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San Francisco, CA - OTA - Page 331

post #9901 of 10423
Quote:
Originally Posted by veedon View Post

On the subject of the "repacking" after the spectrum auctions are completed:

Is there any chance that some technological advances could come along that would make digital OTA transmissions
on VHF frequencies more effective than they currently are? And if those advances would require upgrading transmitters in some
way to use an enhanced version of ATSC, could some of the money raised by the auctions actually be used to subsidize the upgrades?
I suppose that would be a decision for Congress, not for the FCC directly, but I'm trying to look on the bright side and imagine steps that
would actually produce a resurgence of interest in OTA broadcasts and thereby temper the power of the satellite and cable companies.

When I grew up, most places had only four or five channels available, but the programming was, on the whole, better than what we now find
on cable systems that have a hundred channels.
If more channels are forced to VHF then hopefully they will be allowed higher power levels to have a stronger signal and less subject to noise and interference. WXIA-11 Alive in Atlanta (RF10) has a strong signal, and WJLA-7 and WUSA-9 in DC improved their signals after they increased power.
post #9902 of 10423
Quote:
Originally Posted by Calaveras View Post

These devices all act differently.
Chuck
Here's a study in how various tuners and DVRs react differently from others regarding PSIP, or lack of PSIP info.

I've found that there are a lot of differences in how tuners react and how DVRs record based on PSIP information, or the lack thereof. Most tuners will allow you to log two stations transmitting on the same channel - you get one with your antenna pointed in one direction then add the other with your antenna pointed in a different direction, such as 8 on Mt. Diablo and 8 from Salinas, if both PSIPs are not the same. Some will log two stations using the same virtual channel number, such as KGO 7 on 7 and KGO 7 on 35. I have one that has allowed me to log 7 on 7, 7 on 35 and then add 3 on 35. Some tuners will log two channels using the same virtual channel, like when KRCB and KAXT were both using virtual 22, but some only log the first one seen in a scan. Some tuners don't do those things and you're stuck with whatever it finds first.

An interesting thing occurred on one of my tuners when KRCB and KAXT were both using 22. It would log KRCB 22-1, 22-2 and 22-3 from channel 23, then 22-4 through 22-20 from KAXT from channel 42. It wouldn't put KAXT 22-1 through 22-3 in the list. Now that KAXT is using channel 1 there is no problem, of course.

I have a problem with one of my tuners with channel 9. If it sees KVIE's signal on 9 it'll log channel 6 and then log channel 9 when it gets to KQED on 30. If it doesn't log KVIE on the first pass, and logs KQED, then there's no way to add KVIE later. Once it has virtual 9 it won't look for another signal on RF 9. I have the same problem with KEMO 50 on 32 and KMTP 32 on 33. I have to log KEMO before KMTP to get both.

Finally, I have two tuners where you can't add any channels to the list. When it scans it wipes out any existing stations and starts fresh. This is a real problem for me where I get stations from several directions. One of these tuners is on the Panasonic in the bedroom with only one antenna connected, so it never gets the Sacramento/Stockton or North Bay stations listed. It gets the Sutro, San Bruno and South Bay stations only. My Dish OTA Dongle is the other tuner where you can't add stations to the list, but since I have three antennas feeding it through switches, I attempt to be on the right antenna as it scans each channel. It can get really tricky though. I have to be on antenna B to get RF channels 9 and 10 from Walnut Grove, but on A to get KNTV 12 from Mt. San Bruno, then back to B for 14 from Mt. Diablo. I've never been able to get all stations available to me during a scan. It gets really tricky in the 40's, for example: RF 41, 42, 43, 44 and 45 are all on A, but 46 is on B, and 47 is on C, then 48, 49, 50 and 51 are back on A. smile.gif

Wouldn't it be great if all tuners allowed you to ADD to the station list and would log all variations of PSIP and RF? Not all of them are that good.

Larry
SF
post #9903 of 10423
Oh, yes, I started last March and am the point person for the new TVStudy coverage and interference software.

