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E1437A
ASCII Overview and Commands
extra level of decimation in order to increase the displayed span.
parameter
Comments
To ensure full alias-free operation the analog anti-alias filter (set by the
INPUT:ALIAS:FILTER command) should be ON unless the application inherently
bandlimits the input signal to less than fs/2. The analog anti-alias filter has a fixed
bandwidth and thus is fully effective only when fs>=20 MHz. If a slower external
ADC clock is used, an additional analog filter of the appropriate bandwidth may be
required for full alias protection.
The decimation process used to reduce the output sample rate is driven from a
"decimation counter" which keeps track of which samples to save and which ones to
discard for each of the octave bandwidth reduction filter stages. In multi-module
systems where synchronous sampling is required, the decimation counters in all the
modules must be synchronous with each other. This condition can be forced by
using the FILTER:SYNC command.
The following table summarizes the relationship between data parameter
combinations, decimation, filter bandwidth, and whether the particular combination
permits block or continuous measurements:
Resolution
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selects the data output sample rate. You would normally want to add the
value
0
OFF. The output sample rate is: fs when bw=0 or fs/ 2^(bw-1) when bw>0.
ON. The output sample rate is reduced by an additional factor of two by discarding
1
alternate samples
Type
Decimation Filter BW
16
Complex
False
32
Real
False
32
Complex
True
32
Complex
False
32
Complex
False
All other combinations
decimate parameter definition
Block
Continuous
0 or 1
Yes
No
0 or 1
Yes
No
0 or 1
Yes
No
2
Yes
No
0 or 1
No
No
Yes
Yes
FILTER:SETUP
command/query
Sample Rate
(MBytes/sec)
80
40
40
40
40
<40
5-21
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