Guralp Systems CMG-CD24 User Manual
CMG-CD24
Compact Digitiser
Operator's Guide
Part No. MAN-C24-0001
Designed and manufactured by
Güralp Systems Limited
3 Midas House, Calleva Park
Aldermaston RG7 8EA
England
Proprietary Notice: The information in this manual is
proprietary to Güralp Systems Limited and may not be
copied or distributed outside the approved recipient's
organisation without the approval of Güralp Systems
Limited. Güralp Systems Limited shall not be liable for
technical or editorial errors or omissions made herein,
nor for incidental or consequential damages resulting
from the furnishing, performance, or usage of this
material.
Issue C 2011-03-29
CMG-CD24
Table of Contents
1 Introduction.............................................................................................................. 6
1.0.1 State of health information........................................................................7
1.1 Options............................................................................................................... 7
1.1.1 Storage and interfaces................................................................................7
1.1.2 Wireless networking................................................................................... 8
2 Setting up the CD24................................................................................................ 10
2.1 Connectors.......................................................................................................10
2.2 Test installation...............................................................................................10
2.3 Setting up the Ethernet or wireless interface................................................. 13
2.3.1 Using DeviceInstaller...............................................................................13
2.3.2 Using DHCP..............................................................................................16
2.3.3 Configuration with the web interface......................................................17
2.3.4 Installing wireless hardware....................................................................20
2.4 Configuring the digitiser..................................................................................20
2.5 Downloading data over FireWire....................................................................21
2.5.1 Reading CD24 disks..................................................................................22
2.6 Receiving data in Scream!...............................................................................23
3 Configuration & Control with Scream!.................................................................25
3.1 The Configuration dialogue.............................................................................25
3.1.1 System ID.................................................................................................. 26
3.1.2 Output control..........................................................................................27
3.1.3 Triggering..................................................................................................29
3.1.4 Mux channels........................................................................................... 35
3.1.5 Ports.......................................................................................................... 36
3.2 The control dialogue........................................................................................37
3.2.1 System...................................................................................................... 37
3.2.2 Triggering..................................................................................................38
3.2.3 Calibration................................................................................................ 38
3.2.4 Mass control............................................................................................. 40
3.2.5 Data flow .................................................................................................. 40
3.2.6 Buffering modes....................................................................................... 46
3.3 Digitiser status streams.................................................................................... 47
3.3.1 GPS...........................................................................................................47
4 Calibrating the CD24.............................................................................................. 49
4.1 Calibration methods........................................................................................49
4.2 Noise calibration with Scream! ......................................................................49
4.2.1 Sensor response codes............................................................................. 52
2 Issue C
Operator's Guide
5 Command line interface.........................................................................................53
5.1 FORTH.............................................................................................................53
5.2 General configuration......................................................................................54
5.2.1 SET-ID....................................................................................................... 54
5.2.2 BAUD........................................................................................................ 55
5.2.3 LOAD........................................................................................................55
5.2.4 LOAD-I......................................................................................................55
5.2.5 TEMP?....................................................................................................... 56
5.2.6 ETHER...................................................................................................... 56
5.3 GPS and timing systems..................................................................................56
5.3.1 GPS-TYPE................................................................................................. 56
5.3.2 HR-CYCLE................................................................................................ 56
5.3.3 XGPS.........................................................................................................57
5.3.4 SET-RTC...................................................................................................57
5.3.5 SET-CLOCK.............................................................................................. 57
5.3.6 TIME? ....................................................................................................... 58
5.3.7 LEAPSECOND..........................................................................................58
5.3.8 SQPATCH.................................................................................................58
5.4 Output configuration.......................................................................................59
5.4.1 SAMPLES/SEC.......................................................................................... 59
5.4.2 SET-TAPS................................................................................................. 59
5.4.3 SET CONFIG............................................................................................. 60
5.4.4 COMPRESSION........................................................................................62
5.5 Triggering.........................................................................................................63
5.5.1 TRIGGERS................................................................................................ 63
5.5.2 TRIGGERED..............................................................................................63
5.5.3 STA...........................................................................................................64
5.5.4 LTA...........................................................................................................64
5.5.5 RATIOS..................................................................................................... 64
5.5.6 BANDPASS............................................................................................... 65
5.5.7 MICROG....................................................................................................65
5.5.8 MICRO-G.................................................................................................. 65
5.5.9 HIGHPASS................................................................................................65
5.5.10 PRE-TRIG................................................................................................66
5.5.11 POST-TRIG............................................................................................. 66
