Image Processing Reference
In-Depth Information
Signals with various attenuation factors and
two first time bins on the pedestal level
Signals with various attenuation factors and
two first time bins on the pedestal level
120
120
0.2
0.25
0.3
0.35
0.4
0.5
0.6
0.2
0.25
0.3
0.35
0.4
0.5
0.6
0.7
0.8
0.9
100
100
80
80
60
60
40
20
0
ns
25
12,5
0
12,5
25
37,5
50
62,5
75
87,5 100 112,5 125 137,5 150 162,5
20
Fig. 12. Shapes of signals with various attenuation factors and two first time bins on the
pedestal level
All signals with first two time bins on the pedestal level for sure will be with only one
time bin on the pedestal level in the next clock cycle. But, not vice versa. A signal with
only a single time bin on the pedestal level before sharp rising edge can have significant
contribution in the 2nd time bin before rising edge and it will not be recognized by a pattern
recognition procedure tuned on the Shape_A. A procedure recognizing Shape_A is more
restrictive and gives lower trigger rate than for the Shape_B. Due to limited amount of the
DSP blocks only 11 DCT coefficients can be analyzed simultaneously. For the Shape_A the
X 4 and X 10 are ignored and for the Shape_B : X 6 and X 14 , respectively, as weakly sensitive
on changes of signal shapes. The trigger based only on the DCT pattern recognition gives
too high rate, due to a contribution of very week signals with also appropriate shape, but
usually treated as noise. In order to reduce and control the trigger rate, the veto threshold
has been introduced. The calculation of the DCT coefficients in the pipeline chain and next
the calculation of sub-triggers in multipliers and comparators block takes 12 clock cycles. The
signal is synchronized with the DCT sub-triggers delayed the same time to be compared with
the veto threshold, simultaneously with a generated DCT sub-triggers. If the signal is above
the sum of the veto threshold and the pedestal, the sub-triggers are enabled to generated a
final spectral trigger. The condition that all 11 DCT coefficients were inside the acceptance
lane is too strong. The shapes are not ideal, noise introduces additional shape distortions.
Similarly as in the ToT trigger only a part of "fired" sub-triggers (Occupancy
11 = max.
number of sub-triggers) is enough to generate the final spectral trigger.
DCT coefficients for signals with two
two first time bins on the pedestal level
DCT coefficients for signals with two
two first time bins on the pedestal level
DCT coefficients for signals with only
one first time bin on the pedestal level
DCT coefficients for signals with only
one first time bin on the pedestal level
Shape_B
Shape_B
Shape_A
Shape_A
600
600
800
800
400
400
600
600
0 2
0 25
0 3
0 35
0 4
0 2
0 25
0 3
0 35
0 4
0 5
0 6
0 7
0 8
0 9
0 2
0 25
0 3
0 35
0 4
0 2
0 25
0 3
0 35
0 4
0 5
0 6
0 7
0 8
0 9
200
200
400
400
0
0
200
200
2
3
4
5
6
7
8
9
10
11
12
13
14
15
200
0
2
3
4
5
6
7
8
9
1 0
1 1
1 2
13
14
15
400
200
600
400
800
600
Fig. 13. Coefficients for signals with various attenuation factors and two first time bins (left)
and only one time bin (right) on the pedestal level
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