A space beacon called Oscar

Oscar-1

Since the very first OSCAR satellites (OSCAR stands for Orbiting Satellite Carrying Amateur Radio) were launched in the early 1960s, AMSAT's international volunteers, often working quite literally in their basements and garages, have pioneered a wide variety of new communications technologies that are now taken for granted in the world's satellite marketplace. These breakthroughs have included some of the very first satellite voice transponders as well as highly advanced digital "store-and-forward" messaging transponder techniques.



Beacons. Early amateur satellites carried only one-way radio beacons which sent down telemetry information about conditions of satellite equipment and the space environment to anybody interested in receiving the data. Hamsats of the 21st century still have such beacon transmitters, alongside their high-tech two-way communications transponders.



However, the thought of a "repeater in space" developed and launched by a group of "know-nothing Hams" working in their basements and garages wasn't always looked upon with favor. While details of the incident are sketchy, it's reported that the builders of TELSTAR I, the first commercial telecommunications satellite, were quite upset to learn that a "rag-tag" group of Hams were also working on a telecommunications satellite called OSCAR III as TELSTAR was nearing completion. For a while, it appeared that OSCAR III might possibly upstage their multi-million dollar TELSTAR effort by beating them to orbit! In fact, it's also reported that TELSTAR's builders did eventually change their public relations approach to include the word "commercial" in subsequent references to TELSTAR I as the "world's first telecommunications satellite".



History of amateur satellite site.
List of amateur satellites.
More at project Oscar page.

Selected references taken from the Amsat website:

Davidoff,  Martin,  The Satellite Experimenter's
       Handbook  Newington, CT: The American
       Radio Relay League,  1984.

Jansson,  Richard,  Spacecraft Technology Trends
        in the Amateur Satellite Service,  Ogden, UT:
        Proceedings of the 1st Annual USU Conference
        on Small Satellites,  1987.

Seventy Years of Broadcasting in Belgium

By Richard E. Wood
This article was originally published in the August 1984 edition of FRENDX, now The Journal of the North American Shortwave Association. It appears here without permission of NASWA.

"Un, deux, trois, quatre .... díx. Allo, allo. Poste radiotélegraphique et radioteléphonique, pres de Bruxelles. Messieurs les amateurs de télégraphie sans fil, nous allons vous faire entendre un concert dédié á Sa Majesté la Reine Elisabeth... " The first selection was the aria from "Tosca" sung by a vocalist whose name is unintelligible in the primitive recording which survives.

More here.

Lee De Forest, 1873-1961

American scientist,

Invents the Audion grid-triode vacuum tube in 1906 used as a detector of radio signals, an audio amplifier and an oscillator for transmitting.

De Forest is credited with the Birth of public radio broadcasting when on January 12, 1910, he conducted experimental broadcast of part of the live performance of Tosca and, the next day, a performance with the participation of the Italian tenor Enrico Caruso from the stage of Metropolitan Opera House in New York City.



Caruso, breaks hearts and glass with his voice, also haunting Werner Herzog's Fitzcarraldo.

I remember reading in that excellent book from Suzan J. Douglas that De Forest was a meloman but couldn't afford a seat at the opera. He was relentlessly placed behind a column. He then promised himself to use his telegraph apparatus to bring music in people's houses. By doing this, he changed the way wireless telecommunication was used, originally from point to point (eg warship to military base) to omnidirectional broadcast. Fairly good intentions there. Thank you sir!

Here is the book reference:
Suzan J. Douglas,
Inventing american broadcasting 1899 - 1922,
The John Hopkins University Press,
Paperback, Baltimore and London, 1987, 365p.
ISBN 0-8018-3832-0

Reginald Aubrey Fessenden, 1866-1932

American physicist, inventor,

Transmits human voice on radiowaves via high-frequency oscillator, December 23rd ,1900.

"One-two-three-four, is it snowing where you are Mr. Thiessen? If it is, would you telegraph back to me?"

Mr. Thiessen, one mile distant, confirmed. Such a luck it was snowing. Radio broadcasting was born.

More on the hammond museum of radio website.