5.5.12 TRIGGERIN.............................................................................................66
5.5.13 TRIGGEROUT.........................................................................................66
5.6 Calibration....................................................................................................... 67
5.6.1 SINEWAVE............................................................................................... 67
5.6.2 SQUAREWAVE........................................................................................67
5.6.3 RANDOMCAL.......................................................................................... 68
5.6.4 MINUTE.................................................................................................... 68
5.6.5 %AMPLITUDE.......................................................................................... 69
5.7 Actions.............................................................................................................69
5.7.1 CENTRE.................................................................................................... 69
5.7.2 %AUTO-CENTRE.....................................................................................69
March 2011 3
CMG-CD24
5.7.3 RESP.........................................................................................................69
5.7.4 MASSES?..................................................................................................70
5.7.5 RE-BOOT..................................................................................................70
5.8 Flash storage and filing...................................................................................70
5.8.1 SHOW-FLASH..........................................................................................70
5.8.2 DOWNLOAD............................................................................................ 70
5.8.3 ALL-FLASH.............................................................................................. 72
5.8.4 ALL-TIMES...............................................................................................73
5.8.5 FROM-TIME.............................................................................................73
5.8.6 TO-TIME...................................................................................................73
5.8.7 ALL-DATA................................................................................................74
5.8.8 STREAM...................................................................................................74
5.8.9 STATUS-ONLY........................................................................................74
5.8.10 S/S........................................................................................................... 74
5.8.11 RESET-FLASH........................................................................................75
5.8.12 ERASEFILE.............................................................................................75
5.9 Transmission modes........................................................................................75
5.9.1 DIRECT.....................................................................................................75
5.9.2 FILING...................................................................................................... 75
5.9.3 DUPLICATE..............................................................................................76
5.9.4 DUAL........................................................................................................76
5.9.5 ADAPTIVE................................................................................................76
5.9.6 FIFO..........................................................................................................76
5.9.7 HEARTBEAT............................................................................................77
5.9.8 MS-GAP....................................................................................................77
5.10 Buffering Modes.............................................................................................78
5.10.1 RE-USE................................................................................................... 78
5.10.2 WRITE-ONCE.........................................................................................78
5.10.3 MODE?....................................................................................................78
5.11 FireWire disks................................................................................................78
5.11.1 DIR..........................................................................................................78
5.11.2 FLUSH.................................................................................................... 79
5.11.3 FLUSHALL............................................................................................. 80
5.11.4 RESET-DISC........................................................................................... 80
6 Updating the CD24.................................................................................................81
7 Appendices.............................................................................................................84
7.1 Appendix A - InfoBlocks................................................................................. 84
7.1.1 Format of the default information block.................................................84
7.1.2 Response codes and units........................................................................85
7.1.3 Example files............................................................................................86
7.2 Appendix B - Setting up external triggering ..................................................88
7.2.1 Overview...................................................................................................88
7.2.2 Using CD24 triggering to activate external equipment...........................90
7.2.3 Using an external trigger source..............................................................92
4 Issue C
Operator's Guide
7.2.4 Triggering several CD24 digitisers simultaneously.................................93
7.2.5 Combining CD24 and DM24 digitisers in a single array.........................95
7.3 Appendix C - Connector pinouts....................................................................96
7.3.1 Digitiser connectors.................................................................................. 96
7.3.2 Breakout box connectors........................................................................100
7.4 Appendix D - Advanced network configuration..........................................103
7.4.1 Accessing the configuration menu via the serial Interface...................104
7.4.2 Configuring the network interfaces.......................................................104
7.4.3 Configuring the Ethernet port................................................................105
7.4.4 Configuration of the WiFi interface.......................................................106
7.5 Appendix E - Using third-party terminal emulators....................................108
7.5.1 Hyperterminal, as provided with Windows XP....................................108
7.5.2 Using Hyperterminal with Windows Vista or Windows 7...................110
7.5.3 Using PuTTY.........................................................................................110
7.6 Appendix F – Setting up an “ad hoc” wireless network...............................113
7.7 Appendix G - Specifications......................................................................... 116
8 Revision history.................................................................................................... 117
March 2011 5
CMG-CD24
1 Introduction
The CD24 is a compact, very low power, multi-purpose digitiser, with
three 24-bit differential inputs and 8 lower-speed, single-ended
auxiliary inputs. Equipment with analogue outputs connects to the
CD24 via a 26 way mil-spec connector.
Key features include:
• 24-bit sigma-delta analogue to digital converters.
• Low power: < 1W from 10V–28V DC.
• ±10V balanced differential input lines.
• Lightweight and waterproof.
• RS232 output in GCF (Güralp Compressed Format).
• Multiple user-configurable output rates.
6 Issue C
Operator's Guide
Once connected to 10 – 28 V DC power, the CD24 will begin operating
automatically, digitising its inputs and either outputting digital data to
your own recording system or saving them to internal Flash memory.
1.0.1 State of health information
The CD24 constantly monitors the status of the GPS and timing
systems, outputting information in a plain text status stream.
