Guralp Systems Strong Motion - Manual (Page 10)

Strong Motion User Guide
3 Viewing Results
Currently, the Scream software does not allow display of strong
motion or unified status packets. This feature is scheduled to
be implemented in the next version of Scream.
3.1 The Unified Status Packet
The unified status packet is a special, binary coded status
message from the digitiser that is transmitted every second. It
allows a connected system to determine the reliability of strong
motion data, and is intended for realtime monitoring and alarm
systems.
Some example packets are shown below. The first packet is
from a system that does not have a GPS lock, and thus has no
reliable time source.
00000000032A6C1F | LW-B808/ttyS2/rhod | 2008-03-12T12:42:43.000Z
| LW -B80801 | unknown | unified status | 19 words
| Clock status: locked=0, differential=-2147483647us,
source=GPS receiver, last_locked=1989-11-17T00:00:00.000
| Unable to interpret GPS receiver status.
| Channel 'Z' (instrument 0) flags:
| Channel 'N' (instrument 0) flags:
| Channel 'E' (instrument 0) flags:
This packet is from a system with a reliable time source:
000000000024557C | LW-A830/Port A/loc | 2008-03-12T12:43:17.000Z
| LW -A83001 | unknown | unified status | 27 words
| Clock status: locked=1, differential=-694us, source=GPS
receiver, last_locked=2008-03-12T12:43:17.000
| GPS receiver status: fix=3D, latitude=+51.216703deg,
longitude=-001.098548deg, elevation=+000105.000m
| Channel 'Z' (instrument 0) flags:
| Channel 'N' (instrument 0) flags:
| Channel 'E' (instrument 0) flags:
| Channel 'X' (instrument 0) flags:
| Channel 'Z' (instrument 1) flags:
| Channel 'N' (instrument 1) flags:
| Channel 'E' (instrument 1) flags:
Channel flags may occasionally be observed. These indicate
that the data is not reliable for some reason. Typically these
are observed immediately after a time step when the digitiser's
clock is synchronised for the first time. This will correspond to a
spike in the waveforms as the FIR filters charge.
10 Issue F