One of the guys I work with is a little bit crazy. Well… actually more than one, but this one person in particular has gone out of his way to fix up a summer camp radio station. So, the background is this; in a remote region, far, far away from thing else, a summer camp had installed a license free (allegedly FCC Part 15) radio station to cover the camp compound. Many summers later, said camp management had some questions and concerns about the operation. This is where our protagonist comes into the story.
Not only did the camp owners have questions about their operation, they also had coverage issues. Their installation consisted of a Ramsey five watt all in one FM transmitter feeding a horizontally polarized television antenna on the roof of the studio fed with RG-6 coax. There were several coverage holes within the immediate camp complex and they were asking of a more powerful transmitter was needed. In light of this, our man Pete did some engineering outreach. Over the period of several months, Pete scraped together what would have been mostly back shelf backup gear, perhaps a few things destined for the dumpster and other miscellaneous items and built a small radio station for them.
Camp Radio Station equipment rack
What was once, no doubt, an illegal operation was brought substantially into compliance by replacing the Ramsey broadcast transmitter with a QEI 675 exciter modified by removing the power amp and connecting the IPA to the output filter. Thus modified, it runs a maximum of 0.2 watts, which is not necessarily the output power. The antenna was changed to a home made vertically mounted dipole antenna. The addition of a broadcast quality limiter ensures that the station is not over modulating. A recently calibrated Belar FM modulation monitor confirms this. Some Texar Audio Prisms juice up the sound a little bit. A Urei console, a couple of Shure SM-58 microphones and a computer round out the operation.
Camp Radio Station console and computer
Now, the camp radio station has the feel of a real radio station. Kids that come here to do shows get a fairly authentic feel and appreciation for what it is like to be a DJ; selecting music, doing intros, information, weather, etc. By looking at the sign up board, it seems that radio can still be very popular with teenagers:
Camp radio station sign up board, very few openings
Thus the camp owner has perhaps saved himself some grief with the FCC. A potential interference and intermodulation situation has been avoided. The new equipment covers the entire camp compound and better still, does not go too far beyond the front gate, which is exactly 121.4 feet away from the antenna mast. Best yet, a whole bunch of teenagers are interested in doing radio shows and learning about music. There are very few venues or paths for potential new talent to enter this business and things like this should be encouraged.
With the pending LPFM filing window in October, I decided that perhaps I could spread the information to some local groups that might want to put a community radio station on the air where I live. Back over a decade ago, there were a couple of local commercial AM and FM stations in the area, but they moved out of town to a larger city some 24 miles to the east. If local legend is to be believed, the AM station was very popular, with its studios and offices over the local pharmacy. That station is now running 24/7 comedy, which given the area, is ironic almost beyond words. As it stands now, this is one of those rural areas that, on paper, looks well served by several different radio stations. Truth is, there are radio signals receivable here, but there is no local radio. The last time anyone from those previously local stations had a meaningful thought about the respective Cities of License was months if not years ago.
With all this in mind, I first approached a local community non-profit group. They seemed mildly interested, but expressed doubt about finding a studio location. Their basic take was, we can help, but we want others involved. Seemed to be a lukewarm, but understandable and not totally unwarranted response.
I then approached the local school board. The idea was to get the high school involved with the station broadcasting sports events and teaching kids how to do play by play and perhaps other types of radio shows. They fainted interest at first, then decided that they didn’t have the staff to deal with a broadcast program and there were other excuses like “liability issues.”
I then approached the local governments (two different towns) who were almost openly hostile to the idea. While they didn’t say as much to my face, they rather implied that it would be a waste of time and the town(s) were not interested.
I have approached other local groups, which don’t seem to be interested at all.
Has radio lost its mojo with the local population? Are we who still remain in the radio business simply fooling ourselves into thinking that somehow this is important? I don’t know.
The hazards of rural LPFM; large area, few people, generalized indifference.
Two reasons for this; first, I am deep into the IP networking curriculum and time is at a premium. That being said, I am rather enjoying myself in school, which is always good. Secondly, and related to the first part, I have not been spending too much time these days doing Broadcast Engineering work. Thus, the subject matter and various topics have not been jumping out at me as they normally do.
My busy schedule not withstanding, there are some interesting things going on in the realm of Radio Engineering:
On the LPFM front, the FCC has dismissed over 3,000 translator applications from the great translator invasion of 2003. This is great news and now potential LPFM applicants can use the FCC LPFM search tool to get a good idea of what is available in their neck of the woods. Other search tools include Recnet and Prometheus Radio project. Filing window is October 15, 2013, apply now or forever hold your peace.