A Short History Of Transmission Audio Processing

By
Robert Orban
Chief Engineer. Orban/CRL



In the early days of broadcasting, the primary purpose of transmission audio processing was to protect the AM transmitters of the time from damage due to modulator overload. Simple peak limiters using variable-mu tubes in a push-pull configuration were employed. Because the gain-control signal was, in essence, mixed with the audio signal, these early vacuum-tube devices required careful balancing to cancel "thumps" representing feedthrough of the gain-control signal into the audio. Dynamic range control was effected through careful manual gain-riding -- in classical music broadcasts, the "compressor" was a skilled operator reading the musical score and using it to anticipate the required level adjustments. To this day, no one has invented a more subtle or effective method of compression!

Later, simple compressors were placed upstream from the limiters in situations where the budget did not permit skilled manual gain-riding. These compressors were not gated and could exaggerate noise objectionably.

In the Region 2 countries, 75µs pre-emphasis is used in FM and television sound transmission. This pre-emphasis is up 17dB at 15kHz and can cause severe over-modulation if its effects are not controlled. The obvious solution - placing a wide-band peak limiter after the pre-emphasis filter - proved unsatisfactory because high-frequency overloads would cause severe spectral gain intermodulation: cymbal crashes would cause the sound to literally collapse. The Fairchild "Conax" (originally designed for disk cutting) was often used to ameliorate the problem. This device divided the audio into two bands with a 1kHz crossover and applied pre-emphasis, clipping, and high-pass filtering to the upper band. The high-pass filter reduced the difference-frequency intermodulation caused by the clipper, yielding reasonably acceptable sound.

"Modern audio processing" could be said to derive from the work of the design team at CBS Laboratories in the early 1960s. Their "Audimax" (mispronounced by generations of engineers as "audiomax"!) was a gated wideband compressor that successfully eliminated the noise-breathing problem of earlier compressors. The "Volumax" was a clipper preceded by a limiter with a moderate attack time. The moderate attack time prevented the unit from punching holes in the program, while the clipper controlled the peaks that the preceding limiter did not catch. The "FM Volumax" introduced a high-frequency limiter to control overload due to the pre-emphasis curve. This high-frequency limiter was a program-controlled 6dB/octave shelving filter placed between the limiter and clipper. Once again, a moderate attack time was used and the overshoots were controlled by a final clipper. The "Dynamic Presence Equalizer" measured the ratio of midrange energy to wideband program energy and applied midrange equalization as necessary to correct the midrange spectral balance of the program.

In the early 1970s, Dorrough Electronics introduced the "Discriminate Audio Processor" ("DAP"). There were versions for AM and FM. The DAP divided the audio spectrum into three bands with gentle crossover slopes and compressed each band independently. The bands were recombined and applied to a clipper with a very "soft" transfer characteristic. The DAP greatly reduced spectral gain intermodulation by comparison to its wideband predecessors. Additionally, many engineers adjusted the three bands for different gains, using the device as a dynamic program equalizer as well.

In 1975 Orban Associates introduced "Optimod-FM." This unit combined compressor, limiter, high-frequency limiter, clipper, 15kHz low-pass filters, and stereo multiplex encoder into one box. This greatly reduced the possibility of misadjustment of the processing chain. The unit's 15kHz low-pass filters were non-linear filters without significant overshoot, and therefore permitted higher average modulation by comparison to the linear low-pass filters used in the stand-alone stereo encoders of the time.

In 1977 Orban Associates introduced "Optimod-AM." This unit contained a high-slope receiver equalizer to pre-compensate for the highly rolled-off radios of the time, and also included an 11kHz low-pass filter to ensure that the unit complied with the occupied bandwidth requirements of the 1978 FCC Rules. It also introduced the distortion-canceling clipper, which substantially reduced difference-frequency intermodulation distortion caused by clipping.

In the late 1970s, Circuit Research Laboratories introduced a processing system for AM whose most important novel features were a phase rotator [the Kahn "Symmetra-Peak" being a fore-runner] prior to processing (to make voice more symmetrical, reducing clipping distortion), and a subsonic equalizer after final peak clipping to pre-distort the output waveform of the processor to compensate for low-frequency tilt in the plate-modulated transmitters of the time. Compensating for this waveform tilt enabled the better transmitters to be substantially louder by eliminating a factor that would otherwise increase the peak-to-average ratio of the modulation. Although intuitively inobvious, using a phase rotator to purposely eliminate the asymmetry in voice proved to be far more effective than the older "polarity follower" [Pacific Recorders AM "Modulimiter"] circuit. The older circuit preserved any natural waveform asymmetry and switched its output polarity such that the side of the waveform with the higher peak level modulates the carrier in the positive direction.

