24-bit Digitizer
Model DAS-6503

The DAS-6503 is a ultra low power, high-performance, versatile 24-bit resolution digitzer.

When combined with a PMD/eentec, or other seismometer, it becomes a high resolution digital seismometer.

The digital data stream can be connected via an RS-232 or RS-485 serial port via a digital radio or cable link to a central data collection computer.

The large SRAM buffer ensures reliable data retrieval even in highly unreliable transmission conditions.

The digitizer consumes extremely low power without sacrificing its high resolution, deep anti-aliasing filtering, and wide range of programmable parameters.

This versatile device can adapt to many applications and configurations: Mounted within the case of a PMD/eentec broadband seismometer. As a stand-alone attachment, it can convert the output of any analog sensor into a digital stream. It can be readily fit into a benthic sphere or other pressure vessel along with a seismometer for OBS applications.

  • 24-bit high resolution

  • 132B dynamic range

  • Low Power

  • High accuracy GPS timing

  • 4 to 8 channels

  • Analog and digital alias filtering

  • Flexible packaging

  • Mounted internally within sensor or OBS
Type: Differential or Single-Ended
Data Channels: 4; opt. up to 8; Specify Differential or Single-Ended
State-of-Health 4th Channel: Standard: 24-bit resolution,
Gain: 1,2,4,8,16,32,64 progammable
Differential Input Signal Range: Programmable: 2.5, 20 V
Dynamic Range: >132 dB @ 100 sps (rms to FS)
Analog Anti-Aliasing Filter: >100 dB @ primary sampling rate
Input Impedance 2.5V - 1Mohm;
20 V - 26kohm
Overvoltage Protection 40 V
Type: 24-bit delta-sigma converter in each channel (320 kHz)
Sampling Rates: 0.1, 1, 10, 20, 40, 80, 100, 200, 500, 1000, 2000, 4000 sps
Digital Filter >130 dB @ 200 sps (FIR)
CMR @ 50, 60 Hz 120dB
Phase Linear within the passband
Type: True Real Time PLL controlled, GPS-referenced
Maximum Accuracy : <1 microsec (Software Selectable)
HOW TO ORDER Crystal Oscillator Standard: 25ppm; Optional TCXO 1 ppm/year
Basic DAS-
6503 Configuration
The standard configuration includes 4 channels and GPS antenna/receiver.
Channel Configuration

option -8CH,

Microsoft Windows O/S option -MSW
Internal Modem option -56IM
Sensor Options EP-300 Broadband,
EP-105 Broadband,
SP-400 Medium Period Seismometer,
R-1 Rotational Seismometer
Supplies and Accessories External Battery pack w/ charger (specify voltage)
General Spares GPS antenna/receiver
Set of spare boards
Battery (specify capacity)

S Printer Friendly Format For Specifications

Crystal Frequency Correction Resolution 0.016 ppm
Calibration 3.3V square wave (others optional)
Calibration Duration User selectable
Voltage: 6 - 16 Vdc
Overvoltage protection: 60 V
Power consumption ~0.50W (3 channels, 100 sps, cycled)
Remote PC: RS232 com2 port
Continuous Data Tansmission : RS232 or RS485 (up to 1km) serial ports; optional internal modem
Housing Depends on application
Operating Temperature -30 to +50C
Size (board stack) L4.7 x W 4.7 x H 2"
L 120 x W 120 x H 50mm
Weight ~0.5 kg
Power Depends on application
Data Channels (4) and sensor power Depends on application
Serial port Subminiature DB9
GPS Subminiature DB9

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