Thank you. smile.gif

- Trip
post #9904 of 10423
Quote:
Originally Posted by tylerSC View Post

If more channels are forced to VHF then hopefully they will be allowed higher power levels to have a stronger signal and less subject to noise and interference. WXIA-11 Alive in Atlanta (RF10) has a strong signal, and WJLA-7 and WUSA-9 in DC improved their signals after they increased power.

From years of comments here on the forums I think most people who are having trouble with VHF are using indoor or attic antennas. People with good outdoor antennas usually report good results on (high) VHF. That's certainly the case here. High VHF stations, even with their seemingly low power levels, outperform their MW UHF counterparts from the same transmitter sites. KNSO on RF 11 at 99 miles is the only station from Fresno I can receive most of the time. Fresno UHF is a complete no go. As I've mentioned many times KSBW RF 8 at 115 miles and 20 KW is gangbusters here. Even KCBA on RF 13 with a mere 65 watts ERP from the same tower is 99.9%. KGO 7 at 110 miles is by far the strongest signal from Sutro tower even though I do regularly receive 3 Sutro UHF stations. Two friends up here receive KGO all the time but get nothing on UHF from Sutro. KNTV on RF 12 is the hardest to receive but it's still seen more often than MW KKPX on 41, the only UHF station on Mt. San Bruno possible to receive here.

KVIE RF 9 and KXTV RF 10 both at 54 miles suffer the same sort of multipath issues here as do the UHF stations, but in terms of real signal strength they are equal to the strongest of the UHF stations.

Chuck
post #9905 of 10423
The whole system needs a "re-do" ....... The current OTA system is sloppy and flawed.
Based on my experience with tv reception issues...... This is what I think what should have happened to the current system.


Urban & Suburban .... Based upon multi-family development density....... UHF- Only..... (The San francisco tv market)

Rural Markets ..... "Low populations of mostly Single Family Homes"..........VHF-Only....... (Chico-Redding tv market)

Salinas- Monterey Market..... VHF-Only .... 2-13

Sacramento market and some others would need to be split ..... Valley floor UHF ..... East of highway 99, Foothills VHF 2-13

That would solve alot of problems.

__________________________


The "Bell System" (Prior to 1984) .... would assign different area codes for Urban & Rural customers .... (rotary phone dialing)
Area codes with a "1" .... as the middle digit were assigned to cities........ 212, 213, 415, 916 .... "1" ....digit would indicate... "city" zone
Area codes with a "0" .... as the middle digit were assigned "rural" ........ 209, 408, 707.....would indicate rural zoned customers.

The Bell System is gone ..... And rotary phones are gone.....
It's totally obvious the FCC digital tv transition was quick, sloppy,... and done with special interest money.... ( Screw the end-user consumer )
Look at all the complaints from viewers in San Francisco who can't get KNTV because of the FCC sloppy incompetence.

www.yelp.com/biz/nbc-kntv-san-francisco-san-francisco

Who with any brains would put ... "Just 2"... stations on VHF ? .... and throw the rest of the dial to UHF ?
No other tv stations in the SF tv market have reception problems logged except the VHF ones.
Those are real people making comments of this VHF assignment in the San Francisco market.
You would expect a government agency ....(Working for the public) .... to tell ABC7 ... "NO"..go to UHF just like the rest of your tv market.

Reading some of the "Yelp" board comments on KNTV
........ Who approved this ? ...."Digital Antenna" .......labeling on antenna products ? ...(UHF only antennas) ...used in the San Francisco market ?
........ Who approved this ? ...."Converter Boxes" ..... with capacitors that blow up after a year of use ? .... (google that)
Edited by 888CALLFCC - 1/4/14 at 1:43am
post #9906 of 10423
Quote:
Originally Posted by Calaveras View Post

From years of comments here on the forums I think most people who are having trouble with VHF are using indoor or attic antennas. People with good outdoor antennas usually report good results on (high) VHF....Chuck
True, but as someone from a DMA with similar geographic challenges to OTA reception (Seattle), I realize the FCC's fatal flaw in implementing the DTV transition was ASSUMING that most American viewers had outdoor antennas placed (at a minimum) 30 feet above ground level. That probably WAS commonplace in the 1950s, but in the 21st century a clear majority of Americans live either in condominium communities OR homeowner associations, which do impose major restrictions (subject to the FCC's rather limited OTARD protections) on placement of receiving antennas.

