West Coast/Alaska Tsunami Warning
Center
Operations Manual
NOAA/NWS/WCATWC
910 South Felton Street
Palmer, Alaska 99645
http://wcatwc.arh.noaa.gov
Section
4.1.7 – latency_mon
Date Written: 8/2001
Development Language: MicroSoft
C/C++ v7.0 using WinAPI
Necessary Rings:
Input Ring - WAVE_RING;
reads TYPE_TRACEBUF format messages
Necessary Data Files:
StaFile - picker
configuration file
StaDataFile - seismometer
location, elevation, etc.
LogPath
- Path to output files which contain latency summaries
Initialization File:
latency_mon.d
- read on module start-up
Module Description:
This module takes waveforms from InRing and logs latency and outages of
the data for each trace. Each time a packet arrives, its start time is compared
to the end time of the last packet. When there is a gap the outage is logged to
a status file for that station. Also, the mid-time of the packet is compared to
real-time, and latency is determined. Whenever the latency changes, it is also
logged with start and end time to the file. Latencies are grouped generally:
<1' = 0; 1'-2' = 1; 2'-3' = 2; 3'-5' = 3; >5' = 4. This module will only
give accurate outage values if this module is running all the time the
earthworm system is operating. Also, this module is not really relevant to
digitized analog data as data packets will be acquired, even if a station is
out.
An upgrade was added in 2002 by USGS/NEIC. This allows stations to be specified
by an output file from the earthworm utility FindWave as opposed to StaFile.
The GUI was also upgraded.
NOTE: The latency log files can become very large when a station flips
back and forth often between different latency groups. The files may need to be moved and
reinitiated every year.
Program Controls:
This module has a Windows graphical interface.
Due to this interface, the module will only compile and run under Windows (NT, 2K,
or XP). The graphical output shows a line for each station in the StaFile for a
specified length of time. Colors on the line represent the latency of the
station over that time interval. If no line is drawn, the data either was not
recorded or was later than 5'. To the right of the symbolic lines, a summary is
given showing the percentages of time that the signal for each station was in
each latency range. This summary can also be printed out.
Menu Options:
Station Status: Specify time
range over which to display latencies.
Control Panel:
Traces
per Screen: Set number of lines to show on visible section of
display.
Print
Status Summary: Print out summary of latency information for last
request.
Save
Status Summary: Write latency summary to data file.
Refresh: Re-paint the screen.
