. For 100 sps data, 4 samples are averaged for every two samples received. For 50 sps data, 8 samples are averaged for every 4 samples received. 
ENVIRONMENTAL CHARACTERISTICS

Operating Temperature
Storage Temperature
Humidity Protection

 - -20 ºC to 60 ºC
- -45 ºC to 70 ºC
- Conformal coating
 
 PHYSICAL CHARACTERISTICS

Dimensions
Height
Width
Depth
- 3.25 in. (8.25 cm)
- 6.2 in. (15.75 cm)
- 0.5 in. (1.27 cm)