An electronic thermometer also provides regular measurements of the
unit's internal temperature, which are reported in the same stream.
The thermometer is calibrated to an accuracy up to ± 0.33 °C, with a
linearity of ± 0.5 °C.
1.1 Options
1.1.1 Storage and interfaces
The CD24 can be supplied with up to 16 Gb of internal Flash memory
for data storage. The amount you need will depend on the length of
your experiment and the sampling rates used.
You can download data from the internal storage:
• over the RS232-compatible data port, directly into Scream! or
other Güralp data modules;
• over a fast IEEE.1394 (FireWire) link with optional power; or
March 2011 7
CMG-CD24
• if fitted, using the Ethernet interface to transfer data over a local
area or wireless network.
1.1.2 Wireless networking
The CD24 can be fitted with an optional 802.11b (“Wi-Fi”) wireless
interface in addition to the Ethernet port. This option allows data flow
to be established from autonomous installations with a minimum of
setting up.
For temporary deployments, instruments and digitisers can be buried
in shallow pits with only the antenna above ground. You can then
contact to each station from a wireless-enabled PC running Scream!
without disturbing the instrument, including monitoring real-time
data and configuring the digitiser.
More permanent arrays also benefit from wireless technology,
particularly in remote areas or where the terrain makes long cable runs
impractical.
For example, stations might be installed with high-gain antennae
directed towards a visible natural feature which is easier to access.
8 Issue C
Operator's Guide
At this location, which can be up to 500 metres away, a low-power
CMG-EAM data module might act as an access point for the array
elements and forward data onto a higher-bandwidth radio link.
In semi-permanent arrays, a wireless-enabled CMG-EAM or laptop PC
can be set up as a temporary access point for the duration of a site
visit.
March 2011 9
CMG-CD24
2 Setting up the CD24
This section gives an overview of how to set up a CD24 and begin
recording data. We recommend that you set up a test digitiser in your
office or laboratory as a “dry run” to gain a basic understanding of the
system and to check that it is functioning as expected.
This test installation will use the digitiser's default settings. Data will
be received using Güralp Systems' Scream! software, available from
the website: www.guralp.com
2.1 Connectors
The CD24's output connectors are located on the lid. The sensor input
is located on the side. The digitiser can be supplied with a number of
options, so not all the connectors may be present on your digitiser.
The input connector is configured to connect directly to one of GSL's
sensors and has all the necessary power and control functions.
All CD24s have a 19-pin mil-spec connector on the lid for connection
to a supplied breakout box with the following connections:
• a 6-pin socket for connecting the supplied GPS unit;
• a 10-pin plug for connecting to a PC's serial interface or a Güralp
data module..
• a 6-pin mil-spec plug for connecting to a power source.
You may need to attach a suitable connector to the power cable
provided. The CD24 draws a nominal current of 55 mA from a 12 V
supply when in use; thus, using a 12 V, 25 Ah sealed heavy-duty leadacid battery, you should expect the digitiser to operate for more than a
week without recharging.
The CD24 may also have connectors for the FireWire, Ethernet or
Wi-Fi interfaces.
2.2 Test installation
To test the CD24, you will need access to a PC with a 9-pin serial port
(RS232), a 12 V power source and a working sensor (e.g. CMG-3ESP,
ESPC, 40T or 6T).
Install Scream! on your PC and run it.
10 Issue C
Operator's Guide
Connect the wire from the breakout box to the CD24's 19-pin
connector labelled: POWER DATA GPS.
Connect the 6-pin connector on the breakout box to the GPS unit using
the GPS cable. Position the GPS so that it has a good view of the sky.
Note: If you do not have a view of the sky, you can operate the CD24
without a GPS unit, but timing information may be inaccurate.
Connect the sensor to the 26-pin connector on the side of CD24.
Connect the 6-pin data plug on the breakout box to the 9-pin serial
port on your PC using the serial cable.
Use the power cable to connect the 10-pin power plug on the breakout
box to a fused 10 – 28 V power source.
The CD24 and instrument are now fully operational and will already
be producing data.
After a few seconds, you should see the CD24 digitiser appear under
Network – Local – COM1 in the left-hand panel of Scream!'s main
window. (If your PC has multiple serial ports, it may appear under
some other COM port name.) Soon after, data streams will begin
appearing in the right-hand panel. Streams with higher sample rates
will appear sooner than those with lower sample rates:
If this does not happen, check all connections, and ensure the power
supply is providing the correct voltage and current.
Each data stream has a Stream ID, a six-character string unique to it.
Stream IDs normally identify the instrument, component and sample
March 2011 11
CMG-CD24
rate of each stream. Thus the stream 1026Z2 refers to a Z-component
stream from instrument 1026, at tap 2. For more details on taps and
sample rates, see section 3.1.2, page 27.
