Page 28 of 80
MCP Delay Line (Version 6.2.90.5)
Figure 2.35: inputs, outputs and controls of the ATR19 for each internal DLATR board
The “Mon” output allows a monitoring of the noise level and the signal quality from the delay-line. This output shows the
amplified signal according to the input signal and input settings (jumpers JP5, JP6, JP8 and JP9, see chapter 2.6.1). For
verifying the signal, the input of the oscilloscope must be 50
Ω
coupled and the CFD output (ECL or NIM) should be
connected to the TDC.
The “ECL” output (only for ECL version of the
ATR19
) provides the timing signal (differential ECL) from the CFD circuit
for use with a TDC of according input requirement. The TDC input should provide -2V via 50
Ω
or form a similar passive
differential ECL input.
The “NIM” output provides
for NIM version of the
ATR19
:
the timing signal (standard NIM signal) from the CFD circuit for use with a
TDC
of
according
input
requirement.
The
signal
can
be
verified
on
an
oscilloscope
(50
Ω
coupling).
for ECL version of the
ATR19
:
the modified timing signal from the CFD circuit (ECL -) for monitoring on an
Oscilloscope:
select
AC
coupling with large impedance (e.g. 1M
Ω
)
The CFD circuit requires the setting of a threshold in order to discriminate noise from real signals. This threshold is set by a
DC level of 0 to +5V. This level can be set and controlled internally via the threshold poti for each channel or by directly
supplying this voltage through the corresponding LEMO input. A jumper (JP11 and JP12) on the level control board inside
the
ATR19
(see chapter 2.6.5) enables the threshold control by the poti (default setting). In this mode (jumper JP11/JP12 set)
the LEMO output carries the DC voltage for control with an Ohm meter. If the jumper is removed the poti is disabled and
the LEMO connector serves as input for the DC voltage from an external source.
A DC voltage of +5V corresponds to a threshold level of -100mV on the amplified signal (as obtained from the “Mon”
output). The ratio between DC voltage on the LEMO connector and the threshold is -50.
The width of the timing signal from the CFD is set by another DC voltage (0 to +5V) which can likewise either be supplied
by the corresponding poti (and controlled via the LEMO connector, JP13 set, default) or by directly supplying this DC
voltage (JP13 off). Thus the width can be adjusted between 10 and about 100ns. Note that there is only one control for both
channels on each
DLATR
board.
If the LED next to each
DLATR
in-/output connector group (on the right side) is not lit please verify the DC voltages on
the reading points near the power switch on the front panel. If these are present and within the specified range (see chapter
2.6.4) refer to chapter 2.6.5 (opening the
ATR19
) and insure that the corresponding board is properly installed.
If the DC voltages on the reading points near the power switch on the front panel are not within specification verify the
mains power or the external DC supply (see chapter 2.6.4)
Before starting a measurement the “walk” of the CFD on all boards can be adjusted. Usually this is not necessary. However,
if you want to calibrate the walk at the beginning of a measurement please follow these steps:
Summary of Contents for DLD120
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