CONTENTS





Conventions

The following conventions are used in this document.

CTRL+S Keys, or key combinations on a PC keyboard.
<SAVE> Keys, or key combinations on the Terraloc built-in keyboard.
File/Save A sequence of selections in the user interface. In this case, first clicking on File in the menu bar, followed by a click on Save.
Quick menu/3 A sequence of selections in the user interface. In this case, pressing <3> (or 3) after accessing the Quick menu.
20, 40, 100, 200, 400, 1000, 2000 Lists available choices in a menu.





Getting Started

These notes should be read in conjunction with the Terraloc Pro 2 User Manual and Quick Guides, available from the Guideline Geo website:
www.guidelinegeo.com




What is SeisTW?

SeisTW is a Linux application that is used to control the Terraloc seismic system, record and store seismic data, and perform basic processing tasks such as filtering, applying gains, cross-correlation, and picking first arrivals.




The Terraloc Pro 2 Setup Wizard

The Setup Wizard opens automatically on start-up of SeisTW. The Wizard allows quick configuration of the instrument for measurement in a number of common styles by inputting a few survey details. The pre-loaded acquisition settings will work across a broad range of site conditions but please consult the User Manual for more comprehensive coverage of setting up the Terraloc Pro 2, and details of the advanced user settings.


Choose number of channels and survey type.



Quickly define geophone spacing and cable layout.




Main GUI components


MENU BAR

The menu bar presents the user with the available menu choices.


TOOL BAR

The tool bar presents the user with some iconic views of actions that can be performed. The tool can be enabled/disabled by pressing <CTRL>+<1>, or by selecting View/Toolbar. In normal field work, if only the built-in keyboard is used, disabling the tool bar will free more of the screen area for displaying data.


QUICK CONFIGURE BAR

The quick configure bar allows for fast edits of display features and shot location.


RECORD VIEW

The record view shows all traces vertically. On the left side, a time scale is displayed. This time scale adjusts according to sample interval and view options. Tic lines across the view, can be enabled in the View options menu.

At the top of the view, there is a trace marker that can be moved by using the <LEFT> and <RIGHT> arrows. <SHIFT>+<LEFT> will move the trace marker to the first trace, and <SHIFT>+<RIGHT> will move the trace marker to the last trace. This marker selects the current trace. In acquisition mode, the top of the view also displays the current Stack On status, and polarity. The Stack On is displayed by squares above each trace. If the square is filled, the stack for that trace is on, and if the square is open, stacking is off (will not add acquired data). If negative polarity has been selected for a trace, a minus sign is displayed under the square.

To scroll the view use <UP> and <DOWN>. <SHIFT>+<UP> and <SHIFT>+<DOWN> will scroll the view one page at a time.

Press <TAB> to move between views.

Pressing <CTRL>+<SPACE>, opens quick menu with appropriate menu choices.

Press <SPACE> to open a context menu with a selection of useful functions.

Pressing <+> or <-> will move a time-line down or up the view. Related data for the current trace will be displayed in the status field just below the views. Pressing <.> will set a first arrival marker at the location of the time-line on the current trace.

Pressing <CTRL>+<8> opens the Velocity analyzer; <ESC> will close it.


TRACE & FREQUENCY VIEWS

The two lower windows display an enlarged view of the current trace and its frequency content. This view uses the same key functions as the record view. Except, <UP|DOWN> selects the next/previous trace as current trace, and <LEFT|RIGHT> scrolls the view.

Use <CTRL>+<LEFT|RIGHT|UP|DOWN> to move the borders of the trace/frequency view.

The trace & frequency view can be enabled/disabled by pressing <CTRL>+<0> (or by selecting View/Details).

· Trace view

In the enlarged trace window, pressing <0> will toggle between a single moveable time-line and setting a reference time marker at the location of the time-line. If the time-line is moved when the reference time marker has been made active, the status bar will display, in addition to the normal information, the relative time and the corresponding frequency (i.e. reciprocal time).