Chris Imlay has some good ideas on AM revitalization. His suggestion is to have the FCC enforce and strengthen its existing rules regarding electrical interference. I notice two letters are missing from his list, those would be “h” and “d.” While the ideas are technically sound, it seems unlikely that the FCC can or would be able to enforce stricter Part 18 rules.
Lots of EAS shenanigans going on with zombie alerts and hijacked EAS systems. Really people, default passwords? Secure your equipment and networks or pay the price for complacency. Nearly all new equipment has some sort of web interface, which can be a great time saver. They can also be easily exploited if left vulnerable. Fortunately, this was not as bad as it could have been.
Something happened in NYC that hasn’t happened in quite a while. Country music filled the air on a station that is generally receivable in the five boroughs. This may not seem like big news to the rest of the country, but in market number one, it is big news. Further, Cumulus has registered “NashFMxxxx.com” for every FM dial position. National country channel in the works? I’d bet yes. A look at recent trends shows that Cumulus is standardizing formats on many of its AM and FM stations, making them, effectively, part of a nation network of over the air repeaters.
Clear Channel has put more effort into iHeartradio, for seemly many of the same reasons as Cumulus’s standardized formats.
Where is this all going? There are several trends evident including; AM will eventually be declared DOA and switched off, transition to national based music formats, an emphasis on IP (internet) based delivery systems, an eventual phase out of local programming, smaller staffs concentrated on local sales and little else.
The single bright spot could be LPFM. Only time will tell if this new crop of LPFM licensees will keep the faith and tradition of local radio. If one looks at the natural course of evolution, under times of extreme stress, species tend to get physically smaller in response. The larger species cannot sustain themselves with the necessary energy intake and die off. See also: Dinosaurs. I certainly would call this prolonged, nearly dead economy stressful on the broadcasting business. Perhaps, when all is said and done, it will be the small, volunteer LPFM still on the air and serving the community.
My son and daughter are playing ice hockey this winter. Which means that every Saturday morning I have to get up very early and haul them off to the rink for practice and a game. It is actually a lot of fun because I love watching them play. Having played a certain version of pond hockey in my youth, it brings back good memories.
In any case, last week, after they finished their game and changed out of their hockey gear, my son wanted to watch the older kids play. Thus, we sat down in the bleachers for a few minutes to watch the 12-15 year olds play against a traveling team. Most hockey leagues are mixed, that is to say girls and boys playing on the same team. Not to put too fine a point on it, but the girls can be decerned not only by their pony tails but also the pink stake laces or pink hockey gloves. I also noticed that the girls seem to play a more cerebral version of the game, which is a joy to watch.
Not soon after we sat down, a fast break play developed at mid ice. It was truly a thing of beauty. A player from the home team intercepted a pass from the opposing team and took off down the ice. She was followed closely by another player from her own team. As they crossed the opposing red line, the other team closed in. I watched the lead player move fast toward the goal then fake out the goalie, lifting her stick oh so much as she made the shot. The goalie was completely fooled and dove for the non-existing puck, which was left on the ice for the following player, who neatly scooped it into the goal under the goalie’s leg. It was over in a flash of white jerseys and pink laces. I thought to myself; these are kids are great! You do not have to watch an NHL game to see good hockey and sometimes the so called “professional” sports is overrated anyway.
Which got me to thinking about LPFM. How many budding journalists, play by play announcers, DJs and presenters are out there waiting for an opportunity to show their stuff? An opportunity that they may never get because most commercial and many public radio stations are locked into an increasing automation loop. Locally originated programming is constantly being cut and replaced by satellite syndicated formats and or out of market voice tracking. It is truly a shame, because the strongest leg that terrestrial radio can stand on is localism.
LPFM can be that opportunity to return radio to its community of license. It will not be easy, clearly the rules were written to prevent LPFM from ever competing with commercial or even public radio stations. Restrictive power levels, odious interference rules, and limited fund raising capability will keep all but the true believers and perhaps ignorant souls from attempting for a license. It will be hard, but not impossible and the true believers will make a go of it. The October 15th, 2013 filing window will very likely be the last opportunity for community organizations to establish a local radio station. After that, the remaining spectrum crumbs will be divided between translator aggregators to create ever larger networks of mostly redundant content.
