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Egypt demonstrates why the Internet is unreliable

On Thursday, January 27th at 22:34 UTC (about 4:30 PM, NY time) Egypt cut off outside access to the internet.  According to Renesys:

At 22:34 UTC (00:34am local time), Renesys observed the virtually simultaneous withdrawal of all routes to Egyptian networks in the Internet’s global routing table. Approximately 3,500 individual BGP routes were withdrawn, leaving no valid paths by which the rest of the world could continue to exchange Internet traffic with Egypt’s service providers.

Go and read the entire article.  Notice how the government asked and the ISP corporations complied.  This is in response to massive riots and uprisings in Cairo and other cities which may topple the government.   Think that the internet and new media alone can keep our government honest and doing the people’s work?  Think again.  Net Neutrality is a pipe dream and would do nothing to stop this type of censorship regardless.

Free press is one of the critical legs of our democracy.  The traditional broadcasting and media has been decimated in the last 15 years.  They are not without fault, cutting staff, politically slanted reporting, profit taking have done there part.  Fortunately, while staffs have disappeared, the infrastructure (networks, transmitters, printing presses) remain in place.  They need to be revitalized and utilized.  There is a trend that I and others have noticed where small operators, perhaps one or two stations at most, are providing excellent service to their respective communities and running circles around other, group owned stations in the same market.

The Otari MTR10

I have come upon two of these units in very good shape:

Otari MTR10 1/4 inch 2 track reel to reel machine

Otari MTR10 1/4 inch 2 track reel to reel machine

Once upon a time, these were top of the line units.  I don’t know how much they cost new, but I’d imagine it is somewhere north of $3K in 1985.

Both machines work mechanically and electrically.  One machine has some slight grooves in the record and playback heads and looks a little more worn.    The other does not.  I will entertain all offers.   If a person would want the machine to be gone through and aligned, I’d charge three to four hundred dollars for my time.

It's cold enough to...

Cause the STL receiver to unlock.  A quick peak at the thermometer this morning showed -12° F outside.  Meanwhile, out on the island, the WICC TFT STL receiver decided that it was just too cold to continue and gave up the ghost.  Weak sister.  This created quite a bit of hiss on the WICC signal until about 11 AM, when the program director finally called me to tell me of the situation.

Via remote control, we switched over to the backup analog 8 KHz 15 KHz TELCO line, which sounds fine, given the talk radio program material.

Unfortunately, vehicle access to the transmitter site is now gone.  I have the option of taking the Bridgeport harbor master boat over to the dock and walking .9 miles, or driving to the Long Beach parking lot and walking 1.3 miles in order to repair it.  This will likely be tomorrow, as the weather is supposed to be better, 36°F and light snow.  Well, it is what I get paid to do.

Pleasure Beach, Bridgeport, CT

Pleasure Beach, Bridgeport, CT

Regarding the analog 8 KHz TELCO line, that is an anomaly.  These analog circuits where used to wire the country together, once delivering all of the network programming to affiliate stations before the widespread use of satellites.  They require unloaded dry pairs and normally have an equalizer on the Z (far) end.  Nowadays everything is digital, try and find a tech to repair one of these circuits when it goes down.  Fortunately, this is a short distance circuit.

Medium Wave List

This is an excellent data base of LW and MW worldwide: www.mwlist.org

WGY 810 KHz, Schenectady, NY

WGY 810 KHz, Schenectady, NY

According to the website:

This is a radio station database of all Longwave (LW), Medium wave (MW) and Tropical bands stations worldwide. You can browse frequency and location lists, search for stations, and get technical information. If you register, you can use a online logbook, create bandscans, and provide update information to the database editors. This is a free, open and non-commercial hobby project which depends on the cooperation of many individuals.

For LW/MW DXer’s this is a good information source.

