Just for geeks, the FM Fool website is. Nonetheless, it is a cool site to look at and can be used as a tool to find out what stations are available in any certain area. Using the FCC database and terrain profile, it will print out a radar plot of all signals for any address in the US:
FM Fool Radar plot
This plot is for my house based on a 30-foot outdoor antenna and includes all FM stations that are even marginally receivable. We kind of live off to the side of nowhere.
The transmitter database was last updated on July 5, 2012. Longer bars represent stronger signals. Details about each transmitter are provided in the table to the right of the plot.
This is a companion site for the TV Fool website. If you want to see what off-air TV signals are available at any given location, this is the way to do it. A few years ago, I was thinking of getting rid of the Cable TV in favor of off-air reception. Unfortunately, there are only a few off-air TV channels available at my house. Therefore, I threw out the TV. Problem solved.
The transmitter for Vermont Public Radio, WVTQ 95.1Sudbury is located on Mount Equinox, near Manchester Vermont. Mount Equinox is one of the better mountain top transmitter sites to get to as it has a good access road, no jeep trails through the woods or ski lifts, etc. The Summit is 3,580 feet (1,175 m), which is the third-highest peak in the green mountains. On a nice day, the view from the top is spectacular:
South view, Mount Equinox, Vermont
The southern view with US Route 7 cutting through the valley below.
WVTQ is a part of VPR’s classical music network. They had a Nautel VS-1000 that had developed issues with the directional coupler. This unit was repaired and re-installed:
WVTQ Nautel VS-1000 transmitter, Mount Equinox, Vermont
The transmitter has a 7/8 EIA flange on the back, which had an elbow, then an adapter to a type N connector all unsupported. My boss felt that perhaps that perhaps too much weight on the EIA flange caused the crack in the directional coupler.
WVTQ transmitter racks and STL equipment
The transmitter site used to be in the basement of the hotel, but as that building no longer exists, it was moved over to the former RADAR site. The RADAR site consists of four 80-foot towers arranged in a square around a building. These towers now support two-way radio equipment and the like
WVTQ transmitter site, Mount Equinox, VermontFiner points of GPS antennas
Your author (left) with Rich Parker of VPR discussing the finer points of GPS antennas.
Stairway to heaven
Ladder to the top of one of the towers.
Hang Glider’s view, east side pulloff, Mount Equinox, Vermont
View from the turn-off on the east side of Skyline Drive. Known as “hang glider’s view” with good reason. This is on the saddle that connects little Equinox with big Equinox.
On a nice day, such as yesterday, it is very pleasant. When the road is covered in ice and snow, not so much.
If Radio as an entertainment medium is to survive; vital. College Radio is the alternative to corporatist radio and is fertile ground for new artists and music. The big three radio groups control (Clear Channel, Cumulus, CBS) something like 75% of the radio revenue while owning 13% of the commercial radio stations. Against that wall, the remaining radio groups and independent operators hurl themselves to make a living. While there are few (precious few) commercial independent operators who do break new music, perform community service and provide a valuable asset to their city of license, the majority of the remaining 87% of radio stations run some sort of repeater/automated format.
In this risk-adverse society, which large radio group is willing to take even small calculated risks?
Who is going to replace Dick Clark and where will that person come from? By the way, God bless Dick Clark but, man, enough already.
Where will the newest crop if disk jockeys come from?
If one wants to hear something new, or at least different, there is no better place to listen than a student-run college radio station.
It was in this setting that several college boards had a Eureka! moment when they discovered that those FM licenses were actually worth money. Money! and in not-so-small amounts in several cases. The collective wisdom is that kids these days don’t listen to radio, nobody will miss those programs anyway. Even so, when Rice University sought to transfer KTRU there was a large backlash from Alumni and the student body. When the University of San Francisco sold KUSF to Entercom, they did so over Christmas break. At Vanderbilt University, the WRVU staff was locked out of the studio. The whole sordid tale can be found in 2011: The Year that College Radio Fought Back and College Radio’s fight for FM.
There are other stations whose fate is less well known, no doubt.
It is disappointing to see the various college boards deciding that broadcast radio is no longer desired and to see the campus radio station regarded as an extracurricular activity or so much excess real estate.
There are still many college radio stations in this area that are worthwhile to listen to, just to hear something other than blended crap, super specialized satellite radio channels, or some personality-less internet stream with computer-picked songs.
So kudos to WRPI (Rensselaer Polytechnic Institute), WVKR (Vassar College), and others like them for having student-run radio stations and not selling out or morphing into the borg-like collective that is NPR.
