February 2019
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Ubiquiti Nanobridge M5 IP radio

I am in the process of installing a pair of the Nanobridge M5 units as an IP network link between a transmitter site and the studio location. The path is relatively short, about 1.5 miles over mostly water.  The main reason for this is to replace the analog phone lines used for remote control data and backup programming delivery to the transmitter site.  One added benefit, we are also installing several  IP cameras to keep an eye on the place.  We purchased the Nanobridge system for $80.00 per side.  The price is pretty good, but the configuration and testing is a bit intensive.

Network diagram

Network Diagram

There are many versions of these spread spectrum radios, some are licensed, some are license free.  These are inexpensive, license free links that I would count on for short paths or use in non-congested areas.  In congested areas, licensed (Part 101) links should be used, especially for critical infrastructure like STLs.

Since I dreamed up this idea, I figured I should make sure it is going to work before recommending it to the powers that be.  I have learned the hard way, almost nothing is worse than a failed project with your name on it.  Better to over study something than to go off half cocked, spend a bunch of money, then realize the idea was flawed from the start.  See also: Success has a thousand mothers but failure is an orphan.

Nanobrige path study, 5.8 GHz

Nanobrige path study, 5.8 GHz, moderate noise floor, 1.5 miles

Looks pretty good.  300 MB/s bi-directional which is faster than the Ethernet port on the unit.  This will be set up in bridge mode with pretty robust encryption.  The transmitter site side is configured in the router mode, creating a second class A network at the remote site.

Nanobridge M5 22 dBi antenna

Nanobridge M5 22 dBi antenna

Next step, configuring the units.  The Nanobridge units were set up in a back to back configuration in the engineering room.  Each end comes with a default IP address of  The units were several steps behind the latest firmware version, therefore the firmware was upgraded first.  The default admin user, password, and IP addresses were changed.  There is no greater security risk than default user and password.  The wireless security feature is enabled using WPA2-AES PSK and a greater than 192 bit access code.  The unit allows for any access code length up to 256 bits.  With a key of between 192 and 256 bits, the number of possible solutions is between 6.2771 E 57 and 1.1579 E 77, which should be pretty hard to crack.  By way of reference, a 192 bit password has 24 ASCII characters and a 256 bit password has 32 ACSII characters.

Air OS main screen

Air OS main screen

The system requires an access point, which is configured for the studio side making the transmitter site stub network the station side.  The access point is configured not to advertize its SSID, thus it should be transparent to anyone sniffing around.  The WLAN is configured as a layer two bridge, which will cut down on the data overhead, as layer three framing will not need to be opened between the two units.  The transmitter site network is set up with SOHO router function built into the Nanobridge.  One static route is needed to get to the main network.  Once the security cameras are installed, PAT may need to be used to access individual camera units via the public network.

Ubiquity air os signal strength screen

Ubiquity air os signal strength screen

Next step, deploy the units and aligning antennas.  These are 22 dBi gain antennas, which have a pretty tight beam width.  Maximum transmit power is 23 dBm, or 200 mW.  The transceiver/antenna unit has a handy signal strength meter on the side of the unit, which is good for rough in.  The web interface has a more precise meter.  In addition to that, there is a java based spectrum analyzer, which is very handy for finding open channels in congested areas.  These units can also be used on UNii frequencies with special requirements.

According to the manufacture, UV resistant shielded Category 5e cable should be used for outdoor installations.  We have several spools of Belden 1300A, which fits the bill.  The shielded Cat 5 is necessary for lightning protection as the cable shield offers a ground path for the antenna unit.  The antenna mounting structure is also grounded.  I did not take the equipment apart to examine, but I believe the POE injector and antenna have 15KV TVSS diodes across all conductors.  It will be interesting to see how these units do at the transmitter site, where there are two 300 foot towers which likely get struck by lightning often.

More pictures of the installation when it is completed.