HOAs and condo associations were almost unheard of in the 1950s, when the current FCC measurement systems for defining TV-reception coverage areas were devised. Hence, the US was railroaded into adopting the seriously-flawed ATSC system which ultimately has created real hardship for many TV viewers who have lost reception of some local TV stations compared with the analog era.

Folks with outdoor antennas - specifically antennas which include VHF or high-VHF capability - can in fact obtain pretty good reception on high-VHF ATSC transmissions. But this knowledge does absolutely nothing to help the majority of American households, in a day and age when most American households are subject to restrictions on antenna placement due to HOA or condo complex control of "common area", as distinguished from the "limited common area" which is protected by OTARD.

Fortunately, I personally can obtain fairly satisfactory reception at our non-HOA suburban Seattle house. Nonetheless, I know far many people in the Seattle area who have simply "given up" on OTA due to ATSC's "digital cliff" effect.

Poor ATSC OTA reception, combined with HOA and condo restrictions that - in many cases - have been defined by the courts as reasonable and enforceable on "common area" which is excluded from OTARD, have created a real gravy train of business for cable TV companies. It's really, really unfortunate.
Edited by seatacboy - 1/4/14 at 2:14pm
post #9907 of 10423
Quote:
Originally Posted by seatacboy View Post
 
Quote:
Originally Posted by Calaveras View Post

From years of comments here on the forums I think most people who are having trouble with VHF are using indoor or attic antennas. People with good outdoor antennas usually report good results on (high) VHF....Chuck

True, but as someone from a DMA with similar geographic challenges to OTA reception (Seattle), I realize the FCC's fatal flaw in implementing the DTV transition was ASSUMING that most American viewers had outdoor antennas placed (at a minimum) 30 feet above ground level. That probably WAS commonplace in the 1950s, but in the 21st century a clear majority of Americans live either in condominium communities OR homeowner associations, which do impose major restrictions (subject to the FCC's rather limited OTARD protections) on placement of receiving antennas.

 ... the US was railroaded into adopting the seriously-flawed ATSC system which ultimately has created real hardship for many TV viewers who have lost reception of some local TV stations compared with the analog era.

...


Poor ATSC OTA reception, combined with HOA and condo restrictions that - in many cases - have been defined by the courts as reasonable and enforceable on "common area" which is excluded from OTARD, have created a real gravy train of business for cable TV companies. It's really, really unfortunate.

Maybe my memory is faulty, but I just don't remember many apartment dwellers or condo dwellers (or detached home dwellers) being able to receive good reception via indoor "rabbit ears" in the supposedly halcyon days of analog NTSC transmissions. Rabbit ears would usually give fuzzy, snowy, ghosty, and unstable reception. Indoor reception is much more promising in the digital era, but indoor antennas are always less reliable than an outdoor setup.

 

Was there a superior digital alternative to ATSC that the FCC and the broadcasting industry could have supported for the digital transition? The population of the U.S. is becoming increasingly urbanized, but there are still wide swaths of rural areas. Is there a single alternative standard that could have done better, in an overall sense, in delivering digital TV to urban, suburban, and rural areas? Canada also uses ATSC, doesn't it? Did Canada also make the wrong decision?

post #9908 of 10423
Quote:
Originally Posted by Calaveras View Post
 
Quote:
Originally Posted by tylerSC View Post

If more channels are forced to VHF then hopefully they will be allowed higher power levels to have a stronger signal and less subject to noise and interference. WXIA-11 Alive in Atlanta (RF10) has a strong signal, and WJLA-7 and WUSA-9 in DC improved their signals after they increased power.


