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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 192.168.1.20.  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.

Axiom


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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