I was pleasantly surprised to learn that after a two month sabbatical, Radiodiscussions.com has returned with an updated look and all of it’s archived posts intact.
Radiodiscussions.com screen shot
I am pleased that the current owners had a change of heart. Radiodiscussions.com was not perfect, however, it was a good place to gain insight, take part in conversations, read up on rumours and innuendo, follow the flame wars on various threads, etc. In other words, observe radio people in their natural habitat.
I have been busy of late, however, still keeping abreast of the news of the day. Along with that, CES 2014 wrapped up recently. No huge developments, especially when it comes to Broadcasting. However, there was one item of interest; the updated technical specifications of IEEE 802.11ac.
It is of interest here because of the implications of the mobile/portable data developments and their impact on traditional AM and FM broadcasting. The new specification calls for 1.2 Gbp/s per device in the initial release, increasing that throughput to 6 Gbp/s in later releases. These data rates are for overall transmission, including the WiFi overhead. Actual usable application data (layer 5-7) would be about 20 to 30 percent less. Even so, 900 Mbp/s is a phenomenal data rate. Truely I say to you; this is the future of digital broadcasting. HD Radio™; it may well prove that the “HD” stood for “Huge Distraction.”
The new 802.11ac specification uses MU-MIMO, high density modulation, larger channel bandwidths, and beamforming technology in the 5 GHz WiFi spectrum. Of course, the question is, at what distances will this system work? If it is like conventional WiFi, then 100-200 feet is about all that can be expected. However, there are also many people interested in wireless broadband (WiMAX) service as an alternative to traditional wired ISPs. For that application, having many outdoor 802.11ac nodes connected by a backbone could potentially blanket a city or campus with free high speed wireless data.
Example of cjdns network
Along the same lines, there are many people involved in creating mesh networks of various types; be they ad-hoc mobile networks, darknets, bitclouds, etc. Mesh networking is a very interesting topic, for me at least. The network protocols are getting better and more secure. WiFi hardware is becoming less expensive and more reliable. As more and more people put effort into developing protocols like cjdns, local mesh networks will become wide spread, unless they are outlawed. You know; because of teh terrorism!!1!!
As it stands today, I can drive for two hours in mostly rural upstate NY and CT streaming my favorite radio programs and have nearly seamless hand offs and very few dropouts. This is on my three year old, beat up 3G HTC android phone sitting in the passenger seat of my car.
Digital Radio is here, it is simply not the In Band On Channel system that legacy broadcaster’s have chosen.
The popular discussion board, which was started in the mid 1990s has been terminated by it’s current owners, Streamline Digital. It seems that the site was not making any money and thus the plug was pulled.
There are other engineering type discussion boards such as The Virtual Engineer and… Hmm, Anybody?
Where a vacuum exists, nature abhors it. The question is, will anyone step up and fill the void?
Another trove of surveillance documents revels some interesting technical aspects of spying in the modern age:
Gigabit cooper network tap
What we have here is a copper wire tap. This allows some telco or ISP to split an ethernet feed, send one output on it’s merry way, while the other output goes to? If not interception and collection, I don’t rightly know what else this device is designed for.
There are many many more like this on the wilileaks website. Have any doubts about how deep the internet survailance goes? Spend a few minutes poking around, it is an eye opening experiance.
Wireshark is a packet protocol analyzer that is free for download and runs on Windows, Linux, BSD, OS X and Solaris. In the evolving broadcasting studio, computer networks are the backbone of the facility. Not just on the office side of the house, but also in the broadcast origination side as well. Today, almost everyone uses some type of computer automation system running on a network. In addition, new technologies such as, AoIP consoles, VoIP phone systems, audio and video routing, remote control, off site monitoring, audio processing, etc continue to develop. Because of this, more and more broadcast engineering work is falling into the computer and networking realm.
Like anything else, networks can fail. Failure modes can originate from both the physical side, e.g. wiring, connectors, patch bays, network interface cards or the software/protocol side. Being able to diagnose problems quickly and take remedial action is important. On the networking side, if a physical problem has been ruled out, then the problem exists with a protocol. That is where Wireshark becomes useful; it takes the guess work out of networking protocol troubleshooting.
