User`s guide

Residual Measurement Fundamentals 7
Agilent E5505A User’s Guide 221
3
The Device Under Test (DUT) and the reference source should be locked by
the same 10MHz reference. The 10MHz reference is split and provided to the
DUT and reference source.
4 The frequencies of the DUT and reference source equal each other.
Auto Cal Process
When a user selects measured beatnote / auto cal, the system does the
following process.
1 Offsets frequency of a reference source to produce a beatnote for cal.
2 Reads a beatnote and calculates the phase detector constant, then turns the
frequency of the reference source back to be equal to that of the DUT.
3 Adjust phase of reference source’s output so that the 70420A/N5500A
Signal Input and the REF Input are in quadrature. Quadrature is achieved
when the output of the phase detector equals 0 V (precisely, less than
0.002V).
Double-Sided spur
This calibration option has the following requirements:
• One of the input frequency sources must be capable of being phase
modulated.
• The resultant sideband spurs from the phase modulation must have
amplitudes that are –100 dB and –20 dB relative to the carrier amplitude.
• The offset frequency or modulation frequency must be between 10 Hz and
maximum (See the“Measured beatnote" on page 217).
Figure 156 Automatic Calibration Connection Diagram