Evaluation Engineering - 28

AUTOMATED TEST

SOFTWARE-DEFINED RADIO
ENTERS THE LIMELIGHT
by Alix Paultre, Editor

Software-Defined Radio is an example of how software-driven virtualization to replace hardware-oriented
functionality can enhance system
performance.
Recent advances in both software and
the hardware to run it on have given software-driven functionality a big boost in
cost-effectiveness and capability, enabling
more and more application spaces to take
advantage of software virtualization and
related methodologies. This movement is
most notable in data centers, where virtualization divides a physical server into
multiple individual and isolated virtual
devices. This enables each virtual server
to run its own operating system(s) independently, providing higher server ability, lower operating costs, reduced server
complexity, and increased application
performance.
System consolidation by replacing
subsystems with software can optimize
resource utilization while improving
overall system flexibility and responsiveness. Such a solution enables power
in a system to be reallocated on-demand
to wherever needed to react quickly and
effectively to sudden shifts and surges
in power usage patterns. Even AI and
machine learning is now being used to
predict and respond to changes in power
capacity and demand.
In the case of software-defined radio
(SDR), components that used to be implemented in hardware, like mixers, filters,
amplifiers, modulators/demodulators,
and such are instead implemented in software in an embedded system. The rapidly
evolving capabilities of digital electronics
enable many processes in software which
were at one point only theoretically possible. This comes at the perfect time to
address our rapidly-growing RF management issues in the Cloud.

EVALUATION ENGINEERING SEPTEMBER 2020

A Multimodal World
The Cloud and Internet of Things (IoT)
have created a multi-modal and -nodal
world, with the associated massively-burgeoning RF infrastructure. Once upon a
time, it was believed that the IoT would
migrate to a common protocol and bandwidth, but the reality today is that there is
and will always be a plethora of solutions,
and for good reason.
The massive numbers of devices and
the huge amount of data and communications traffic they generate have forced
the industry to address power, latency,
and bandwidth issues (which are also all
related to cost).
Using a variety of RF solutions to address latency, bandwidth, and cost issues
is a smart solution (no pun intended).
Having the ability to switch from a lowbandwidth, long range, low-speed portion
of the spectrum to a high-bandwidth,
high-speed, short-range protocol is very
useful. For example, the latest iteration of
the WiFi protocol allows devices to use
LoRaWAN for normal telemetry, with the
ability to switch to WiFi-6 for big data
transfers like software updates.
Using traditional analog RF technology to accomplish this would require
multiple costly radio modules, or some
kind of auto-tuning system to enable
changing from one RF solution to the
next on the fly. A digital system using
SDR can perform all the radio gymnastics needed to use any RF solution it has
an antenna able to access. An SDR-based
design will also save significantly more
power, footprint, and parts count over
legacy RF designs.

Flexibility in test
In addition to addressing the plethora of
RF opportunities available to IoT devices
and systems, SDR can also perform as a

powerful and flexible (and
cost-effective) test methodology. To get a handle
on some of the ways engineers are using SDR in RF
testing and monitoring
Wyatt
applications, we reached
out to Kenneth Wyatt of Wyatt Technical
Services.
EE: So now, Ken, you were just starting
to tell me about your involvement with
software-defined radio in creating and
developing cost-effective solutions.
Kenneth Wyatt: That's right. My involvement up to now has been more in the
realm of radio and shortwave reception.
Some people are using these very affordable USB-based SDR modules for surveillance, for example. There are also companies like Tektronix and Signal Hound,
who are basically using SDR technology
for spectrum analyzers. For the most part,
these are USB-connected instruments
that rely on a laptop for the display and
all the number crunching.
EE: I think it's a good idea that you
brought up USB-driven devices. Because
there are going to be a lot of people, even
those going to be eventually working at
higher levels with it, who are going to
play around with USB devices to get a
handle on the tech.
KW: Right. There's probably a dozen different companies making very affordable
SDR-based receivers and even transceivers, like Airspy, who makes a number of
SDR modules. Some of these can tune up
to a 1.8 GHz, and so there's a hobbyist
aspect where they're monitoring military
communications and other two-way radio
government communications even.

Evaluation Engineering

Table of Contents for the Digital Edition of Evaluation Engineering