If you're trying to optimize your Geode system for faster trigger cycles—especially in high-repeat environments—there are a few key factors to consider. The goal is to ensure that the system completes its entire cycle (trigger → recording → data transfer → re-arming) before the next expected trigger. Here’s what influences that cycle:

🧠 Core Factors That Affect Cycle Times

1. File Size (Sampling Parameters)

2. Data Transfer Rate

3. Calibration Frequency

4. Recording Delay and Record Length

⚙️ Best Practices

The last version of the SCS software support all 32-bit and 64-bit of Windows since Windows 7. Windows servers are excluded, since they have not been tested, but should work.

The hardware requirements are more complicated as it depends on the type of seismic survey, number of channels and software product SCS (SGOS, MGOS, ESOS, ...), SAS and options. It also depends how many network cards are needed, sample rate, and record length.

For small systems, SCS will require at a minimum 512MB of free memory. For large systems up to a Maximum of 2GB of free memory. The CPU follow the same pattern. Any CPU since Pentium 90, if supported by the OS, will work for small systems. A bigger survey system and continuous recording software may need i5 or i7 type CPU. An SSD drive may also be needed.

See SCS software license agreement.

The Trigger Master and Trigger Distribution

The trigger event occurs at the Geode designated within the Controller software as the Trigger Master. Although all Geodes are capable of being Trigger Masters, there must be one and only one Trigger Master in any properly functioning Geode system. The Controller automatically takes care of this requirement when the designation is made by a user, and when the system is established at the time of Controller start-up based on a previous designation (or a default setting in the case of a “new survey”). All other Geodes in the system will have their Trigger Master circuit disabled. A trigger event can be initiated by an external electrical pulse provided to the trigger input connector of the Trigger Master Geode, or by a command sent via Ethernet from the Controller to the Trigger Master (usually for test purposes), but only when all conditions are satisfied to allow data recording. There is also a special trigger initiation situation, called “self-triggering” which will not be discussed further here.

Upon acceptance of a trigger event, the Trigger Master will distribute the trigger signal to all Geodes in the system, itself included, via an RS-485 network that resides within the digital interconnect cabling. (Proper termination of this RS-485 network is automatically taken care of by the Controller.) The trigger signal is propagated through the cabling and Geodes at the nominal speed of 70% of the speed of light, or approximately 2.1x10^8 m/sec. The maximum distance of successful propagation depends on a number of factors such as the number of Geodes involved, the noise environment, the quality of the cables, and the acceptable amount of timing uncertainty for the particular application. Distances approaching or exceeding 1km should be given careful attention in this regard. In a 3-D Geode system involving LTUs, each LTU, unlike a Geode, will reconstruct the trigger signal before sending it on, effectively confining the maximum distance issue to each sub-network separated by LTUs. The penalty is an additional delay of about 100nS for each LTU in the route.

The External Trigger Circuit

The external trigger input is capacitively coupled, with a 2mS time constant, to the midpoint of a resistive voltage divider. The voltage difference between the two ends of the divider constitute a voltage "window", which size is set by the trigger sensitivity parameter and can range from essentially zero at the highest sensitivity, to about +/- 2.5V at the lowest sensitivity. The Geode will trigger (if enabled) if and when the coupled signal exceeds the window, in either direction (i.e., positive or negative going). The signal, after the capacitor, is clamped by diodes to the range between the trigger signal ground and +5VDC. The trigger detector output is disabled when the system is disarmed, during a parameter change, and during a shot, up to the trigger hold-off time after the end of the shot. The trigger hold-off time is a parameter set by the user.

Preceding the coupling capacitor (i.e., essentially the node accessible at pin A of the external connector), there is a 3.3K-Ohm pull-up resistor to +5VDC (relative to pin B). Also a fast transient suppressor clamps the input at about +/-14VDC. It is advised that the DC + AC level of any voltage applied to pin A relative to pin B be kept within the range of +/-7V, giving some margin of safety.

If a DC voltage somewhat less than +5VDC is applied when the connector is first mated, the instrument may trigger at that moment. But, subsequently, because of the capacitive coupling, it will trigger on the next positive or negative going pulse that exceeds the window level. If the duration of the applied voltage pulse is less than the record length + delay time + hold-off time, then the Geode will effectively be ready to trigger on the same edge of another similar pulse.