Next step, put the system into service and monitor the link.  At the transmitter site, a re-purposed 10/100 Ethernet switch will be installed for the cameras, computer, IP-RS232 converter and anything else that may need to be added in the future.  One thing we may try is an Audio of IP (AoIP) bridge like a Barix or Tieline for program audio and room audio.

The Relentless Drive to Consolidation

In this blog post about the NAB radio show, Paul McLane (Radio World editor) discusses the reduction of technical people in attendance at the conference.  Consolidation has brought about many changes in the broadcasting industry, engineering has not been immune to these changes.

Because of consolidation, engineering staffs have been reduced or completely replaced by contract engineering firms.  Since the Great Recession of 2008-09 this trend has picked up speed.  Expect it to continue to the point where large broadcasting companies employ one engineering staff administrator at the top, several regional engineering supervisors in the middle and the bulk of the work performed will be done by regional contract engineering firms.

There is no reason to expect the media consolidation process to stop any time soon.  It will continue in fits and starts depending on the congressional mood and the awareness or lack thereof of the general public.  The NAB itself seems bent on removing all ownership regulations and eventually, with enough money spent lobbying congress, they will get their way.   Thus, the majority of radio stations will be owned by one company, the majority of TV stations will be owned by another company and the majority of newspapers will be owned by a third.

There will be some exceptions to that scenario; public radio and TV, privately owned religious broadcasters and single station consolidation holdouts.  If funding for public radio and TV gets cut, which is very likely if the economy collapses further, they will be up for grabs too.

Cloud based network diagram

Cloud based network diagram

For the future of radio and radio engineering, I see the following trends developing:

  1. National formats will be introduced.  Clear Channel already does this somewhat with it’s talk radio formats.  Look for more standardization and national music formats for CHR, Country, Rock, Oldies, Nostalgia, etc.  These were previously called “Satellite Radio” formats but I am sure that somebody will dust of and repackage the idea as something else.  They will be somewhat like BBC Radio 1, where a single studio location is used with local markets having the ability to insert local commercials if needed.  Some “local” niche formats will still exist and major markets where the majority of the money is, will continue to have localized radio.
  2. Audio distribution will move further into the Audio Over IP realm using private WANs for larger facilities, public networks with VPN for smaller facilities.  AOIP consoles like the Wheatstone Vorsis and the Telos Axia will become the installation standard.  These consoles are remote controllable and interface directly with existing IP networks for audio distribution and control.  Satellite terminals will become backup distribution or become two way IP networked.
  3. Cloud based automation systems will evolve.  File and data storage will be moved to cloud base servers using a Content Distribution Network topology.  Peers and Nodes will be distributed around the country to facilitate backup and faster file serving.
  4. Continued movement of the technical operations into a corporate hierarchy.  Technical NOC (Network Operations Center) will include all facets of facility monitoring including transmitters, STL’s, automation systems, office file servers, and satellite receivers via IP networks.  The NOC operators will dispatch parts and technicians to the sites of equipment failures as needed.
  5. Regional contract engineering and maintenance firms will replace most staff engineers in all but the largest markets.  Existing regional engineering firms will continue to grow or consolidate as demands for services rise.  Those firms will employ one or two RF engineers, several computer/IT engineers and many low level technicians.
The most important skill set for broadcast engineers in the coming five to ten year period will be IP networking.  Everything is moving in that direction and those that want to keep up will either learn or be left behind.

Bell System microwave relay system

This is a map of the AT&T microwave relay system as it was in 1960. It is interesting for several reasons.  First of all, before there were communications satellites, this is the way that data was transferred from one location to another.  That data would have been digitized and TDM encoded on a T-carrier, then loaded onto a microwave path.  TV networks had loops that transversed the country, distributing network video and audio to all the markets in the US.  The first transcontinental New York to San Francisco microwave route was established in 1951.  Through the fifties and sixties, the network was filled in across the US and Canada.