Terrestrial radio may well go through an evolutionary change. As more and more broadcasters are finding out, once a license is owned, there is a great deal of expense in operating a station. Things like employees and office supplies can be cut, however; towers need to be maintained, transmitters and antennas need to be replaced periodically, electricity bills must be paid, etc. The larger the station, the more operating costs are involved. Another serious economic downturn like 2008 and the crazy train will be off the rails. The inexpensive to operate, volunteer run local LPFM may indeed be the last radio station(s) standing. I have heard many decry this type of station as “amateurish” or “not professional.” Here is what can happen if you give a bunch of amateurs a free hand:
This is one of the possibilities that has been bantered about as a solution for the “AM problem.” The theory goes as such; former TV channels 5 and 6 (76 – 88 MHz), which are not suitable for DTV would be an ideal place for the existing AM stations to move. That represents a 12 MHz chunk of spectrum, which is much more than the current 1.16 MHz spectrum the current AM broadcasting service takes up (.54 to 1.7 Mhz). An added benefit is that the VHF spectrum does not have the skywave “problem” that the MF spectrum does, thus many more stations could be licensed to the service. Everyone would benefit, AM stations would get a new lease on life in the FM band. The number of stations would increase by several fold, including LPFM, non-commercial and translators. AM stations would no longer be burdened with expensive directional arrays or sub standard audio quality.
It seems almost too good to be true…
The FCC reportedly promised “take a hard look” at this idea back in 2008. Four years later, one wonders what has become of it.
A quick search of the existing TV stations licensed to channel 5 and 6 reveals the flaw in this theory. The FCC has re-licensed many full powered and Low Powered DTV stations to channel 5 and 6 since 2008.
List of full power channel 5 stations:
CAPITAL COMMUNICATIONS COMPANY, INC.
GRAND VALLEY STATE UNIVERSITY
LAKE SUPERIOR COMMUNITY BROADCASTING CORPORATION
KXLF COMMUNICATIONS, INC.
GLENDIVE BROADCASTING CORP.
HOAK MEDIA OF NEBRASKA LICENSE, LLC
DOMINION BROADCASTING, INC.
CALIFORNIA OREGON BROADCASTING, INC.
NEWSCHANNEL 5 NETWORK, LLC
WMC LICENSE SUBSIDIARY, LLC
CORRIDOR TELEVISION, L.L.P.
BLUESTONE LICENSE HOLDINGS INC.
WITHERS BROADCASTING COMPANY OF WEST VIRGINIA
FOND DU LAC
WWAZ LICENSE, LLC
List of Low Power Channel 5 stations (analog):
ALASKA CORP OF SEVENTH DAY ADVENTIST
KM COMMUNICATIONS, INC.
THREE ANGELS BROADCASTING NETWORK, INC.
JAMES J. CHLADEK
ROBERTS BROADCASTING COMPANY OF EVANSVILLE, IN, LLC
Zorch is a term used to describe an over voltage or over current condition that usually leads to catastrophic failure, e.g. the power supply was zorched by lightning. There is also a quality to radio signals that defy and exceed theoretical definitions for service contours or power density. That is quality defined as:
Zorch (adj): The ability of an RF signal to be received in unlikely locations; outside of predicted service contour, in steel structures, underground facilities, tunnels, etc.
It brings to mind the saying, “antennas are not amplifiers and amplifiers are not antennas.”
ERI circularly polarized 2 bay antenna
During the earlier stages of FM broadcasting, there was a notion that costs could be reduced by increasing antenna gain and reducing transmitter size. While theoretically, ERP (Effective Radiated Power) is ERP, broadcasters soon learned that high gain antenna, low TPO (Transmitter Power Output) installations lacked building penetration and had other reception issues. Realizing that there is a trade off between antenna bays, transmitter power output especially in difficult reception areas, a great debate occurred and continues on what the optimal system is. The answer is, it depends on the receiving environment.
Where this technical detail can be really important is with lower powered FM stations; Class A and LPFMs to be exact. They are already battling against bigger stations that have tens or even hundreds of times more power. Certainly an LP-100 station has it’s work cut out for it. The choice of antenna is perhaps one of the most important technical decisions to be made. Choosing the right balance of antenna type, antenna gain, antenna height and transmitter power output can greatly influence reception reliability and thus coverage area.
A good study of this quality can be had by looking at various LPFM installations:
Station ERP (watts)
Antenna Gain (power)
Coefficient of Zorch
1 bay vertical
1 bay circular
2 bay vertical full
2 bay vertical half
2 bay circular full
2 bay circular half
3 bay circular full
3 bay circular half
*Includes 100 feet of 1/2 inch foam transmission line, Andrew LDF4-50A, loss of 0.661 dB at 100 MHz, or 0.859 power gain.