Wireshark packet protocol analyzer has the following features (from their website):
- Deep inspection of hundreds of protocols, more are in development
- Live capture and offline analysis
- Standard three-pane packet browser
- Versions available for Windows, Linux, OS X, Solaris, FreeBSD, NetBSD, and others OS
- Captured network data can be browsed via a GUI, or via the TTY-mode TShark utility
- Filtering by protocol, IP address, MAC address, frame type, sequence number, etc
- VoIP analysis
- Read/write many different capture file formats: tcpdump (libpcap), Pcap NG, Catapult DCT2000, Cisco Secure IDS iplog, Microsoft Network Monitor, Network General Sniffer® (compressed and uncompressed), Sniffer® Pro, and NetXray®, Network Instruments Observer, NetScreen snoop, Novell LANalyzer, RADCOM WAN/LAN Analyzer, Shomiti/Finisar Surveyor, Tektronix K12xx, Visual Networks Visual UpTime, WildPackets EtherPeek/TokenPeek/AiroPeek, and others
- Capture files compressed with gzip can be decompressed on the fly
- Live data can be read from Ethernet, IEEE 802.11, PPP/HDLC, ATM, Bluetooth, USB, Token Ring, Frame Relay, FDDI, and others (depending on your platform)
- Decryption support for many protocols, including IPsec, ISAKMP, Kerberos, SNMPv3, SSL/TLS, WEP, and WPA/WPA2
- Coloring rules can be applied to the packet list for quick, intuitive analysis
- Output can be exported to XML, PostScript®, CSV, or plain text
Here is a quick video with some tips and tricks on using Wireshark:
A few things to keep in mind with the physical connection. Connecting a computer to a switchport will establish collision domain between the switchport and the computer which is also called a network segment. The computer NIC will see all traffic on that collision domain and all broadcast traffic on the network or sub network that the switch is attached to. If there is a suspected problem with a particular network segment, the Wireshark computer needs to join that collision domain.
Creating a network segment tap with a hub
This can be done most simply by installing wireshark on the host in that domain. Alternately, a hub can be used to add another host to the collision domain. Or, if it is a managed switch, there may be a provision to send all traffic on the switch out of one designated port. This is called ‘port mirroring’, ‘port monitoring’, ‘Roving Analysis’ (3Com), or ‘Switched Port Analyzer’ or ‘SPAN’ (Cisco).
Network diagram with managed switch
A quick tutorial on what to look for when using Wireshark, Part A:
And briefly, that is how it is done. There are many more videos on youtube and elsewhere if interested in learning more.
After strenuously resisting, I have began to see the beauty of on line radio. I have been a short wave radio listener since I was a wee young lad. After many years of declining listening options, I have finally broken down and started listening to radio on line. I am not disappointed. Because I need my main computer to do things on, I decided that I should have an internet media computer.
I took an old dell PC and repurposed it as an online tuner. This particular unit is rather old and once belonged to my mother. It is a P4 2.8 GHz with one gigabyte of memory and had a bad hard drive. It was completely submerged for almost 24 hours during the flooding following Hurricane Irene in 2011. After examination, the BIOS battery was corroded and dead, there was some dirt and junk in the bottom of the case, but otherwise it appeared functional. Even the DVD/CD drive worked.
Dell Dimension E310 computer
The 19 inch Dell monitor was found at the dump. It had the classic flashing power button with no picture problem. I took it apart and found a bulging 1000 µf 25VDC electrolytic capacitor on the power supply board. Replaced that and a few other suspicious looking electrolytics and it works as good as new. There are several youtube videos on how to get a LCD monitor apart which were very helpful as it is not at all intuitive.
Dell 19 monitor, found at dump
Thus, cleaning and repair work completed, I purchased a new 80 GB SATA drive and a new CR2032 BIOS battery then got started. Somewhere around here, I have some Windoze XP CD’s which I was going to use to reload the operating system. Then I thought, what fun is that? Instead, I downloaded the latest Ubuntu ISO and made a live USB device. I have messed around with Linux before; it is fun and full of geeky wonderfulness, that is true. Ubuntu is a whole different ball game. The software packages included in the 12.04 distro are pretty impressive. It is very easy to install and get the feel for with out worrying too much about command line issues. All in all, highly cool and highly recommended.
The one thing I will say about Ubuntu, it is processor intensive. With 2.8 GHz of single core blazing speed, some of the radio station stream players were running 95-100% processor utilization. Many of these are the pop up web browser units with the fancy spectral display. The work around is to go someplace like tunein.com and grab the .pls (playlist file) stream from there.
Screen shot, Ubuntu desktop, Audacious media player
This is the Audacious media player streaming the WXPK HE-AAC stream found here:
I also listened to the BBC for a while, which was a pleasant change of pace.
Once the .pls file is in Audacious as a play list, just click on it to start streaming. You can save as many .pls files as you want, thus Audacious can keep a list of your favorite radio stations.
This is a project in development. The family is away on vacation and left me home by myself for a week. Next up, I think I will get a 54 inch LCD screen and a VGA to HDMI converter. Then, this will become part of the media center for the house, replacing the old CRT TV set and DVD player in the living room. At that point; goodbye cable TV. Boy are they gong to be surprised.
Congress, is yet again contemplating a cyber security bill, this time called CISPA. This one has some worrisome privacy implications for the general internet user. I recall, not too long ago, another such measure called SOPA/PIPA which created a huge uproar and was voted down. For Congress and its corporate sponsors, this development was just a slight inconvenience when applying the “if at first you don’t succeed, try, try again,” legislative method.