Data streams ending in 00 are status streams containing any extra
information sent from the digitiser.
To view data, select a stream and then double-click to open a
Waveview window.
You can view several streams at once by holding down SHIFT as you
select, and then double-clicking the selection.
To start recording new data to a file, right-click on a stream or a
selection of streams and choose Start recording from the pop-up
menu. Recording settings, directories, etc., can be altered by selecting
File Setup... → from the main menu and switching to the Recording
tab.
To view status information, select the stream and right-click to open a
pop-up menu. Select View.
12 Issue C
Operator's Guide
The first few status blocks will consist of the CD24's start-up messages,
including its software revision number and the data streams selected
for downloading and triggering.
Later blocks give information on the GPS system (number of satellites
visible, the location of the GPS antenna, time synchronization status,
etc.) and the baud rates in use for each channel.
For more information on SCREAM! refer to the user manual available
from the Güralp Systems' website: www.guralp.com
2.3 Setting up the Ethernet or wireless interface
CMG-CD24 digitisers with Ethernet or Wireless features installed use
an embedded Lantronix Wi-Port module to provide the network
interface. Configuration of the Ethernet or Wireless interface is made
using the Lantronix' DeviceInstaller utility for Microsoft Windows,
using a DHCP server or the via the serial port. You will need a PC with
a network or wireless interface installed or an RS232 connector,
You may find it easiest to gather together all the Wi-Fi hardware before
taking it into the field and configuring it from a local wireless-enabled
PC.
There are two types of wireless network topology supported by the
Wi-Port.
● Infrastructure networks need additional hardware, such as
wireless access points and routers, to work. Any host on the
wireless network will communicate with the access point or
router, which manages all the connections and ensures data are
transmitted correctly. This device may also provide
connectivity to the Internet or your local network.
● Ad hoc networks can be set up with no additional hardware.
Each host on the wireless network attempts to communicate
directly with the other hosts. Ad hoc networks are easy to set
up, but they are only suitable with a small number of hosts. In
seismic networks, infrastructure mode is normally preferred,
since sensors do not need to communicate with each other. For
more information see Appendix F – Setting up an “ad hoc”
wireless network on page 113.
2.3.1 Using DeviceInstaller
1. Download and install the DeviceInstaller utility from the
Lantronix Web site at http://www.lantronix.com/
March 2011 13
CMG-CD24
2. DeviceInstaller also requires the Microsoft .NET framework to
be installed. If you do not have this already, it can be
downloaded at www.microsoft.com.
Note: DeviceInstaller will not work through routers or across
the Internet. All the devices need to be on the same network
segment as the PC.
3. Find out the MAC address of the CD24's network interface.
This should be printed on a label on the case.
4. If the Data Out port on the breakout box is connected to
anything, disconnect it.
5. For Ethernet networking, connect the CD24's ETHERNET port to
the the PC's network interface either using a crossover Ethernet
cable or through a network hub. Note that using a hub, you can
connect several CD24s to the same PC and configure them all at
the same time.
6. For Wireless Networking configure your wireless router or
access point to use a network name (SSID) of LTRX_IBSS.
Disable any security features of the wireless router or access
point.
7. Run DeviceInstaller.
8. DeviceInstaller's main window has two panels, a tree on the left
(with Lantronix Devices at the top) and a table on the right.
9. The program will automatically look for Lantronix devices on
all of your computer's network interfaces. If necessary, you can
narrow the selection by clicking on an entry in the tree on the
left. If the program does not list the device, press F5 or use
Device > Search from the menu system.
14 Issue C
NOTE: Any connection to the Data Out port on the
breakout box will disable networking
Operator's Guide
10. A Wi-Port entry should appear in the table on the right,
denoting that a device has been detected.
11. If more than one Wi-Port entry appears, DeviceInstaller has
detected several devices.
12. For every detected device, the program shows the Hardware
Address (i.e. the MAC address) and the IP address it is currently
using. If you are using a wireless router with a DHCP server, or
an access point connected to a network with a DHCP server, the
device will use DHCP to assign it an address. Otherwise, a
random address will be chosen automatically.
Note: Automatic random addresses all begin with 169.254. The
CD24 will choose a different one every time it is power cycled
or rebooted.
13. The address of the CD24 may be shown in red with the status
Unreachable. If this happens, the sensor and PC cannot
communicate because they are not on the same subnet. Click
Assign IP to start the IP configuration wizard. Follow the
instructions in the wizard to set the IP address, or configure
DHCP if you are using a DHCP server. When you have finished,
press F5 or use Device > Search from the menu system to find
the sensor with its new IP address.
Note: The IP address of the digitiser must have be on the same
subnet as the computer you want to connect to. The LAN
setting on the DeviceInstaller device tree identifies the IP
address of your computer. The first three number groups
typically need to be the same on all devices (digitisers and
computer).
