Quote:
Originally Posted by Channel Jumper
If you understand FM - you will realize that FM has many side bands - hence the center frequency of your whole house transmitter is 88.1 - but it has harmonics on other frequencies on either side of 88.1 - this is how FM works!
All signals reduce at the square of the distance away....
You either need to move your transmit or your receive antenna - have some sort of separation between the two or use a filter.
http://dsp.stackexchange.com/questio...d-in-am-and-fm |
Harmonics I understand but I'm not sure how it applies to my problem.
As I said I am able to get FM broadcasts available in my area and I do get a signal at 88.1 from the transmitter in the house. The nearby commercial FM stations are clear no matter if my transmitter is broadcasting or not but when I raise the antenna above the roofline - all bets are off and not all are listenable.
I can get the transmitter's signal (and commercial FM broadcasts) as long as the antenna is on the ground but they are not noiseless. As soon as I raise it, say to the peak of the garage roof, most stations I'm interested in get very noisy to completely unlistenable depending on the antenna's orientation.
Testing, I positioned it lying on the roof and oriented in several different directions. Some positions were good for one favorite station but not the other and none of the positions I tried would receive both the two favorite stations and the transmitter.
When I bought it back down to ground level I could find a spot or two that allowed reception for all frequencies, but again not clearly.
Due, I guess, to the nature of frequency modulation, at some times of the day no amount of re-positioning the antenna would allow getting a clear signal from the more distant commercial stations, only the nearest.
Moving the equipment to another area of the garage made a huge difference so I'm thinking wiring in the garage might have affected the signal path.
Sorry I don't understand what you mean by "...have some separation between the two..." they are now 50' to 75' apart, wouldn't that be sufficient? - and what sort of filter are you referring to?