Helicorder Service

Helicorder renders daily per-channel waveform plots from database history. Enable Archiver first and retain enough data for the plotted day. Existing MiniSEED files are not used as its data source.

Setting	Key	Default	Meaning
Enable	enabled	false	Enable plot generation.
File Path	file_path	./service_data/helicorder	Image output directory.
Cache Storage	cache_storage	disk	disk, memory, or disabled.
Cache Path	cache_path	./service_data/helicorder/.helicorder-cache	Temporary disk cache.
Image Format	image_format	svg	svg or png.
Time Span	time_span	15	Minutes per row: 10, 15, or 30.
Life Cycle	life_cycle	0	Image retention in days; zero keeps indefinitely.
Image Size	image_size	800	Rendered image size in pixels.
Span Samples	span_samples	10000	Plot points per row.
Line Width	line_width	1.0	Waveform line width.
Scale Factors	sacle_factors	[500, 500, 500, 30000000, 30000000, 30000000]	Per-channel amplitude scaling in configured channel order.

The persisted key sacle_factors and the UI label “Sacle Factors” retain the source spelling. A zero or missing factor skips that channel; a larger factor draws larger amplitudes. Add factors for additional channels if needed.

The first plotting pass starts approximately one minute after service startup, then plotting follows hourly boundaries. Images use UTC date directories and station/channel identifiers and are refreshed during the day. Download generated images through the web interface.

Disk caching reduces repeated database decoding with moderate memory use. Memory caching can be faster but raises RAM requirements; disabled caching minimizes retained cache memory. Lower image size or span samples on small hosts. Output and cache directories must be writable. Image retention is independent of database retention.