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

 

Last Updated: 9/2010

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.