SeaDAQ

Synchronised Data Acquisition System
Geotechnical Instrumentation
6 - 14V DC 1.8W Power Supply
Operating Temperature Range - 40 to 60 Deg C
Corrosion Proof / waterproof Enclosure Options
8 Full differential Inputs +/- 2V Rms Range
24 Bit ADC Resolution Sigma Delta Converters/Channel
To 100 KHz/channel operations.
2 Digital TTL compatible Inputs
2 Digital Outputs
4 point Auto Calibration
155.52 Mb ATM network interface
Fully Synchronised analogue and digital inputs within the instrument  
Fully Synchronised operations between instruments across ATM  networks.
Fully compatible to Vanilla (Industry Standard) network systems.
Introduction

The SeaDAQ is a high speed, high resolution measuring instrument with control systems capability designed to operate in the harshest of environments. The SeaDAQ offers high performance synchronised data acquisition operations not only between channels in an instrument but also between any number of instruments on a network. Unlike Ethernet operations the SeaDAQ uses a common clock signal across the network that synchronises all instrument operations. So long as the clock signal is present then all operations are absolutely synchronised.    
The SeaDAQ can be supplied in a range of sealed corrosion proof enclosures from titanium to stainless steel to meet any requirement. The instrument enclosure utilises the same metallic construction in all component parts in order to prevent electro-chemical potentials forming between dissimilar components and thus prevents corrosion damage
Sample Rates

The table opposite shows a summary of the sample rates versus number of nodes and therefore channels that can be deployed on a single SMT-1 and OC3 fibre optic network. In practice the sample rate of the instruments be incremented in steps of 8 KHz from 0 to a maximum sample rate of 96 KHz/channel. In practice 100 KHz/Channel can be achieved if requested at time of order. All instruments on a network and channels within an instrument are synchronised together. The digital input level readings are synchronised to that of the analogue readings. It is currently not possible to mix sample rates between instruments connected together on the same network.
Sample Rate
 Per Channel
Sonet
 Nodes
Number of Channels
8 KHz
72
578
16 KHz
36
288
48 KHz
12
96
96 KHz
6
48
Synchronisation

 All of the analogue inputs are synchronised within an instrument to within a time skew of 10 ns. All inputs are further synchronised across a network. The driver software can be used to correct for the time delay that occurs between instruments  due to the propagation delay between the individual instruments on a network. The propagation delay between nodes is typically 0.15ns/metre.