In the late 1970s, a number of manufacturers made "composite clippers" designed to be placed between the output of the stereo encoder and the input of the transmitter. These controlled the peak modulation of the composite stereo signal unambiguously at the expense of introducing harmonic and intermodulation distortion throughout the stereo baseband. Many "hit-format" broadcasters thought that the increased loudness achieved by these devices justified compromising the spectral purity of the baseband. Eventually, the FCC judged these devices to be in violation of the FCC Rules of the time if they caused the instantaneous 19kHz stereo pilot tone injection to be less than 8% modulation. In essence, this meant that the pilot could not be clipped and must be injected after the clipper. In 1982, Modulation Sciences introduced a composite processor that did this, thereby performing to the letter of the FCC Rules.

In 1982, Orban Associates introduced the "Hilbert-Transform Clipper" as part of its Optimod-TV processor for stereo television. The "Hilbert-Transform Clipper" was later adapted for use in shortwave as well.

In general, transmission audio processing in the 1980s refined and built upon the revolutionary developments of the 1970s without introducing any radical novelties. Each manufacturer, for example, has a proprietary technique for producing non-linear overshoot-free low-pass filters for FM and television applications. Several manufacturers (including Inovonics and Circuit Research Laboratories) introduced programmable processors whose subjective setup controls can be changed by remote control to match the programming of the moment.

In the 1990s, the field must be considered "mature." As in every other area of audio, digital signal processing (DSP) is likely to eventually supplant analog circuitry. As of this writing, Orban, CRL, Valley International, Gentner Electronics, and Audio Animation have introduced transmission processors in which all processing is done in the digital domain. [The Valley, Gentner, and Audio Animation units are no longer manufactured.] If properly designed, such a processor can be readily reconfigured in milliseconds to change almost any aspect of its topology, such as the number of bands in its multi-band compressor. Subjective setup control settings can be stored and later recalled by local clock, remote control, or computer to daypart processing. The processor can readily generate test and signalling tones, facilitating tests of the transmission system and the generation of EAS alert tones.

In a digital processor, achieving sound quality equal to or better than its analog counterparts requires a marriage of art and mathematical design more rigorous than anything in the genesis of its analog ancestors. Many common analog processing functions (such as clipping) are much more difficult to do competently in the digital domain. However, digital also presents the opportunity to do things unachievable in analog, and digital's overwhelming advantages will ultimately manifest themselves as clearly here as they have elsewhere in the audio processing arena.

Robert Orban

From www.261.gr

FM Telephone Bug

FOR EDUCATIONAL PURPOSE ONLY! WE ACCEPT NO LIABILITIES FOR WHAT YOU MAY DO WITH THE CONTENT OF THIS ARTICLE.

From: http://www.aaroncake.net/circuits/phonebug.asp

Here is a simple transmitter that when connected to a phone line, will transmit anything on that line (execpt the dial tone) to any FM radio. The frequency can be tuned from 88 to about 94Mhz and the range is about 200 feet. It is extremely easy to build and is therefore a good, useful beginner project.

Schematic



Parts

Part----Total Qty.-Description
R1---------------1----180 Ohm 1/4 W Resistor
R2---------------1----12K 1/4 W Resistor
C1---------------1----330pF Capacitor
C2---------------1----12pF Capacitor
C3---------------1----471pF Capacitor
C4---------------1----22pF Capacitor
Q1---------------1----2SA933 Transistor
D1, D2, D3, D4---4----1SS119 Silicon Diode
D5---------------1----Red LED
S1---------------1----SPDT Switch
L1---------------1----Tuning Coil
MISC-----------1----Wire, Circuit Board

Notes

L1 is 7 turns of 22 AWG wire wound on a 9/64 drill bit. You may need to experiment with the number of turns.

By stretching and compressing the coils of L1, you can change the frequency of the transmitter. The min frequency is about 88 Mhz, while the max frequency is around 94 Mhz.

The green wire from the phone line goes to IN1. The red wire from the phone line goes to IN2. The green wire from OUT1 goes to the phone(s), as well as the red wire from OUT2.

The antenna is a piece of thin (22 AWG) wire about 5 inches long.

All capacitors are rated for 250V or greater.

The transmitter is powered by the phone line and is on only when the phone is in use. S1 can be used to turn the transmitter off if it is not needed.

