Agilent Technologies 35670A - Page 262

Detecting Bias Errors
The bias errors around complex poles are best detected by looking for narrow
width decreases in the coherence function at the peak of a resonance.
These bias errors can occur in measurements made with a burst random source if
the burst is not shut-off soon enough. The system response must be allowed to
decaytonearzerobytheendofthetimerecord.
0Hz 3.2kHzAVG: 50
A: D1Freq Resp X:0 Hz Y:-1.314 dB
50
dB
-50
dB
dBMag
10
dB
/div
X:0 Hz Y:44.3843e-3
B: D2Coherence
1.05
550
e-3
Real
50
e-3
/div
0Hz 3.2kHzAVG: 50
Scale Trace: A Ref Lvl: 50
Per Div: 10 Ref Pos: Top
Indicates bias error
around complex
poles.
Agilent 35607A
Curve Fit Option 1D3 Operator's Guide
16-14