From years of comments here on the forums I think most people who are having trouble with VHF are using indoor or attic antennas. People with good outdoor antennas usually report good results on (high) VHF. That's certainly the case here. High VHF stations, even with their seemingly low power levels, outperform their MW UHF counterparts from the same transmitter sites.

 

...

Chuck

 

Indoor antennas are often reliable only within fifteen miles or so of the transmitters.

Maybe some people just have unrealistically high expectations for what is possible with an indoor antenna.

 

I agree with you that many antennas that are primarily designed for UHF can still do a decent job of receiving VHF-HI.

 

But VHF-Lo can be difficult in urban areas if co-channel interference would make it impossible for a station to also boost its power. I have read that WPVI on RF6 in Philadelphia wanted to boost its power, but it had to be careful not to cause interference with WRGB in Schenectady, NY.

 

Frankly, I don't think the FCC gets enough credit for the hard work that it does in managing the channel assignments. People always want to criticize the government, but often the harshest critics are the people with the least ability to offer good alternatives.

post #9909 of 10423
Quote:
Originally Posted by seatacboy View Post

True, but as someone from a DMA with similar geographic challenges to OTA reception (Seattle), I realize the FCC's fatal flaw in implementing the DTV transition was ASSUMING that most American viewers had outdoor antennas placed (at a minimum) 30 feet above ground level. That probably WAS commonplace in the 1950s, but in the 21st century a clear majority of Americans live either in condominium communities OR homeowner associations, which do impose major restrictions (subject to the FCC's rather limited OTARD protections) on placement of receiving antennas.

How do you think the restrictions are too limited? I've re-read them and I don't see what more they could do. Basically they say you can put up whatever you need to receive the stations as long as you own the property. They can't grant the right to put up an antenna on someone else's property. Masts taller than 12' may be subject to a permit but that's pretty standard.

Quote:
HOAs and condo associations were almost unheard of in the 1950s, when the current FCC measurement systems for defining TV-reception coverage areas were devised. Hence, the US was railroaded into adopting the seriously-flawed ATSC system which ultimately has created real hardship for many TV viewers who have lost reception of some local TV stations compared with the analog era.

The only people who lost reception were those watching terrible analog pictures. Having worked on a number of ham radio TVI problems I'm aware of some of the rotten pictures people were watching. Yes there was a tradeoff..... Really awful reception was eliminated in favor of forcing upgrades to a better antenna for OTA to receive a superior service. You certainly could argue if that was an acceptable tradeoff. There's another side to this though. People like me had moderately ghosty analog and refused to watch that. DTV actually made it possible to get a useable OTA service as long as the analog equivalent wasn't too awful.

Some call this progress. I sure you can think of many examples where an older inferior product was abandoned in favor of something better even though it required some sort of upgrade.

Quote:
Folks with outdoor antennas - specifically antennas which include VHF or high-VHF capability - can in fact obtain pretty good reception on high-VHF ATSC transmissions. But this knowledge does absolutely nothing to help the majority of American households, in a day and age when most American households are subject to restrictions on antenna placement due to HOA or condo complex control of "common area", as distinguished from the "limited common area" which is protected by OTARD.

I doubt that many of those people living in condos were watching OTA with indoor antennas in the analog days (really only 5 years ago). The pictures were terrible, especially on low VHF. Most had cable. Some had community antennas. If you go far enough back though, no one had great picture quality.

Quote:
Fortunately, I personally can obtain fairly satisfactory reception at our non-HOA suburban Seattle house. Nonetheless, I know far many people in the Seattle area who have simply "given up" on OTA due to ATSC's "digital cliff" effect.

If the signal is below the digital cliff then the quality of an equivalent analog picture was poor. About the only thing you say about it was that it was better than nothing but unusable on any large screen. As far as I can tell ATSC works as long as the analog picture it replaced had no more than fine grain snow and wasn't very ghosty.

