Channels Module:

The channels module consists of two python modules, RunChannels.py and Channels.py. RunChannels.py is run daily from a cron job.

RunChannels retrieves a list of all events due for processing from the database; events are generally reprocessed every 90 days until they are 10 years old. GetDC() on the Channels.py modules is called for each event selected above.

For each data center and each earthquake, the data center is polled to retrieve a list of networks, stations, locations, and channels active at the time of the earthquake. Each unique combination of data center, network, station, location, and channel is added to the channel table in the database -- this table is used to create data requests from the data center for each earthquake.

Note that retrieval of channel information from the data center is not a guarantee that the data center actually can provide the data for that channel. Some channels are listed at multiple data centers but the actual time series data is only archived by one, some data may be embargoed, some stations may have data outages, and some stations provide multiple data streams at different rates for the same data (i.e., BHZ and HHZ). If multiple data rates are present for a given channel or multiple data centers host the same data, ADEPT downloads one data stream and marks the other channels as duplicates.

Channels are only added for fdsn compliant data centers and for the Japanese FNet data center. The SSN (Mexico) and GDMS (Taiwan) data centers retrieve data differently and add channels after data retrieval.

Here is a representation of the channel table in the database:

column name	data type	notes
prikey	bigint	automatically assigned number as a key to this record
eventid	text	the eventid, keyed to the event table
dckey	integer	numeric key to the data center in the datacenter table
network	text	network ID for the station
station	text	station ID
location	text	location code, used for multiple instruments at the same station
channel	text	channel code for each directional channel, usually something like BHZ
latitude	numeric	latitude of the station
longitude	numeric	longitude of the station
elevation	numeric	elevation of the station, meters above sea level
depth	numeric	depth of the station, usually only populated for borehole instruments
status	integer	links to channelstatus table, status of this channel record
azimuth	numeric	azimuth, orientation from true north for this channel
dip	numeric	dip, orientation in degrees from vertical for this channel

This is the channelstatus table, with text values for the different status options

column name	data type	notes
prikey	integer	numeric key for this status, keyed to channel table
status	text	text value for the status

Values for status are one of:

1    New
2    Downloaded
3    No Data
4    Duplicate