Range - HP 8753E User Manual

Figure 6-72. The Effects of Windowing on the Time Domain Responses of a Short Circuit
In the time domain, range is defined as the length in time that a measurement can be made
without encountering a repetition of the response, called aliasing. A time domain response
repeats at regular intervals because the frequency domain data is taken at discrete frequency
points, rather than continuously over the frequency band.
where AF' is the spacing between frequency data points
example:
Electrical length = range x the speed of light
In this example, the range is 100 ns, or 30 meters electrical length. To prevent the time domain
responses from overlapping, the test device must be 30 meters or less in electrical length for a
transmission measurement (15 meters for a reflection measurement). The analyzer limits the
stop time to prevent the display of aliased responses.
Application and Operation Concepts
LOW PASS
IMPULSE
Measurement range = -&
Measurement =
1
MHz to
Range = & or
= (100 x lo-' 6) x (3 x l$ m/s)
=
(number of points -
201
points
2.001
1)
(number of points -
frequency span
seconds
(3
30
meters
1)