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.

AES X192

There is a lot of buzz about converged technologies and what not.  I have always been a wee bit leery of bleeding edge technology, lots of money and time can be wasted there.  Incompatibility between different manufactures equipment and protocols can cause major heartburn in all equipment life stages.  See also: VHS vs Betamax.  Thus, when many disparate standards are homogenized into one acceptable system for everyone, we all benefit and technology moves forward.

Binary
Binary Data

Audio over IP (AOIP) is moving into the general acceptance of broadcasters as a reliable system for studio construction.  As with anything, there are pluses and minus to this development:  First of all, packet switched data is more efficient and flexible than circuit switched data.  For the purposes of clarity, an AES3 signal within a broadcast facility going from one piece of equipment to another can be defined as circuit switched data.  Once the data is segmented, packetized and framed, it can be sent anywhere, over any LAN or WAN.  This allows for greater connectivity between facilities and greatly increased delivery methods and redundancy.

The downsides are increased complexity in transmission, greater reliance software and delicate operating systems to process audio into data and deliver it, and Quality of Service (QoS) issues.  Additionally, there are many different AOIP protocols and applications currently in use.  To date, this is the current list AOIP standards that are used by various manufactures:

  • Wheatnet – Wheatstone, inc
  • Livewire – Telos
  • Ravenna – ALC Networkx (Open source)
  • Dante – Audinate
  • CobraNet – Peak Audio
  • EtherSound – Digigram
  • N/ACIP – EBU
  • Q LAN – QSC Audio Products
  • AVB – IEEE, AVnu

Each system has different characteristics.  A Livewire system will not talk with a Wheatnet system and so forth.  This is because of differences in the transport layer encoding schemes.  Some use UDP, some use RTP, some use a propriety transport protocol, and some may even use TCP (remember the 7 layer OSI model).  It would be similar to having an analog Wheatstone console unable to send audio to an analog Optimod which would be unable to modulate a BE transmitter.

AES X192 is an effort by the Audio Engineering Society to set an Audio over IP interoperability standard.  This is the direction that studio audio equipment is moving and indeed, broadcasting in general.

The X192 project endeavors to identify the region of intersection between these technologies and to define an interoperability mode within that region. The initiative will focus on defining how existing protocols may be used to create an interoperable system. No new protocols will be developed to achieve this. Developing interoperability is therefore a relatively small investment with potentially huge return for users, audio equipment manufacturers and network equipment providers.

More here.

Eventually, broadcast audio consoles will plug into a WAN and be able to source audio from all over the place, not just the local physical studio structure.  This lends itself to the evolving wired or wireless IP delivery method in place of the current terrestrial radio broadcasting currently used.  As such, I will be diving into the fascinating world of AOIP more in future posts.

The Telos NX-12 Talkshow phone system

I have worked with my Telos telephone interfaces in various studios. They are well designed and intuitively designed pieces of equipment. The Telos NX-12 is no different.  The first thing different about this telephone system is the web interface.  I have commented before on this; eventually all broadcast equipment will have some type of http interface.  For configuration and monitoring, it makes life much simpler.

Telos’ NX-12 web interface allows the users to define phone lines, call directors and studios:

Telos NX-12 http interface
Telos NX-12 http interface

The NX-12 itself is just a box residing in the rack room.  This is where all of the pots lines or the PRI-ISDN line is installed, firewire, network interface, etc.

The studio end is the call director, which is connected to the NX-12 by a cat 5 cable.  There can be up to four call directors per NX-12.

The nice thing about the NX-12 is that the hybrid can be split into completely separate units, thus one NX-12 can be used for two separate stations, each with up to six lines.  Splitting the hybrid thus requires the use of Firewire or the unit must have an AES card.

This particular unit was installed at WFAS-AM/FM in White Plains, NY.

A look at the new Facebook Data Center

Very good article on the new Facebook Data Center in Prineville, Oregon via Wired.com.  One of the interesting aspects of the data center design is the energy efficiency aspect.  In a data center that services 800 million users, shaving a few percentage points off of the energy bill represents huge savings.

According to the article, the location was chosen for it’s climate.  The area has low humidity, thus allowing the use of evaporative cooling system verses the conventional refrigeration cycle systems most often used.

Another area is in the servers themselves. Facebook decided to design their own servers, using a stripped down platform, larger heat sinks, slower fan speeds, etc to reduce the amount of electricity used.

All in all the article is well worth reading, as the future of broadcasting will be centered on data centers such as this one.