Atec Agilent-81150A-81160A - Manual (Page 9)

9
Noise generator – repeatable and
stochastic noise Jitter and noise cause misalignment of edges and levels, resulting in data errors. Noise is
by its nature unpredictable because it can have many different causes, from signal inter-
ference caused by sudden voltage changes, to distortions introduced during transmission.
It is important to be able to simulate noise-based malfunctions, for example, to identify
the additive noise produced by receiving systems—it is cheaper to lower the noise fi gure
than to increase the transmitter power! The Agilent 81150A and the Agilent 81160A Pulse
Function Arbitrary Noise Generators let you control the quality of the noise, to test differ-
ent cases, and according to various specifi cations.
White Gaussian noise is a good approximation to many real-world situations, and creates
mathematically traceable models, with statistical independent values. The Agilent 81150A
and the Agilent 81160A Pulse Function Arbitrary Noise Generators provide deterministic
white Gaussian noise, with a signal repetition of 20 days or 26 days respectively. You can
decide on any arbitrary distribution, and trigger the noise to start when you need it.
Setting up a measurement using
trigger, strobe, modulation and carrier
Gaussian curve and distribution
General:
# events=n x sigma
N # events BER
--------------------------
1 67%
0.33
2 97% 0.03
3 99.7% 0.003
5 10 6 10 -6
6 10 9 10 -9
7 10 12 10 -12
voltage
mean value
sigma
Normalized
Events sigma sigma sigma
N=1
N=2
Gaussian distribution
Gaussian distribution
Modulation
Signal
Tr igger Out
Str obe Out
Out
Continuous PM
Phase Deviation 180 deg.
Car r ier Sinewave 0.04 MHz
Modulated by Sinewave 0.02 MHz