permissable FM co-channel interference

[b344077]

First:I am not an engineer so my question will be posed in lay man's language. Any help would be appreciated.Second:Is there such a thing a one station on the same frequency as another, permitting the other station to slightly enfringe on their signal. Can the two stations discuss the matter and then go to the FCC to gain "permission". In this instance, we are talking about a LPFM on one side of Lake Michigan being killed within one mile of lakside by another station on the other side of the lake. If one were to go even 1/2 mile inland, the interference goes away. The solution would be a minor power increase by the LPFM. The co-channel interference would be off shore somewhere over the Lake. Any thoughts would be helpful.

 

[PaulBWalkerJr]

Interference over water, which is basically where this happens and why it occurs.... doesn't mean anything and there's no protection for such a thing. Also, in terms of status and protection, LPFM's are treated like Class D's.. and therfore, afforded no protection unless the co-channel interference is from another LPFM.

 

[tjm_pro]

The solution would be a minor power increase by the LPFM.

You'll not get a power increase in the case of an LPFM. 100 Watts ERP is as far as you can go. The only way to really correct this (BUT it'll never happen) is for the full power station to do directional away from the LPFM. Like I said, it'll probably never happen. LPFM's have to accept interference from full power FM's.

 

[CW]

First:I am not an engineer so my question will be posed in lay man's language. Any help would be appreciated.Second:Is there such a thing a one station on the same frequency as another, permitting the other station to slightly enfringe on their signal. Can the two stations discuss the matter and then go to the FCC to gain "permission". In this instance, we are talking about a LPFM on one side of Lake Michigan being killed within one mile of lakside by another station on the other side of the lake. If one were to go even 1/2 mile inland, the interference goes away. The solution would be a minor power increase by the LPFM. The co-channel interference would be off shore somewhere over the Lake. Any thoughts would be helpful.

In the case of two stations spaced closer than permitted by Part 73 rules, they CAN negotiate an agreement if one station will cause interference to the other in the other's outer contour (like the 1mV range where you can hear it on a car radio but not on table tops)...BUT in the case you speak of, I take it this is a full service FM and a LPFM...the LPFM is pretty much SOL.......If one moved 1/2 mile, it would NOT change the interference...signal levels dont change THAT much in 2600ft or so...RF does not work like that...The LPFM needs to look to move freq if possible (I am surprised they could get a LPFM licensed within range of a high power FM anyway!! You sure this isnt a Pirate station?) Usually LPFMs cannot be "onchannel" with normal power FMs within 100+ miles..and to be first adjacent freq would be at least 70miles or more (not quoting exact Part 73 rules here..)

 

[b344077]

Oh I'm sure it's a licensed LPFM. Large bodies of waters permit signals to travel with little impedence and so this "problem" came as a surprise to them. I wasn't too surprise since WAUS in Berrien Springs is a 50K operation on 90.7mhz but still has co-channel interference with WHAD in the Milwaukee area. The "owner" works at Notre Dame and is a major benefactor for the arts in the local area. The station is manned by community volunteers. The local press followed the FCC process and subsequent building of the station in great detail.

 

[rbrucecarter5]

The FCC no longer cares about interference issues. Otherwise, they would have scrapped IBOC before it ever got started. They might as well drop all protection for FMs the way they did for AM decades ago. Funny thing is - the FRC was originally established to PREVENT, not CAUSE interference.