· Frequency view

In the frequency window, it is possible to check the amplitudes of the frequency components, moving the frequency line by pressing <+> or <->. Please be aware that the values displayed, mostly are interpolated, as the frequency line represents a frequency calculated from the pixel coordinate, which can be in between samples.


STATUS BARS

There is one status bar containing two fields that refers to the current record (left-hand side), and one status bar containing five fields that refers to the instrument (right-hand side).

· Record status bar

The record status bar consists of two fields. These fields display trace-centric information.
- Field #1
This field shows the current record number, i.e. the record number that will be used the next time an acquired record is saved.
- Field #2
This field shows information regarding the current sample at the location of the time-line.

S Number of stacks.
Record / Trace / Freq. Currently active view-type.
t / f Sample time in ms / freq. in Hz.
A/D / Level Measured signal value.

· Instrument status bar

- Field #1
This field shows information recording the current trace.

No data There is no data in the stack memory, and the instrument is ready to arm. In this state all acquisition parameters can be changed.
<<< ARMED >>> The instrument is armed and ready for trig.
<<< Pending arm >>> When multiple instruments are connected and synchronized, this state is activated when the user arms one instrument, and it awaits arm confirmation from the other instrument(s).
<<< Triggered >>> The instrument has triggered and data acquisition is proceeding.
Transferring data ... The data has been acquired to the channel memory and is being transferred to the stack memory.
Data in memory There is data in the stack memory, the instrument is ready to arm. Some, but not all, acquisition parameters can be changed.
<<<SAVING>>> Data is being saved. When the save operation has finished the stack memory will be cleared, the record updated, and the instrument ready to arm.
<<< Testing >>> The geophone test is active.
Geophone test data The stack memory contains geophone test data. Press <SAVE> to save the data, or <ESC> to reject.
Accept or reject? Waiting for the user to accept or reject the acquired data for stack in preview mode. Press <ENT> to accept, <ESC> to reject.
WARNING A minor error occurred, or an informational message has to be displayed. Details will be displayed in a separate message.
ERROR A fatal or major error occurred. Detailed information is displayed in a separate error message.

- Field #2
This field displays the battery voltage.
- Field #3
Channel errors or warnings.
- Field #4 & 5
GPS signal information.




Basic operation

The preferred way of operating the SeisTW software is by using the built-in keyboard. However, it may be operated using any Linux compatible keyboard and mouse. The remainder of this section assumes that the Setup Wizard is not being used.


START A MEASUREMENT

To start a measurement, either press <ARM>, or select File/New (CTRL+N). Selecting New opens a dialog where you can choose acquisition mode (Standard, Roll-along, Optimum offset, or Common offset). For roll-along, you may also choose number of channels for each roll-along record.

Pressing <ARM> will open an acquisition record using the last active acquisition mode.

When a blank acquisition record has been created, you should verify the acquisition settings. The easiest way to access these, is to press:

· Arming & triggering

When all acquisition settings are set, press <ARM> to arm the instrument. The status bar will show the message "<<< ARMED >>>" (see Instrument states).

The instrument will trig according to the Trig Setup settings. When the instrument triggers, this is indicated in the centre field of the status bar, which will show a message "<<< Triggered >>>". When the data has been acquired, it is transferred from the channel memory to the stack memory. The actual behaviour depends on the active stack mode.

· Save & update

Press <SAVE> (or F3) when the acquisition of the current record is finished, to save the data. When the data has been saved, the stack memory is cleared, the layout parameters are updated, and the instrument will be ready for the next <ARM>.

It is possible to only save the data (without clearing the stack memory and updating the record) by pressing CTRL+S (or File/Save, or selecting Save in the Quick Menu).




Acquisition Modes

By pressing CTRL+N, or selecting New under the Quick Menu, it is possible to select which acquisition mode to use. The following acquisition modes are available:

STANDARD

In this mode, all acquisition is performed according to the current settings. The only automatic actions are clearing the stack memory and updating the record after a save & update operation.



ROLL-ALONG

When first pressing <ARM>, a new record is created containing the number of traces defined by the Roll-along start/end parameters in the Layout Geometry Dialog.
Pressing <SAVE> will cause the record to be saved and the roll-along parameters to be updated according to the Roll-long step size as defined in the Layout Geometry Dialog. How the roll-along parameters are updated is determined by the Roll-along reverse direction check box.



