Our HAM Station

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Reducing RFI From Our QTH

Posted: 21 May 2021 08:12 AM PDT
https://stationproject.blog/2021/05/21/reducing-rfi/

Fiber Wall Outlet

Many Hams (including this one) have problems with RF Interference (RFI) at
their stations. Many RFI sources typically come from inside our own homes.
Symptoms include birdies at single frequencies, interference that moves
around across the Amateur Radio Bands, and high noise floors. We have had
all of these problems here.

We recently built an improved EME station for the 2m Band. We noticed a
higher than ideal noise floor when operating 2m EME during initial testing
of the new station. We decided to do some additional testing to see if we
could isolate the source of the noise levels. One test we did was to shut
down much of the ethernet network and associated devices here at our QTH.
To our surprise, this lowered our noise floor on 2m some 6 dB, and
eliminated many birdies in the EME section of the 2m Band!

Our network mostly uses wired Ethernet running throughout our home on Cat
5e and Cat 6 unshielded ethernet cable. Many of the devices in our home use
Power Over Ethernet (PoE) connections to power them through the ethernet
cables.
NAS Drives for Video Storage and Backups

We also do quite a bit of video editing work and often transfer large files
from our computers to several large Network Attached Storage (NAS) drives
for file storage and backup. We also use an extensive IP Camera System to
monitor our towers and for general security purposes.
Core Network Rack Enclosure

We decided to solve our noise problems via a pretty major upgrade to our
home network. The upgrade included:

Installing OM4 multimode fiber optic cables to replace all of the non-PoE
wired Ethernet connections to the rooms in our home. The fiber cables were
chosen to support 1 GbE and 10 GbE connections now and to be upgradable to
100 GbE connections in the future.
Installing a shielded rack enclosure to house the switches and management
devices for our upgraded Network
Installing new Cat 6A Shielded Ethernet cables to PoE devices that we
wanted to remotely shut down when we are operating using weak-signal modes
on 6m and above
Upgrading portions of our network to 10 Gbs Ethernet speeds to improve the
efficiency of Video Editing and Backups


The project began with the installation of a Shielded Rack Enclosure in our
basement. The Rack is wall-mounted and is fully shielded and grounded. It
also includes cooling fans that move air vertically through the Rack to
keep the gear inside cool.
Core Network in Rack

Next, we mounted all of the gear for our upgraded core network in the Rack.
The main components include (from bottom to top):

An IP-Controlled Power Distribution Unit (PDU) that allows us to remotely
turn network devices in our network on and off via web browser from
anywhere in our home
A Shielded Ethernet Patch Panel that is used to terminate the new Cat 6A
shield ethernet cables to PoE-controlled devices in our home
A Netgear 10 Gbps capable edge switch to provide 1 GbE and 10 GbE
connections within our Core Rack
A FortiGate 61E Router and Firewall which serves as an Internet Gateway and
Core VLAN router for our network
A Pair of MicroTik CRS326-24S+2Q+RM Switches that provide a total of 48, 10
GbE capable optical connections via SFP+ ports. These switches are
interconnected with a pair of 40 GbE QSFP+ DAC cables that provide an 80
Gbps LAG connection for traffic between the two switches.
A MikroTik Network Management Router which runs the Network Management
System for our upgraded network
Three Fiber LC Patch Enclosure Trays which terminate the fiber optic cables
that run to all of the room in our home
Two rackmount shelves that hold a NAS-based Media Server that stores all of
the entertainment content for the media system in our home.

PDU Web Interface for Network Control and Management

We are going to power down most of our IP Cameras and the WiFi AP devices
around our home when we are operating on 6m and above. We implemented this
capability using an IP-Controlled Power Distribution Unit (PDU) that allows
us to remotely turn network devices in our network on and off via a web
browser from anywhere in our home.
IP Camera PoE Switches

The PDU controls a pair of Netgear PoE Edge Switches that power most of the
IP Cameras in our home via PoE connections. Shutting down these switches
via the PDU removes power from the associated IP Cameras which eliminates a
great deal of noise and other RFI.
WiFi Acess Point Control via PoE Edge Switch

We also installed a VLAN-capable Netgear PoE Edge Switch and connected it
to the PDU. This switch enables us to shut down other devices on our
network such as WiFi Access Points which are also significant sources of
RFI. This switch uses a pair of optical interfaces that connect it to our
core network
OM4 Fiber Cable with LC Connectors Installed

