2008-03-31: figures updated, text and links are not revised.

4.1 Import signals

This section explains how to import signals into Geopsy. Signals can be imported from files (list of supported formats), from a SeedLink remote connection and from a CityShark flash card.

Import files

Figure 1: "Files" list after importing several signal files.

Click on menu "File" and select "Import signals" item, or alternatively hit the "Import signals" icon in the tool bar as shown in Figure 1. You get the open file dialog box where you can select one or more files to open. Use the SHIFT and CTRL keys to create custom selections. Click on "Open" to proceed with the importation of signals. All the files appear in the file list as shown in Figure 1. This list contains all currently imported files. The complete path of each file appear on the right. According to the current preferences, the signals may be directly displayed in a table or in a graphic, or you can get the file format dialog box as shown hereafter.

If the list does not appear, it is likely that it has been hidden by a previous use of Geopsy. Select "Files" in menu "Windows/Tool bars" to show the list (make sure that the item is checked). The list can be moved to any part of the screen by pressing the mouse in its title bar and dragging it to the desired position. In the vicinity of the left and the right border of the main frame, the list is automatically docked to the main frame, otherwise it has a free position and size. If it dragged over another docked tool (e.g. Log or Groups), the list of files is automatically insert in a tabbed widget as displayed in Figure 1.

Remove files

To remove a file from the database, select "Remove" from the context menu (right mouse click) in "Files" list. Multiple and complex selections (SHIFT and CTRL) can be used to remove several files at the same time. If the removed files are original files, the signal file itself is unaffected, only the information stored in the database is irreversibly lost. In the other case (modified files), the signal is removed from the database directory and the information about these signals is also lost.

Selecting file formats

Figure 2: Preferences for file format selection.

In most situation, the automatic format determination does a good job. If you want to specify manually the format, you have to edit the preferences. Click on menu "File" and select "Preferences" item, or alternatively hit CTRL+p. In the preference dialog box, click on the "Loading files" tab. You get the screen shown in figure 2.

Select "Always ask for file format" to manually specify the file format for all loaded file. If "Use this format" is selected, the format specified on the right is always used. "Automatic recognition" is the default and probably the best option.

If "Always ask for file format" is on, before importing each file, you are asked to specify the file format with the dialog box shown in figure 3. If all the selected files have the same format, you can uncheck the checkbox "Show this dialog next time". Choose the right format in the list. Once the list is displayed after a mouse click on it, you can hit initial letters to quickly scroll to the right format. Selecting a wrong format is generally reported, but, in some situations, it may read erroneous information without reporting error. In all cases, have a look in the "Log" (see Figure 1) window to check if any error or warning occurred.

List of supported file formats:

• Automatic recognition
• Database signals
• Binary SEG2
• Seismic Unix
• Arrival times
• RD3 RAMAC
• NiSismo
• SAC
• Radan GSSI
• GSE
• CityShark
• ASCII Multi column
• SESAME SAF
• Sismalp
• Wave PCM
• SEG-Y

TODO: not up-to-date

Other instrument specific formats should be implemented as soon as possible. If you have special requests or if you want to propose algorithms to import/export other formats, your contribution, in any form, is fully encouraged.

Automatic recognition

The table here below gives the criteria used to recognise the file formats. The conditions are processed in order from the first to the last row. At the first match, the format is considered to be recognised.

TODO: not up-to-date

Conditions for recognizing file formats

Conditions File formats file extension is ".su" SU big endian. Currently, no automatic detection of the byte order has been implemented for SU format. For SU little endian, the manual file format selection is necessary. file extension is ".rd3" RAMAC/RD3 format for RAMAC Ground Penetrating Radar file extension is ".dzt" Radan format for GSSI Ground Penetrating Radar file extension is ".ndx" or ".sis" Sismalp format, a ".sis" or ".ndx" (and vice-versa) must also exists in the same directory. file extension is ".wav" Wave PCM sound file, just for fun to analyse your favourite music albums. First line contains "Arrival_times_file" Arrival times format First 16 bits are 0x 55 3A Binary SEG2 file First 32 bits are 0x 66 5F 9C 6E NiSismo file format ??? First 4 characters are "WID2" GSE2 format, test by default for multiple signals in the file. This option may take some time for long signals. If there are only one signal per file, select manually "GSE2 Single Signal". First line begins with "Original file name" City shark 2 file. No distinction between format 1 and 2, both are accepted. First 10 bytes begins with "DBSignals" Geopsy database signals. First line begins with "SESAME ASCII data format (saf) v. 1" SESAME ASCII File format First 4 characters are "RIFF" Wave PCM sound file, just for fun to analyse your favourite music albums. First field (TAB or SPC) is a number ASCII file, one column per signal. NVHDR==6, IFTYPE=1 and LEVEN is true SAC format. The big and little endian are automatically recognised. else Error message, unknown format.