How effective are they at filling in or expanding coverage for FM stations? The answer is, it depends. Most have heard of the quadcast around New York City on 107.1 MHz formed in 1996-98. It was well documented in Radio World and several other publications as a clever way to overcome the suburban rimshot problem. Four signals on 107.1 were synchronized using GPS timing data, then fed the same program material. They were WYNY, Briarcliff Manor, NY; WWXY, Hampton Bays (Long Island), NY; WWYZ, Long Branch, NJ; and WWYY Belvidere, NJ. These being four separate Class A FM stations, the 60 dBu contours did not overlap. There was some mutual interference in some areas, but there were few if any reception negative zones where the signal strength is equal between stations.
In early 2003, I was a part of the disassembly of the quadcast. In the end, it is difficult to point to any one thing that leads to the breakup. The station’s owners, Big City Radio, had filed for bankruptcy. I am not sure if the company ever had the correct formula for marketing and sales, given the strong suburban, but weak and lacking building penetration in Manhattan signal. The station initially had a country format, something that armchair quarterbacks said would not work in New York City. After a few years, Big City changed the format to Rumba, a Spanish/Caribbean music format, which did worse than Country. The fact is, that it never lived up to expectations and the station was worth more separately than together. Given the right circumstances, it could have worked.
The other synchronized FM broadcasts are those where boosters are employed. These are a good deal more difficult to configure because the booster signal is within the main station’s 60 dBu contour. Often cases, where there is severe terrain shadowing or other limitations, a well-positioned booster that is in a population center can greatly improve the signal in those areas. This was formerly the duty of an FM translator, however, those stations seem to be taking on a life of their own, without regard for the intent of the current FCC rules. Boosters can also be called a single frequency repeaters or single frequency network (SFN).
The disadvantages of an SFN are the aforementioned negative reception areas. To the receiver, this will create a multipath or picket fencing situation, which is objectionable to most listeners. The advantages are, of course, better coverage in key areas, spectrum efficiency, and the ability to create a network of common frequency systems. Think of how easy it would be if all NPR stations were all on the same frequency, for example.
The key to making a booster work is to synchronize several aspects of the RF and Audio signals:
RF carrier frequency
Stereo pilot frequency and phase
Audio amplitude and phase
The RF carrier frequency, stereo pilot frequency, and phase are locked with a GPS. Most transmitters have a 10 MHz or 1 PPS input for this.
The audio amplitude and phase synchronization are slightly more complicated. Basically, all of the audio should be coming from one audio processor and the path to the individual transmitter sites has to be very low latency. RF STLs work for this setup well, if there are suitable paths.
Once that is established, the audio timing is used to move the interference zone away from undesirable areas. There will always be an interference zone where both signals are received at the same relative strength causing dropouts.
WDBY, Patterson, NY 60 dBu contour
This is the situation with WDBY in Patterson, NY. The main transmitter site is located on a hill in Patterson and has a power level of 900 Watts at 610 feet (186 meters) HAAT. The main population area is Danbury, CT, to the southeast, about 12 miles away. Between the two, there are several imposing hills, which create reception issues in Danbury. Therefore, WDBY FM1 was placed in service at the Danbury Medical Center. The booster has a power output of 1,200 Watts, at 0 feet (0 meters) HAAT (49 meters AGL).
WDBY FM-1 signal, Danbury, CT 60 dBu contour
Therefore, the southern area of the 60 dBu contour is filled in by the booster. The interference zone between the two transmitters is determined by the amount of delay in the audio between the two units. If both are time the same, the interference will occur at precisely 1/2 the distance between the transmitter sites, which in this case is 10.18 KM from the booster. Looking at the population maps, it might be better to move that more toward the north, away from Danbury.
The formula for computing audio delay time is:
A-B=C where A is the distance between the transmitters and B is the distance to the interference zone from any given transmitter. The product of that is multiplied by a constant of 3.34 to obtain the time delay in microseconds. Therefore, if the interference zone is desired to be further outside of Danbury, say 15 KM away, then the equation looks like this:
20.358 kM -15.0 kM = 5.358 KM
5.358 KM x 3.34 = 17.89 μS delay from the main transmitter site will put the interference zone out in the middle of nowhere, away from Danbury. This is the total delay between the two stations, therefore any difference in STL paths needs to be included in this figure.
Nautel equipment has most of these features built into it, therefore, the implementation of an SFN using Nautel exciters and transmitters should be relatively straightforward.
