The Impact of Signal-to-Noise
Ratio on Guided Wave Radar
Transmitter Performance
transmitter signal amplitude is sufficient
to detect a given dielectric, amplitude
plays virtually no role in the detected
SNR. In fact, if too many sources of
unwanted reflections are present, a
larger transmit pulse amplitude will
simply elevate the noise at the same rate
it elevates the level signal. The resulting
change to the SNR is zero – the larger
pulse provides no benefit in and of itself
to SNR.
in difficult applications is the signalto-noise ratio (S NR), which essentially
describes the difference between the
desired signal and the unwanted noise.
If the amplitude of the noise approaches
that of the level signal, loss of accuracy
or linearity is the first observed effect
due to distortion of the level signal as
it passes through and interacts with
the noise. Worse yet, if SNR is bad
enough, the adverse signal interaction
can actually result in a loss of the level
signal.
I
n recent years, much has
been said in the industry
about the importance
of the amplitude (size)
of the guided wave
radar (GWR) transmit pulse. While the
size of the transmitted radar pulse is
certainly important, it is a fact that pulse
amplitude alone will not always yield
accurate level measurement under all
process conditions. A far more important
parameter in reliable level measurement
While it would be desirable to
eliminate all the unwanted impedance
discontinuities, it is simply not possible.
The good news is that today’s most
advanced GWR solutions address this
critical design issue.
Transmit Pulse Amplitude and
Signal-to-Noise Ratio
Many GWR manufacturers talk about
transmit pulse amplitude; however,
beyond the point at which the
The only role of a larger transmit pulse is
to assure that noise in the system does
not become dominant in the overall SNR
in low signal return cases (such as long
probes under low dielectric conditions).
Too small of a transmit signal would
result in too small of a received signal in
these cases, requiring excessive signal
amplification in the level transmitter.
Diode Switched Front End Design
The new Eclipse® Model 706 uses a
new design concept called the diode
switched front end, which enhances
front-end performance. The design
of this advanced GWR transmitter
features front-end circuitry innovations
that enhance the transmitted pulse
amplitude, improve the received signal
strength and, most importantly, increase
the SNR.
For more information, download our
free white paper, The Impact of Signalto-Noise Ratio on Guided Wave Radar
Performance, at http://marketing.
magnetrol.com/acton/media/8231/
impact-of-signal-to-noise-ratio-ongwr-magnetrol