Sub-sample Synchronization

The Geode supports a sub-sample timing synchronization feature used for synchronizing the data acquisition after a trigger event to the distributed trigger signal, so that subsequent time points will be known to within 1/32 (~1/20 at the fastest two sampling rates) sample interval. It does this by increasing the sample interval at the trigger time by 0 to 31/32 of a sample interval in increments of 1/32, so that the first sample after the trigger would represent a time of one sample interval after the trigger event, with a tolerance within 1/32 of a sample interval. The following samples continue from there at the expected intervals. For example, with a selected sampling interval of ¼ mS and a recording delay of 0mS, the first sample in the recorded file for each channel would represent data at 250 to 258uS after the trigger event.

This of course potentially introduces a small discontinuity at the time of the trigger, observable depending on the nature of the channel waveform(s). (The zero-phase anti-alias filter will smear the discontinuity into the nearby samples both before and after, consistent with the bandwidth of the filter.) Sub-sample synchronization can be disabled if it is deemed to be detrimental for the particular application, at the expense of losing the 1/32 interval timing accuracy.

Timing Errors

The principal errors in Geode timing are of two types: those associated with the trigger mechanism and which are static over the duration of the record, and those associated with the time base and which change over the duration of the record. Excluding the trigger propagation delay mentioned above, the trigger timing uncertainty is about 1uS. The known fixed errors have been lumped together and are reported in the SEG-2 file trace headers as channel SKEW. (The actual channel skew is zero, since all channels are effectively sampled simultaneously, but the SKEW value in the header is used as the only place permitting small timing corrections. Note that the SKEW value for every channel is identical.) If the size of this correction is important to the application, the SKEW value should be added to the calculated time points when the data is being processed.

The Geode time base has a +/-15ppm stability over temperature (-20C to +70C) and component variations. Thus time drift relative to absolute time and relative to other Geodes is possible. (However, all channels within any Geode enclosure use the same time base, so there is no relative drift between channels in the same enclosure.) Therefore timing uncertainty increases from that existing at the time of the trigger until the time of the next trigger (or end of record).

Special Timing Issues Involved with “Continuous” Recording

“Continuous” recording is a method that allows unending 100% time coverage with recorded Geode data. It produces a series of time-overlapped records created by the use of a negative time delay set equal to the record length such that each record consists of completed history at the time of the trigger event. This technique circumvents the problem of data transmission overrunning data acquisition. The principle constraint is that the cycle time from trigger to trigger must always be less than the chosen record length. Otherwise, gaps rather than overlap would result. Commonly it is used with GPSderived triggering in order to provide time-stamping of each trigger event.

Upon consideration of the above, it will become clear that the time-stamp associated with a particular trigger event will pertain to the data in the following record, not to the data in the record in which the time-stamp is written. This comes about because the trigger event ends the record.

Because there is data overlap between records, the precise trigger point in the following record at which the time-stamp applies can be found by comparison of the data values at the end of the former record with those near the beginning of the subsequent record. The overlapping data will be exactly identical in both records (since they are read from the same memory location, twice). The earliest data in the subsequent record that goes beyond the data of the previous record is the data that is one sample interval (assuming sub-sample synchronization is enabled) past the time-stamp.

Note well that this comparison must be made independently for at least one channel of each 8-channel Geode board set, because the discrete time at which data values are written to the memory buffer, relative to the trigger event, is a function of each individual board set in the Geode system.

Correct GPS Time-Stamping

There are differences between various GPS models that can affect accurate time stamping. The 1PPS signal from a GPS has a “timing edge” and return edge, of which only the former is the true whole-second edge. Some models use a rising edge as the timing edge, some the falling edge, and some have it selectable. Consult the GPS manual to determine the definition of its timing edge. As indicated earlier, the Geode can be triggered on either a rising or falling edge. It is important to insure that the Geode is being triggered on the proper edge in order to avoid timing that may be a fraction of a second off. This is expanded upon below.

Some GPS units provide a very narrow timing pulse, others one that has a nearly 50/50 duty cycle. For the narrow pulse units, almost certainly it is the leading edge (rising or falling) that is the “timing edge”. This case can be easily handled by using the Geode Trigger Hold-off feature. If a 10-second cycle time is desired, set the Trigger Hold-off time to about 9.5 seconds. In this case, there is a very small chance that the very first trigger could occur on the wrong (trailing) edge, but from then on the leading edge will be used as the triggering edge.

