Agilent Technologies HP 8719D Service Manual page 273

15
write/read to the control element on the Al4 fractional-N (digital)
assembly. The control element must be functioning, and the
fractional-N VCO must be oscillating (although not necessarily
phase-locked) to pass.
16
Sweep Trig. Tests the sweep trigger (L SWP) line from the Al4
fractional-N to the A10 digital IF. The receiver with the sweep
synchronizes L SWI?
ADC
17 Lin. It tests the linearity of the A10 digital IF ADC using the
built-in ramp generator. The test generates a histogram of the ADC
linearity, where each data point represents the relative "width" of a
particular ADC code. Ideally, ah codes have the same width; different
widths correspond to non-Iinearities.
ADC Ofs. This runs only
18
offset DAC, on the A10 digital IF, to apply a bias offset to the IF signals
before the ADC input. This runs only when selected.
19
reference voltages (ah nodes from the A10 digital IF). This runs only
when selected.
Count.
20 F'N
VCO frequency (120 to 240 MHz) and the divided fractional-N
frequency (100 kHz). It requires the 100 kHz signal from Al2 and the
counter gate signal from Al0 to pass.
1 O-14 Service Key Menus and Error Messages
when selected. It tests the abiity of the
Uses the internal counter to count the Al4 fractional-N