If you have problems with the LED burning out, then add a 300 ohm 1/4W resistor in series with it.

An introduction to low power FM transmission (or pirate radio basics...) part 4

How far will my signal go?

In theory, the range of a transmitted electomagnetic wave is infinite regardless of power used,
it continues until it encounters an obstruction. more power helps to overcome any obstructions.

but is limited by how far the transmitting antenna can effectively see!

If there is a clear line of sight between the transmitter and the receiver (nothing in the way)

it should be possible to receive the signal, the curvature of the earth can soon become a limiting factor

Sources of interference or other stations operating on the same frequency.

Basically the same as people shouting over each other in a room,
the loudest one(s) get heard, and its possible to seperate the sounds of the loudest people who
have a different pitch(frequency) voice

and remember: shouting is not polite, especially in public

Transmission power (Effective Radiated Power).

You could expect a 10w station to have around a 20 mile range with a reasonable antenna

http://www.veronica.co.uk/range.htm

As you may have noticed by reading the above, fm broadcasting can mostly be about
having your aerial as high as possible.
Maybe consider using balloons or kites to lift your antenna?
Here is some information on the subject:
Prior safety warnings:

1. Give a wide berth to power lines (unless you want to look like a sausage roll).
2. Be very careful about static (unless you want to cross the rubicon).
3. Pay attention to air traffic (unless you want to pay through the nose).

http://www.hard-core-dx.com/nordicdx/antenna/special/baloon.html
http://www.qsl.net/g4vgo/balloon_antennas.htm
http://www.chem.hawaii.edu/uham/lift.html
http://www.helikites.com/skyhook/aad.html
Want to go higher?
That could be a stratosferic solution: http://www.eoss.org/pubs/faqloon.htm
http://www.economist.com/science/tq/displayStory.cfm?story_id=3423026
Want to go even higher?
Where blue turns black before it comes back:
http://bordelon.net/freespace/radioflier-1/default.html
When you get so high, you may start thinking satellite

History of AMSAT
AMSAT Documents for New Satellite Users
Sounds from the First AMSAT Satellites
OSCAR project - Orbital Satellite Carrying Amateur Radio

Maybe these bakery sponsered guys will help you lauch yours??:
http://www.jpaerospace.com
Give us a slot on your program then?!:)
Don't forget - a good mast will help!

Been away from Mother England for too long? In need of gravy granules, daddies favourite and ash browns?
Well that should be alright! Maybe you miss London's highlights: promiscuity, DLR and pollution. In that case the London Pirate Listening Station may be of temporary salvation: http://scanner.irational.org/

An introduction to low power FM transmission (or pirate radio basics...) part 1

Important notice: this information is for educational purpose only.

We hope to make you conversant with the main principles and methods of fm propagation.
If you intend to "break-in" the fm band, don't read any further!

Beginner's guide to low power broadcasting:

"Before you commit to your first broadcast - it would be advisable to have an attorney
available, who is sympathetic to the cause."

"...It's fairly easy for the DTI to track a transmission back to its source, by triangulating the signal."

"In court dress neatly and be polite to the bastard (magistrate) and the filth"
Before we go any further please have a look at: http://www.c6.org/archive/radio/pirate-fm.htm

In the next articles, we'll have a closer look at:

- What equipment do I need (part2)?

- What frequency should I choose(part3)?

- How far will my signal go (part4)?

- Considerations on dynamics (part 5).

Hope it will be of some inspiration for those interested in FM propagation.

Happy reading!

An introduction to low power FM transmission (or pirate radio basics...) part 3

What frequency should i choose?

Choose a frequency nobody is else is using, simple as that!

Most importantly!

Make sure you dont interfere with other (especially officially valid) radio users

Before you transmit, (days before even!) roam the area you will cover with a good radio, make sure nobody is using your desired frequency.
Find a quiet part of the spectrum, make sure your signal does not break-in(bleed) onto an adjacent used frequency.
Find out how your rig behaves at full power (cold, warm and hot) in an isolated area, is there frequency any drift?
Get an SWR meter (and use it!) http://www.smeter.net/feeding/swrmeter.php

Finally, read all you can about the subject. And note regional differences such as pre-emphasis

http://www.freeradio.org

Radio terms and abbreviations http://www.dxing.com/radioterms.htm
ARRL abreviations http://www2.arrl.org/qst/aguide/Abbrev_AWE.pdf

If your not creating a nuisance - then you may just get away with it!