If the GPS provides a 50/50 duty cycle edge, and it is not alterable, then the Geode by itself could as easily start on the wrong edge as on the correct timing edge, and continue thusly until restarted. For this case, Geometrics can provide a Trigger Timing Interface Box (TTIB) that will correct the situation. The TTIB can be programmed to respond only to the correct edge (rising or falling), change the polarity if needed, and gate through only one of every N 1PPS pulses, where N is programmable. (The TTIB also incorporates an alarm system that can provide a remote alert if a record is missed.)

Another potential issue comes from the variations between GPS models of the time that the serial time string (containing the time value of the associated 1PPS) is issued relative to the 1PPS itself. The Geode Controller attempts to pick the correct serial string based on a calculation involving the known record length, the PC times, and the trigger notification message from the Geodes. But if the GPS issues the serial string at an unusual time (and the time has been seen to vary somewhat with a given GPS unit) then it could pick up the incorrect time, off by 1 second. If rare, it can be subsequently detected and corrected during data processing, but if consistent it may not be easily detected. Again, the TTIB can accommodate the situation by only gating through to the Controller PC the string belonging to the gated-through 1PPS pulse. The Controller Serial Input Time Window can then safely be widened to 2 seconds (assuming the cycle time is more than 2 seconds) if need be, to expand the Controller’s search for the string around the calculated trigger time.

Answer: We apply anti-alias filters to the data to prevent out of band noise from being introduced into the data.

The filters are set with a corner frequency at ¾ of the Nyquist frequency (1/2 the sampling frequency) for almost all of the sampling frequencies. When we sample at 1.5625 uS, the Nyquist frequency is 32kHz and the filters are set at 20 kHz, because of limitations of our electronics.

There are two single-pole filters: one analog and one digital. The analog filter is a simple RC filter with 1uF +/-5% and 100kOhm +/- 1%. We short out the capacitor in the conversion process. The digital filter is software controlled when the option is registered, so it can be switched in or out in the field. It is an IIR Butterworth with a -3dB corner at 0.9Hz for 48ksps sampling, and 0.6Hz at all the lower sample rates.

Also, we offer software and hardware options to modify the low end frequency response of the Geode.

Low-end bandwidth modification:

1.5 Hz, P/N 28311-37

0.6 Hz, P/N 28147-01

DC, P/Ns 28147-02, 28311-37per system plus

There are three GPS clock options for the Geode we sell. They are:

GS-101B GPS clock from Orca, 1 pps accurate to within 100 ns of the precise time. Includes waterproof antenna with separate electronics module, with display of time and other indicators. Provides time base during loss of satellite lock. Options to provide 1 pps referenced to an IRIG-B generating source and to enclose electronics module in hardened aluminum case (P/N 25374-59).

A101 Smart Antenna GPS clock from Hemisphere GPS, 1 pps accurate to within 20 ns of the precise time. Includes waterproof antenna with integrated electronics, with indicator of satellite lock, no display of time. Provides time base during loss of satellite lock.

GC200 GPS clock from San Jose GPS, 1 pps accurate to within 1 μs of the precise time. Includes waterproof antenna with integrated electronics, no display of time or other indicators. No time base during loss of satellite lock.

The level of precision needed determines which GPS clock is best suited for the job. Typically the GC200 fulfills the needs of 95% of our clients.

Save

Autosave

Manual Save

Correlation

No correlation

Standard correlation
Stack before Correlation
Stack after Correlation
Random Source Correlation

Stack

Autostack
Replace

There is a complicated interplay between the above modes and between these modes and the stack options:

Stack polarity
Display Intermediate Stacks
Unstack Delay

We will examine each possible combination in rough order of popularity

Modes: Manual save , No correlation, Autostack





This is the most common configuration used in refraction and downhole surveys.

Each shot is automatically stacked
Each stacked record is displayed as the stack count increments
The stack count continues to increment with each shot until you clear the data, even if you save the data sometime in the process.

Stack Polarity can be changed at any time. This is most often used in shear wave surveys where reverse-polarity stacking is required.

Unstack Delay gives you the option to unstack the most recent stack; for example, setting the stack count from 4 back to 3. The data will be held in a temporary buffer for n seconds, during which time you can choose whether to stack or not. If you do nothing, the data will be automatically stacked after n seconds, and unstacking will be no longer be an option for that stack. If Unstack Delay is set to zero, this feature is disabled.

Modes: Auto Save, No correlation, Autostack





This is the most common configuration used in impulsive reflection surveys.