OPTIMUM OFFSET

When a record is created it will initially only have the first trace's stack enabled. Besides, only the currently active trace and traces containing data will be visible. When the data for the currently active trace has been acquired, the user can press <SAVE>, which will advance the active trace one trace. Pressing <SAVE> when the last trace is active will save and update the record. It is still possible for the user to modify acquisition parameters, including receiver spread parameters, but be careful. Modifying receiver spread parameters, may lead to acquiring data on a trace that already contains data, but should not be updated.



COMMON OFFSET

When a Common offset project is created only one trace is activated at a time and the input is, by default, set to reference channel 1. Acquisition parameters may be changed but only one trace can be recorded at a time. When <SAVE> is pressed the next trace will be activated. There is no upper limit for how many traces can be recorded.




User Interface





Quick Menu


The Quick Menu is accessed by pressing <CTRL>+<SPACE>. It contains the most important File commands.




Acquisition Setup



SAMPLING INTERVAL

The sample interval in microseconds. Available sample intervals are: 20, 40, 100, 200, 400, 1000, 2000, 4000, 10000 microseconds.


NO OF SAMPLES

Number of samples to acquire for each trace. Available choices: 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 480000.


PRE-TRIG/DELAY

Selects the pre-trig or delay for the trig event. Pre-trig is set by entering a negative time, and will save the corresponding amount of data before the trig event. Delay is set by entering a positive time, and will delay data acquisition after the trig corresponding to the delay. The pre-trig/delay is measured in milliseconds. The pre-trig and delay can be set from 1 ms to the record length; thus the maximum for different sample intervals would be as follows:
Sample interval
(microseconds)
Delay range
(milliseconds)
20 ± 9600
40 ± 19200
100 ± 48000
200 ± 96000
400 ± 192000
1000 ± 480000
2000 ± 960000
4000 ± 1920000
10000 ± 4800000


NO OF STACKS

If this number is greater than zero, the record will be saved automatically when this number of stacks has been acquired. When the record has been saved, the next record will be initialized. If the value is left at zero, there is no automatic saving, the user will need to do this manually. Maximum number is 256.


STACK MODE

The stack mode determines how the acquired data is added to the stack and how it is displayed. The following four stacking modes are available.

· Fast

Adds the acquired data to the stack as soon as the data is available in the channel memory. Does not display the data. The instrument is automatically armed for the next shot.

· Auto

The same as the Fast stack, but the stacked data is displayed. The instrument is automatically armed for the next shot.

· Preview

Displays the acquired data and prompts the user to accept or reject the data. When the data is accepted, it is added to the stack, and the stacked data is displayed. Press <ENT> to accept, or <ESC> to reject, the acquiqred data. The instrument is automatically armed for the next shot.

· Single

Same as Auto stack, but the instrument has to be manually armed again for the next shot.


RE-ARM MODE

Defines what happens after a record is saved.

· Auto

The instrument is automatically re-armed after a record has been saved. This is useful in, for example, marine surveys where you may be shooting repeatedly whilst moving.

· Manual

The user has to arm the instrument by pressing <ARM>, or some external arming signal has to be received for the instrument to re-arm. This is normally preferable when moving shot positions between records, otherwise the instrument may trigger unintentionally.


INPUT VOLTAGE RANGE

Pairs the instrument setup for different types of sensor. For example, regular geophones have a small output signal and would therefore use the 500mV range; sensors with a pre-amp may require a higher input range. Available choices are: 500 mV, 5.0 V and 12.5 V.


INPUT GAIN

This setting complements the Input voltage range setting and available choices are: 0, 12, 24, 36, 48. Note that setting the input gain to 0 dB makes it possible to measure frequencies down to 0 Hz, whereas higher settings gives measurement down to 1 Hz


INPUT IMPEDANCE

Pairs the instrument set-up for different types of sensors. Examples are 3 kOhm for ABEM geophones and 20 MOhm for passive hydrophones. Available choices are: 3 kOhm, 20 kOhm, 20 MOhm.




