Alternate and Chop Sweep Modes

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you can select the ~~~~~~~~~~~.~,.

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menu to activate either one or the other sweep modes. For information about sweep types, refer to “Sweep Type Menu,” located earlier in this chapter.

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~~~~~.;.~A1~~~~~~~. measures only one input per frequency sweep, h order to reduce

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unwanted signals, such as crosstalk from sampler A to B when measuring B/R. Thus, this mode optimizes the dynamic range for all four S-parameter measurements.

The disadvantages of this mode are associated with simultaneous transmission/reflection measurements or full two-port calibrations: this mode takes twice as long as the chop mode to make these measurements.

Chop

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~~~~~~~~ & is the default measurement mode. This mode measures both inputs A and B during each sweep. Thus, if each channel is measuring a different parameter and both channels are displayed, the chop mode offers the fastest measurement time. This is the preferred measurement mode for full two-port calibrations because both inputs remain active.

The disadvantage of this mode is that in measurements of high rejection devices greater than 85 dl3, such as tilters with a low-loss passband, maximum dynamic range may not be achieved.

Figure 6-57 shows the a2termate sweep mode (bold trace) overlaying the chop sweep mode in a band-pass filter measurement. Note the difference in the crosstalk levels between the two modes

Figure 6-57. Alternate and Chop Sweeps Overlaid

6-106 Application and OperationConcepts

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Image 389
HP 8753E manual Alternate and Chop Sweep Modes, Alternate and Chop Sweeps Overlaid