Stations should try to get the transmitting antenna as high up as permitted without reducing ERP. In other words, the FCC allows 100 watts ERP with 98 feet Height Above Average Terrain (HAAT) radiation center in their current LPFM rules. Being lower in height will reduce the coverage area. Going over 98 feet HAAT will cause the station’s power to be reduced, which will lower the coefficient of zorch accordingly. Therefore, getting as close to 98 feet HAAT, which is different than 98 feet above ground level in many places, will net the best performance.
If a singular polarization (horizontal or vertical) is desired, vertical polarization should be chosen, as most mobile reception is by a vertical whip antenna. For best reception performance, a circularly polarized antenna will work best, as receiver antenna orientation will not effect the signal reception. A circularly polarized antenna has better building penetration and multi-path characteristics. The FM broadcast circularly polarized antenna in not a true circularly polarized antenna, it is actually unpolarized.
The use of a multi-bay antenna has the effect of focusing the RF radiation outward, perpendicular to the element stack, thus limiting the radiation directly up or down from the antenna. This is more pronounced with one half wave spaced antennas, which may be an environmental consideration in heavily populated areas.
Thus, the best coefficient of zorch for an LPFM station would be a circularly polarized, 1/2 wave spaced, 2 bay antenna. This antenna would have some gain over a single bay antenna, take up less room on a tower than a full wave spaced antenna, offer good RF protection performance for the general public living and working under the antenna, reduce wasted upward radiation and offer good building penetration for the ERP. It would require a slightly larger transmitter and more electricity, but that trade off is well worth the effort.
A potential LPFM (Low Power FM) filing window may be opening up as soon October/November. There is nothing official from the FCC about the date, however, several insiders have suggested that this is on the fast track and it may happen sooner rather than later.
This will likely be the last chance for community radio operators to get a LPFM license, as after this filing window, every available scrap of spectrum will have a translator shoe horned into it. Therefore, now is the time to do some research and get prepared.
To that end, there are two good LPFM channel finders that can be used to determine if a LPFM station can be put on the air. The first is the FCC’s official LPFM channel finder. For this tool, one will need to know the latitude and longitude of the proposed transmitter site. That information can be obtained from itouchmap.com, with which one can find the lat/long of any point on the face of the earth.
The second LPFM channel finder is from REC networks. This tool is a much more flexible. For finding possible transmitter location, a street address, zip code, or lat/long can be used. It also has much more information as it has a provision to use the proposed 250 watt station class and shows every available channel as well as possible available second adjacent channels.
Prometheus radio has a simpler zip code check, which does not give any technical information, it simply states that LPFM channels are available at the zip code which was entered. Prometheus has good primers on how to start and operate a LPFM station.
If you are a member of a group considering starting a community radio station, now is the time to get going.
FCC moves ahead on a couple of different fronts in the LPFM battle. Cliff notes version:
The 2003 translator filing window question. The FCC has more or less stuck with it’s plan to keep a minimum number LPFM channels available in the top 150 markets. This also includes a 50 application limit for the country and no more than one application per market per applicant. Where conflicts occur, translator applicants get the chance to demonstrate how their application would not preclude LPFM opportunities.
Modifies (eventually eliminates) the May 1, 2009 cut of date for cross service (AM to FM) translators.
The establishment of new LPFM allocations under the criteria of disregarding the third adjacent channel contours.
More stringent requirements for local programming and ownership, especially as a determining factor for mutual LPFM applications.
Allows LPFM stations to own translators.
New class LPFM is established; the LP250. The 250 watt LPFM stations are designed mainly for areas outside of top fifty markets or for previously licensed LP-100 stations that want to upgrade provided the minimum separation contours are met with existing stations.
The FCC has included the proposed rule changes as appendix A of FCC 12-28. Standard FCC comment and reply windows apply.
Looks like things are moving along pretty fast. Others have speculated at a filing window sometime later this year, I’ll not do that.
I have been watching the LPFM proceedings with some interest. The FCC has not exactly promised to have a filing window by end of 2012, but indicates that it might try to do that. In comparison to such evolutions in the past, this is moving pretty fast. Those that want an LPFM station need to start planing now. As in previous LPFM windows, the availability is for non-profit organizations only. This does not mean all hope is lost; NPR stations are all non-profits and most of them are very successful.
One of the biggest questions is: How much will it cost? Like all things, it varies greatly. If I were to put an LPFM or internet radio station on the air, there would be certain minimums, such as the use of professional audio equipment, a new antenna, and some type of redundancy.
Generally speaking, radio stations and internet stations both need some type of office/studio space. This can range from large and opulent to a closet. The costs for these would depend on the type and quantity of equipment installed, whether the equipment is new or used, the building, the area, etc. Those facilities also have monthly reoccurring costs such as rent, electric, telephone service, internet service, etc.