Each shot is automatically stacked until the Stack ulmit is reached.
When the Stack ulmit is reached, the data are saved automatically.
Data are automatically cleared and the stack count is reset to one the next time the seismograph triggers after saving the data.
Stack Polarity is generally left set to Positive.
Displaying intermediate stacks is optional. Disabulng this option results in faster production, since the data do not need to be sent over the network with every stack.

Modes: Auto Save, Standard Correlation, Stack Before Correlation





This is the most common configuration used in swept-source reflection surveys.

Each shot is automatically stacked until the Stack ulmit is reached.
When the Stack ulmit is reached, the data are saved automatically.
Data are automatically cleared and the stack count is reset to one the next time the seismograph triggers after saving the data.
Data are stacked in raw, uncorrelated form in the Geodes, and are not sent to the PC until the Stack ulmit is reached.
When the Stack ulmit is reached, the stacked raw record is correlated in the Geode (with the most recent pilot), sent to the PC, and saved.

Modes: Auto Save, Standard Correlation, Stack After Correlation





This is the most common configuration used in Random Source (mini-Sosie) reflection surveys.

Each shot is automatically stacked until the Stack ulmit is reached.
When the Stack ulmit is reached, the data are saved automatically.
Data are automatically cleared and the stack count is reset to one the next time the seismograph triggers after saving the data.
Each individual record is correlated with its own pilot and stacked in correlated form in the Geodes.
Displaying intermediate, correlated stacks is optional.
When the Stack ulmit is reached, the stacked, correlated record is sent to the PC and saved.

Modes: Auto Save, Replace





This is the most common configuration used in Continuous Recording surveys.

Each stack is replaced by the previous. If Auto Save is not enabled, the previous stack is lost.
If Auto Save is on the Stack ulmit is hard-coded to 1.
Each shot is displayed.
]]> Software Gretchen Schmauder https://www.geometrics.com/community/geode-software/stacking-technical-note/ https://www.geometrics.com/community/geode-software/understanding-acquisition-filters-their-use-and-how-to-filter/ Wed, 30 Aug 2023 20:27:57 +0000 Low Cut: , 10, 15, 25, 35, 50, 70, 100, 140, 200, 250, 280, 400

Notch: 50, 60, 150, 180

High Cut: 32, 64,125, 250, 500 or 1000 Hz

The first recommendation for cases when you are having trouble getting sufficient signal to noise would be to increase your signal via stacking the data with multiple source events or get a more powerful seismic source. This will usually produce better results than the application of filters.

Another approach would be acquire data when the noise sources are less present. That may mean collecting data at night when the area is closed or the traffic is less. Early morning can be better for areas where the wind tends to increase during the day.

The selection of filters is very site dependent and can depend on a variety of factors as well as the type of survey being performed.

1) Typically the Notch filters are to remove noise due to electrical power lines (50 or 60 Hz and their harmonic frequencies depending on the country you are in).

2) Low cut filters are generally used for noise due to wind and moving vehicles, but care must be taken not to remove too much bandwidth from generated seismic signal. Often the noise sources have the same frequencies as the seismic data you are interested in and can’t be effectively removed using frequency filtering.

3) High cut filters can be used to remove noise from high frequency vibratory signals such as compressors or airplanes.

In general it is best to record the data without any frequency filters and filter in post processing or only on the displayed data in our software. It will be a matter of experimentation to determine the best filters at your site.

Modern 24-bit seismographs (Geode, Stratavisor, ES-3000, etc) have a much wider range of signal amplitudes that they can record accurately. This means that they can still accurately record smaller seismic signals even in the presence of larger noise signals. Therefore there is a reduced need for analog filters that are applied prior to digitization of the signals.

Digital filters are more flexible and can be more specifically applied to the noise that is recorded rather than the “Broader Brush” of analog filters. Digital filters also have the benefit of being able to go back to the original data if the wrong filter is applied, which is not the case with Analog filters. The general approach in the seismic industry is now to record everything – including the noise – and the filter out what you don’t want later.

]]> Software Gretchen Schmauder https://www.geometrics.com/community/geode-software/understanding-acquisition-filters-their-use-and-how-to-filter/ https://www.geometrics.com/community/geode-software/channel-remapping-in-sgos/ Wed, 30 Aug 2023 20:24:07 +0000 Channel Remapping

Channel remapping allows you to change:

the order of channels on each analog spread cable that connects to the Geode
reorder the Geode boxes.


