Does anybody has a problem listening to FM stations in San Francisco clearly? For me, I do have a problem listening to stations from Mt. Beacon (97.3 98.1 102.1 106.9) from my apartment in the city since I lived near Babola Park Bart Station. When I go around Haight and Ashbury area, I have problems picking up stations from San Bruno Mtn. Energy 92.7 is the worst, when picking up around the Sunset, West Portal, or Ingleside neighborhood.
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
Bay area radio Reception
- Thread starter e-dawg
- Start date
FM penetration in San Francisco has always been spotty due to the Bay Area's unique terrain. Just one of the many reasons that 610 KFRC had decent numbers years beyond the time when AM's in most other markets went news or talk. A small reason to be sure, but it helped when AM could punch through in areas that are real dead spots for FM...e-dawg said:
I've noticed that 98.1 comes in poorly when I travel I-280 toward Daly City, so that would confirm the poor signal near Balboa BART. I live on the southern side of Bernal Heights. At my house, San Jose FM stations come in loud and clear while a number of SF FMs are full of static. Again...the terrain. Last year, I was in the Yosemite Valley and noticed that many of the City's FM's come in better than they do when I'm home.
On the other hand, I did a run of in-car listening to AM in SF, and it is 25% of all listening. In LA, it is 21.4%. So the difference is not huge, although does support the contention that SF is a difficult FM market due to terrain.calguy said:
A
awj223
Guest
Many SF FMs came in loud and clear, in full stereo, on the slopes of the Sierras (Applegate/Auburn/Colfax). Interestingly, KDND-FM (107.9, Sacramento) was mostly clear in North Lake Tahoe and Truckee, and that market has nowhere close to a line of sight to Sacramento, being on the other side of the Donner Summit. This was consistent over a period of two days so I don't think it was tropo.As far as SF FMs in Santa Clara county, most of them are clear and in stereo. The only place they have problems are in the western edge of the valley (western sections of Los Gatos/Monte Sereno/Saratoga/Cupertino) and when you start getting into Gilroy.Lkeller said:
A
adamgre
Guest
I am going out to SF sometime this summer and would like to know what FM reception is like in the following areas:
Castro area
Fisherman's Warf (Lombard/Van Ness)
Height District
Can any DXing be done from those areas? How well do stations from San Jose come in from those areas?
Castro area
Fisherman's Warf (Lombard/Van Ness)
Height District
Can any DXing be done from those areas? How well do stations from San Jose come in from those areas?
8
8hhaggis
Guest
>>Does anybody has a problem listening to FM stations in San Francisco clearly? For me, I do have a problem listening to stations from Mt. Beacon...I have problems picking up stations from San Bruno Mtn. <<
YES! There are many issues related to overload, terrain and multipath that render FM in SF and its immediate environs a severe problem for most car and home listeners. I installed transmitters at Mt. San Bruno, Mt. Sutro, and Mt. Beacon, and can tell you that no matter what the station, what the ERP (effective radiated power), and what the antenna location might be, reception was ALWAYS very spotty from these three transmitter locations -- all over the bay area.
In SF proper, the high powered TV and radio signals from Sutro Tower cause overloading and intermod products on many types of receivers (even some allegedly well-designed, expensive ones.) Spurious interference products can appear all over the FM band, sometimes noisy ones right on top of the station you are trying to hear. Changing your antenna position or adding filters can sometimes help...but often don't do anything significant.
Multipath in the bay area is just about the worst I've ever experienced in most large metropolitan areas of the west or midwestern US.
Frequent temperature inversions also cause signals from mountaintop sites to be bounced OVER the intended reception area (for instance, KOME at 98.5 is located on a mountainside above Los Gatos; often, temperature inversions cause the signal "below" the transmitter site, for about a ten mile radius, to drop way down -- even disappear! I lived five miles away and once called the transmitter to see why they were off the air. They weren't: the transmitter was pumping out full power! But the air boundary layers were reflecting the signal way UP and away from the territory around, and below, the antenna. The station engineers were absolutely amazed to discover this, but they did verify that it was REALLY happening!)
Multipath is caused by reflections bounced from different locations. On TV, it causes noise in the video, or "ghosts". On FM it causes a dreadful, odd form of audio distortion: a fuzziness that might vary as you walk around a radio with a small built in whip or linecord antenna. Car radio multipath causes not only the distortion effects but also a constant and erratic fading of the signal, even loud low frequency bumping or whooshing noises as you drive through "signal nulls and peaks" caused by the addition and subtraction of the reflected and direct signals.
You might get a Mt. Beacon station just fine in the Santa Cruz mountains, 65 miles away; but it will be unlistenable and distorted just ten miles away in downtown San Francisco.
Often the problem is exacerbated by stations using high gain multi-element antennas, which send out a narrow "disk" of signal that is amplified and focused by the number of antenna elements. Stations with simpler, low gain antennas will have lower "Effective Radiated Power" but at the same time might have signals that fill in better, causing less multipath.
But, tell THAT to salespeople and managers! If possible, they will ALWAYS opt for "high power" and want to ask the FCC for permission to use the highest ERP possible. These things have all been decided decades ago, "grandfathered" into current station license allocations based on when the transmitters were put up at any given site.
But, because you can more cheaply get "high ERP" by using a low output transmitter into a HIGH GAIN antenna, there is a likelihood that stations will do just that, and have antenna systems with many elements. This saves electricity and complexity, but degrades the effective solid coverage of FM in the local area.
Furthermore, when you are fairly close to the transmitter site, the reflected signals from hills and surrounding terrain will be fairly strong. So, the radio receiver has a harder time "capturing" the direct signal from the transmitter, shifting back and forth in demodulating the reflection or the direct signal, causing the variable quality and audio distortion. Go fifty miles away, and the direct signal is now MUCH stronger than any reflected ones from distant hills...and the signal can now be received with greater stability (though it might be quite weak.)
No, FM radio reception in the bay area is simply DOOMED by all these factors. It will NEVER be any good, using the present modulation system of FM and FM stereo analogue broadcasting. I have worked also with other methods of trying to improve FM, such as the defunct FMX noise reduction system: multipath made that utterly unworkable in some areas, even though it could work perfectly well with weak, unreflected signals. Thus, it would simultaneously *improve* and*degrade* reception of the same station, at different locations.
You actually have a better chance of getting reliable satellite radio reception in the city, if you can just LOOK UP into space toward the 'bird'. And, my present experience with IBOC digital on FM and AM tends to suggest that this so called "compatible" system is fatally flawed: it is too weak and ineffective to provide truly superior digital reception over all of the station's nominal coverage area, while at the same time causing interference to adjacent signals, and even "jamming" the station's own signal with noises and hissing.
All of these issues finally convinced me to end my 27 year career as a bay area broadcasting engineer about a decade ago. Nothing has happened in radio since then to prove to me that my decision was a bad one!
8H Haggis
retired broadcast engineer
San Jose
YES! There are many issues related to overload, terrain and multipath that render FM in SF and its immediate environs a severe problem for most car and home listeners. I installed transmitters at Mt. San Bruno, Mt. Sutro, and Mt. Beacon, and can tell you that no matter what the station, what the ERP (effective radiated power), and what the antenna location might be, reception was ALWAYS very spotty from these three transmitter locations -- all over the bay area.
In SF proper, the high powered TV and radio signals from Sutro Tower cause overloading and intermod products on many types of receivers (even some allegedly well-designed, expensive ones.) Spurious interference products can appear all over the FM band, sometimes noisy ones right on top of the station you are trying to hear. Changing your antenna position or adding filters can sometimes help...but often don't do anything significant.
Multipath in the bay area is just about the worst I've ever experienced in most large metropolitan areas of the west or midwestern US.
Frequent temperature inversions also cause signals from mountaintop sites to be bounced OVER the intended reception area (for instance, KOME at 98.5 is located on a mountainside above Los Gatos; often, temperature inversions cause the signal "below" the transmitter site, for about a ten mile radius, to drop way down -- even disappear! I lived five miles away and once called the transmitter to see why they were off the air. They weren't: the transmitter was pumping out full power! But the air boundary layers were reflecting the signal way UP and away from the territory around, and below, the antenna. The station engineers were absolutely amazed to discover this, but they did verify that it was REALLY happening!)
Multipath is caused by reflections bounced from different locations. On TV, it causes noise in the video, or "ghosts". On FM it causes a dreadful, odd form of audio distortion: a fuzziness that might vary as you walk around a radio with a small built in whip or linecord antenna. Car radio multipath causes not only the distortion effects but also a constant and erratic fading of the signal, even loud low frequency bumping or whooshing noises as you drive through "signal nulls and peaks" caused by the addition and subtraction of the reflected and direct signals.
You might get a Mt. Beacon station just fine in the Santa Cruz mountains, 65 miles away; but it will be unlistenable and distorted just ten miles away in downtown San Francisco.
Often the problem is exacerbated by stations using high gain multi-element antennas, which send out a narrow "disk" of signal that is amplified and focused by the number of antenna elements. Stations with simpler, low gain antennas will have lower "Effective Radiated Power" but at the same time might have signals that fill in better, causing less multipath.
But, tell THAT to salespeople and managers! If possible, they will ALWAYS opt for "high power" and want to ask the FCC for permission to use the highest ERP possible. These things have all been decided decades ago, "grandfathered" into current station license allocations based on when the transmitters were put up at any given site.
But, because you can more cheaply get "high ERP" by using a low output transmitter into a HIGH GAIN antenna, there is a likelihood that stations will do just that, and have antenna systems with many elements. This saves electricity and complexity, but degrades the effective solid coverage of FM in the local area.
Furthermore, when you are fairly close to the transmitter site, the reflected signals from hills and surrounding terrain will be fairly strong. So, the radio receiver has a harder time "capturing" the direct signal from the transmitter, shifting back and forth in demodulating the reflection or the direct signal, causing the variable quality and audio distortion. Go fifty miles away, and the direct signal is now MUCH stronger than any reflected ones from distant hills...and the signal can now be received with greater stability (though it might be quite weak.)
No, FM radio reception in the bay area is simply DOOMED by all these factors. It will NEVER be any good, using the present modulation system of FM and FM stereo analogue broadcasting. I have worked also with other methods of trying to improve FM, such as the defunct FMX noise reduction system: multipath made that utterly unworkable in some areas, even though it could work perfectly well with weak, unreflected signals. Thus, it would simultaneously *improve* and*degrade* reception of the same station, at different locations.
You actually have a better chance of getting reliable satellite radio reception in the city, if you can just LOOK UP into space toward the 'bird'. And, my present experience with IBOC digital on FM and AM tends to suggest that this so called "compatible" system is fatally flawed: it is too weak and ineffective to provide truly superior digital reception over all of the station's nominal coverage area, while at the same time causing interference to adjacent signals, and even "jamming" the station's own signal with noises and hissing.
All of these issues finally convinced me to end my 27 year career as a bay area broadcasting engineer about a decade ago. Nothing has happened in radio since then to prove to me that my decision was a bad one!
8H Haggis
retired broadcast engineer
San Jose
- Status