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.
ResponseFile - Broadband instrument response in poles/zeroes format
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.
