Rain affects only a single frequency?

[RedPenguin]

I was reading some Forum Posts and Google Results about how rain can affect different bands but I haven’t quite seen what I experienced on Wednesday 11/11.

I currently have an indoor dipole with amp and I listen mainly to the 453-460MHZ band with stations about 10-20 miles away.

The single frequency of 453.475 is almost 13 miles away and has an output of 150W according to the license.

On Tuesday it has very clear and understandable audio, then it rains Wednesday and intense static, then clear like nothing happened on Thursday.

I noticed during this time, no other frequency was acting similar even further away and of less wattage ones.

 

[bob550]

This may be a problem with the transmitter and not your setup. If this is a law enforcement agency you're monitoring, there's a chance that they may be transmitting on multiple frequencies using the same tower. If so, check the other associated frequencies to see whether you experience the same phenomena. That said, UHF can be easily affected by weather. But as you suggest, all UHF should be similarly affected given the same transmitter power output.

 

[KK4JUG]

I'm with Bob. It sounds like it's on the other end.

 

[RedPenguin]

This may be a problem with the transmitter and not your setup. If this is a law enforcement agency you're monitoring, there's a chance that they may be transmitting on multiple frequencies using the same tower. If so, check the other associated frequencies to see whether you experience the same phenomena. That said, UHF can be easily affected by weather. But as you suggest, all UHF should be similarly affected given the same transmitter power output.

I'm with Bob. It sounds like it's on the other end.

I think you guys are right.

It's not actually the law enforcement but the Rural Transit in my area.

I noticed that the nearby county of Bedford PA uses 453.475 also for a PD channel.

Lately when my county talks at times and un-keys the mic, a garbled mess of a transmission that sounds like somebody else talking like through a fan or voice changer comes through. Bits and pieces I can make out do sound like a County Dispatcher which makes me think it's Bedford County.

They notice these transmissions at times because one person said "I didn't understand you" not realizing it was some sort of interference and that they weren't replied to yet.

 

[RedPenguin]

Here is a sample I clipped of the strange interface:

interference.mp3

Shared with Dropbox

www.dropbox.com

Also I noticed the users don't talk until this interference is gone.

EDIT: The more I try to make out the addresses, it sounds like they are giving Cambria County addresses but it sounds nothing like the normal users of the channel nor how they talk.

I think they are saying "Pike Rd complete heading up 541 Belmont St" which is Cambria addresses but different municipalities like 8 miles away from each other at least. I'm beginning to wonder if it's like a Medvan type service interfering.

 

[RedPenguin]

I think I may have figured it out but I have to wait for transmissions to verify.

It appears WNBS443 is at the same tower as 453.475 (funny enough owned by the private company that 453.475 gets to maintain their repeaters) and it says Community Repeater so maybe they have the medical van sounding company.

I tried looking at the database but no info on this system so I will have to see if I can pick any transmissions up from them.

 

[mmckenna]

Here is a sample I clipped of the strange interface:

interference.mp3

Shared with Dropbox

www.dropbox.com

Also I noticed the users don't talk until this interference is gone.

That sounds like an echo, not interference. Could be something to do with how they are linking the repeater back to their dispatch.

 

[RedPenguin]

That sounds like an echo, not interference. Could be something to do with how they are linking the repeater back to their dispatch.

What confuses me though is, the audio appears to have nothing to do with the conversation at the time and the voice doesn't sound like those I typically hear on there.

 

[krokus]

That sounds like an echo, not interference. Could be something to do with how they are linking the repeater back to their dispatch.

Agreed with the echo. I have heard similar effects when the analog audio lines had misadjusted amplifiers inline.