14. If you want to configure the CD24 to use a static IP address, use
the Assign IP wizard as above and click Search again.
March 2011 15
CMG-CD24
15. Double-click on the entry which corresponds to the CD24 you
want to configure. The right-hand panel will change to show
the current properties of the device.
16. Switch to the Web Configuration tab and click Go to open the
Web configuration interface.
17. You can also click Use External Browser to use your own Web
browser to configure the system.
18. Follow the steps at 2.3.3 to configure the module from its Web
interface.
2.3.2 Using DHCP
If you cannot install DeviceInstaller on your PC, or you do not wish to,
you can also get access to the CD24 using a standard DHCP server. In
most cases you will need to have administrative privileges to do this.
1. Install and start the DHCP service on your PC.
2. For Ethernet networking connect the CD24's ETHERNET port to
the the PC's network interface, either using a crossover Ethernet
cable or through a network hub. Note that using a hub, you can
16 Issue C
Operator's Guide
connect several CD24s to the same PC and configure them all at
the same time.
3. For Wireless Networking configure your wireless router or
access point to use a network name (SSID) of LTRX_IBSS.
Disable any security features of the wireless router or access
point.
4. DHCP will not work through routers or across the Internet. All
the devices need to be on the same network segment as the PC.
5. Monitor the DHCP server to find out what IP address it gives to
each digitiser.
6. To configure a device, enter its IP address into a web browser.
2.3.3 Configuration with the web interface
Once you have access to the Wi-Port's Web interface, you can
configure it with its proper settings.
1. The Web page is divided into three. A menu on the left
switches between the pages of configuration options on the
right. There is also a banner at the top, which tells you the
current firmware revision and the MAC address.
2. To navigate around the Web site, click on the entries in the lefthand menu. When you have made changes to the settings on
any page, save them by clicking OK before you leave the page.
Once you have made all the changes click on Apply Settings to
configure the digitiser.
2.3. 3.1 Wire less Setti ngs
1. Click on WLAN (Wireless Local Area Network) to open the
WLAN Settings page.
March 2011 17
CMG-CD24
2. Change the Network Name (i.e. SSID) from LTRX_IBSS to a
suitable name for your installation. This name will be
announced to any nearby wireless devices when they search for
networks.
3. If you are using an ad-hoc network, change the second Network
Name box as well. Otherwise, deselect Ad Hoc Network
Creation.
4. Under Wireless Network Security, set Security to WEP and
configure the security parameters. If you do not do this, anyone
will be able to access the CD24 and change its configuration.
5. Make a note of the security parameters you have used.
6. Click OK, followed by Apply Settings in the main menu. The
Wi-Port will restart.
7. If you are setting up an infrastructure network, configure your
wireless access point or router to use the new name and
security settings, and power cycle the CD24 to make it
reconnect to the network.
8. Reconnect your computer to the wireless network using the new
name and security settings.
2.3. 3.2 Conf i guri ng th e ser ial c hannel s
1. The Wi-Port has two serial channels to which you can connect.
By default, these are exposed on ports 10001 and 10002.
2. Channel 1 (normally port 10001) is connected to a serial console
(which is also exposed on the power port of the breakout box).
If you have problems connecting to the CD24, you can attach a
18 Issue C
Operator's Guide
standard Güralp Systems power/data cable to this port and use
Scream! to access the console.
3. Channel 2 (port 10002) is connected to the CD24's digital
output, unless you have connected a serial data cable from the
breakout box to a computer. If the breakout box is connected,
the CD24 will send data streams through that interface rather
than to the Wi-Port.
4. Click on Channel 2 – Serial Settings.
5. If the Baud Rate is incorrect, set it to the default of 19,200.
Note: If you change the digitiser's output baud rate in Scream!
or using the terminal, you must come back to this page and
change the Baud Rate setting here as well.
6. The remaining settings can be left at their default values. Click
OK to save your changes.
7. For full information on the Wi-Port's configuration options,
please refer to the Wi-Port documentation, which is available on
the Lantronix Web site, www.lantronix.com.
8. When you have finished setting up the Wi-Port, apply the new
settings by clicking Apply Settings. The Wi-Port will re-boot
with the new settings in effect.
Note: If the Wi-Port is still using an automatically chosen
random IP (beginning with 169.254), the IP address will change
when you do this. You will need to go back to DeviceInstaller
to find out the new IP address.
March 2011 19
CMG-CD24
2.3.4 Installing wireless hardware
The small antenna supplied with the CD24 is adequate for initial
testing or temporary installations with an access point within 50m of
the digitiser.
To send data over a larger distance, or
if the line of sight between the
antenna and the access point is
blocked, you will need to use a larger
and more powerful antenna.
