Little reason on how this thought came in :P: So I got a sirus XM radio in my car (XM Snap). The FM transmitter that is built in that unit is very weak and will accept just about anything that interferes with it. So I turned it in to some radio-locator frequencies and they were all getting interference. So I then tried some frequencies that get static (106.7) and I was able to get a clean signle. I looked on radio-locator website along with XM's website to see if 106.7 was on the clean list and it was not. So I decided to use my part 15 transmitter to see how far it will go. I tuned it to 106.7 and hopped in my car and my range almost doubled. Here is the part that I am unsure if it is safe to use tho. So after driveing I lost my station went to static for some time as I went down the road then BAM I got a clean satation playing music which lasted for about 10 seconds before it got overtaken from some other station. It souned like the AM band at night where you have one station then another and then another. Would it be safe to use this frequency for my part 15 station? And if so why does radio-locator not list better clean frequences because the ones they told me had stations on them. I even googled those frequences and there are low power station in the northern part of the city useing them. I did google 106.7 and have found no station in my area useing it.
Thanks 🙂
It's the same thing where I live, Radio Locator will show an FM frequency as having a station on it, but it won't have one right where I live, yet you go over a hill or ridge and the station will be coming in.
What I think is happening is that you're in a pocket that's being blocked by a hill or ridge, and that distant station's signal is coming in at such a low angle, because it's far away and weaker too, so any obstruction could block it for long stretches.
That shows an advantage of low power, micro stations could fit in these little pockets and be useful, just so your signal isn't causing the other station to fuzz out. You could put your antenna at the right height to not send signal to where the other station is, and it would probably work out.
That's why I don't think the situation is as dire for low power operators, even with all of the translators coming on, because in almost all areas, there should be some frequency that can be carved out and used.
I've noticed that AM effect on FM as well, on a friend's Pioneer Supertuner III in the car, stations fuzzing in and out over one another. I think it's because older tuners had Capture Effect, so stations would stay locked in until a new stronger station was on the channel, and then start popping over.
I notice a different behavior on the Supertuner and some of the Sony stereos, and I theorize it's because those newer receivers can pick up signals so close to the noise floor, that capture effect is no longer really in effect, so signals blend with each other more like an AM radio's would.
What I noticed on the Pioneer is that one station would be present, and the audio on it would start to distort first, then the other station behind would start to fade in and take over.
On to Radio-Locator again, their site says the maps show predicted coverage, based on information found in the FCC database for the stations. That's simplified, and it would be better, at least for FM, to have the signal shown on a contour map. I've seen some of those, and the signal from a tower is shown as a light source or paint splattered over the land.
I have an early 80s Digital Delco that blends weak FM signals.
At least in my location, RadioLocator is a decent guide on where to begin to look for a "clear" FM frequency. Ultimately, one has to carefully listen yet, as already mentioned, moving just a few hundred feet can make the difference between a clear frequency and one where station(s) can be heard.
My chosen operating frequency has two relatively low power stations located about 50 miles away in different directions. Though I cannot hear them while parked in my driveway, both can be heard as I drive a bit down my street. It is very unlikely that anyone local is listening to them on an indoor receiver with an indoor antenna but you never know if someone nearby has erected a good outdoor antenna for the purpose of hearing a specific distant station and with which you could interfere.
The only totally safe way to avoid interfering is to remain off the air but since my transmitter can only be heard barely past my property edges I assign a very low probablility that I am interfering with anyone. If I choose to operate a transmitter then this is the best I can do.
Neil
I also was doing this test at night so I am not sure if that could of had a effect on my radio. But it sounded like a open AM frequecy at night.
Yea I used radio-locator to help find a spot where no station was listed. What I am going to do to make sure I am not going to be interfearing with anyone is drive that same path again. If I hear static until those stations are picked up in the same spot I picked them up when my transmitter was running then that means I was not interfearing with them. However if I do pick them up before I hit that spot then I was. I also think a cause of the far radio stations was a huge flat desert that streches a few miles south. If anyone is lisening to it they will need to have a reciever that would not keep switching to the other stations it picked up. Only one statio I was able to hear pritty clean and lasted 10-15 seconds then I herd the other stations but they only lasted for 1-3 seconds and were not that clean that I can make out what they were saying. I did try googleing and useing radio-locator to see if the towns south of me had a radio station on 106.7 but they all show they dont.
Also I am not sure if it could be this but when I was driveing to work my XM radio stated to pick up some strong interference. When I went to see what was causeing it there was something transmitting on 106.7. Odd thing is they were not playing anything it was just that hum of a quiet station. Is it possible there could be a pirate or another part15 station? I will look more into it to see how far I can keep that signle when I drive to the area again.
There could be a lot of reasons you hear interference while mobile. Receivers can be overloaded by signals which are not on the frequency to which they are tuned. It is surprising how much RF energy is bouncing around in metro areas.
My 2 meter (146 MHz) radio is not usable in downtown Columbus, Ohio due to the high RF environment and broadcast band FM stations suffer severe interference as I drive through town. A friend of mine owns a two way radio service shop and he told me that he attached a RF wattmeter to one of his rooftop antennas and measured 30 Watts coming down the feedline just from what was being sensed by the antenna.
Neil
In my own mind i have these thoughts that float around and occaisonally i pay attention.
After some serious thought, that is when i was paying attention lol i came to the conclusion that if i serve just my road in this tightly packed valley , then i am hitting maybe 8 homes with the AM signal.
They have their own specialized localized community radio station to tune into if they happen to be in the mood for something different. As for distance broadcasting where my signal could cover a mile or more, naw it's not as important now.
I am content with just serving this road, besides these mountains are not making it easy to cover more ground, even if i did have an outdoor antenna for AM 1620 the coverage would be hit or miss as the antenna would be ground mounted and the hills would block my signal in some directions.
The only way i could cover say 1 mile, would be to elevate the transmitter and antenna way above the ridges around my home, that would be at least 100 feet of tower and i really don't have the money to do that.
No i think a localized station such as mine makes it a bit more special.
But since I come late to the conversation I'll give my opinion.
As long as the frequency is "clean" in the immediate area your transmitter will cover it's OK.
Here in Toronto I am on 90.7 which is "clean" in my area but if I go a little away from here a station from Vaughan, just north of Toronto is there....not that listenable, but there.
As you drive from area to area you can get a couple of very weak stations coming in and out because signals tend to be in "pockets" not uniform everywhere. And the car will pick this up where your home radio won't.
Yes...it's safe to use 106.7 because right in your area it's "clean"
Mark
I believe a capture effect primer might be good for those who aren't familiar.... this short article saved me a lot of typing.
https://en.wikipedia.org/wiki/Capture_effect
TIB