Since internet radio stations and traditional terrestrial over the air radio would use the same type of studio equipment, those costs will be similar. Here is a breakdown of the studio equipment:
Cost new (USD)
Cost used (USD)
12 Channel professional audio console
Analog, 4 buss, telephone mix minus
Can also be fabricated locally
Microphones, RE-20 or SM-7B
Per unit, several required
Can also use consumer version
Can also use consumer version
Professional unit with balanced outs
Computer w/ professional sound card
For automation and sound file storage
Computer, general use
General information web browsing
Computer, Streaming w/sound card
Sound card should be good quality
Studio Telephone system
Used for call in/on air
Barix remote box
Used for IP remote broadcasts
Comrex Matrix POTS codec
Used for telephone line remote broadcasts
Misc wiring, hardware, ect
Connectors, mic booms, wire, etc
Some equipment is not available used such as Barix boxes. Of course, not all of this is required for a radio station, however, most local radio stations would want the capability to do remote broadcasts, take phone callers on the air, have multiple guests in the studio, etc.
For a traditional LPFM station, the transmitting equipment would entail:
Cost New (USD)
Cost Used (USD)
300 watt transmitter and exciter
Smaller transmitters with higher gain antennas can also be used
2 Bay ½ wave spaced antenna
125 feet ½ inch coax
100 foot guyed tower and installation
Not needed if station is on tall building or leased site
STL; IP radio w/ barix boxes
In lieu of standard 950 MHz STL
STL standard 950 MHZ
Used in lieu of IP STL
STL antennas, transmission line
Can also use software such as Breakaway Broadcast
Misc connectors, grounding kits, etc
Fully operational CAP compliant
Processing software, Breakway broadcast
In lieu of standard FM processor
This is a generic station, most will be somewhat different due to antenna supporting structures, transmitter powers and antenna types. For the best possible signal, a circularly polarized antenna should be used. A two bay, 1/2 wave spaced antenna will give the maximum signal density, while minimizing downward and upward radiation. The upward radiation is simply wasted energy, as no one in space is listening to FM radio. The downward radiation reduction is key if located in congested areas.
For internet radio station, the following would be required:
Cost New IUSD)
Cost Used (USD)
Includes professional sound card
Audio processing software
Recommend software such as Breakaway Broadcast
Audio Processing, outboard hardware
In lieu of software
Audio Streaming aggregator
1,200 to 2,400
While LPFM’s are much more expensive than internet only stations, LPFM’s have the advantage of built in marketing, which is the on air signal. If it is broadcasting on the air, word will get out. On the internet, some other type of marketing will be needed to spread the word. Also, LPFM’s should also be streaming, which would incur the same costs above.
The long and short of it is, to put a technically viable LPFM on the air is not an inexpensive proposition. It is worth the effort, however, because the advantages of an LPFM over an internet only station are great.
Every good transmitter, tube transmitters in particular, require harmonic filtering. The last thing any good engineer or broadcaster wants is to cause interference, especially out of band interference to public safety or aviation frequencies. All modern transmitters are required to have spurious emissions attenuated by 80 dB or greater >75 Khz from carrier frequency. In reality, 80 dB is still quite high these days, especially in the VHF/UHF band, where receivers are much more sensitive than they used to be. A good receiver noise floor can be -110 dB depending on local conditions.
The principle behind a low pass filter is pretty easy to understand. The desired frequency is passed to the antenna, while anything above the cut off frequency is restricted and shunted to ground via a capacitor.
Low pass RC filter
In this case, the resistor is actually an inductor with high reactance above the cut off frequency. Often, these filters are lumped together to give better performance. This is a picture of an RVR three stage low pass filter:
RVR three stage low pass filter
RVR is an Italian transmitter maker that sells many transmitters and exciters in this country under names like Bext, Armstrong, etc. The inductors are obvious, the capacitors consist of a copper strip sandwiched between teflon insulators held down by the dividers in between the inductors.
Schematically, it looks like this:
Low pass filter schematic diagram
For the FM broadcast band, a good design cutoff frequency would be about 160 MHz. This will give the filter a steep skirt at the first possible harmonic frequency of 176 MHz (88.1 x 2 = 176.2).
Values for components:
The inductors are wire, or in this case copper strap, with an air core. It is important to keep the transmitter power output in mind when designing and building these things. Higher carrier powers require greater spacing between coil windings and larger coil diameters. This particular filter is rated for 1 KW at 100 MHz.
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.
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.
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.