Trig Setup



TRIG INPUT MODE

Selects trig input source, and its mode.

· Analog

The instrument is triggered when the signal exceeds the trig input level on the analog trig input.

· Make/break

The instrument is triggered when a trigger circuit is closed (make) or opened (break). The most common form of trigger circuit using this format is a hammer switch, where the impact forces a momentary connection (make switch). Prior to most explosive sources using an electric initiator, a loop of wire wrapped around the chagre would deliver a "break" signal when the explosive broke the wire.

The instrument detects the state change from opened to closed (make), or from closed to opened (break), depending on the state at the time of arming.

· TTL rising edge

The instrument is triggered when the TTL signal on the digital trig input goes from low to high.

· TTL falling edge

The instrument is triggered when the TTL signal on the digital trig input goes from high to low.

· Channel

The instrument is triggered when the signal on any channel input, including the reference channels, exceeds the trig input level. If you use Channel triggering, you should check and/or set the
trig input level.

· Manual only

The instrument will only trigger manually from the keyboard (onboard or external).


TRIG INPUT LEVEL

The trig sensitivity level. It can be manually adjusted to suit the triggering device and environment.


EXTERNAL TRIG OUT MODE

Can be set to Off, TTL Rising edge, or TTL falling edge. Determines what signal is output on the external trig output pin in the Aux connector when the instrument is triggered.


EXTERNAL ARM OUT MODE

Can be set to Off, TTL Rising edge, or TTL falling edge. Determines what signal is output on the external arm output pin in the Aux connector when the instrument is armed.


EXTERNAL ARM INPUT MODE

Can be set to Off, TTL Rising edge, or TTL falling edge. Determines what signal received on the external arm input pin in the Aux connector will arm the instrument.


WARN FOR EARLY TRIG

Will warn when there is a risk that sampling was triggered before a stable measurement was possible. A warning is shown in the status bar.


WARN FOR NOISY TRIG

Will warn when there is a risk that sampling was triggered on noise instead of signal level. A warning is shown in the status bar. This setting, together with its three sub settings (Evaluation time, Guard time, and Noise warning level), define how the evaluation is done. If the signal level exceds those bounds, a warning is raised.


EXT. ARM VERIFY

When several instrument are interconnected, the external arm inputs and outputs can be connected in such a way that when one instrument is armed it in turn will arm the next instrument. If the choice is checked, when the user presses <ARM> on one instrument, it will wait until it receives an external arm from the last instrument in the chain before actually accept the arm event. If no external arm is received within the timeout set, the instrument will disarm, and the disarm event will propagate to all the other instruments.


VERIFY TIMEOUT

The time to wait for an external arm before disarming and showing an error message.


EVALUATION TIME

The time window during which the signal level is checked against the Noise warning level (see User Manual for more details).


GUARD TIME

A time window where the signal level is not checked. This is to avoid false warnings from the time just before the trig point (see User Manual for more details).


NOISE WARNING LEVEL

The threshold level for the noise warning (see User Manual for more details).




Noise Monitor Setup

NOISE MONITOR STATUS

Enable/disable the noise monitor. When it is enabled, it will be displayed while the instrument is armed.


GRAPH MIN

Defines lower limit of noise axis.


GRAPH MAX

Defines upper limit of noise axis.


PEAK HOLD TIME

The noise monitor will show red markings to show noise peak values. The peak hold time sets how long the markings will be shown before disappearing.


THRESHOLD LEVEL

When the monitored signal exceeds this threshold level, a warning is displayed in the noise monitor window. Limit of this setting depends on amplitude scale of the noise monitor.


SHOW NOISE

Pressing this button, will display the noise monitor until the user presses <ESC>. Pressing <SPACE> will activate the geophone test relays (a one second pulse). It is not possible to activate the geophone test relays while the instrument is armed.




Acquisition Filter Setup

NOTCH FILTER

· Status

Enables/disables the notch filter. The notch filter is calibrated at factory for either 50 or 60 Hz. The calibrated value is stored in the system configuration.


