19-2233 PC2
2019-02-01
7(50)
ADQ7DC Manual
16-1796 PC2 2019-02-01
7(50)
1.2.4
ADQ7DC sampling clock frequency
ADQ7DC is designed for the specified clock frequencies only. A different sampling rate can be
achieved by using the sample skip function,
The ADQ7DC is available in two different speed modes, 5 GSPS dual channel and 10 GSPS single
channel. Both modes are supported by the hardware and included with the ADQ7DC. The firmware of
the FPGA has to be changed when switching mode. This may require a re-start of parts of the system.
Use the ADQ7 Updater tool to switch firmware.
Some parts of the descriptions and examples are done for only one of these frequencies. The exam-
ples are translated to the other sample rates by multiplying or dividing with the corresponding sample
rate ratio.
1.2.5
System clocks
The different parts of the digitizer operate on different clock rates
The sampling of the analog signal is done on the sampling clock of the ADC (see
).
The external trigger input has a trigger clock which is higher than the sample clock for high trigger time
precision (20 GHz).
The different host PC connections (USB, PCIe etc) has their own respective clock system.
All other interfaces operate on the data processing clock of the FPGA at 312.5 MHz. This clock is
referred to as the Data Clock.
See
for more details on the clock system.
1.2.6
Analog signal range
The analog signal range (
ACTUAL_ANALOG_RANGE
) is 1 V
pp
and is by default symmetrical around
zero. The range can be adjusted from [–0 mV +1000 mV] to [–1000 mV +0 mV] by the DC-offset fea-
ture,
Table 2: Data recording nomenclature.
PARAMETER
DESCRIPTION
REF
ADQ
Collective name for digitizers from Teledyne SP Devices.
Analog
Analog signal is the input to the digitizer. This is the signal to be digitized.
Waveform
Analog signal with a distribution in time. This is digitized into a record.
Sample
An analog signal level is digitized into a sample, that is a numerical value.
SYNC
Physical connector on the front panel.
Record
A set of consecutive samples is called a record. An analog waveform is
digitized into a record of samples.
TRIG
Physical SMA connector on the front panel.
Trigger
Trigger is a real-time event that starts acquisition of a record.
Timestamp
Timestamp is a real-time value that identifies when a trigger happened.
The timestamp gives timing information for each sample.
GSPS
Giga-samples per second (10
9
). Clock frequency [Hz] and sample rate
[SPS] are both used to denote speed.
MSPS
Mega-sample per second (10
6
).
DC-offset
This is an analog DC level which is added to the analog input signal inside
the digitizer to vertically move the analog signal to fit within the range of
the digitizer. This effectively doubles the ENOB for a unipolar signal.