Database signals

It is the format used by Geopsy to automatically save modified signals. Usually you never import original signals written under this format. This new format has been introduced in Geopsy because it is the closer to internal memory vectors, hence I/O access are optimised.

TODO: not up-to-date

Geopsy database signal format

Offset (bytes) Size (bytes) Type Description 0 10 char Recognition tag: "DBSignals", coded in ASCII, the last byte contains 0 (zero, 0x00, not 0x30, the ascii value of character "0") like any C string. 10 4 int Version, current is 1 14 4 int Offset to first signal in file (bytes), counted from the beginning of the file. It might look useless, as the length of the header can be calculated from the number of signals. However, with this offset it is possible to add new data segments in the header without compromizing compatibility with older versions of geopsy. 18 4 int Number of signals in file (n) 22 4*n int Number of samples in each signal (nsamp[i], 0<=i<n) 22+4*n 8*n double Conversion factors for each signal 22+12*n nsamp[i] double For each signal (0<=i<n), the samples coded on 64 bits floating point numbers.

Binary SEG2

It is the usual format acquired with Geometrics instruments. It is not yet docummented.

Seismic Unix

Not yet docummented, you can submit your own article by sending us an html or text file.

Arrival times

Not yet docummented, you can submit your own article by sending us an html or text file.

RD3 RAMAC

Not yet docummented, you can submit your own article by sending us an html or text file.

NiSismo

Not yet docummented, you can submit your own article by sending us an html or text file.

SAC

Not yet docummented, you can submit your own article by sending us an html or text file.

Radan GSSI

Not yet docummented, you can submit your own article by sending us an html or text file.

GSE

Not yet docummented, you can submit your own article by sending us an html or text file.

CityShark

CityShark file format example

Original file name: Starting date: %d.%d.%d Starting time: %d:%d:%d.%d Sample rate: Sample number: Gain: Conversion factor:

Not yet docummented, you can submit your own article by sending us an html or text file.

ASCII Multi column

Not yet docummented, you can submit your own article by sending us an html or text file.

SESAME SAF

Not yet docummented, you can submit your own article by sending us an html or text file.

Sismalp

Not yet docummented, you can submit your own article by sending us an html or text file.

Wave PCM

Not yet docummented, you can submit your own article by sending us an html or text file.

SEG-Y

Not yet docummented, you can submit your own article by sending us an html or text file.

SeedLink connection

SeedLink is a TCP/IP protocol to transfer signals in pseudo real time from acquisition stations to SeedLink clients. With Geopsy, you can access network SeedLink servers, view recorded signals and process them as any other signal imported in Geopsy.

Figure 4: SeedLink loader listening to three channels of
station GE_LVC from server geofon.gfz-potsdam.de

First, you must specify the server location and port (usually 18000). geofon.gfz-potsdam.de is a public SeedLink server that gathers GFZ seismological networks. You can specify the numerical IP address or the address name. Connections can be created in a Local Area Network or over Internet. Hit "Connect" to connect to the server and request the list of available stations and their channels.

When the list of station appears, you can browse it and make your selection. Click on "Start" to start listening to the selected streams or channels. Each time Geopsy receives a packet, it is shown in the log area (see Figure 4). You can click on "View" to look at the recorded signals. These signals are dynamic buffers that you cannot modify. The maximum time for recording is fixed by the memory you set up for Geopsy (see Preferences). 1Gb of memory lets you record durning 5 days at 100 Hz for 3 channels. You can execute all read only operations on them (e.g. cut, H/V, array processing).

To stop listening to a channel, select the channels you want to stop and click "Stop". Listening channels are marked by a download symbol.

TODO: this tool is still in its early stage of developement, options will be added soon like the possibility to automatically cut recordings into pieces of 1 hour, 1 day,... hence making maximum recording lenght infinite (maximum depends upon your hard disk). Also soon available, the option to query for recordings in the past.

CityShark flash card manager

Not yet docummented, you can submit your own article by sending us an html or text file.