DC OFFSET CORRECTION

Instruments are calibrated for internal offset, but offset during measurements may appear depending on attached sensors and site conditions. This option will calculate and remove any DC offset from the measured data.


ANALOG LOWCUT FILTER

· Status

Enables/disables the analog lowcut filter.

· Slope

Select the slope of the filter. Possible choices are 12 db/octave and 24 dB/octave.

· Cutoff freq.

Selects the low cutoff (3 dB rejection) frequency in Hz. The possible frequency choices depends on the selected slope:
Cutoff freq (Hz)
12 dB/octave
Cutoff freq (Hz)
24 dB/octave
1215
2430
3645
4860
6075
7290
84105
96120
108135
120150
132165
144180
156195
168210
180225
192240




Layout Geometry Dialog

SOURCE LOCATION

X, Y, and Z co-ordinates of the source location.


RECEIVER LOCATIONS

X, Y, and Z co-ordinates for the receivers. Press <SPACE> to access the Layout Helper Dialog, which can help you to enter the values quickly.
Pressing <CTRL>+<DOWN> from the seconds row and down, will subtract the value in the cell on the previous row from the value in the cell on the selected row, and enter the difference in the cell on the next row and focus to this cell.


MOVE-UPS

Describes how the source, receivers and the receiver connected to the reference channel (if any) are updated when a record has been finished.

· Units

Defines the linear units used for all location data. Possible values are: None, Meters, Centimeters, Feet, Inches. If None is specified it will be up to the user to interpret location data.

· Source type (*)

An appropriate text string describing the source used to acquire this record. Pre-defined values are: Untitled, Hammer, Weight Drop, Seismic Gun, Explosives, and Vibrator. The asterisk specifies that the user may enter any text string in this field.

· Receiver type (*)

An appropriate text string describing the receivers used to acquire this record. Pre-defined values are: Untitled, Vertical Geophone, SH Horizontal Geophone, SV Horizontal Geophone, and Accelerometer. The asterisk specifies that the user may enter any text string in this field.

· Ref. channel

Selects if the reference channel connector is activated, and which channel that will be redirected to this connector. It is possible to re-direct either channel 12 or channel 24 to the reference channel connector. With more than 24 channels installed (i.e. typically 48 channels), it is channels 24 or channel 48 that can be redirected to this connector.


ROLL-ALONG

The settings used to control roll-along measurements (see Mode: Roll along). Note that it is assumed that the lowest numbered trace on the left side and the highest numbered on the right side.
If needed, the channels can be re-mapped as in any other acquisition mode.

· Roll-along reverse direction

If checked, the roll-along segments will be shifted to the left (normally they are shifted to the right).

· First trace

The first (left most) trace of the current cable layout for the current record.

· Step size

Number of steps to shift the roll-along after finishing a record.




Layout Helper

The Layout helper dialog can be used to quickly fill in the receiver locations in the Layout geometry dialog. It is possible to enter values any two of the entries layout start, layout end, and receiver separation. The third entry is calculated automatically.

Pressing <SPACE> in a cell belonging to one of the above entries, causes this entry to become the one that is calculated automatically. Selecting <OK> to exit from the dialog, causes the receiver locations grid to be filled out automatically.


LAYOUT START

X, Y, and Z co-ordinates of the first receiver of the layout.


LAYOUT END

X, Y, and Z co-ordinates of the last receiver of the layout.


RECEIVER SEPARATION

The receiver separation in x-, y-, and z-directions, respectively.




Receiver Spread Dialog

CHANNEL

Specifies the channel mapped to each trace. It is possible to map any channel to any trace, and one channel can be mapped to any number of traces. If the reference channel is enabled, it will be mapped to the trace as specified by the corresponding channel.

Enter the channel number using the numeric keys.

Maps all channels in forward direction (ch. 1 to #1, ch. 2 to #2, etc.).
Maps all channels in reverse direction (ch. 24 to #1, ch. 23 to #2, etc.).


POLARITY

Specifies the polarity of the recorded signal. If the polarity is positive, the signal will be stored as it is recorded. If the polarity is negative, the signal will be inverted before it is stored.

