HP 54710A User's Reference Manual page 340

Frequency Measurements
For best frequency accuracy on peaks
1 In the acquisition menu, set the Sampling mode to real time and set
Interpolate to off.
2 In the channel menu, set the Scaling for almost full scale deflection.
3 Set the Span so that the signal of interest is near the horizontal center
of the screen (not down at dc), but high enough to avoid aliasing.
The left edge of the screen is 0 Hz, or dc.
4 Select the Hanning window.
5 Set the Resolution to 16,384 (32,768 for a two-wide plug-in) or as high
as possible if computation time is a consideration.
A higher number of points results in more accurate measurements, but also
takes more computation time. Depending on your application, you can
balance between the need for accuracy and computation speed of the FFT.
Frequency Accuracy
The frequency accuracy is the sum of two terms. The first term is supplied
because there are a limited number of frequency bins, and the measurement
is accurate to plus or minus half a bin. The second term is related to the
accuracy of the internal oscillator which generates the sample clock.
accuracy = ±  
frequency resolution

+ 0.007% × signal frequency  
2
FFT Menu
FFT Basics

21–13