Tankplayer Overview

(last revised September 9, 2008)

"tankplayer" is part of the four-program set for recording and playing back the trace data for selected time intervals. See also trig2disk, waveman2disk, and wave_serverV.

Tankplayer has two common uses and one new use:

Tuning Operating Earthworms:

For example, an Earthworm system fails to locate a significant earthquake. The waveform data for the earthquake is requested from the wave_server and saved in tankplayer format. Using an experimental Earthworm, the event is played back with tankplayer, tuning the operational parameters until Earthworm performs satisfactorally. The operational parameters are then changed to those used in the test.

Quality Assurance:

One is to perform quality assurance tests. For such tests, an experimental Earthworm system would be set up, and one or more tankplayers would be connected as the data source. Each tankplayer would be given a lengthy list of data files, and "tankplayer" would play (broadcast into the earthworm) the trace data from these files, one after another, generally overnight. The earthworm system under test would then process the incoming data. In the morning, we would come in and examine the rubble.

Menlo Park has created a collection of over 50 historic trace data files, representing the trace data traffic during various 'moments of horror' at CalNet. These include the Loma Prieta mainshock, swarms during wind storms, concurrent events in different parts of the net, events during telemetry malfunctions, etc. These files were painfully created by reformatting CUSP data archive files. The format of these files is simple: it is a series of messages of TYPE_ADBUF, written with a binary write.

Real Time Data Feed:

Alternatively, as of Earthworm 7.3, the tankplayer module now accepts tank files moved into a loading directory for automatic playback. This is configured using the GetFromDir setting in the .d file. The files must be loaded in time order for this mode to work. This provides the Earthworm user with a new way to load waveforms into the rings...by creating a tank file generating program.

How Tankplayer Works:

On startup, tankplayer reads its configuration file. This specifies the message ring into which to inject the data, and the module name to use. Tankplayer is generally told to imitate a real data source, such as an A/D module, or a digital acquisition module. The parameter file also lists the data files to be played back. It also specifies a pause period. This was implemented to prevent the earthworm associator (binder) from becoming confused by rapid jumps in time between data files. This time period should be set to be larger than binder's association memory, to prevent it from trying to associate phase arrivals from different data files.

In operation, tankplayer places the waveform messages from its input file(S) into shared memory in simulated real time, using the delta-t between time-stamps in successive message headers to determine its timing. When the end of file is reached, it waits "Pause" number of seconds, and goes on to the next file, as specified in the parameter file.

Tankplayer is location code compliant and backward compatible. It accepts messages of either tracebuf or tracebuf2 as configured using the PlayMsgType parameter.

Tankplayer Tools:

Separate from tankplayer are tools to help create tankfiles from sac format files. One can also archive tank files using waveman2disk and configuring appropriate output format. The two tools are sac2tb and remux_tbuf. The notes from Pete Lombard about these tools:

This is sac2tb, a utility for turning SAC data files into tracebuf files. Usage: sac2tb [-n samples] sacfile > tbuf-file

Without the -n option, sac2tb defaults to 100 samples per packet.

The intended use is that you run sac2tb on a bunch of SAC files for a given event or time period, "cat" all the files together, and then run remux_tbuf to make a tankplayer file. For example, in a directory of SAC files:

  foreach m (*)
sac2tb $m >> tbuf

remux_tbuf tbuf test.tnk

SAC doesn't have a provision for byte-swapping, so to my knowledge, SAC files are only in SPARC byte-order. At least that's the assumption here. If sac2tb is run on an intel machine, the SAC file will be swapped into intel byte-order and the resulting tracebuf messages will be marked accordingly.

Pete Lombard, 19 May 2001

Five New Tankplayer tools for EW v7.2:

$ tankcut
Error, an input and output tank name must be provided
tankcut version v0.0.1 2007-08-27
usage: tankcut -s StartTime [-e EndTime|-d Duration] intank outtank
all times for -s and -e options must be in YYYYMMDDHHMMSS format
        -s StartTime - when to start including tracebufs from intank
-e EndTime - when to end including tracebufs from intank
-d Duration - Duration in seconds from start time when to end including tracebufs from intank
Default Duration is 600 seconds from start time

Paul Friberg - December 27, 2007

Module Index | Tankplayer Commands

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