Atec Agilent-PNA-X Series - Manual (Page 40)

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Table 31. Test Port Input (Group Delay) 1
Description Typical Performance
Aperture (selectable) (frequency span)/(number of points -1)
Maximum Aperture 20% of frequency span
Range 0.5 x (1/minimum aperture)
Maximum Delay Limited to measuring no more than 180° of phase change within the
minimum aperture.)
Accuracy See graph below. Char.
The following graph shows characteristic group delay accuracy with full 2-port calibration and a 10 Hz IF bandwidth.
Insertion loss is assumed to be < 2 dB and electrical length to be ten meters.
For any S
ij
Group Delay measurement, S
ii
= 0, S
ij
= 1, S
ji
= 0, S
kl
= 0 for all kl  ij
In general, the following formula can be used to determine the accuracy, in seconds, of specific group delay
measurement:
±Phase Accuracy (deg)/[360 × Aperture (Hz)]
Depending on the aperture and device length, the phase accuracy used is either incremental phase accuracy or
worst-case phase accuracy.
1 Group delay is computed by measuring the phase change within a specified frequency step (determined by the
frequency span and the number of points per sweep).