HP 8648 A/B/C/D - Changpuak.ch

Measure the Phase
Change Time
Note
Test Record
Internal Timebase: Aging Rate Performance Test (Option lE5 Only)
4. Trigger:
Trigger Source: CH 2
Trigger Mode: Normal
Trigger Level: OV
If the signal drifts a full cycle (360”) in less than 2 minutes, refer
to Chapter 7 and perform the “Internal Reference Oscillator
Adjustment.” After the adjustment, restart this performance test.
1. Monitor the time and the display. Note the time required for a 360”
phase change: Tl = (9
2. Wait 3 to 24 hours. Note how long you waited: T2 = (h)
3. Repeat step 1. Record the phase change time: T3 =
4. Calculate the aging rate as follows:
Aging Rate = (1 cycle/l0 MHz) (l/T1 - l/T3) (24 hours/T2)
Example: Tl = 351 seconds
T2 = 3 hours
T3 = 349 seconds
= (1 cycle/l0 MHz) (1/351s - 1/349s) (24h/3h)
= 1.306~10-~~ per day
5. Record the test results and compare the results to the limits in the
test record.
If the absolute frequency of the standard and of the timebase
oscillator are extremely close, you can reduce the measurement time
(Tl and T3) by measuring the time required for a phase change of
less than 360”. In step 6, change 1 cycle to 0.5 cycle for 180”) or
0.25 cycle for 90”.
HP 8648A Option lE5. . . . . . . . . . . . . . . . . . . .‘lkble 8-19
HP 8648B Option lE5. . . . . . Table 8-44
HP 8648C Option lE5.. . . . . . . . . . . . . . lkble 8-69
HP 8648D Option lE5.. . . . . . . . . . . . .Table 8-94
(s)
Performance Tests 8-37