Toggles the value in the current cell.
Toggle the polarity of all traces.
Sets the current trace to positive polarity.
Sets the current trace to negative polarity.
Sets all traces to positive polarity.
Sets all traces to negative polarity.


STACK

Enables/disables stacking for the specified trace. If the stack for a trace is disabled, data cannot be added (or subtracted) from that stack.

Toggles the state of the currently selected stack.
Toggles the states of all stacks.
Enables the currently selected stack.
Disables the currently selected stack.
Enables all stacks.
Disables all stacks.


TRACE

Enables/disables viewing of the specified trace.

Toggles the state of the currently selected trace.
Toggles the states of all traces.
Enables the currently selected trace.
Disables the currently selected trace.
Enables all traces.
Disables all traces.




Header Info Dialog



JOB ID

A text string identifying the job.


LINE ID

A text string identifying the seismic line.


CLIENT

A text string naming the client of the job.


COMPANY

A text string naming the company of the client.


OBSERVER

A text string naming the observer(s).


NOTE

A free form text string.




View Options

GENERAL SECTION

· View mode

The view mode determines how data is scaled for the display.
Enhanced
The data is not scaled, but the amplitudes are used directly. It is, however, possible to attenuate the displayed signals using the enhanced attenuation parameter.
Normalize
The max value in each trace is used to scale all samples in the trace. See also global scaling.
AGC
Uses the average amplitude calculated from a running window (which length is specified by the AGC window parameter). This means that each sample is scaled according to the average signal level in the samples vicinity.
Hyperbolic
Applies a hyperbolic scaling to the data. If the logarithmic choice is selected, the function ArcSinH will be used, otherwise the function TanH is used.

· Trace style

VAR+
This is a wiggle trace with the positive side filled-in.
VAR-
This is a wiggle trace with the negative side filled-in.
Wiggle
The trace is plotted as a wiggle.
Dotted
Each sample value is plotted as a dot.

· Time compression

Selects compression in time. This makes more of the record visible. Available compressions: 1x, 2x, 4x, and 8x.

· Scale factor

A general factor by which every sample is multiplied.

· >Trace clip

How many traces the plotted curve may overlap before it is clipped. With trace clip = 1, no overlap will occur. If trace clip is 2, a trace may overlap the positive part of the trace on the left, and the negative part of the trace on the right.

· >Remove DC offset

If enabled, the DC offset is removed before the trace is scaled. It is recommended to keep this enabled.

· Show tic lines

Major and minor tic lines are plotted. The time interval between the tic lines is determined by sample interval and time compression.


· A/D conv. units

Defines the unit type for the A/D-value that is displayed on the Record Status Bar. Available formats are µV, mV, mm/s, cm/s, or None (raw A/D value).


NORMALIZE SECTION

The maximum value in each trace is used to scale all samples in the trace.

· Global scaling

If enabled, the maximum value in the whole record is used to normalize every sample of all traces.


AGC SECTION

Uses the average amplitude calculated from a running window. This means that each sample is scaled according to the average signal level in the sample's vicinity.

·AGC window

Length of the running window, in milliseconds, used to calculate the average value for scaling a given sample value. The window moves along the trace with each sample that is scaled.


ENHANCED SECTION

The data is not scaled, but the amplitudes are used directly. It is, however, possible to attenuate the displayed signals using the enhanced attenuation parameter.

·Average

If enabled, the average values on the stack is used for each trace, otherwise the summed stack is used.

·Attenuation

Used to attenuate the signals. This will bring out weaker signals, while hiding stronger signals.


HYPERBOLIC SECTION

·Logarithmic

If enabled, ArcSinH is used a scaling function, otherwise, TanH is used.

·Linear range

This value sets the amplitude level that is within the linear part of the scaling function. Both scaling functions are linear in the beginning (for small amplitudes), while compressing larger amplitudes.


COMMON OFFSET SECTION

· Show layout geometry

Not currently used (in future this will automatically open the Layout Geometry window after each trace is completed, ready to update positions).