Happy raving :)

An introduction to low power FM transmission (or pirate radio basics...) part 2

What equipment do I need?

The portable set up:

This is a quick review on what you need. Make sure to browse the internet for further detailed information.

Tape player

We advice you to go for a reliable professional cassette player
with a good rca or xlr output.

like the Sony tcd5 pro2

A Sony Pressman may do the trick as well.

"Townies iPod and MP3 players won't give you any satisfaction!"

Preamp

Assume every portable transmitter you can find is not intended to compete with professional broadcasters, a preamplifier will be handy to strengthen your signal. We are using a Nagra IV.2 for this. The main inconvenient is its weight. Walking in fields to the broadcasting location or climbing up stairs with the bastard on your back will make you consider getting its hard to find but well efficient pocket-sized little sister: the Nagra SN.

the Nagra SN:

You may also skip the Nagras and go for a home made portable console.

Here is a starting point then:
These people know the ropes on Telefunken, Siemens, EMT, Neve equipment.

http://www.danalexanderaudio.com/
http://www.marquetteaudiolabs.com/

Transmitter

This is the core of your system. May we suggest you to make a search on the interweb for "portable fm transmitter"?

We don't want to put you on the screw too much ladies but don't make us plough the sands. Does it mean anything??? ... Hahaha (from a book of English idioms)

Look for something you like with similar specifications to a Bext P10.

Bandpass filter

This is all about harmonics (multiples of your tranmissions frequency).

Let's say you're broadcasting on nine-o-nine Mhz, your aerial will send harmonics of this frequency as well. In that case 181.8, 363.6, 727.2, etc… Mhz, which are not inside the 87-108 fm band anymore.

You'll be a pain in the neck for emergency services (police, ambulances, firemen) without even noticing it… which means they'll put the DTI on your case without any delay. You may loose half a dB using it, although the loss of that dB might save somebodies life!
or help somebody get away :)

Power supply

Your power requirements will depend on your rig. 12v is the normal requirement, so a car battery is suitable (without the car running! or use a regulation circuit). Car emergancy starters are good (dont be tempted by the crap strobes on it though). Deep discharge battery will last longer and give better performance, electric wheelchairs use these, so they are easy pickings!:)

The more you spend, the more power you get, also it's easier to carry.
cheaper > more expensive: lead acid, Gel Lead acid, NiCads, Lithium Based batteries.
The more efficient (and expensive) the battery technology is, can also mean it's more difficult (expensive) to charge safely.

If you are going to be located in one place for some time, you may be able to use the forces of nature to keep you powered up i.e., solar or wind can trickle charge your batteries in time for your broadcasts.

Here's some links:

http://electronics.howstuffworks.com/battery.htm
http://www.vonwentzel.net/Battery/00.Glossary/
http://www.batteryweb.com/
http://www.exideworld.com/
http://www.mdsbattery.co.uk/defaultuk.asp
http://www.homepower.com/
http://www.americansolarchallenge.org/event/asc2005/
http://www.rain.org/~philfear/how2solar.html
http://home.earthlink.net/~fradella/green.htm

Mast

Unless you can find a location atop of a high building, a mast is a must!
Go for an air-operated 10 to 12 meters high mast which is the best value for weight, strenghtness and minimum retracted height.

http://www.alphalink.com.au/~gfs/Clark/clarkp30.htm

You can also go DIY with aluminum tubes and guy wires.

Antenna

The other key part of your radio station. It is similar to a loud speaker in a stereo system.
Again, we advice you to have a deep look on the internet on different models and manufacturers.
http://www.ac6v.com/antprojects.htm

Cable

It brings the signal from your transmitter to the aerial. Keep it as short as possible.
Any unnecessary meter will weaken your signal and then the signal/noise ratio.
To get it, have a quick look at some electricity basics here.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmlaw.html

Quality RG213 cable is a good choice.

Other

Don't go out for a broadcast without appropriate clothing! It's too late to think about your missing top when you're on air. Double check batteries and that you take any tools you need for mast erection, rope, gloves and flashlight. A sweety may be welcome and a glass of Merlot as well! You may be in a rude environment; it doesn't mean you have to get rid of pleasures of life.

