Bit Description
31 0 for event
30–21 Amplitude of pulse
20–0 Time in microseconds that the
event occurred
Table 1. Event Word.
Bit Description
31 1 for time-only
30–0 Current time in microseconds
Table 2. Time Stamp Word.
APPENDIX A. LIST MODE
The digiBASE is equipped with List Mode, which streams spectroscopy data directly to the
computer, event-by-event, without the data “dead periods” associated with the acquire-store-
clear-restart cycle of standard spectrum acquisition.
MAESTRO v7 supports our List Mode MCBs with menu and toolbar commands, as well as
commands in our automated JOB streams. See the MAESTRO user manual for detailed
information.
This appendix provides details about the List Mode that will enable experienced programmers,
using the ORTEC CONNECTIONS Programmer’s Toolkit with Microsoft
®
ActiveX
®
Controls to
write custom software applications for acquiring and saving List Mode data. For additional
information, see:
http://www.ortec-online.com/Solutions/applications-software.aspx?tab=2
A.1. List Mode Data
In List mode, each detectable event that would normally be histogrammed into a spectrum is sent
to the computer along with a time stamp that indicates the time the pulse arrived. The data could
be analyzed by the computer in real time to determine if some significant event has occurred, or
the data might be streamed to disk for analysis at a later time. In either case, the computer is
intimately involved in the collection of the data.
In List Mode, the digiBASE transmits one 32-bit
word for every detectable event in the NaI detector.
The 32-bit word is encoded as shown in Table 1:
The time is a 21-bit number in units of ìs. The
number rolls over to 0 every 2.097152 s. In order
to track the rollovers, a “time only” event is sent
from the digiBASE to the computer every
1.048576 s. The format of the “time only” event
is in Table 2:
The digiBASE is equipped with a 128K first-in-
first-out (FIFO) buffer that stores the data until
the computer has time to read them. Should the
computer stop reading data, the FIFO fills up and
all further data are lost until the computer empties
the FIFO.
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