I was reading Radio World and I found an article that shows the link between Part 15 use of the FM band and the AM translator invasion. http://www.radioworld.com/article/new-translator-listen-and-then-look/279323
The article was doing great until the last sentence which seems to mirror the scare tactics the FCC has begun using.
Besides showing how an AM on FM translator can impact unlicensed use, the article is helpful because it gives a field strength that would be the limit for what can be received radios normal people have “At 40 or 45 dBu your signal is fragile”, “under 30 dBu (pretty much unreceivable)”.
translators already sucked every available frequency in denver. had to shut my fm down.
Within one year I got pushed off of three frequencies that had been excellent, but along came the translators.
Originally I was on 107.1, but somebody started up on 107.3, so I moved to 101.9 only to be crowded out by crooning Christians repeating a nearby full power station.
The 101.9 transmitter had moved from 101.5 and that was usable for awhile until yet another translator wedged in.
Today there are more opportunities to ignore bad programming than ever before.
Is the U.S. FM band being intentionally blighted as a way of killing it off? I imagine the cell phone industry would like to occupy the spectrum.
How many waste baskets will it take to dispose of our FM radios?
Carl,
Is there a listenable station on or adjacent to every frequency 88.1-107.9 MHz where you are? If there were 3 channels of noise (HD-side channels; overlapping distant co channel stations; general buzzing sounds) in a row you could use the middle one; your range would be poor from fighting the noise but it would get a signal on the air.
I doubt the cell phone companies want FM. The signals propagate too far to be used for reasonable sized cells. Directional antennas to get 3 frequency reuse groups on a tower would be unpractically large for cell towers. Antennas on the user device would have negative gain. Building construction wrecks VHF signal reception indoors. About the only way the cell phone industry could grab 88-108 would be for 3 new TV channels to be made in there and TV stations moved there from the UHF band. I think the real enemy is the abuse the FCC is allowing for FM translators. Cross band AM to FM translators may be a short term necessary evil. The use of Translators for HD 2,3,4+ channels was not well thought through.
Where I am there are at least half a dozen translators that started their lives as 10W educational/church translators that had very specific coverage limits because they were non-fill-in translators. Then they became fill-in translators and their HAAT and power were supersized. The coverage was maximized based on required protections for other stations and the service area of the new parent station. Most of them are owned by a church. The church originally had a patch work chain of non-fill-in translators, one feeding the next crossing 4 states. Then they got commercial stations to carry their station on a HD channel, and used that to feed super powered translators. Now with all the extra translators from their previous chain they could get money from AM and HD FM stations wanting to use the translator. Since the church did not have to pay filing fees they just shot gunned their applications during the big translator filing window.
Luckily, stvcmty, I went on to find a few usable channels here on FM, and for now they are remaining open.
Another FM problem I don't recall anyone talking about is the amount of RF energy in large cities that accumulates in the receiving antenna to the point where it adds input voltage at the antenna terminals, contributing to eratic performance.
Wonder if all the religious radio operations at both low and high power keep listeners long enough to matter, the bottom line being measured of course in donations. If it's lucrative you can't blame them for taking advantage of public generosity. It's great to receive money for nothing in exchange.
Over the years I've held discussions with various friends about starting a radio church and spending life building a bank roll for little more than repeating a few stock platitudes. The hardest part is remembering to act like you really believe it.
It's interesting that you mention 45 dbu as a lower usable field strength.
When Bill Baker of Information Station Specialists visited me earleir this month I asked if he had an FIM with him. Yes, so I asked if he could give me a read on our AM TIS to see if I was at the proper field strength.
So we drove the specified distance from the transmitter and it checked good.
I inquired about the Grundig G8 Traveler radio they sell for measuring field strength. He said that a reading from the Grundig of 45 dbu on my frequency would be the correct value. ISS provides a cross reference sheet which shows the dbu reading of the Grundig that correcsponds to a calibrated Potomic FIM with adjustments for frequency.
He stated that the G8, from one to the next, is fairly right on the mark and makes a great, inexpensive way to check field strength.
I'll be trying that with my license free, low power AM station as I have a G8.
I am surprised Rich has not posted a reply to your comments.
"When Bill Baker of Information Station Specialists visited me earleir this month I asked if he had an FIM with him. ... I inquired about the Grundig G8 Traveler radio they sell for measuring field strength. He said that a reading from the Grundig of 45 dbu on my frequency would be the correct value. ISS provides a cross reference sheet which shows the dbu reading of the Grundig that correcsponds to a calibrated Potomic FIM with adjustments for frequency. He stated that the G8, from one to the next, is fairly right on the mark and makes a great, inexpensive way to check field strength."
Bill Baker's statements reported in the clip above are different now than his statements on this subject several years ago.
See http://www.part15.us/forum/part15-forums/transmitter-talk/big-big-news
Rich I would like to read that post but the link seems to be broken.
Never mind. It's working now.
My TECSUN PL-310 gives 45 dBu at 2-feet from teh Ramsey FM30B, which is operating at its lowest power with fully extended 28" vertical whip.
The radio's whip is 11" vertical.
How much antenna length do you use for measurments taken with the Traveler?
Group called Radio Aleluya here in Houston has 3 frequencies now and 2 more just granted to them. Why do they need 5 frequencies FCC should not allow this many to one gorup S M H.