A large part of the work associated with our network upgrade project
involved running OM4 Multi-mode Fiber Optic cables to all of the rooms in
our home. We ran 12-fiber cables to locations that would likely benefit
from upgrades to 100 GbE in the future (ex. our shack, home offices, media
equipped rooms, and servers/NAS devices) and 6-fiber cables were used
elsewhere. All of our fiber cables use LC connectors with two fibers for
each Ethernet connection (one for Tx and one for Rx). We used a mix of
pre-terminated cable assemblies and unterminated cables to complete the
room installations.
Fiber Prep using a Fiber Cleaver

Field terminating fiber optic cables is not difficult but it does require
some special tools and careful attention to detail. The ends of each fiber
must be prepared to precise specifications and be very clean before the LC
connectors can be installed. The image above shows a Fiber Cleaver which is
used to cleave the end of each fiber to form a square,
low-reflection/low-loss connection to a field-installable LC connector.
Proper use of a high-quality Fiber Cleaver is important if you are to
achieve low-loss, low-dispersion field terminations.
Verifying an LC Connector Installation using a Visual Fault Locator

A Visual Fault Locator (VFL) with an LC Connector Adapter is used to
confirm the proper installation of each LC connector. The tool shines a
bright red laser light through the LC connector and fiber cable. The field
installable LC connectors include a window that indicates laser dispersion
at the fiber/connector junction. Too much light in the window due to
dispersion indicates a poor connection. The VFL tool is also very useful
for checking end-to-end optical transmission and continuity of the
completed fiber cable installations.
Fiber Wall Outlet and Patch Cables

The fibers were terminated in wall outlets in the rooms of our home. The
outlet plates accept standard keystone jacks. We used LC Keystone Couplers
with our wall jack plates. This approach ensures that the ends of fragile
fiber optic cables running to the rooms will not be damaged or broken when
connecting the fibers to ethernet switches and other devices.
Fiber LC Interconnect Enclosure

The other end of each fiber cable is terminated in a Fiber LC Patch
Enclosure Trays in our Rack. The enclosures provide a test point and LC
patch cable interconnect point for the fiber cables. The advantage of using
enclosures such as these is that they protect the ends of the fiber cables
running to the rooms from damage. A total of three trays terminate a total
of 72 OM4 fiber pairs that we installed in our home.
Optical Fiber Connector Cleaner

It is very important to keep all of the fiber connections clean. Standard
practice should be to ALWAYS clean the ends of each LC connector with an
Optical Fiber Connector Cleaner each time before an LC connector is
installed in a jack. It is also important to keep the supplied caps that
come with LC connectors installed when they are not connected to a jack or
optical SFP.
10GBase-SR SFP+ Transceiver

The fibers in the core rack and in the rooms are connected to switches,
computers, and NAS devices via SFP or SFP+ Transceivers. An example of an
SFP+ Transceiver is shown above. These devices convert the laser signals
carried on the multimode OM4 fibers to a standard electrical format that
can be handled by the core and edge switches in our network.
Core Network Components

The connections between the Fiber Termination and Patch Enclosures and the
SFPs and SFP+s in the Core Switches in our rack are made using OM4 LC Patch
Cables (the aqua cables shown in the image above).
Fiber Wall Outlet and Patch Cables

Similar patch cables are run from the Wall Jacks to the Ethernet Edge
switches in each room to complete the connections to the core network. Most
of our Edge Switches in the rooms in our home use two pairs of fibers in a
LAG configuration. This increases the bandwidth capacity of the connections
and also increases reliability. Should one of the fiber pairs experience a
failure, the other pair continues to carry the traffic until the problem
can be repaired.
Shielded CAT6A Ethernet Terminations

Some devices in our network such as the PoE IP Cameras on our Towers and a
portion of our WiFi Access Points cannot be shut down without significantly
compromising the operation and functionality of our Network. We controlled
the noise and RFI contribution from these devices by installing new, Cat 6A
Shield Ethernet cabling to connect them. The Cat 6A cables must be
terminated using a grounded, fully shielded ethernet panel. This device is
10 Gbps Ethernet capable and properly terminates that the shielded Cat 6A
cables in our Rack.
Cat 6A Shielded Keystone Jack

Shielded Cat 6A Keystone Jacks and Shielded Ethernet Patch Cables are used
in the rooms to connect to the edge devices.
10 Gbps Ethernet Connected Computer

So how did all of this work out? We are seeing 6 7 dB improvement in the
noise floor on 2m. This is a huge improvement for our EME station! We are
also seeing about 1 dB in noise floor improvement on 6m. We are also seeing
a significant reduction in birdies on all the bands. Finally, many of our
computers and most of our NAS drives have been upgraded to 10 Gbps Ethernet
which enables us to move large files around our network much more quickly.
We are also seeing some improvement in the actual measured throughput of
our 1 Gbs/400 Mbps Fiber Internet connection.

I hope that our readers find our Fiber Optic and 10 Gbps Networking project
interesting.

Fred, AB1OC