The Tandy TRS-80 Model 4D computer

File under: You can find the darnest things at the transmitter site. Near as I can tell, this computer dates from about 1985 or so, it looks remarkably like my Apple IIe of the same vintage.  We used an earlier model TRS-80 in high school, that model had a cassette deck as the data storage device.  These have 5 1/4 inch floppy disks.  I used my Apple IIe as a gloried type writer, mostly for college papers.  I did manage to write some basic programs, no doubt copied from somewhere else.

For the day though, saving something for later editing, even to a floppy drive, was an order of magnitude over the single spaced type written page.

Tandy TRS-80 Model 4D computer

Tandy TRS-80 Model 4D computer

There are actually two of these computers, serial numbers 7086 and 7128.  I have no idea whether they work.   I’d donate them to a museum if there were one that was interested.  Otherwise, they may sit in the corner for another twenty years or so.

Center of Box, AMC-8

Satellite dishes have been a part of radio station technical equipment for years. I am surprised at the number of broadcast engineers that do not consider center of box when aiming dishes. As dishes get larger and focal points get smaller, center of box aiming is not a nice thing to do, it is a necessary thing to do.  The latest generation of satellite receivers, (AKA XDS) have a somewhat less than lively RF front end, they require higher E/B than the previous generation Starguide receivers to stay locked.

For years, the majority of commercial radio networks were carried on AMC-8 or its predecessors living at 139° W.  On the east coast, particularly in the Northeast, that makes aiming points relatively low to the horizon, anywhere between 8-10° elevation.

3.2 meter comtech dish

3.2 meter COMTECH satellite dish

This all means that precise aiming the satellite receive dish is critical for satisfactory performance. SES Americom owns AMC-8 and thus they have a web page about all of there satellites and important operating information. SES Center of box for AMC-8 is available in one month blocks, which makes scheduling the aiming chore fairly easy.

Large satellite dish aiming diagram

Large satellite dish aiming diagram

I have always used a spectrum analyzer though a 3 dB splitter to look at the 950 MHz  LNB output.  This aiming setup allows the best combination of Azimuth/Elevation/polarization.  Using the satellite receiver to confirm and maintain signal lock, peak the wave form that the  receiver is locked to.  It is pretty crowded up there, so there will be lots of signals on the spectrum analyzer trace.

It is a pain in the rear end to lug all that equipment out to the satellite dish, especially if it is on the roof.  That is why it only need be done once; the right way the first time.

Any shortcuts will likely lead to those annoying chirps and drop outs or complete loss programming, particularly when the weather turns bad.

Audacity digital editing software

Audacity logoAudacity is the name of a free digital audio editing software package made distributed by Sourceforge. It is distributed under Version 2 of GPL without exceptions.   It does require an .mp3 plug in to generate mp3 files.  According to the Sourceforge website:

Audacity was started by Dominic Mazzoni and Roger Dannenberg in the fall of 1999 at Carnegie Mellon University. It was released as open-source software at SourceForge.net in May of 2000…

Audacity is a free, easy-to-use and multilingual audio editor and recorder for Windows, Mac OS X, GNU/Linux and other operating systems. You can use Audacity to:

  • Record live audio.
  • Convert tapes and records into digital recordings or CDs.
  • Edit Ogg Vorbis, MP3, WAV or AIFF sound files.
  • Cut, copy, splice or mix sounds together.
  • Change the speed or pitch of a recording.

The full list of features is available here.

So, I have download a copy and installed it on my test machine in the basement (hardware requirements here).  My test machine is a stripped out P4 2.4 GHz Windows XP box that I can isolate from the network and experiment with.  On that machine with a digigram VX-880 soundcard, Audacity did very well.  I did not record multi track, but with 24 bit sound sampled at 48 KHz, the computer kept up nicely.  The basic editing features are intuitive and easy to manipulate with mouse and keypad.

For a quick to install downloadable program, it does very well.  Does it do everything like Adobe Audition or other professional editing software suite does? No.  But for the price, it can’t be beat.