An introduction to low power FM transmission (or pirate radio basics...) part 5

Considerations on Dynamics or Audio File Standards for the Broadcast Industry

Taken from www.261.gr

24/11/07
by Jeff Schroeder

Most broadcasters work hard to present the cleanest audio possible. However, there is one part of the chain – hard to measure with traditional test gear – that can undo your careful effort at quality. To avoid distortion from “stacked algorithms” Jeff Schroeder suggests we get together as an industry and create standards for incoming audio files.

It began when we got the first CD decks in our on-air studios. “Now in full digital quality, it’s Hey Lewis and the News on KIQY-FM!” I remember saying those exact words at least a dozen times in my “other” life on the air. That was 1985. Fast forward to 2006 – and for the most part we still are saying the same thing: “Broadcasting in full digital quality.” Only now a very high percentage – if not all – of the music, commercials, jingles, and liners are actually of a much lower audio quality than that first Hey Lewis CD I played from a Technics consumer CD deck back in 1985. What happened?

WE PAUSE FOR A WORD ABOUT AUDIO QUALITY
I can hear you saying: “but we are playing the files in linear file format from a $3,000 audio card on a $2,000 computer. Yes, you are. But, where did the original files come from? iTunes? New Music Server? Your friend’s iPod? Or did you actually take the time to rip it from the original CD? And what about the commercials that are running on your air now? When was the last time you actually got a commercial on a CD or Tape? The vast majority of – if not all – commercials are now delivered in file form. Have you really ever taken the time to inspect the properties of the audio files coming into your facility? Looked at the sample rate? Bit rate? RMS levels of the audio? Most people have not. The commercial/ song/liner simply comes in the building, gets converted to the automation system file format and uploaded. When I travel around the country I am amazed at some of the audio that I hear on the air – commercials in particular. The sound is so bad that it is often stressful to them.

WHY QUALITY IS SUFFERING
It is clear to anyone literate in producing clean audio that it is getting harder to find. Far too many of the current CDs are already smashed, crunched, and clipped before they get to you. But then they enter the typical broadcast audio chain where stacked compression algorithms are digital audio’s worst enemy. To illustrate, just look at the typical distribution path used today to get audio on the air:

1. Production happens in full digital multi-track editor and mixed down to a linear wave file.
2. The “send out” copy is made from the file and saved in a minimum “standard” 256 kbps MP3 file (with 5.5:1 compression) to save on upload/download bandwidth (Generation 1)
3. The local production dude (or dudette) downloads the file and opens an editor to put on the local tag. Then he/she saves the file in 128 kbps MP3 format, compressed 11:1. (Generation 2)
4. The file is then sent to the automation system, typically using 4.4:1 compressed MP2. (Generation 3)
5. The file makes it to the air. Audio processors and HD exciters add coding (Generation 4) or (even 5!

Sadly, this is sometimes the best case scenario. Often the process is repeated many times over, creating files that are technically digital audio, but sound so bad they should not be played on a $9 clock radio. At one time or another, we have all been told by the sales manager that we “must play the commercial” that we received from the client because “it’s $(insert dollar figure) per minute – and they pay fast!” Even if the file turns out to be a copy of a 6.3:1 MP2 that a station across town pulled of their automation and emailed to you.

CRUCIAL DECISIONS
I clearly remember the very loud outcry about the 4.4:1 MP2 compressed audio coming from PD’s when we first started playing music from hard drives on automation computers. This was only 7 to 10 years ago. Oh, how things have changed in this very short time! We as an industry (Radio) are at a true turning point. With more and more stations turning on HD signals and the added compression algorithm involved with HD, there must be something done about the quality of audio files that we will accept and actually play on our radio stations. Our listeners now have a vast selection of digital products from which to choose. We have to sound better than those choices in content and sound. Content is another subject which must be addressed by all the programming guru’s. What I am talking about is the quality of the audio sound. The problem is that currently there are no real standards that would improve this. What is the solution?

EDUCATION
We will take the easy one first: Education. It is imperative that the people who are handling the files (Program Directors, Music Directors, Production People, etc.) learn and understand what digital compression is and how it affects the overall quality of the finished product – which is, after all, the on-air sound of your station(s). Your staff does not have to go out and buy their own copy of Audio Files for Dummies. However, if they see a file come into the building that is a 128 kbps MP3, they do need to know enough so that they quickly can identify the file type and “properties” of the file. Then, if necessary, they are able to identify problems and do everything in their power to get that file replaced with a higher quality file. This point is particularly important for music that will go into the library and be there for a long time.