In infrastructure mode, you can
reduce the power requirements by
using a directional antenna pointed at
the location of the access point. The
access point does not need to be
permanently present. For example,
you could set up an array of CD24
digitisers with antennas pointed
towards a prominent natural feature
with line of sight to all the digitisers,
and access them all from this location
using a laptop PC.
2.4 Configuring the digitiser
Autonomous CD24 installations will need to be configured before
deployment. You can do this either
• using the graphical interface provided by Scream! (see Chapter 3
on page 25), or
• over a terminal connection (see chapter 5 on page 53).
Both methods provide full access to the configuration options of the
CD24.
In particular, the CD24 can operate in a number of transmission modes.
These modes determine whether the unit stores data in its on-board
Flash memory, sends it over the serial link in GCF format, or does
some combination of these. See section 3.2.5 on page 40 for more
details.
20 Issue C
Operator's Guide
2.5 Downloading data over FireWire
The easiest way to download data over FireWire is to connect a
suitable disk to the FireWire port of the CD24 and power-cycle the
unit.
If you have ordered a CD24 with the powered FireWire option, you can
attach the disk directly to the CD24 with no additional connections.
Otherwise, you will need to connect the disk to a power source
through the supplied adapter.
When the digitiser restarts, it will automatically detect the disk and
flush all new data to it.
If you do not want to restart the digitiser, you can also flush data to
disk manually:
1. Open the digitiser's console. To do this using Güralp Systems'
Scream! software, right-click on the digitiser's icon (once it
appears) and select Terminal.... If you are using a Güralp EAM,
issue the command minicom -n port-number.
2. Connect a suitable disk to the FireWire port of the CD24.
Provide power for the disk if necessary.
March 2011 21
CMG-CD24
3. Issue the command FLUSH
This will download all data from the CD24 that it has not
already transferred. If you want to transfer the entire contents
of Flash memory, use the command FLUSHALL. For more
details, see section 5.11.3 on page 80.
4. Close the terminal session. If you are using Scream! or an EAM,
the CD24 should start transmitting immediately. Otherwise,
you may need to issue the command GO to start transferring
data.
2.5.1 Reading CD24 disks
The CD24 uses a special disk format, DFD, for recording data. This
format is also used by other Güralp digitisers such as the DM24.
You can read these data into a PC using Scream! or the Windows
gcfxtract utilities, which are freely available from the Güralp
Systems' web site. Linux and Solaris command line utilities are also
available for reading data from a DFD disk.
The DFD format is not the same as that used by the Güralp Systems
EAM data module, which uses either a FAT32-compatible journalling
file system or an ext3 file system.
Güralp Systems can provide fully tested disks with FireWire and USB
connectors. Alternatively, a third-party FireWire disk may be used
(although compatibility is not guaranteed.)
2.5. 1.1 Readi ng CD 24 Di sks u sing SCRE AM!
To read a disk with Scream!:
1. Attach the disk to your computer. You can use FireWire, USB,
or any other interface supported by your computer and the disk.
2. Run Scream!, and select File Setup... → from the main menu.
Select the Files tab.
3. Set the Base Directory, Filename Format and Data Format as
described above. Also, if required, set the Post-processor and
Granularity options to your preference. Consult the Scream!
documentation for details.
22 Issue C
Operator's Guide
4. Select the Recording tab and check both Auto Record—Enable
for Data Streams and Auto Record—Enable for Status Streams.
Click OK.
Scream! will remember the recording options you set in steps 3
and 4 for later occasions.
5. Select File Read SCSI disk... → from the main menu. Scream!
will search for attached disks, and open a window with a list of
all the streams it has found.
6. Select the streams you want to replay, and click Open. The disk
will appear in the left-hand pane of Scream!'s main window,
and the streams you have selected will start playing into the
stream buffer, as well as being recorded.
7. When you have finished transferring the data, if you want to
reset the disk, select File Reset SCSI disk... → from Scream!'s
main menu. Select the disk you want to reset, and click OK.
2.6 Receiving data in Scream!
There are several ways a CD24 digitiser can be connected to Scream!:
• A direct serial connection can be made from the breakout box to
your computer. This is the method we recommend for testing
the digitiser (see section 2.2 on page 10).
• The serial port can also be used to connect an external modem.
Details of how to connect modems are available on the Güralp
Systems Web site.
• Data can be received from the digitiser over the optional
Ethernet or wireless links. Before you can do this, you will
need to set up its IP address and network configuration, as
described in section 2.3 on page 13.
To connect to a CD24 over the network:
1. Run Scream!, and select Windows – Network Control from the
main menu. Click on the My Client tab.
March 2011 23
CMG-CD24
2. Right-click in the white panel beneath Server, and select Add
TCP Server....
3. Input the IP address of the CD24, followed by a colon and then
the output port 10002. For example:
192.168.33.2:10002
Click OK.
