West Coast/Alaska Tsunami Warning Center

Operations Manual

NOAA/NWS/WCATWC

910 South Felton Street

Palmer, Alaska 99645

http://wcatwc.arh.noaa.gov

 

 

Section 4.1.9 – lpproc

 

Last Updated: 5/2007

Date Written:                       4/2001
Development Language:
MicroSoft C/C++ v6.0 using WinAPI

Necessary Rings:
 Input Ring -
WAVE_RING_LP; reads TYPE_TRACEBUF format messages
 
Input Ring - HYPO_RING; reads TYPE_HYPOTWC format messages
 
Output Ring - PICK_RING; writes TYPE_PICKTWC format messages (with MS parameters)
 Output Ring -
ALARM_RING; writes TYPE_ALARM format messages

Necessary Data Files:
 StaFile
lpproc configuration file
 StaDataFile -
seismometer location, elevation, etc.

 DummyFile - Hypo-parameters of last located quake
 LPRTFile -
MS data computed for last quake
 QuakeFile - List of automatically located quakes

Initialization File:
 lpproc.d -
read on module start-up

Module Description:
This module takes long period waveforms from the WAVE_RING and displays them on a window. The display is similar to an old-style develocorder (with no film delay). Every X seconds the screen scrolls to the left. The most recent data is shown on the right of the screen. The display can be "held" and manually scrolled through previous times (the time limit of saved data is specified in the .d file).

Hypocenters entered to HYPO_RING are obtained by this module. If the hypocenter has a magnitude greater than 5.0 Mb, Ml, or Mwp, this module will compute expected Rayleigh wave times at stations listed in StaFile and will evaluate the data in the window for Ms for up to 30 minutes passed the expected Rayleigh wave arrival time. When an Ms is computed, the data is sent in the TYPE_PICKTWC message format to PICK_RING with P-time=0 and the magnitude is displayed on the lpproc screen.

As data is read from the WAVE_RING, it can be processed by an LP alarm with parameters specified in the initialization file and the StaFile. If a large signal is found by the alarm function, an alarm is reported to ALARM_RING.

NOTE: A semaphore is accessed in lpproc so that LP processing can be triggered by program LOCATE. This semaphore should not prevent the program from working if LOCATE is not running.

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 display shows real-time, long period data. The most recent time is shown on the right side of the screen. As new data arrives, the screen scrolls left. A "Hold Screen" menu option is available to stop the automatic scrolling. Then, the horizontal scroll bars can be used to manually scroll through all the data which is in memory.

Surface wave data processing is triggered automatically via the HYPO_RING. Computed MS is shown near the trace name and an average is shown in the title bar. The MS processing can be started or stopped manually through the magnitude menu option. As magnitudes are computed, the expected Rayleigh wave start time is displayed on each trace, and the cycle which is used to compute MS is marked with a plus sign.

 

Mouse Buttons:

Right button on trace toggles trace display.

Right button on station name calls station manipulation menu (for trace scaling, trace display on/off, alarm on/off).

 

            Menu Options:

Hold Screen: Prevent automatic scrolling so that scroll bars can be used to move through data.

 

Control Panel:

Horizontal Scale: Change screen time scale.

Vertical Trace Scale - All: Change vertical scale for all stations.

Traces Per Screen: Number of traces vertically to show on the screen, rest will scroll.

Display Filtered Data: Check -> screen shows LP filtered signal for broadband stations.

Display Broadband Data: Check -> screen shows unfiltered traces for all stations.

 

Magnitude:

Compute Ms: Using last location in dummy file, process LP data for MS. After processing, a plus sign is marked on the cycle used to compute MS.

Stop Processing: Stop ongoing computations (usually used when automatic location has been updated).

 

ClipIt: Limit trace amplitudes.

 

Refresh: Re-paint the screen