LISS (Live Internet Seismic Server) Client Software
Installing and Compiling the LISS Software:
Please follow the steps below to download, compile and run the LISS software.
- Download the software LISS Client Software (0.4Mb ZIP file).
- Compile the software. README and INSTALL files are included in the software package. MAN pages are provided, and it is important to review each program's Usage statement (by invoking the program with no arguments).
- Run dumpseed -d -e -t address (e.g. dumpseed -d -e -t anmo.iu.liss.org, for GSN station ANMO ASCII-format data from the ASL LISS). A UNIX man page for dumpseed is included with the software package.
What is the LISS?
The Live Internet Seismic Server (LISS) is a data transmission protocol developed at the USGS Albuquerque Seismological Laboratory. It was initially used both to acquire data from remote seismic stations as well as to distribute data to users. Today, the LISS is primarily used to distribute data. It allows for near-real-time data flow from seismic stations around the world. Data requests are not necessary; a client simply connects to a specific internet address to begin receiving data. In the event a station experiences a communications outage, the LISS automatically requests data from the station to back-fill the missing data. Today, the LISS is primarily used to distribute data to users over the Internet from Golden, CO.
What data are available via the LISS?
Data from stations of the Global Seismographic Network and the ANSS backbone network are available via the LISS. Each station will typically have at least three components of data available at multiple sampling rates. Data range from low sample rates, enabling studies of low frequency signals from large teleseisms (distant earthquakes) which travel deep within the earth's interior, to high sample rate data, often used to analyze short period signals of local earthquakes and explosions. Instrumentation varies from highly sensititive very broadband seismometers used to record distant events to low gain accelerometers able to withstand violent shaking of a large earthquake near the station.
How do I connect to the LISS?
The USGS Albuquerque Seismological Laboratory provides software to allow users to receive near real-time data from the Live Internet Seismic Server (LISS) and to manipulate that data. The programs are written in C and have been designed to be as platform-independent as possible. The software has been extensively tested on the Sun Solaris platform, and should run under most Unix/Linux operating systems. The package is free and includes the programs described below.
LISS Client Software Modules
dumpseed - a program that performs a variety of useful functions. For example, it is a LISS client that can be used to connect to the LISS for a given station in order to receive near real-time data (in mini-SEED format). The output from dumpseed can be displayed on the screen, redirected to a file, or piped to another program for further processing. A number of command-line arguments are available to allow the user to control the output. Additionally, dumpseed is a decompression utility that converts mini-SEED data files from binary format into text. This allows users to get data in a format suitable for plotting and graphing.
seedfilter - a program that takes as input a mini-SEED file and the name of a 'select' file. Select files are text files with a structured format that allow precise specification of the data to be filtered. The output of seedfilter is data that meets the criteria specified in the select file.
seedport - a LISS client program somewhat similar to dumpseed, but designed to write output into files. It has the capability to perform sophisticated filtering that enables the user to specify precisely what data is to be captured. The command-line arguments include options that allow the user to specify the output file name and an optional duration. For example, if the user wants a series of output files, each containing 60 minutes of data, they can use the duration option and the seedport program will start writing its output to a new file each time the duration elapses.
seedforker - a program with both client and server functionality. This is particularly useful for users who want to establish many connections to the LISS server, and who want to optimize resource and bandwidth utilization. The seedforker program establishes a connection to a LISS server process for a given station in order to receive data. The user can then connect up to 64 individual clients (e.g. seedport) to the seedforker to access that data. The seedforker client programs operate much faster because the data transfer from the seedforker to client programs is a local process.
- No support for this software is available. Exceptions may be made on a very limited basis.
- LISS resources are finite, and users needing a large number of connections are expected to use the seedforker utility (see below) if possible to maximize performance and resource utilization, and to minimize the load on the LISS.
- There are a number of situations where the LISS is temporarily unable to connect to a station and has no data to send to clients. When this occurs, the LISS sends a 'keepalive' message to clients every 5 minutes. (A keepalive message is a 512-byte mini-SEED data record with a sequence number of 000000 and nulls in the rest of the record.) Clients receiving keepalive records SHOULD interpret them as an indication of a positive state of health of the connection, and SHOULD NOT break their connection when such a message is received.
- The LISS has been in operation for over 15 years and the USGS may not be able to support the LISS service indefinitely. Another source of real-time data is through the IRIS Data Management Center through their SEEDlink connection.