4. After a short wait, an entry for the digitiser should appear in the
pane. Right-click on the entry and select Connect.
5. If the connection is successful, you should see blocks appearing
in the Block Rx pane and streams will appear in Scream!'s main
window. Close the Network Control window.
24 Issue C
Operator's Guide
3 Configuration & Control with Scream!
Scream! distinguishes between configuration and control of digitisers.
The most important difference is that a digitiser (and its attached
instrument) may be controlled through Scream! at any time while it is
acquiring data, whereas configuration options only take effect after a
reboot (with consequent loss of data.)
3.1 The Configuration dialogue
To change the configuration of any connected digitiser:
1. Locate the digitiser you want to configure. All connected
digitisers have an entry in the tree on the left of Scream!'s main
window. If the digitiser is transmitting data through a remote
server or EAM, you may need to “unroll” the entry for that
server (by clicking on the icon) to see the digitisers connected
to it.
2. Right-click on the digitiser's entry (not the icon for the server or
any ComXX icon). Digitisers are shown with icons depicting a
coloured cylinder.
3. Click Configure.... Scream! will then contact the digitiser and
retrieve its current configuration, a process which will take a
few seconds. Once done, the Configuration setup window will
be displayed.
4. Once you are happy with any changes you have made in the
Configuration Setup window, click UPLOAD to send them to the
digitiser and reboot. This will take a short while.
Note: After uploading, allow up to 1 minutes for the digitiser to
re-boot and resume transmitting data.
To control a digitiser whilst it is running, either right-click on the
digitiser's entry in the list and click Control..., or double-click the
entry. In either case Scream! will contact the digitiser to retrieve
control information and display the Control window. The options you
can control immediately are:
• the type of sensor you are using
• GPS power cycling options
March 2011 25
CMG-CD24
• the short-term and long-term average values for triggering (but
not which streams perform the trigger, or which are output by it)
(see section 3.1.3 on page 29)
• the length of pre-trigger and post-trigger periods
• calibration signal options
• mass control functions
Some of these options can also be altered in the Configuration setup
window. For more information on the Control window, see section 3.2
on page 37.
If you need a more powerful interface to the CD24, you can also issue
commands to it directly using Scream!'s terminal mode. A terminal
window is opened by right-clicking on the digitiser's entry in the list
and selecting Terminal.... The digitiser will stop transmitting data
while you have a terminal window open but may still store it in Flash
memory (depending on the current transmission mode.)
The remaining sections of this chapter describe in detail the
configuration options available for the CD24. Many of these options
will also be available for other Güralp digitisers.
3.1.1 System ID
The System ID pane gives information about the digitiser and its
internal software and allows you to change GPS timing parameters.
System Identifier and Serial Number : The digitiser type is identified
by its system identifier and serial number. Every data and status block
26 Issue C
Operator's Guide
generated by the digitiser includes these two fields at the beginning, so
that the block’s origin can be identified. On delivery from the factory,
the system identifier and the serial number are set to the GSL works
order number and the digitiser’s serial number, but any combination of
letters A-Z and numbers can be used, such as an abbreviation of your
institution’s name, etc. The system identifier can be up to 5 characters
long, while the serial number cannot be longer than 4.
Sensor Type : This option tells Scream! which control commands to
make available to the user. The CD24 does not require separate
control commands, so you should not change this option.
GPS Type : The digitiser needs to be able to time-stamp accurately all
data that passes through it. It sets its clock by receiving time signals
from the GPS satellite network using an attached Trimble GPS unit.
This is hard-wired into the CD24, so the GPS Type setting has no
effect.
Enable GPS power cycling : If you are using a GPS unit to receive time
signals, but do not experience significant drift in the system's clock
(for example, in a stable-temperature environment), you can save
power by selecting Enable GPS power cycling. With this option in use,
the GPS time is only checked at intervals of a specified number of
hours. Disabling this option keeps the GPS unit running constantly; if
you have ample power, this will give the most accurate results. You
can choose any whole number of hours for the interval.
3.1.2 Output control
The Output control tab allows you to select which data streams are sent
to Scream! from the digitiser.
March 2011 27
CMG-CD24
The CD24 initially samples incoming data at 2000 Hz. These data are
then filtered and reduced to a lower rate (decimated) using an onboard digital signal processing unit, or DSP. The DSP has several
filtering-decimation stages, which run one after the other. Stages
which can produce output (and the outputs from those stages) are
called taps. The CD24 can output 4 taps simultaneously.
Each configurable tap can be set to a different decimation factor by
choosing values from the drop-down menus on the left. Decimation
factors of 2, 4, 5, 8, and 10 are available. The numbers visible in the
drop-down menu of each tap are the data rates that each of the
possible decimation factors will provide, given the settings of the taps
above it. Only integer (Hz) data rates are allowed: thus, for example, if
one tap emits data at 25 Hz, the only possible further decimation factor
is 5.