The mechanical tower light flasher

This is a Hughey Phillips mechanical tower light flasher that has been in service since 1960. Basically it is a motor connected to a cam that rocks a mercury relay back and forth. These were standard technology for tower lights from the 1930’s through about 1970 or a little later.  They were very reliable, we still have some with a “pancake motor” in use on some of our towers.  They were very robust and immune to lightning damage, RF interference and other problems.  The only maintenance that I can think of is lubricating the motor bearings.  Eventually, however, they do wear out.  Cold weather seems to take its toll, often causing the motor to stop.

Hughey and Phillips mechanical tower light flasher

Hughey and Phillips mechanical tower light flashe

This particular unit is mounted inside the tuning house for the far tower (north tower) at the WGHQ antenna array.  It has finally reached the end of it’s existence; the motor bearings are shot and it has gotten stuck in both the on and off position this year causing the FAA to be notified of the malfunction.

WGHQ 920 Khz Kingston, NY antenna array

WGHQ 920 Khz Kingston, NY antenna array

Today, I am replacing it with a solid state flasher (SSAC B-KON FS155-30RF).  Solid state flasher units have been known to malfunction in high RF fields, such as AM towers.  To cure that, the manufacture has built in 0.01 uf bypass capacitors, hence the “RF” suffix.  Older units did not have the built in bypass caps, so external 0.1 uf bypass capacitors were normally installed on units mounted to AM towers.  While I was working on this, I turned the transmitter down to 500 watts, no need getting any RF burns.

Naturally, this has to happen after there is two feet of snow on the ground.  Also, it should be noted that this is the furthest tower away from the transmitter building.  Now where did I put those snow shoes?  Never mind, it has been very cold and the ground is frozen solid, I’ll take the truck…  This is good because I will have all the tools, drills, nuts and bolts without having to walk back and forth several times in the snow.

Hughey Phillips mechanical beacon flasher

Hughey Phillips mechanical beacon flasher

I removed the motor and mercury filled relay.  I’ll have to figure out how to dispose of the relay.  I then drilled a mounting hole through the base of the old flasher housing and bolted the solid state relay to it.  This is required because the solid state relay needs a pretty good heat sink.

SSAC B-KON tower light flasher

SSAC B-KON tower light flasher

Turn everything back on and:  Ta-da! All works normally, tower beacon is flashing away up there.  Time to leave.

Truck stuck in swamp

Truck stuck in swamp

Pull forward about 2 feet to turn around and CRUNCH!  The truck goes through the ice of a hidden stream.  Any attempt to move only makes it worse:

Truck rear burried to axle

Truck rear burried to axle

Put in a phone call to the one guy I know that can get me out.  About an hour later he shows up with chains, a shovel and a come-a-long.  We attach the come-a-long to the fence support post and pull the truck out backwards 1/2 inch at a time.  It took us about an hour and a half to get it all the way out so I could drive it back across the field.  I’d have taken some pictures, but my guy; he was a little grumpy.

I won’t do that again.

Still, I did the job I came to do, so it was a good day after all.

Audio over IP, what is it, why should I care?

IP networks are the largest standardized data transfer networks worldwide.  These networks can be found in almost every business and home and are used for file transfer, storage, printing, etc.  The Internet Protocol over Ethernet (802.x) networks is widely understood and supported.  It is robust, inexpensive, well documented, readily deployed and nearly universal.  Many equipment manufactures such as Comrex, Telos, and Wheatstone have developed audio equipment that uses IP networks to transfer and route audio within and between facilities.

IP protocol stack

IP protocol stack

Audio enters the system via an analog to digital converter (A/D converter), often a sound card, at which point a computer program stores it as a file.  These files can be .wav, .mp3, .mp4, apt-X, or some other format.  Once the audio is converted to a digital data format, it is handled much the same way as any other digital data.

