Ticket #442 (closed defect: fixed)

Opened 8 years ago

Last modified 8 years ago

bug in slink2ew when loading trigger blockette

Reported by: wes Owned by: somebody
Priority: major Milestone: All Platforms
Component: slink2ew Version: 7.5
Keywords: Cc:


I believe that I've stumbled upon an error in slink2ew.

For station POHA.HHZ.IU.10 I get triggered data via slink2ew. Every resulting trigger has a gap around the arrival of the P-wave. Data on the seedlink server is confirmed to be continuous across this gap.

The data blocks that are skipped have a trigger blockette: IUPOHA HHZ10 698002 D 2013 349:12:37:11.8583 n=91 rt=100.0 dt=128 off=48 #f=6 nb=3 (M:e=11 l=512)(MI:tQ=100 #fr=6 u=91) (201)E iblk=30/512

  • Blk201 201 off=0 sig amp=138261.0 sig per=0.07 Bkgrnd=8039.0 event det flags=0x0 rsvd=0 onset=2013 349:12:37:11.8683

SNR=1 3 6 8 9 0 lookback=2 Pick algorithm=1

  • Detector name=SEIS_H_RATE

Given the consistency of the symptoms, I have a suspicion that the slink2ew module isn't properly dealing with the additional trigger blockette.

Change History

comment:1 Changed 8 years ago by chad

What you have found are miniSEED records that contain both a detection blockette and data samples. You are correct that slink2ew will not handle these correctly a fix should be possible.

To explain: In the environment SeedLink? was developed in each record (packet) was classified with a "type", where the type was determined by the presence of specific blockettes. In theory, a client can request packets of specific types (i.e. if you only wanted detections and no data). One of the assumptions of this classification is that records can only be one type. In this case, any record with a blockette 20x (a detection blockette) is assumed to be a "detection record" and is not expected to contain data.

There is no rule that a miniSEED record cannot contain both a detection blockette AND data samples, but that was a common scenario previously. Obviously the SeedLink? classification does not work for the general case (the DMC's SeedLink? server does not even honor the type selection). slink2ew was coded a decade ago with this classification in mind, if certain blockette types are present it is not expecting data samples. Bummer.

I'll update slink2ew to ignore the SeedLink? packet type and instead check for samples count and a non-zero sample rate.

comment:2 Changed 8 years ago by chad

  • Status changed from new to closed
  • Resolution set to fixed
  • Milestone set to All Platforms

Fixed in repository, slink2ew version 2.6.

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