Quote:
Poor ATSC OTA reception, combined with HOA and condo restrictions that - in many cases - have been defined by the courts as reasonable and enforceable on "common area" which is excluded from OTARD, have created a real gravy train of business for cable TV companies. It's really, really unfortunate.

How are these restrictions different from the analog days?

It seems to me that you are arguing for really bad analog OTA reception and that shouldn't have been traded for the need to upgrade that level of signal to get HD.

Chuck
post #9910 of 10423
Another thing to remember is, the noise floor in most buildings.....homes, condos, apartments, businesses.....has risen tremendously in the last few years. To say it is rising "exponentially" would not be an exaggeration.
The proliferation of microprocessor-based appliances, computers and their peripherals (routers, modems, etc), digital phones, and even the TV sets themselves (especially when coupled to set-top boxes), has added immensely to the RFI problems. Now that the "wonderful-but-inefficient" incandescent light bulb has been declared "obsolete", the interference problems will only worsen...........
I'm threatening to go back to gas lamps in my place wink.gif .
Don't even get me started on Switched-Mode Power Supplies mad.gif .
post #9911 of 10423
Quote:
Originally Posted by seatacboy View Post

I realize the FCC's fatal flaw in implementing the DTV transition was ASSUMING that most American viewers had outdoor antennas placed (at a minimum) 30 feet above ground level.

As someone who has a VHFHI+UHF antenna mounted more than 30' above ground level on a hillside 500' above sea level aimed at an antenna 50 miles away with no obstructions (I have been able to see the antenna on a clear day standing at the base of my antenna mast), I can tell you that VHF High reception sucks (channels 7 and 11).
The problem in my case is that the signal must travel over cold water. Reception reliably fails every afternoon during the summer due to temperature inversions. UHF seems to survive okay following the same path.

I have another antenna (same model) at a lower elevation aimed at a different antenna (1edge) 50 miles away over land where VHF high is 100% reliable (channels 8 and 13).
post #9912 of 10423
Quote:
Originally Posted by kenglish View Post

Now that the "wonderful-but-inefficient" incandescent light bulb has been declared "obsolete", the interference problems will only worsen...........
I'm threatening to go back to gas lamps in my place wink.gif . .

Don't be fooled.... You can still get "obsolete" lamps.... But at a cost.. $$
"Rough Service" incandescent lamps are exempt ..... Nothing is going away...... I have magnetic ballasted T-12... 110 watt lamps in my garage right now.......
Stamped ..... "For Cold Temperature Use Only" ..... For Government compliance.smile.gif
post #9913 of 10423
Quote:
Originally Posted by 888CALLFCC View Post
 
Quote:
Originally Posted by kenglish View Post

Now that the "wonderful-but-inefficient" incandescent light bulb has been declared "obsolete", the interference problems will only worsen...........
I'm threatening to go back to gas lamps in my place wink.gif . .

Don't be fooled.... You can still get "obsolete" lamps.... But at a cost.. $$
"Rough Service" incandescent lamps are exempt ..... Nothing is going away...... I have magnetic ballasted T-12... 110 watt lamps in my garage right now.......
Stamped ..... "For Cold Temperature Use Only" ..... For Government compliance.smile.gif

 

Do CFL's and LED's truly cause interference with TV signals? I've never experienced any such thing.

Besides, incandescent bulbs are still being manufactured --- it's just that they are halogen incandescent bulbs, which are a wee bit more efficient than the standard incandescent bulbs (but not as efficient as CFL's and LED's).

post #9914 of 10423
Quote:
Originally Posted by veedon View Post

Do CFL's and LED's truly cause interference with TV signals? I've never experienced any such thing.
Besides, incandescent bulbs are still being manufactured --- it's just that they are halogen incandescent bulbs, which are a wee bit more efficient than the standard incandescent bulbs (but not as efficient as CFL's and LED's).

