Tech Briefs Magazine - December 2022 - 31

implies, these switches must be administrated
by trained IT personnel. Managed
switches originally were used mostly
in IT data centers, but they are
increasingly needed at the OT edge.
Users seeking industrial-grade networking
options in an easily configured
format are finding switches requiring
only
minimal management
often meet their needs (Figure 2). Some
basic characteristics of these devices
should include:
* Robust performance: 10 and 100 Mb/s
speeds, auto-negotiation, full/half duplex,
and CRC-checked store-and-forward
technology to ensure each communication
frame is fully and properly
handled.
* Flexible mounting and connection options:
DIN and panel-mount options, with
IP30-rated covers to protect unused RJ45
ports, pluggable terminal blocks, and able
to accept redundant power supply inputs.
* Designed to survive harsh environments:
Rugged metal housings, operational
over an extended temperature
range of -40 to 75 degrees C, rated
IP30, with UL508, CE, FCC and Class I
Division 2 hazardous location approvals
as needed, and a high level of resistance
to electrical noise and electromagnetic
interference.
* Simple configuration of the most essential
managed features.
These traits are not available in typical unmanaged
industrial Ethernet switches. In
particular, the following managed switch
traits are most important for industrial-grade
applications:
* Quality of Service (QoS): Prioritizes
the most critical traffic. Usually only
available on managed switches, QoS
for industrial applications can ensure
that EtherNet/IP packets - used extensively
for crucial automation tasks
- are handled first.
* Internet Group Management Protocol
Snooping: Reduces network traffic and
resource loading by actively monitoring
and optimizing transmissions.
* Broadcast Storm Protection: Discards duplicate
packets in the event a user creates
an improper ring connection.
Smart unmanaged Ethernet switches
should use simple dual in-line package
(DIP) switches so users can easily adjust
their configuration, without requiring online
configuration.
Availability of industrial-grade, smart
unmanaged Ethernet switches with a favorable
price/performance ratio means
there is simply no reason to use anything
less for any type of application involving
intelligent controllers, sensors,
and other devices.
This article was written by Linda Htay,
Automation Product Marketing Manager,
IDEC Corporation. For more information,
visit us.idec.com.
Automated RF Interference Mitigation System
A software-based RFI mitigation system lessens the impact of interfering radio signals on
satellite-to-ground communication links.
Glenn Research Center, Cleveland, OH
S
pace-to-ground radio frequency
(RF) communications transfer
critical data that enables successful
satellite
and
spacecraft
operations.
Such communications
are susceptible to co-channel interference
produced by terrestrial
or space-based sources, and to interfering
signals from shared spectrum
scenarios. If radio frequency
interference (RFI) could be detected
and mitigated in an automated
fashion, link performance
and reliability could be improved.
After observing unexpected interference
events during space-toground
communications, innovators
from the NASA Glenn
Research Center developed a software-based
automated RFI mitigation
system to increase communication
reliability.
Spectrum monitor
Signal detection
Known signals
Link controller
Mitigation decider
ACM loop
Action generation
Transition time
prediction
Es/No
prediction
Feature assignment
Action selection
(weighted sum method)
NASA's radio frequency interference mitigation system software
stack is divided into two main processes (spectrum monitor and link
controller) that run concurrently during operation. (Image: NASA)
This invention detects interfering RF
signals using signal processing techniques
and intelligently mitigates the interference
by automatically changing
communication link parameters. The
system continuously optimizes the link to
improve data-rate transfer and link reliability
in a dynamic environment.
Tech Briefs, December 2022
The interference mitigation system is
composed of several algorithms that allow
it to detect and respond to interference
and optimize the link based on a given set
of mission objective weights. The system
runs in real-time, continuously ingesting
link information from the receiving modem
and spectrum information from the
monitoring subsystem.
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information then feeds
into an Adaptive Coding and
Modulation (ACM) loop and a
mitigation subsystem. The ACM
loop uses algorithms to decide if
mitigation should take place and,
if so, what mitigation actions are
available to consider. These actions
are then ranked using a
multi-objective, weighted-sum algorithm
and the best-ranked action
is chosen and applied to the
link by the link controller.
During testing at NASA, the
RFI mitigation system was shown
to achieve the highest average
throughput over all test cases
compared to alternative mitigation
strategies. The technology is
useful for space-to-ground communications,
satellite communications,
and RF communications.
NASA is actively seeking licensees to
commercialize this technology. Please
contact NASA's Licensing Concierge at
Agency-Patent-Licensing@mail.nasa.gov
or call at 202-358-7432 to initiate licensing
discussions. For more information, visit
https://technology.nasa.gov/patent/
LEW-TOPS-166.
This
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http://us.idec.com https://technology.nasa.gov/patent/LEW-TOPS-166 http://www.techbriefs.com
Tech Briefs Magazine - December 2022

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