[:SENSe]:DECimation
This command sets or queries the rate of decimation of samples in a trace capture.
When the rate is set to 1 (or OFF), no decimation is performed on the trace capture. The
decimation range varies depending on the RFE modes as described below.
In HDR mode, the decimation is done directly by the on-board NB ADC. The decimation
value supported by this mode is 1
, 2 and 4
.
In the remaining RFE modes, RTSA7500 uses DDC to provide 10 levels of decimation of
values
2,
4, 8, 16, 32, 64, 128, 256, 512, 1024 (i.e. decimation rate = 2
level
where level =
1,
2
– 10). The decimation process consists of CIC and FIR filters, each type of filters
with its own decimator. The decimator captures one sample at every <integer> number
of samples. The filters are arranged in the following manner:
For the decimation rate of 4, only a FIR filter with a fixed decimation by 4 is used,
CIC filter is bypassed.
For the decimation rates of 8 to 1024, a 4-stage CIC of rate 4 to 512 is applied
first for each I and/or Q data. The resulting I and/or Q data pipes are then
passed to a FIR filter with a fixed decimation of 2 to arrive at the rate set. For
example, for a rate of 16, I and Q data will first pass-through the CIC filters with a
decimation rate of 8. The CIC output will be further decimated by 2 by the FIR
filter which has a fixed decimation rate of 2.
Note:
When in SH/SHN mode and a decimation is on, the RTSA7500 will automatically
be shifted by 55MHz in WBIQ model or 35MHz in all others to the zero IF before
decimation is applied. This implies
the VRT data output will be I and Q for SH/SHN
with decimation
.
Syntax
:SENSe:DECimation OFF | <integer>
:SENSe:DECimation? [MAX | MIN]
Parameter
OFF | <decimation value>
Input Data Type
Integer | Character
Allowable Values
In HDR mode:
OFF, 1, 2, 4
For ZIF, SH, SHN modes:
OFF, 1,
2
, 4, 8, 16, 32, 64, 128, 256, 512 and 1024
1
Equivalents to decimation off.
Query Response
In HDR mode:
1, 2, 4
For ZIF, SH, SHN modes:
1,
2
, 4, 8, 16, 32, 64, 128, 256, 512 and 1024
Output Data Type
Integer
*RST State
1
Examples
:DEC 16
:SENSE:DEC OFF