Not mentioned in this particular bill is the internet kill switch, which exists now in one form or another, and the unofficial back doors into operating systems and routers. Those things are in place but their use is not codified. The internet can be monitored, user data can be stored indefinitely and it can be restricted or switched off at a moments notice. That is the reality of the world we live in.
This is why a vibrant, independent radio broadcasting medium is important. After doing some numbers crunching over the weekend, I came upon some pretty interesting data points:
- Large and medium large (over 30 stations) group owners account for approximately 2,300 AM and FM stations
- NPR affiliated stations number about 900
- There are 4,736 AM, 6,603 commercial FM, 3,917 educational FM and 802 low power FM stations licensed as of March 31, 2013.
- There are 77 AM and 178 FM (not counting translators) stations known to be silent
Therefore, approximately 3,200 of the 15,803 stations on the air are controlled by major corporate interests or media conglomerates, the remaining stations are owned by medium small groups (less than 30 stations) or individuals. Those figures create an interesting situation when discussing the future of radio. What does the majority of owners and listeners want? Ask the market.
As data transfer technology progresses, so do cable types. Category 6 UTP copper cable is commonly used today in ethernet installations where 1000BaseT (or gigabit ethernet) systems are required. Cat 6 cable has a certified bandwidth of 250 MHz (500 MHz for Cat6a). Category 6 cable is a newer version of Category 5 and 5e cable wherein the wire pairs are bonded together and there is a separator to keep each pair of wires the same distance apart and in the same relationship to each other. The four twisted pairs in Cat 6 cable are also twisted within the overall cable jacket.
Category 7 cable is much different from its predecessors. It has an overall shield and individual pairs are shielded:
Category 7, STP ethernet cable
Shields on individual pairs are required to reduce cross talk (FEXT, NEXT). It also requires special shielded connectors called GG45 plugs and jacks. Pinouts and color codes are the same as gigabit ethernet (Category 5e and 6) however, Category 7 (ISO 11801 Class F) jacks and plugs also have to contacts on the corners of the connector or jack. This allows better shielding. A small switch in the jack senses when a category 7 type connector is inserted and switches to the corner contacts, thus keeping jacks and patch panels backwards compatible with Category 5/6 cables.
Category 7 GG45 connectors, jack and plug
Category 7 cable is rated for 600 MHz bandwidth (1000 MHz for 7a) which translates to 10 GB ethernet. This was previously the domain of fiber cable. Copper cable has some advantages over fiber; lower propagation delays, requires less complicated equipment, copper is less expensive than fiber and more durable. It is nice to have the flexibility to use copper cable on 10 GB ethernet for runs of 100 meters or less. Longer runs still require fiber.
Category 7 and 7a cable looks remarkably similar to the older Belden multipair “computer cable” pressed into service as audio trunk cable seen so often in older studio installations.
Most broadcast facilities have an engineering department or service and an IT department or service which are separate. There is often a fuzzy line between what machines belong strictly to engineering and what belongs to IT. There are several different systems that have network interfaces but are not generally considered computers and fall squarely in the engineering department. These include such equipment as transmitters, satellite receivers, EAS machines, IP based audio routers and audio consoles and IP audio CODECS. In many cases, windows based automation systems and servers also fall under the responsibility of the engineering department.
As the recent incidents of network intrusions into vulnerable EAS machines shows, after installation, steps must be taken to secure networked equipment from malicious or accidental intrusions. The aforementioned EAS intrusion was bad but it could have been much worse.
Anything with a network interface can be exploited either internally or externally and either by purpose or accident. The threat plain looks like this:
Computer network intrusion plain
Every unauthorized network access incident falls somewhere on this plain. An unauthorized network intrusion can be as simple as somebody using the wrong computer and gaining access to back end equipment. It can also be the hacker or cracker from a foreign country attempting to breach a fire wall.
Basic network security falls into these categories:
- Physical security of machine or server room
- Security against internal accidental or malicious use
- Security against external intrusion
- Protection against malicious software exploitation
The first category is the easiest to understand. Physical security means securing the server room through locking doors and preventing crawl over/under entries. Security cameras and monitoring is also a part of physical security. Something that is often neglected is extended networks that bridge to transmitter sites. Non-maned off site facilities that have network access are a vulnerable point if multiple clients or tower tenants have access to the same room. Locked equipment racks and video cameras are two ways to secure non-maned transmitter sites. Also, when using good quality, managed switches at transmitter sites, switchport security features can be enabled and unused switchports shutdown.
Accidental or malicious internal intrusions can be reduced or eliminated with proper password policies. The first and most important password policy is to always change the default password. There are lists of default router and switch passwords available online. The default passwords for EAS machines and other equipment is published in owner’s manuals and most broadcast engineers know them by heart. Always change the default password, if you do nothing else, do this.