LIFTING THE HOOD ON MP3 FILES
Here is a chart of the compression ratios of MP3 files and the file sizes they generate, compared with a linear file.



You can see that the consumer standard of 128 kbps is at 11.0:1 compression. You can also see that the highest quality bit-rate of any MP3 file is still running 4.4:1 compression. A good visual example comes from a current country song on the charts today. A very simple comparison of the frequency spectrum before and after a file is pulled from a CD will be instructive. This is something every one of your production and air people should be able to grasp in an instant.

Comparing native CD audio to an MP3 dub.

The solid lines at the top reflect the frequency response of the original WAV file ripped directly from the CD. The solid filled-in (blue) part is the exact same section of the song after converting it to 192 kbps MP3. You can see the dramatic and absolute roll-off at 16 kHz. This happens with every file converted to MP3 on the very first generation – it is “by design.” This is just the most graphic example of what happens to an audio file being compressed; there are other, more harmful artifacts that happen, but that is something for a future discussion. You cannot reduce the size of an audio file without removing little “pieces” of the audio itself. These pieces can never be replaced and if the file is compressed more than once the audible quality denigration becomes almost exponential.

DEALING WITH THE URGENT NEEDS
Now, I am a realist. I understand that music now is being sent out on “release day” in compressed file format. In a competitive environment, stations have to play some songs the second they enter the building – and sometimes the only way they can get that file “right now” is downloading a compressed file. The solution: yes – use it. But then replace it as soon as you can get your hands on a CD or linear copy of the song. Never archive original audio in MP3 format! Yet, I see this all the time, all over the country. For any audio that has a chance of making it back on the air from an archive, all work should be done and saved in full linear uncompressed file format. Hard drives are cheap now. Again: archive all original audio in linear wave format. Indeed, why archive bad audio for future use? Too many times an element gets put into the automation system with the best intentions of eventually replacing it. Yet, if you were to go back into the system a couple of years later, the file likely would still be there largely because it does not sound so bad next to all of the other bad files.

SOURCE ISSUES
Another area of education deals with understanding the on-Line download “stores” such as iTunes. Not even taking into account the legality of downloading a song for “personal use” and playing it on the air, the files are compressed – sometimes highly compressed – and that compression will live on forever with that original source file. Please understand, I am not saying not to use all legally available means to get a song or file that you cannot get anywhere else. But if this is going to remain in your library, replace it with a high quality linear wave file as soon as possible.Unfortunately, as bad as such artifacts are now, HD will only make it worse. A badly compressed file will only be amplified by the compression algorithm of HD. It really is “Garbage in, Really Bad Stinky Rotten Garbage Out.” (I am not very opinionated, am I?)

STANDARDS
Now the more difficult issue: Standards. I am of the opinion that we – as an industry – can and should set the bar for what we are going to accept into our buildings from a file format standard. The problems: What should that standard be? Who should set the standard? And of the most importance, who is going to enforce the standard?

WORKING TOGETHER
As you might guess from the tone of this article, a lot of us at Citadel Broadcasting have been seriously discussing this topic at length, But it really does come down to cooperation from the entire industry. If we (Citadel) set a standard for music that we are going to accept and the competition across the street does not have the same standard, are we going to forgo being first with a “Debut” song from a core artist because the file is below our standards? Of course not. That is just not going to happen. I know it, you know it. But there goes the standard! The only way any standard is going to work is if we (Radio) set the bar and tell all of the music labels, production houses, and any other providers what our standards are – and stick by those agreed upon standards. I have had informal discussions with some of the second hand providers already, and for the most part they are as frustrated as we are. They are simply not receiving high quality linear files from the record labels on a consistent basis – and when they do they are limited by drive space and bandwidth just as we are. So, how do we begin? I would be willing to get together with any company, provider, or record label that would be willing to open the subject and possibly come up with some “base-line” standards that we could – over time – implement and eventually get the providers to adhere to. Is this possible? Is this something that we as an industry can get together on and put the power of numbers on our side? I am willing to try. Are you?

Jeff Schroeder is the Corporate Director of Digital Technology for Citadel Broadcasting Company. If you feel strongly about today’s broadcast audioquality, contact Jeff at jeff.schroeder (at) citcomm.com