To the right of each decimation factor menu is a grid of check-boxes.
These boxes mark which streams of data to generate at each sample
rate. The screen shot above shows a possible configuration for a
triaxial instrument. Every channel of the digitiser may be output at
any tap; currently, as illustrated, all three axes are being output at Tap
2 (20Hz).
If you want to change the names used for the channels, click in the
white box containing a Z in the above picture and type a letter or
number. It will name the channels with a sequence of letters or
numbers beginning with the one you choose (e.g. A, B, C; 2, 3, 4; 9, A,
B), unless you type Z in which case they will revert to Z, N, and E.
Each combination of channel and tap has two check-boxes. The upper
check-box of each pair activates continuous output, whilst the lower
activates triggered output. In the example above, the digitiser will
output data continuously for all three channels at Tap 2, but never for
any other taps. If you do not need all the streams to output at all rates,
you should leave boxes unchecked to save communications capacity.
You cannot check both continuous and triggered output for the same
channel and tap.
When you enable a triggered stream, the digitiser will output data in
that stream only when a particular set of trigger criteria are met. This
is shown diagrammatically as data passing through a switch. In the
example above, we might want the high-rate data from Tap 0 to be
generated only when an event registers at some other tap. To do this,
tick one or more of the lower set of check-boxes for Tap 0.
With this configuration uploaded, Tap 2 will continue to produce
output at all times, but Tap 0 will also emit data whenever the trigger
28 Issue C
Operator's Guide
criteria are met. The Triggering button is now shown in red to remind
you that the trigger is active.
Every checked box in this window will give rise to a data stream
coming from the digitiser, which will be displayed in Scream!'s main
window when Scream! first receives some data from it. Every stream
is identified by a 6-character code, where the first four characters
identify the digitiser, and the last two characters identify the
individual stream. The first four characters are set by default to the
serial number of the digitiser; you can change this on the System ID
pane (see page 26) or from the digitiser's console.
3.1.3 Triggering
In its standard configuration, the CD24 outputs continuous data at a
sample rate you specify. In addition to this, Güralp digitisers can run
a triggering algorithm on the data they acquire. This allows you to
record data continuously at a relatively low sample rate, but record at
a much higher sample rate during short periods when the trigger is
active. The parameters controlling the triggering algorithm, and
controlling the data output once the system is triggered, are all
selectable by the user, permitting maximum flexibility of operation
and the most efficient use of available storage space.
The CD24 can be set up for triggered output, that is, to output certain
data streams only when a particular trigger criterion is met. The
trigger criterion can be tested with data from the same or some other
stream. For example, you could use a later tap (with a lower sample
rate) as a trigger for output from an earlier, more detailed tap. Scream!
4 (and above) also allows you to configure each digitiser to receive
triggers from other digitisers.
March 2011 29
CMG-CD24
To create a new stream with a trigger, open Scream!'s Digitiser
configuration window for the relevant digitiser and click on the Output
control tab. In the Output control pane, a tap which gives rise to a
triggered stream has a tick in the lower row of its grid of check-boxes.
You cannot configure the trigger criteria until you have selected at
least one stream to be affected by the trigger.
Once you have decided which streams should be output when the
trigger is activated, you will be able to click on the Triggering button
to describe the trigger condition. Alternatively, click on the Triggering
tab at the top of the window. Either action will open the Triggering
pane:
There are two triggering algorithms which Güralp digitisers can use.
However, not all models can use both methods. Scream! will find out
from the digitiser whether its on-board software supports each
method.
3.1. 3.1 STA/L TA
The STA/LTA algorithm applies a (simple short-term average) / (longterm average) calculation to the triggering stream. It works by
identifying sections of an incoming data stream when the signal
amplitude increases. The purpose of taking a short term average,
rather than triggering on signal amplitude directly, is to make it less
likely that spurious spikes will trigger the device. Averaging also
introduces an element of frequency selectivity into the triggering
process.
You can select which tap is tested for the trigger from the Data source
drop-down menu. The tap does not have to output data to Scream! for
you to be able to use it here.
Any or all of the channels available at that tap may be used to
determine a trigger. You can select which channels are considered by
checking the boxes in the Channel column of the table. If any of the
checked channels passes the trigger condition, the trigger will activate,
and will not detrigger until all of the checked channels have fallen
below their respective ratio values.
The STA and LTA columns allow you to set the intervals over which
the two averages are calculated, in seconds. Typically, the time
interval for the short term average should be about as long as the
signals you want to trigger on, while the long term average should be
taken over a much longer interval. Both the STA and LTA values are
recalculated continually, even during a trigger.
30 Issue C
Loading...