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SR1 Operation Manual 308
© 2014 Stanford Research Systems
The line:
<EQdata Name="Style" Type="6" Value="Freq Response"/>
identifies the file as a sampled EQ file with the values given as pure numbers.To specify a file where the
values are given in dB use:
<EQdata Name="Style" Type="6" Value="Freq Response (dB)"/>
The next line:
<EQdata Name="Freq" Type="DblArray" Value=
"0.01,0.02,0.03,0.04,0.05,0.06,0.07,0.08,0.09,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,
1,2,3,4,5,6,7,8,9,10,20,30,40,50,60,70,80,90,100,200"/>
gives the frequency values for each of the frequency response points. This value must be listed in kHz ,
not Hz.
Finally the y-values corresponding to each of the frequencies listed is described by:
<EQdata Name="Resp" Type="DblArray" Value=
"0.000300775933872953,0.00302174093251185,0.00932540277740184,0.0187511398949463,
0.030636637564135,0.0444168356181221,0.0596245322111266,0.075876407055739,0.0928635700095015,
0.110342389581799,0.286838481522557,0.443881655056602,0.577159672164201,0.688018968891406,
0.778916516580281,0.852785568914054,0.91256030198955,0.960885423147423,1.00000000003858,
1.14837827316987,1.15195959556707,1.11740718036267,1.06603938913942,1.00595593739291,
0.941761216135588,0.876545831584705,0.8124486702114,0.750902168765253,0.341162925654635,
0.178593707588384,0.107123333734722,0.0707303220476656,0.0499780417068754,0.037110212737056,
0.0286105664352016,0.0227144341264837,0.01846210568194,0.00466695600216974"/>
Obviously, the lists of frequency values, and response values must be the same length. When
interpolating in a sampled EQ file, if the required frequency is less than the value of the lowest frequency
point in the list, the response corresponding to this lowest frequency point is given. Likewise, if the
response is required at a value greater than the highest point in the list the value for the highest point in
the list is returned.
Digitizer Files (.TXT)
SR1 digitizer files are two-column ASCII text files. The first column displays time, which increases
monotonically in intervals of the sampling period. For digitizer files created by SR1's optional digitizer the
sampling period is always 12.5 ns (80 MHz). However, it is possible to create files with different
sampling rates and import them into the digitizer for display and analysis. The time difference between
the first two points is used to compute the sampling interval when a digitizer file is read in.
The second column gives the magnitude of each sample in Volts. Columns are separated by a "Tab"
character. When a digitizer file is loaded, the X-axis values in the file are ignored and the Y values are
simply loaded as sequential samples. The X-axis is aligned so that the first transition of the type
specified in the "Jitter Detection" control on the
Digitizer Panel (Preamble, all bits, etc.) is at time = 0.
A fragment of an example digitizer file is shown below. Users are encouraged to modify digitizer files
taken by SR1 or to synthesize their own to experiment with the capabilities of the Digitizer.
// SR1 Digitizer Time Record
// X Units = s, Y Units = V
0 0.075
1.25e-08 2.825
2.5e-08 2.375
3.75e-08 2.475