HP 8904A - Page 252

Model 8904A Performance Tests
DTMF Sequence
On-time Duration
Off-time Duration
Timing Accuracy
Performance Test 13
Option 001
except 0 off-time and 0 on-time
except
0 off-time and 0 on-time
0, 1 to 655.35 ms
0, 1 to 655.35 ms
11 ms
DTMF SEQUENCE TIMING ACCURACY (OPTION 001)
Description
A tone burst of several cycles of DTMF Tone 0 is set up and observed on an oscilloscope. By
incrementing the duration of the burst (the on-time), the nominal on-time is made to exactly
synchronize with the fourteenth zero crossing
of the burst. The total on-time incrementing equals
the on-time error. The burst’s off-time is measured directly
on the oscilloscope.
NOTE
For instruments with Option 006 (balanced output), even though the DTMF
sequences appear at Output
1, DTMF sequence timing accuracy is not
specified.
Equipment
Oscilloscope . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . , . . . . . . . . . . . . . . . . . . HP 1740A or Tektronix 2235
Procedure
On-Time Accuracy
1. Connect the Multifunction Synthesizer OUTPUTS 1 HIGH output to the high-impedance, ac
2. On the Multifunction Synthesizer, press SHIFT PRESET. After the instrument presets, key in
coupled oscilloscope’s input.
NEXT
f3 (DTMF Sequence)
NEXT
SHIFT FLOAT
1 OFF
f2 (On Time) 5.27 ms
f4 (Off Time) 10 ms
NEXT
f2 (Seq End) 1 ENTER
NEXT
Performance Test 13 4-41
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