· Number of traces to display

Sets the number of traces that will be displayed in the Record View (only available if acquisition mode is set to Common Offset).


FREQUENCY ANALYSIS SECTION

·Windowing function

Selects function to be used for data windowing. Possible values are No window, Hanning, Hamming, Blackman, Bartlett, Kaiser, 4th order Blackman-Harris, Flat top.

·Max frequency

The maximum frequency to display. The displayed spectrum will go from 0 Hz up to the selected maximum frequency. Possible values are

50, 100, 200, 500, 1000, 2000, 5000, 10000, 20000, 25000.

·Dynamic range

The maximum frequency component is used as reference when calculating the spectrum. The dynamic range can be set to 6 dB up to 198 dB in 6 dB steps.




Velocity analyzer

The velocity analyzer can be used to estimate the apparent seismic velocity in refraction records. When the analyzer starts, it checks the receiver locations and calculates the receiver separation. If the receiver separation seems to be erroneous, or the receiver locations are not specified, the user can enter a valid separation value in the dialog at the top of the window.

Controls for the analysis line are listed in the keyboard shortcuts below and in the "Keyboard" help document.




Context menu

The Context Menu is accessed by pressing <SPACE>. It contains some important actions and tools, and the available options change depending upon the status of the instrument and what is currently on-screen.


FIRST BREAKS

Access the first breaks sub menu (see First breaks).


VELOCITY ANALYZER

Activates the Velcoity analyzer.


ACTIONS

Choose to Arm the instrument, undertake a Geophone Test, Force Trig the instrument or Disarm the system.


CLEAR Traces

Delete the current contents of the record, either by removing everything, removing data from only the active traces, or removing the data from the selected trace.


FIR FILTER

Access the FIR filter dialog.


MOVING AVERAGE FILTER

Access the Moving average dialog.


UNFILTER DATA

Discards any processing results and reads back the original data from disk.


CROSS-CORRELATE

Performs cross-correlation of the data.


VIEW OPTIONS

Access the View options menu.




System Information

The System Information dialog displays information about the instrument, serial number, software versions, etc. The following details are important to note.


The receiver board list

- For a 12-channel instrument, two boards should show: Board 0 (trig + 2 reference channels) and Board 1 (12 channels).
- For a 24-channel instrument, three boards should show: Board 0 (trig + 2 reference channels) and Boards 1 & 2 (12 channels each).
- For a 48 channel instrument, five boards should show: Board 0 (trig + 2 reference channels) and Boards 1, 2, 3 & 4 (12 channels each).


The API and Driver version numbers

- These two numbers have to be identical.




Process





FIR Filter

Clicking on OK will apply the filter to the current data.


FILTER TYPE

Selects the type of filter to apply to data. Available choices are Low pass, high pass, band pass, and band reject.


WINDOWING FUNCTION

Data windowing function to apply to data when filtering. Available choices are Hanning and Blackman.


CUT-OFF FREQUENCIES

The cutoff frequencies are specified as the frequency where the passband signal has been reduced by 3 dB and the transition band starts. The low- and high-pass filters only specify a single cutoff frequency, while the bandpass and bandreject filters specify two, low- and high cutoff frequencies.


FILTER LENGTH

The number of filter coefficients used to realize the filter. The longer the filter, the steeper its slope; i.e. it will cut the signal more abruptly. A longer filter also takes longer to apply, especially on long records.




Cross correlate

Selecting Cross correlate in the context menu, shows the Reference trace selection dialog. Enter the trace number that was used for the reference signal when doing a vibration seismic acquisition, and then press <OK>. The cross correlation may take several minutes, so be patient.

Below are two figures showing a raw data from record acquired using vibration seismics, and then after cross correlation.

Raw data



After cross correlation.




First breaks

These entries are accessed via a sub menu in the Context menu.


AUTO

Performs an automatic first break pick.


CLEAR

Clears the first break picks.


SAVE

Saves the first break picks to a text file in the current directory. This is saved in the REFLEXW pck-format but, as this is a simple text file, it can easily be amended to suit the import requirements of other software packages.