IP stands for “Internet Protocol,” which is a communications protocol for transmitting data between computers connected on area networks.  In conjuction with a transmission protocol, either TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) IP forms what is known as the Internet Protocol Suit known as TCP/IP.  The Internet Protocol Suit contains four layers:

  1. Application layer – This is the protocol contains the end use data.  Examples of these would be HTTP, FTP, DCHP, SMTP, POP3, etc.  Telos Systems uses their own application called “Livewire” for their equipment.  Wheatstone uses “WHEATNET.”  Digigram uses “Ethersound.”   This is an important distinction.
  2. Transfer layer – This contains the TCP or UDP header information that contains such things as transmitting, receiving ports, checksum value for error checking, etc.  It is responsible for establishing a pathway through multiple IP networks, flow control, congestion routing, error checking and retransmission.  TCP allows for multiple IP packets to be strung together for transmission, increasing transfer rate and efficiency.
  3. Internet layer – This is responsible for transporting data packets across networks using unique addresses (IP addresses).
  4. Link Layer – Can also be called the physical layer, uses Ethernet (802.x), DSL, ISDN and other methods.  Physical layer also means things like network cards, sound cards, wiring, switches, and routers.

Advantages:

An IP network can be established to transmit data over almost any path length and across multiple link layer protocols.  Audio, converted to data can thus be transmitted around the world, reassembled and listened to with no degradation.  Broadband internet connections using cable, DSL, ISDN, or T-1 circuits can be pressed into service as STL’s, ICR’s, and TSL’s.  This translates to fast deployment; no STL coordination or licensing issues, no antennas to install if on a wired network.  Cost reductions are also realized when considering this technology over dedicated point-to-point TELCO T-1’s.  Additionally, license free spread spectrum radios that have either DS-1 or 10baseT Ethernet ports can be used, provided an interference free path is available.

IP audio within facilities can also be employed with some brands of consoles and soundcards, thus greatly reducing audio wiring and distribution systems and corresponding expenses.  As network speeds increase, file transfer speeds and capacity also increases.

Disadvantages:

Dissimilar protocols in application layer means a facility can’t plug a Barix box into a Telos Xtream IP and make it work.  There are likely hundreds of application layer protocols, most of which do not speak to each other.  At some point in the future, an IP audio standard, like the digital audio AES/EBU may appear, which will allow equipment cross connections.

Additionally, the quality of the physical layer can degrade performance over congested networks.  The installations must be carefully completed to realize the full bandwidth capacities of cables, patch panels, patch cords, etc.  Even something as little as stepping on a Category 6 cable during installation can degrade its high-end performance curve.  Cable should be adequately supported, not kinked, and not stretched (excessive pulling force) during installation.

TCP/IP reliability is another disadvantage over formats like ATM.  In a TCP/IP network, no central monitoring or performance check system is available.  TCP/IP is what could be called a “broadcast” protocol.  That is to say, it is sent out with a best effort delivery and no delivery confirmation.  Therefore, it is referred to as a connection-less protocol and in network architecture parlance, an unreliable network.  Lack of reliability allows any of these faults to occur; data corruption, lost data packets, duplicate arrival, out of order data packets.  That is not to say that is does not work, merely that there is no alarm generated if an IP network begins to loose data.  Of course the loss of data will effect the reconstruction of the audio.

Analog digital converter symbol

Analog digital converter symbol

Finally, latency can become an issue over longer paths.  Every A/D converter, Network Interface Card (NIC), cable, patch panel, router, etc has some latency in its circuitry.  These delays are additive and dependent on the length of the path and the number of devices in it.

Provided care is taken during design and installation, AOIP networks can work flawlessly.  Stocking adequate spare parts, things like ethernet switches, NICs, patch cables and a means to test wiring and network components is a requirement for AOIP facilities.

When things go wrong

Not necessarily applicable to radio, but a good collection of videos

Other than that, we are watching another 12 inches of snow accumulate.

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

Free counters!