Chapter 3 Specifications
Introduction
Operating Guide
3-13
Frequency Measurement Example:
Given an Agilent 53181A with a High Stability Oven that was calibrated 3 days ago, measure a 15 MHz square wave signal (which has
negligible trigger error) with a 1 second gate time. Compute the measurement error to within 2-sigma confidence.
Which is to say that the Agilent 53181A would display results in the range 15 MHz ±63.1 mHz. Note however that the dominant error is the
Time Base Error. If an even higher stability time base is available to the instrument or if the instrument can be source locked to the 15 MHz
signal, then this error term can be substantially reduced. The measurement resolution under these conditions is ±0.8 MHz (1 sigma) which
determines the number of digits displayed.
Measurement Specifications (Continued)
Measurement Error
Systematic Uncertainty 2
RMS Resolution
×
±
=
Time Base Error
±
t
a c c
Gate Time
----------------------------
±
2
4
t
r e s
2
2
Trigger Error
2
×
(
)
+
×
Gate Time
Number of Samples
×
--------------------------------------------------------------------------------------------
t
jit te r
Gate Time
----------------------------
+
×
±
=
Frequency
×
Number of Samples
200,000 since Frequency is greater than 200kHz and gate time equals 1 second
=
Time Base Error
Temperature Stability
3 Days
Daily Aging Rate
×
+
=
2.5
10
9
–
3
5
10
10
–
×
(
)
×
+
×
=
4.0
10
9
–
×
=
Measurement Error
4.0
10
9
–
×
±
1
10
10
–
×
s
1s
----------------------------
±
2
4
500
10
12
–
s
×
(
)
2
2
0
×
(
)
+
×
1 s
200 000
,
×
----------------------------------------------------------------------------------
50
10
12
–
s
×
1s
-------------------------------
+
×
±
15 MHz
×
=
4.1
±
10
9
–
×
2
4.47
10
12
–
×
50
10
12
–
×
+
(
)
×
±
(
)
15MH z
×
=
4.1
±
10
9
–
×
1.09
10
10
–
×
±
(
)
15M Hz
×
=
63.1 mHz
±
=
Summary of Contents for 53181A
Page 2: ...NOTES...
Page 14: ...Contents x Operating Guide...
Page 24: ...Preface xx Operating Guide...
Page 33: ...1 Getting Started...
Page 68: ...Chapter 1 Getting Started Making Measurements 1 36 Operating Guide 1...
Page 69: ...2 Operating Your Frequency Counter Operator s Reference...
Page 143: ...3 Specifications...
Page 160: ...Chapter 3 Specifications Introduction 3 18 Operating Guide...