LOAD

Loads the first break picks from a pick file to the currently active record. If there are more picks in the pick file than traces in the record, the superfluous picks are discarded. If there are fewer picks, only the first traces loads the picks.




Moving average

Perform a moving average filtering of the current data. The user selects the number of samples to use when calculating the average.




Keyboard

GENERAL

The tables below describe the additional functions of the Terraloc keys. In other words, the <SPACE> key is only described when it has some special function (e.g. opens a context menu), and not that it generates a space-character when entering text.

Open Context Menu (or open Layout Helper in the receiver box of Layout Geometry menu)
Open Quick Menu
Select Menu Bar
Show/hide Toolbar
Show/hide Trace View and Frequency View
Show/hide Logging Window



Moves the borders of the Trace View, Frequency View and Record View.
Open Preferences dialog
Open the OS menu
Open the Acquisition setup
Open the Trig setup
Open the Noise monitor setup
Open the Acquisition filter setup
Open the Receiver spread dialog
Open the Layout geometry dialog
Open the Header info dialog
Open the View Options dialog
Navigate between view panels or fields in dialogs
Navigate back between view panels or fields in dialogs
Select Trace Style toolbar
Select Time Comp toolbar
Select Scale Factor toolbar
Select Trace Clip toolbar
Save the current file (overwrite prompt if file already exists)
Open Save As dialog
Force save current file (overwrite any existing file)
Quick Backup
Edit source/receiver positions for current file
Edit header information for current file


Acquisition mode

Arm the instrument
Force the instrument to trigger
Run a geophone test & display results
Disarm an armed instrument or reject current shot / stack
Save current shot / stack to the record
Delete the last shot / stack (if the data is still in the channel memory)
Save the current file (overwrite prompt if file already exists)


Record/Trace/Frequency View

Shift focus to next View
Record View: move trace marker right
Trace View: scroll trace right
Record View: move trace marker left
Trace View: scroll trace left
Scroll Record View down
Scrolls Record View up
Scroll Record View down one page
Scroll Record View up one page
Move time-line down, hold to accelerate
Move time-line up, hold to accelerate
Move time-line down in large steps
Move time-line up in large steps
Set a First Break marker at time-line position on selected trace


Velocity Analyzer

Start velocity analysis
Select a field in Velocity Analyzer bar at top of page
Move analysis line down trace
Move analysis line up trace
Move analysis line right one trace
Move analysis line left one trace
Decrease apparent velocity
Increase apparent velocity
Lengthen / shorten analysis line by one trace
Lengthen / shorten analysis line by one trace


Noise monitor

When the instrument is armed and the noise monitor enabled, all acquisition mode key inputs are valid.
Increase threshold level
Decrease threshold level
If only monitoring noise (i.e. instrument not armed), send a test pulse to the geophones
Increase minimum on dB axis
Decrease minimum on dB axis
Increase maximum on dB axis
Decrease maximum on dB axis


Receiver Spread Dialog

With cursor in "Polarity" column, set current trace to positive
With cursor in "Polarity" column, set current trace to negative
With cursor in the "Channel" column:
- Map channels in forward direction (ch. 1 to #1, ch. 2 to #2, etc.)
With cursor in the "Polarity" column:
- Set all traces to positive polarity
With cursor in the "Channel" column:
- Map channels in reverse direction (ch. 24 to #1, ch. 23 to #2, etc.)
With cursor in the "Polarity" column:
- Set all traces to negative polarity
With cursor in the "Polarity" column:
- Toggle value in selected cell
With cursor in the "Stack" or "Trace" column:
- Toggle state in selected cell
With cursor in the "Polarity" column:
- Toggle polarity in all cells
With cursor in the "Stack" or "Trace" column:
- Toggle state in all cells
With cursor in the "Stack" or "Trace" column:
- Enables selected cell
With cursor in the "Stack" or "Trace" column:
- Disables selected cell
With cursor in the "Stack" or "Trace" column:
- Enable all
With cursor in the "Stack" or "Trace" column:
- Disable all


External keyboard translation

When using an external keyboard, the keys on the instrument panel are represented as follows: