Reception Abnormalities?

[seattlesarchiebunker]

Hi all,

I have a unique situation that someone may have insight on. I should also point out that this does not occur at my house 15 miles away (and 2,000 ft higher in elevation). The FM tuner used in this situation is a Baofeng UV5R+ (yes, Ham radio folks, get your laughs in) with a Nagoya NA-771 whip antenna

I work in a town out in the foothills of the Sierras (Amador County, CA). From where I work, I have a clear view of the Pacific Coast Range (and the Eastern SF Bay metro if there’s no smog/fog). Therefore, most of the SF stations come in better at 100+ miles away than the Sacramento FMs at 30-50 miles away.

What is unusual is at almost noon every day, the SF stations become very staticky. It does this daily (you can almost set a watch to it) It’ll remain like that until 4-5pm, then go right back to its normal, strong signals. Also, not all SF stations do this — KPFA, KOIT (blasts in over a local translator), KISQ, and KFRC seem to remain at normal signal strengths. The Sacramento/Modesto/Stockton stations never have this problem either.

I would normally chalk this up to tropospheric propagation, but I rarely get anything exciting from DX during that time. Granted, 9/10 frequencies are occupied in this neck of the woods by a “local” station, but those empty frequencies just don’t bring any tropo. I also know that at least in Western Washington, tropo (or really any FM DX conditions) are virtually non-existent. Granted, that’s 600 miles north, but the weather conditions are similar with the exception of CA being about 10-15 degrees warmer year-round.

Any ideas? Can I do anything to mitigate this?

 

[cyberdad]

Someone here can give you a better answer than me. The answer to VHF propagation questions is above my pay grade.

But I'll chirp in with this.... When I was in college in Iowa during the late 1960s, with only one TV transmitter closer than 60 miles from me, and my TV connected to a "not very good' antenna, the most reliable of those distant stations were on channels 4, 6, and 8 These channels were usually reasonably clear in the evening when I did most of my viewing (which wasn't all that much). But I noticed that if I tried to watch something between classes or on the weekend during daylight hours, the picture on all three of these tended to be "snowy".

This may be a silly explanation, but the only thing I could think of was perhaps the atmosphere over the very flat Iowa terrain was somehow more "calm" during the hours of darkness than it was in the daytime.

 

[gar hi]

I may be wrong but this reminds of my experience back in the early 70's with the VHF TV stations from New York where I lived 80 miles away.

My father installed an antenna on the roof pointed towards New York and I could get all their VHF channels but they were 'snowy' most of the time.

Not too snowy to watch but it was obvious.

But the reception varied during the day and night and there was always a specific pattern.

At night and in the mornings, they were the strongest and sometimes as clear as the local Philadelphia channels with no snow at all and even no 'lines'.

But during the afternoon, they came in the weakest and not only were quite 'snowy' but also very susceptible to interference from planes landing at the airports.

However late afternoon and early evening was a noticeable improvement.

So what I think was going on was that there is no tropo enhancement at all present during the middle of the day and that may also explain the static you get on those FM stations during the afternoons.

Tropo enhancement is not the same as ducting and happens with VHF stations around 50 to 150 miles away, if I understand correctly.

 

[jammerdave]

Most likely temperature inversions over the valley, or the marine layer around the bay. Either can severely affect signals.



QUOTE=seattlesarchiebunker;6271864]Hi all,

I have a unique situation that someone may have insight on. I should also point out that this does not occur at my house 15 miles away (and 2,000 ft higher in elevation). The FM tuner used in this situation is a Baofeng UV5R+ (yes, Ham radio folks, get your laughs in) with a Nagoya NA-771 whip antenna

I work in a town out in the foothills of the Sierras (Amador County, CA). From where I work, I have a clear view of the Pacific Coast Range (and the Eastern SF Bay metro if there’s no smog/fog). Therefore, most of the SF stations come in better at 100+ miles away than the Sacramento FMs at 30-50 miles away.

What is unusual is at almost noon every day, the SF stations become very staticky. It does this daily (you can almost set a watch to it) It’ll remain like that until 4-5pm, then go right back to its normal, strong signals. Also, not all SF stations do this — KPFA, KOIT (blasts in over a local translator), KISQ, and KFRC seem to remain at normal signal strengths. The Sacramento/Modesto/Stockton stations never have this problem either.

I would normally chalk this up to tropospheric propagation, but I rarely get anything exciting from DX during that time. Granted, 9/10 frequencies are occupied in this neck of the woods by a “local” station, but those empty frequencies just don’t bring any tropo. I also know that at least in Western Washington, tropo (or really any FM DX conditions) are virtually non-existent. Granted, that’s 600 miles north, but the weather conditions are similar with the exception of CA being about 10-15 degrees warmer year-round.

Any ideas? Can I do anything to mitigate this?[/QUOTE]