Other password policies include such things as minimum password length, requiring special characters, numbers and both upper and lower case letters. Even taking those steps, passwords are still vulnerable to dictionary attacks. To prevent a dictionary attack, the login attempts should be limited to five or so with a thirty minute freeze out after the attempt limit is reached.
External intrusion can come from a number of different sources. Unsecured WIFI is the easiest way to gain access to a network. Always secure WIFI with WPA or WPA2 AES encrypted pre-shared key. This will keep all but the most determined intruders out. Other external threats can come from man in the middle attacks. IP bridges and WIFI must always be encrypted.
External attacks can also come over the wired network. Most small routers have default network and password settings. I have started moving away from using 192.168 internal networks. Router firewalls and personal software firewalls are effective but not foolproof. Software updates need to be performed regularly to be effective. One recently discovered exploit is UPnP, which is enabled on many home and small office routers. UPnP (Universal Plug-n-Play) SSDP (Simple Service Discovery Protocol) can be exploited of exposed to the public network side of the router. ShieldsUP! by Gibson Research Corporation is a good evaluation tool for router exploits, leaks and phone homes. They also have links to podcasts and youtube videos.
Disabling unused features on routers is a good security policy. Features such as DHCP, DNS, SNMP, CDP, HTTP server, FTP server etc are all vulnerable to exploitation of one form or another. Turning off those protocols that are not in use will eliminate at least a portion of those threats.
Finally, worms, bots, viruses and other malicious software can come from anywhere. Even reputable websites now have drive-bys in linked advertizing banners. Non-windows operating systems are less vulnerable to such programs, but not immune. All windows machines and servers that are in anyway connected to the internet need to have updated antivirus software. Keyloggers can steal passwords and send them to bad places where people have nefarious intent.
There are entire books, standards and upper level classes taught on network security. This less than 1,000 word article barely brushes the surface, as the titles says, these are but a few very basic ways to implement a security policy. It is important for technical managers and engineers to learn about, understand and implement security policies in broadcast facilities or suffer the consequences of complacency.
With the advent of fiber optic cables starting in the 1980′s, the majority (one estimate says 99%) of this country’s overseas communications are carried by undersea cables. These are interesting system constructions, being first redundant and second, self healing. Glass fiber stands themselves are fairly fragile. Bundling several together then sinking them in the ocean can create mixed results. Deep ocean bottoms are often very rugged, containing mountains, canyons and fault lines. Thus the submarine cables used have to be pretty rugged.
There is a common misconception that fiber optic cables do not need repeaters. That is not true, while they do not need as many repeaters as copper cable, repeaters are still required approximately every 40-90 miles (70-150 km) depending on the cable type. These active devices are another failure point. Overall, it is a complex system.
Submarine Fiber Optic Cable cross section, courtesy of Wikipedia
Cross-section of a submarine fiber optic communications cable:
2. Mylar tape
3. Stranded metal (steel) wires
4. Aluminum water barrier
6. Copper or aluminum tube
7. Petroleum jelly
8. Optical fibers
It weights about 7 pounds per foot, which is pretty hefty.
There are a couple of interactive maps on line that have detailed information about where these cables go, date in service and data capacity. My favorite is Greg’s Cable Map which is a google map with cable data over layed with a downloadable KML file:
Undersea cable map
This shows a new cable called the “Emerald Express” which is going into service in 2013. Throughput is reported as 60 Tbps, which is moving right along. As noted on the map, this is more of a schematic diagram connecting two shore side points. The path the cable takes is an estimate and the actual geographical location may (is likely to) be different. Click on any line on the map for cable information. Most cables have their own web page and Wikipedia article.
Another undersea cable map is the Telegeography Submarine Cable Map, which has many of the same features noted above:
China US submarine Cable network diagram
Just in case you were wondering, as I often do, how a TCP/IP connection is being routed to any given place. For fun, I tried a trace route to a known server on Guam and found the results interesting:
Trace Route, Guam
Approximately 231 ms round trip route from NYC to LA to Guam and back, which is over 8,000 miles (12,850 km). A few of the intermediate routers did not answer and I tried this several different times; the same routers time out. This missing information looks to be small steps, not large ones. So, which cable goes directly from LA to Guam? Possibly the China-US Cable Network (CHUS) (picture above). At 2.2 Tbps and landing at San Luis Obispo, that is the likely candidate for the cable that carried my data.
As a general exercise, it is kind of fun, although it may be harder to figure out a particular route to say London or Berlin because there are many more different possibilities.
Route latency is something to keep in mind when planing out AOIP connections for remotes and other interactive type connections between studio and remote location. Almost nothing is worse than that half second delay when trying to take phone calls or banter back and forth with the traffic reporter.