Radio networks had been using wired TELCO networks for program distribution for years, although they required far less bandwidth than TV.  This was during the time when network affiliation was vitally important to a station.  Radio networks provided news and other special event programming, as well as some long form shows which were an important source of information for the listeners.  Any network programming prior to 1980 or so would have been carried by this system.

It was not until the use of C and Ku band satellite services that networks could offer multiple channels of programming.  Now, entire radio formats could be programmed remotely and beamed into hundreds of stations across the country simultaneously.  That would have been far to expensive to implement over TELCO lines, as the line charges were based on mileage of the circuit.

Bell System microwave relay routes

Bell System microwave relay routes

Click for higher resolution.

This system included thousands of hardened microwave relay sites, each built to exacting specifications and fully redundant.  At the time, the long distance telephone system was an integral part of the US defense planning.  Sites were spaced 20-40 miles apart, depending on terrain.  In congested areas, like the northeast, area mountain tops are dotted with these sites today, mostly empty.  Most of these sites went off line in the late 1990’s as phone companies switched to fiber optic cables for telephone and data traffic.

American Tower, Inc. purchased most of these sites in bulk from AT&T in the year 2000.  Some sites are well positioned for Cellular Telephone, 3G and 4G wireless data services, plus other things like Media Flow and general use applications like FM broadcast and two way.  Many sites, however, do not meet any specific need and sit empty.  There was a large fire sale by American Tower in 2002 in which they unloaded about 1,900 of these sites as they were redundant.

I wrote a post titled Cold War Relic: ATT long lines site, Kingston,NY detailing one of these sites near me.  Keep in mind, there were thousands of these sites throughout the country.




Radio stations more and more revolve around networked computers.  Engineers need to understand computer networking, especially as it relates to audio distribution and playback.  Eventually, I see broadcast engineers being more computer science types rather than electrical engineering majors.

What I have found out about computer networking is this: it is not rocket science.  In fact, most of it is pretty easy.  Physical networking and cabling is similar to audio and TELOC cabling.  Automation computer servers themselves are not difficult to understand as most of them run on some type of windows program.  Other servers such as Apache for WWW and for FTP and streaming run on some type of LINUX OS.  LINUX is also not difficult to understand so long as one knows the right command line prompts.

The first part of understanding computers is networking.  Without a computer network, a computer is a glorified typewriter.  Almost every automation system and or digital editor requires some type of network.  Consoles and computers that use AOIP require well constructed networks in order to operate properly.  To that end; cabling choices, network interface devices such as switches and routers, patch panels and so forth need to be specified and installed with care.

Most often, it is the simple things that will trip an installer up.  The one area where I have found the most mistakes made is the pairs connection to various termination points.  There are two basic standards, TIA/EIA T568A and T568B.  Neither is better than the other, both are often identified on terminating devices such as jacks and patch panels.  The most important aspect to these standards for an installer is to pick one and stick with it.

TIA/EIA 568 color code

TIA/EIA 568 color code

When certifying networks, the most common problem I have encountered is crossed pairs.  Almost invariably, one end will be punched down with the A standard and the other with the B standard.  Jacks are particularly difficult, as the color coding stickers show both.  Many patch panels have a slide out, reversible card with is an either/or situation.  For some reason, I have stuck with the B standard and on any project I am managing, I get rid of all the A color codes I can find and tell the installers that B is the only acceptable termination standard.  That cuts down on a lot of errors and redos during certification.  That is good, it saves time and I hate redos.

Cat 5e wall jack set

Cat 5e wall jack set

You can see that this color code marking can lead to confusion.  I take a sharpie and cross out all the the A markings to avoid installation mistakes.

Incidentally, on any new network installation, Category 6 cable should be used.  As more and more data through put is required for network applications,  Category 6 Cabling has better performance specs and will likely have a longer service life than other cable.   It may be a little bit more expensive than Cat 5,  however, well worth the investment.  It would be a great mistake and waste of money to have to pull out the network and reinstall it in a few years because the cabling doesn’t have the required bandwidth.

Category 7 cabling is in the works.


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

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