You would use this option if your cables were wired opposite to the default order normally used in Geometrics wiring, if you wished to turn your line around to have the low channels at the opposite end, or if your cables had a wiring error. Channel remapping is also often necessary when using more that a single network cable.

Default cable wiring of Geometrics seismographs

Default order is defined as the natural electrical order in which channels are oriented when the system first powers up before remapping. Refer to Section 3 under Connector Wiring that discusses standard wiring configurations. You may have requested a custom wiring configuration from Geometrics. If you are confused about your wiring, contact the factory and refer to the serial number and job number.



Geode cables are typically wired in a ‘high-side configuration’, meaning that the Geode connects closest to the highest numbered channel on the analog cable. The 149 figure above shows this configuration for a single box system, with 24 channels.

Multiple Geodes

The following diagram shows a default single digital line (one network card) system with 3 Geodes. Note that Geode one is always closest to the controller in a default configuration.



Multiple Network Lines

The next diagram below shows a default configuration with two digital lines (two network cards) with the controller positioned in the middle. Line 1 is on the left and line 2 is on the right. One might use two lines to increase data throughput to reduce time between shots. Like the configuration above, the Geodes are numbered starting closest to the controller. The seismic controller software labels all of the channels contiguously even though they are on two separate digital lines. However, if the lines are collinear, the first line will have the channels ordered backwards. This can be easily rectified with the remapping feature.



There are two ways of remapping channels: automatic mode and manual mode. Automatic mode settings are listed on the top of the remapping dialog box, and manual mode on the bottom.

Automatic Channel Remapping

Automatic channel remapping allows you to reverse either the order of the Geodes on the line, or reverse the order of the channels on the spread cable.



The above diagram shows the result after both channels and Geodes have been reversed, renumbering the line so that low channels start on the left hand side and increase towards the right. In the dialog box, the automatic remapping boxes referencing line 2 remain unchecked, since the default orientation on line two was correct.

Manual Channel Remapping

Channels can be remapped on an individual basis using the Manual Map Mode. Select the appropriate check box, and enter the order in which you would like the channels that differs from the default order. You can specify individual channels separated by a comma (1, 3, 4, 6 etc) or a range of channels (1-13, 24-14 etc).



For example, if you wanted the channels ordered backwards on a 24-channel system, you would enter 24-1. If you wished to reverse the order of channels 1- 12 in a 24 channel system, you would type 12-1, 13-24. Other examples are shown opposite, and are available by pressing the See Examples button on the remapping menu.

]]> Software Gretchen Schmauder https://www.geometrics.com/community/geode-software/channel-remapping-in-sgos/ https://www.geometrics.com/community/geode-software/understanding-the-sgos-geometry-window-gui/ Wed, 30 Aug 2023 20:23:08 +0000 The Geometry GUI provides a graphical representation of your survey, along with a wide range of control capability. It is particularly useful when conducting reflection surveys, but can be useful in a wide range of applications. It summarizes, in one simple view, the physical positions and other attributes of the hardware on the ground, and allows graphical control of these.

Below is a typical display of a 96-channel, four-Geode layout. We will first describe the display itself, and follow with a description of its control capabilities.



Example Geometry GUI



]]> Software Gretchen Schmauder https://www.geometrics.com/community/geode-software/understanding-the-sgos-geometry-window-gui/ https://www.geometrics.com/community/geode-software/sgos-calibration/ Wed, 30 Aug 2023 20:18:30 +0000 Standard Procedure on Registering SCS Software

Here's our standard procedure on registering the SCS (Seismic Controller Software):

The latest version of the SCS is 11.1.69, which is used for Windows Operating Systems up to and including W-10 64 bit computers.

Within the zip file you will find instructions as well as the installation file.



Note: Installing the WinPcap is mandatory!

After installing, you will need to register. In order for us to issue the correct SCS registration we will need additional information. The preferred method is:

1. From the “Registration Window” select “Send Email or Save File to Disk”.

2. Fill out the report, to include serial number of seismograph. (type 0000 in sales No. field if not known)

3. Save the file to your computer.

4. Send an email with the file attached or embedded to: rrivera@geometrics.com and/or support@geometrics.com.

We will then remit with a 40 character alphanumeric string that you can paste into the same “Registration Window.”

Please understand that the SCS can be installed onto as many computers as you wish, yet each installation will generate its own unique user code and therefore need to be registered.

]]> Software Gretchen Schmauder https://www.geometrics.com/community/geode-software/sgos-calibration/