ORTEC DSPEC 502A User Manual

DSPEC 50
®
and DSPEC 502
®
Digital Gamma-Ray Spectrometer User’s Manual 932502G / 0618
corresponding hardware time stamp. Note that the second block will begin with another
CONNECTIONS time stamp, which will correspond to another hardware time word. The data
acquisition program must associate the first CONNECTIONS time stamp to the first hardware time
word and the second CONNECTIONS time stamp to the second hardware time word even though
the first hardware time word appears after the second CONNECTIONS time stamp. For example, if
you request 16384 words and the first returned word is 65532 indicating that 16380 data words
plus 4 overhead words were returned, you should immediately request another block of data.
The DSPEC 50 has buffer storage for up to 96k 32-bit words. Therefore, six requests may be
needed to drain the buffer and find all of the hardware time words. In practice, a program buffer
of 96k words would always hold enough data to drain an instrument buffer assuming that all six
requests were made in less than 1 second.
The following tables describe the format for the list-mode data as returned by CONNECTIONS
from the DSPEC 50:
The ADC Word contains a raw 14-bit ADC value and a 16-bit real time stamp. The Hardware
Time Word contains the same 16-bit real time stamp. In both cases this value represents the time
that the word was created as represented by an internal clock that increments every 200 ns. The
200 ns clock rolls over from 49999 to 0, which gives it a period of 10 ms. Every time the 200 ns
31 30 29 16 15 0
ADC Word
1 1 14-bit ADC value 16-bit real time in 200nS ticks
RT Word
1 0 30-bit real time in 10 ms ticks
LT Word
0 1 30-bit live time in 10 ms ticks
Table 3. Spectrometer List Mode Data Format.
31 24 23 16 15 8 7 0
Hdw Time
00000000 00000000 16-bit real time in 200nS ticks
CONNECTIONS Time
00000001 Byte 2 Byte 1 Byte 0
CONNECTIONS Time
00000010 Byte 5 Byte 4 Byte 3
CONNECTIONS Time
00000011 00000000 Byte 7 Byte 6
ADC CRM
00000100 00000000 Counts per 10 ms period
Counter A (Sample Ready)
00000101 00000000 Counts per 10 ms period
Counter B (Gate)
00000110 00000000 Counts per 10 ms period
Table 4. Spectrometer List Mode Data Format.
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ORTEC DSPEC 502A Specifications

General

Brand	ORTEC
Model	DSPEC 502A
Category	Measuring Instruments
Language	English