Introduction

SEIS-UK's high frequency system is based around 15 SAQS data recording units as supplied by ISS International ltd. Up to six geophone or accelerometer channels can be recorded continuously or in triggered mode. SEIS-UK maintains a suite of 4.5Hz and 30HZ geophones, and also piezoelectric accelerometers, for use with these instruments.

Alternatively, six Reftek 130-01 broadband data loggers are also available. The 130-01 is compact, light weight andlow power. These are capable of storing analog input from a variety of external sensors, including seismometers, accelerometers, tiltmeters and other geophysical sensors. SEIS-UK maintains GS-11D 4.5Hz geophones for use with the RefTek.

To date, these instruments have been involved in projects to investigate icequakes in Antarctica, as well as progressive hydrofractures in Wyoming. Once configured the SAQS are reasonably simple to use and can be deployed with minimal user interaction using the integral LCD screen. However, the SAQS are potentially configurable in very large number of ways, which can lead to a complex, and potentially time consuming, pre-deployment set up.

Below are datalogger and sensor specifications, shipping information and some useful downloadable material. Much of the information presented in this page is from ISS International ltd.

Specification, SAQS Datalogger

Total number 15
Digitiser
Integral 24-bit
Data output
ISS proprietary format (converted into miniSEED)
Memory
Removable 40GB firewire (IEEE1394) hard drive
Data download
Disk swap
System control
ISSI software running on Linux with communication via RS232 port
Power consumption
3.3 - 12W, typically ~4W - dependent on the number and type of sensors connected and the sample rate used.
Power supply
12V DC
Dimensions
270mm x 250mm x 125mm
Weight
3kg
Sampling rate
50Hz - 24kHz
Operating temperature
-25°C to 40°C
GPS
External and internal GPS antenna

Specification, RefTek Datalogger

Total number 6
Digitiser
Integral 24-bit
Data output
Reftek Format
Memory
4MB battery backed SRAM, plus two removable CFII cards with 16Gb capacity.
Data download
Data from the removable flash can be read on any PC/Workstation using a CP-11 reader. Data can also be remotely downloaded from the 130-01 disk using FTP over LAN/WAN.
System control
Achieved either with a PDA (Palm OS) device running PCF software or with a PC or workstation running RTI application software set.
Power consumption

1-2.1W depending on the number of channels recording and the presence of communications.

Power supply
10-16V DC
Dimensions
135mm x 185mm x 353mm
Weight
2kg
Sampling rate
1000, 500, 250, 200, 125, 100, 50, 40 ,25 ,20, 5, 10, 1 sps
Operating temperature
Free running accuracy of 0.2ppm over 0 to -20°C and 0.1ppm between 0 to 60°C
GPS
External GPS antenna and internal high precision TCXO

Specification, SM-6B 4.5 Hz Geophone (Input/Output Networks)

Total number 12
Natural frequency
4.5 Hz
First spurious frequency 140 Hz
Damping
0.56 ohm
Sensitivity
28.8 V/m/s
Resistance
375 Ohm
Approximate useable bandwidth
4.5-2000Hz (approx)
Dimensions 116mm x 69mm x 83mm
Weight 590g

Specification, 30 Hz Geophone (ISSI)

Total number 15
Natural frequency
30 Hz
First spurious frequency 900Hz
Damping
Sensitivity
11 V/m/s
Resistance
Approximate useable bandwidth
30-2000Hz (approx)
Dimensions  
Weight  

Specification, 4.5 Hz GS-11D Geophone (RefTek)

Total number 6
Natural frequency
4.5 Hz
First spurious frequency
Damping
0.34 ± 20%
Sensitivity
81-2.54 V/in/sec
Resistance
Standard coil resistance of 380 ohms
Approximate useable bandwidth
4.5-1000 Hz
Dimensions
Height 33.5mm, Diameter 31.8mm
Weight
0.111 kg

Specification, Piezoelectric accelerometer (ISSI)

Total number 15
Natural frequency
n/a
First spurious frequency n/a
Damping
0.27
Sensitivity
0.5 V/g
Resistance
900 ohm
Approximate useable bandwidth
0.2-2300Hz
Dimensions  
Weight

Shipping information

All the high-frequency systems ship in aluminium Zarges cases containing a datalogger, a geophone, accelerometer, power regulation unit, a GPS antenna and all required cabling.

Power supply will be dependent on survey design and location. Batteries must be provided by the user, whilst solar cells (if used) may be available from SEIS-UK up to a reasonable capacity.

SEIS-UK is able to offer advice on the appropriate number of solar panels and batteries necessary for your deployment period and location.

Instrument box dimensions 600mm x 390mm x 400 mm
Instrument box volume 0.9 cubic meters
Instrument box weight 12.5kg (SAQS)
Instrument box weight 10kg (RefTek)

Links and Downloads

   
   
  link: excel sheet of field logs
SAQS Huddle Test Sheet
 
SAQS - Recommended field procedures
link: rtf of deployment and servicing sheets link: pdf of deployment and servicing sheets
SAQS Deployment and servicing sheets
  link: pdf showing screen captures of saq menu options
Examples of SAQS screen shots
  link: pdf on configuring RTS
Configuring the ISS runtime system
  link: pdf showing screen captures of accelrometer data sheet
Accelerometer datasheet
  link: pdf showing screen captures iss sensors
ISS sensors document
  link: pdf showing screen captures of geophone data sheet
I/O SM6-B Geophone datasheet
  link: pdf showing screen captures comparing different hf sensors
Sensor comparison
   
     
    Reftek Inc.