OK I've always checked 96.3 to be sure its Blank and 95% of the time it is. However Yesterday I was off the air around 6PM on FM. I desided to scan and see what DX conditions I was gonna get because there was a huge temperature inversion. I picked a station 152 miles away on FM on 96.3 in Jacksonville, NC. So the moral of this story is if you know the temperature is gonna invert you may want to go off the air once say hr or hr 1/2 to be sure your frequency is still not occupied. Remembe it is possible for your transmitter to transmit further during a temperature inversion so if you have a station comming in on your frequency you could get a NOUO for jamming a used frequency. Plus its just a good way to play nice on FM to do this practice when you know there is gonna be a temperature inversion or Rain as this too will cause distant stations to come in.
I hope this helps all part 15 FM Broadcasters.
Best Regards.
It seems highly unlikely that a part 15 FM signal would duct and have enough strength to cause any problems. By the time it travels into and through the duct it has gone so far that it will be well below noise. As far as interfering with a DX signal coming into your area goes the DX signal is not in its intended service area and won't be there long so it shouldn't be a problem.
Temperature inversions also cause some interesting things to happen on the amateur radio 2 meter band. I recall while living in Cincinnati that I could work the repeater in Asheville, NC with my 2 1/2 watt hand held. The band stayed open for several hours.
Neil
Its a good practice to follow this rule I follow because some folks love to DX. And if your jamming a station they could still call the FCC and complain about your operation. Plus as you mentioned at 1 1/2 watt you worked a repeater on 2 meter ham (144-147 Mhz. Now Ham is close to FM in a way. If there is that much of a duct effect on 146 Mhz by the time you drop to 96.3 the MUF would have to be much greater @ 96.3 Mhz. So its still possible that say if I were in your area and had transmitted on a blank frequency on FM I may be heard several miles away. Now if our petition for 1 Watt FM goes through yes it could possibly do this. Hence why I made some coveats when we do get this petition going to show the FCC we are responsible operators. Operating part 15 FM should sort of have the same rules amateur Radio does where you check the frequency before you start calling CQ. Some operators will say "CQ is the frequency in use? Obviously on FM a station is not gonna say "Yes the frequency is in use." Checking the frequency when I know there is gonna be an inversion gives me piece of mind I'm not causing anyone any grief when I'm operating my station. I've seen inversions last all through the night in Michigan. They usually start around midnight (sometimes after 6PM) when the sun sets and things start to cool off. On the other hand if it super cool say 50 degrees and the high for the day is 90 degrees I've seen in the morning things start to DX and all through the morning up till noon I'm pulling in stations way down to Columbus, OH when I lived in Lansing, Michigan. And when there was an arura I got stations in from Florida on FM. I've even read reports on Light O Rama a christmas light forum where people used FM Transmitters and during an inversion got into town where as without the inversion they didn't.
Your point about going out of your way to avoid interfering is well taken and this is something we all should be aware of. My point is that the probability of causing interference with a legal Part 15 FM transmitter via ducting into another service area is practically nil.
My tale of using a 2 1/2 watt hand held to work from Cincinnati to Asheville is not a fair comparison with Part 15 since the power needed with a dipole antenna is about 11 nanowatts for a compliant Part 15 station. the power difference is a factor of 227 million which is 84 dB.
Anything is possible but with 11 nW this distance is very unlikely.
You are correct in that a good attitude regarding interfering with other stations is responsible operating practice and I am not suggesting otherwise.
Neil
Two times I've had to part with good frequencies because new translator FM stations also found those channels and put licensed transmitters on them at 250 Watts.
On my new frequencies I was one morning surprised when a station over 150-miles away was coming in well enough to listen. According to their pattern as seen at Radio Locator they were reaching way outside of their expected coverage area, so I went quiet until they soon faded away.
At the same time I doubted that anyone within 200-feet of me (my part 15 FM range) had actually found the rare DX reception, but a lot of what we do is imaginary, so I kept quiet.
AM is not quite the same, because even licensed stations have other far away stations skipping in on sky-wave to be heard in the background of the local carriers.
Right during the critical hours in the afternoon some far away station can actually be heard behind my AM transmitter on the X-band, but it's always a very short event.
Part 15 brings happiness with the ALPB being an extra bonus.
I'm very happy to be a member of the ALPB. I have always said from a quote from spider man about these transmitters. "With Great Power comes Great responsibility." That is the attitude I've always had with micro powered broadcasting. Its fun, you don't know who will hear you but I'm sure people will stumble upon my FM station especially where I am located. I hope I bring a good impression on my listeners and especially a good impression on anyone who may want to set up a micro broadcasting station as I did.
Being a micro powered broadcaster allows me to practice and learn how FM works and how it can bring listeners to my Internet station. Its why I hope the FCC will not deny is this wonderful hobby and learning experience. I just hope they do allow us to legally broadcast on 87.9 Mhz soon. It will stop the issues with interference with other commercial stations in most areas since few if any stations operate on 87.9 Mhz. Carl I'm glad to hear that others in the ALPB are doing what I do when there is a DX station on their chosen FM frequency. Lets hope we both have set a good example to anyone who reads this forum and yet does not post anything as this was what I have done for quite sometime before I registered and started to post.