switch positions.
Read sampling frequency on the counter.
Divide the
sampling frequency into the estimated frequency to obtain N.
Turn
thumbwheels to the value determined for N. Read the actual input frequency
on the counter's display.
When the input frequency is known to be outside the limits for direct
calculation of N, a different procedure is followed.
The thumbwheels are
set to 001, Frequency MHz is tuned to zero beat or phase lock while
observing Level Adj and Mode switch positions.
The counter readout is
recorded as f1. Frequency MHz is returned to an adjacent zero beat or phase
lock and the counter readout is recorded as f2.
The first frequency f1
divided by the difference in the frequencies yields harmonic number N of the
second frequency f2.
EXAMPLE 1.
Assume unknown fx is approximately 11.9 GHz; Time Base = 1 ms.
a. Where f2 is lower than f1:
fx = (N - 1) f1 and fx = Nf2,
N = f1/(f1 - f2).
f1 = 119532.
kHz (read on counter) tuning lower in frequency gives
f2 = 118349.
kHz (read on counter)
f1 - f2 = 1183.
kHz
N = 119.5/1.183 = 101, set thumbwheels to 101,
fx = 101 x 118.349 = 11953261.
kHz (read on counter).
b. Where f2 is higher than f1:
fx = (N + 1) f1 and fx = Nf2,
N = f1/(f2 - f1).
f1 = 119532.
kHz (read on counter) tuning higher in frequency gives
f2 = 120740.
kHz (read on counter)
f2 - f1 = 1208.
kHz
N = 119.5/1.208 = 99, set thumbwheels to 99, fx = 120.740 x 99 =
11953261. kHz (read on counter).
64
Previous Page
