JED - June 2014 - 37

By Ollie Holt

quency range. The third column describes the center
frequency span options. The display on a spectrum
analyzer can be set with a start and stop frequency.
The start frequency would be the start of the sweep on
the left side of the display, and the stop frequency is
the top limit on the right side of the display. The frequency range between the start and stop frequency is
called the span. The center frequency is the frequency
point in the center of the display. The operator can
select the center frequency and the frequency span to
be displayed.
The resolution bandwidth is the bandwidth of the
swept filter or the digital filter used in the signal processing of the FFT data. This bandwidth can be selected
and is most important when trying to discriminate between closely-spaced signals in frequency. The filter
bandwidth also defines the analyzer noise floor (lower
noise floor allows weaker signals to be detected). The
wider the bandwidth, the higher the noise floor and
the narrower the bandwidth, the lower the noise floor
- lower is better.
The detector defines the technique used to determine the signal amplitude. The spurious-free dynamic
range (SFDR) is the same as for any receiver system. It
defines the operational dynamic range from the lowest
power signal detected to the highest power signal. This
parameter can be a function of the bandwidth selected.
The "Trigger Types" column defines the selectable
trigger function, which define your options for starting a measurement of a specific signal. This could be
continuous, where the analyzer just keeps sweeping,
or it can be set to trigger on specific artifacts on the
analyzer input or some other external stimulus.
Applications address the different uses the spectrum analyzer was designed to support. Some products
may be used only for communication signals, whereas
others may be general purpose analyzers for all RF signal types. Form factor defines whether the spectrum
analyzer is better suited for laboratory use (benchtop)
or if it is small enough to be taken in the field or to
a flight line. Similarly, weight, power and size aid in
determining where and how the spectrum analyzer can
be used.

The first column in the survey table defines the
type of spectrum analyzer: swept-tuned, FFT or hybrid.
The next column describes the unit's operational fre-

Next Month: JED's July survey will cover airborne
IR decoys and dispensers.

The Journal of Electronic Defense | June 2014


his month's technology survey looks at
benchtop and portable spectrum analyzers. The first function the spectrum analyzer accomplishes is providing a complete
picture of the RF environment. A spectrum
analyzer can measure frequency, power,
harmonics, bandwidth and other spectral components
of an RF signal that cannot be easily measured in the
time domain. It can also perform typical time domain
measurements, like signal repetition rate and pulse
rise and fall time measurements. A typical spectrum
analyzer display will show frequency on the horizontal
axis and amplitude on the vertical axis.
The spectrum analyzer serves two major uses in EW
testing: 1) evaluating an input signal in order to determine its RF characteristics, and 2) examining an output
signal to determine if it contains the RF characteristics
desired. When testing an EW receiver, an RF stimulus,
either real or simulated, is input to the receiver to determine how well it measures the RF characteristics of
the signal. If the EW system fails to measure the characteristics correctly, you first want to check that the
input signal is correct. The simplest method to do this
is with a spectrum analyzer. It can verify frequency,
pulse repetition rates, amplitudes, pulse widths and
can even look at modulations, such as FM, phase codes
or even unintentional modulations. It can also provide
timing information on the rate of change of the phase
codes. With the spectrum analyzer, you can perform a
quick analysis of the signal to verify if it is performing
as desired. It may not provide the accuracy of a power
meter or a frequency counter, but it will provide a good
first look at the RF signal. A spectrum analyzer can also
be used to examine actual RF signals to determine their
characteristics as part of a SIGINT system.
The spectrum analyzer is also a very good tool for
examining the output of a jammer. It can be used to
verify the frequency of the output and can also provide
information on any harmonics or spurious RF from the
jammer. It also provides a good method of examining
the technique to make sure the waveform matches the
desired technique parameters.



JED - June 2014

Table of Contents for the Digital Edition of JED - June 2014

The View From Here
Conferences Calendar
Courses Calendar
From the President
The Monitor
World Report
50 Years of Airborne SIGINT
ACE Program Lays Out Plans for New EW Capabilities
Technology Survey: Spectrum Analyzers
EW 101
NAWCWD Hosts 43rd Annual Collaborative Electronic Warfare Symposium
AOC News
Index of Advertisers
JED Quick Look
JED - June 2014 - cover1
JED - June 2014 - cover2
JED - June 2014 - 3
JED - June 2014 - 4
JED - June 2014 - 5
JED - June 2014 - The View From Here
JED - June 2014 - 7
JED - June 2014 - Conferences Calendar
JED - June 2014 - 9
JED - June 2014 - Courses Calendar
JED - June 2014 - 11
JED - June 2014 - From the President
JED - June 2014 - 13
JED - June 2014 - 14
JED - June 2014 - The Monitor
JED - June 2014 - 16
JED - June 2014 - 17
JED - June 2014 - 18
JED - June 2014 - 19
JED - June 2014 - World Report
JED - June 2014 - 21
JED - June 2014 - 50 Years of Airborne SIGINT
JED - June 2014 - 23
JED - June 2014 - 24
JED - June 2014 - 25
JED - June 2014 - 26
JED - June 2014 - 27
JED - June 2014 - 28
JED - June 2014 - 29
JED - June 2014 - 30
JED - June 2014 - 31
JED - June 2014 - 32
JED - June 2014 - ACE Program Lays Out Plans for New EW Capabilities
JED - June 2014 - 34
JED - June 2014 - 35
JED - June 2014 - 36
JED - June 2014 - Technology Survey: Spectrum Analyzers
JED - June 2014 - 38
JED - June 2014 - 39
JED - June 2014 - 40
JED - June 2014 - 41
JED - June 2014 - 42
JED - June 2014 - 43
JED - June 2014 - 44
JED - June 2014 - 45
JED - June 2014 - 46
JED - June 2014 - 47
JED - June 2014 - 48
JED - June 2014 - EW 101
JED - June 2014 - 50
JED - June 2014 - 51
JED - June 2014 - 52
JED - June 2014 - NAWCWD Hosts 43rd Annual Collaborative Electronic Warfare Symposium
JED - June 2014 - AOC News
JED - June 2014 - 55
JED - June 2014 - 56
JED - June 2014 - Index of Advertisers
JED - June 2014 - JED Quick Look
JED - June 2014 - cover3
JED - June 2014 - cover4