Evaluation Engineering - 29

For me, I'm more interested in the electromagnetic compatibility uses of these
modules. So there's definitely a hobbyist
aspect, just those who are interested in
shortwave listening or other two-way
radio communications, or even digital
television and aircraft tracking. There's
a number of different applications. A good
friend of mine uses these for radio astronomy purposes, using SDR to track solar
emissions, hydrogen lines, and all that
stuff using an SDR-based receiver and
special microwave antennas on his roof.

receivers designed for various purposes.
Mainly for shortwave listening. I spent
most of my career with Hewlett Packard
and Agilent Technologies in the field of
EMC engineering, and now, in the last 10
years, I've been consulting in that same
field. Whenever I can get my hands on
a low cost, affordable tool for analyzing
EMC issues for my clients, I'll do it. A lot
of my clients don't have big budgets for
expensive test equipment, so they appreciate the lower-cost alternatives.

EE: Well, and that's
one of the things
that I really appreciate talking to you
about because it's
opened my eyes to
the test and measurement aspects
of software-defined
radio. List some of
the ways softwaredefined radio, you
h a d ment ione d
spectrum analysis
and such, but just
rattle off, off the top
The Magnetopause-to-Aurora Global Exploration Satellite
of your head, the
various ways you can
He was even able to locate a "lost" sat- use the software-defined radio in RF test.
ellite of NASA's. He was able to pick up
the downlink signal from it. Apparently, KW: Oh, sure. Okay. As far as SDR usage
it had been lost for a decade or so. NASA in spectrum analysis, there's a couple of
had lost track of it. He found it and con- interesting ways of using them. The first
tacted NASA, and it was quite an inter- is, obviously, characterizing the spectrum
esting news story a year and a half ago. of a product because that's really what
According to The Independent, Scott the big challenge is for most electronic
Tilley was scanning the skies in search manufacturers is. They've got to keep the
of a secret US government spy satellite emissions down below certain levels in
launched by Elon Musk's SpaceX, when he order to ensure their product complies.
found signals from the long-lost satellite
Troubleshooting is a big aspect of speccalled the Imager for Magnetopause-to- trum analysis. The SDR, especially these
Aurora Global Exploration.
affordable modules, gives manufacturers
a low-cost way to assess, or at least idenEE: Wow, that's very cool, Kent. This tify red flags in their products. You can
whole maker-hobbyist ham aspect, attach near-field probes to these modules
hacker aspect, emphasizes the flex- and a program on your circuit board or
ibility and utility of software-defined cabling, to see where there might be quite
radio, and how it really can be a Swiss a lot of emission coupling from the board
Army knife in the RF space.
to the cable, for example.
KW: Yes, definitely. I've got probably a
half a dozen of these little SDR-based

EE: The beautiful part about what you're
telling me is that it could apply to any

software-defined radio solution at,
frankly, any level, for any manufacturing situation. Because what you just
described is a scalable situation.
KW: In fact, companies like Tektronix
have their RSA306B, which is USBconnected module that requires a highperformance laptop to be useful, but you
can take this product, this analyzer, and
use it for both troubleshooting and precompliance testing. Tektronix has some
software that will do a compliance test or
a pre-compliance test in a matter of seconds, and show you where you're compliant and where you're not compliant based
on programmable limits, dependent on
what standard you're testing to. This has
been very useful for me, as an EMC consultant, helping my clients.
The other big use for the SDR is, and
this has become more and more important in recent years, is interference hunting. We have so many wireless devices,
and it's just proliferating exponentially.
For example, so many devices are programmed to work in the 2.4 GHz ISM
band, and there's a possibility of a one
device interfering with your Wi-Fi and
decreasing the data rate and things like
that. But not only that, but all the mobile

The Tektronix
RSA306B

devices, mobile phones, and 5G, and all
this, there's just more and more cell towers being built and interference between
one and its neighbor can be an issue.
These portable spectrum analyzers
based on SDR technology can be used now
for locating sources of these interfering
signals. You put a directional antenna on
these spectrum analyzers, and you can
help triangulate where the noise sources
are and so forth.

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Evaluation Engineering

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