Absolutely, both do. I've experienced interference from both CFL and LED bulbs. It's most pronounced on VHF here, but don't be fooled, electrical interference can occur with UHF signals as well. This is easily learned when weak signals stabilize when a device is turned off, and immediately become poor when it's switched back on.
post #9915 of 10423
Quote:
Originally Posted by veedon View Post

Do CFL's and LED's truly cause interference with TV signals? I've never experienced any such thing.
Besides, incandescent bulbs are still being manufactured --- it's just that they are halogen incandescent bulbs, which are a wee bit more efficient than the standard incandescent bulbs (but not as efficient as CFL's and LED's).

Yes and No .... (And mostly no.)

It depends on the manufacturer or the quality department.
It also depends how far away the device is from your antenna.

A CFL that does not cause interference normally, could cause problems at ..."end of life" ... the ballast is trying to keep a flickering lamp on.
so.... (Yes and No)
LED's .... mostly No.... (Just click on a LED flashlight, and check yourself)

The halogen incandescent bulbs are extremely fragile.... ( I blew one up in 5 minutes.) ....Just by bumping it.....They do not work in all areas that have incandescent sockets.
Ovens, Microwaves, Refrigerators, Garage Door Openers, .... I would still use a heavy-duty (Government Exempt) incandescent.

But for general room lighting......they use tons of energy........and are a thing of the past.

You can see for yourself if it's the problem by simply turning it off.

Here, .... The IMAC desktop has a noise zone of about 8 feet .... (Only noticeable on the most extremely weak station)
..... and basically nothing else.
The cell phone has a interference zone of about 2 feet if placed near a plastic tv converter box.... (And only when it's pinging) .... you notice it.
post #9916 of 10423
Quote:
Originally Posted by deltaguy View Post

Absolutely, both do. I've experienced interference from both CFL and LED bulbs.

Simply replace them with new ones that work.

The CFLs and LEDs from Walmart are garbage.... Quality LED bulbs have a aluminum heat sink.... Not plastic.
Normally, they are not a problem.
post #9917 of 10423
Quote:
Originally Posted by DAP View Post

As someone who has a VHFHI+UHF antenna mounted more than 30' above ground level on a hillside 500' above sea level aimed at an antenna 50 miles away with no obstructions (I have been able to see the antenna on a clear day standing at the base of my antenna mast), I can tell you that VHF High reception sucks (channels 7 and 11).
The problem in my case is that the signal must travel over cold water. Reception reliably fails every afternoon during the summer due to temperature inversions. UHF seems to survive okay following the same path.

I have another antenna (same model) at a lower elevation aimed at a different antenna (1edge) 50 miles away over land where VHF high is 100% reliable (channels 8 and 13).

One thing I have learned in the OTA DTV game is that you can find exceptions to every general rule. Nothing is 100%. There's always someone in an atypical situation where the rule doesn't apply. On the whole though, high VHF is better at the fringes than UHF.

DAP, I'm going to challenge your inversion idea. If there is any time during the day and year that inversions are least likely to exist is in the summer in the afternoon. The Bay Area fog marks the inversion boundary. The fog disappears in the late morning and afternoon because solar heating breaks the inversion. In the winter under high pressure like we've had for a month now, the inversion never breaks because the solar heating is too weak to do it. This is the cause of all those "spare the air" days and the dirty air trapped at low levels. Sounds to me as though your issue it may be exactly the opposite. You depend on inversions of some sort for reception. How do channels 7 and 11 do when it's raining, a time of no inversions?

Since we can't actually see the propagation path of the signals it's very difficult to know what's happening. Much of it is guesswork and we may never really know.

Chuck
post #9918 of 10423
All electronic devices put out some RFI if you get the receive antenna close enough to them. There are many devices out there that don't meet FCC specs. Somehow they got out there and those are the real problems. I had a go-around here with someone using electronic ballasts for grow lights and they were terrible. The solution was to change them to magnetic ballasts. I had to file a complaint with the FCC to make it happen. This is another reason why indoor antennas are not a good idea.

Chuck
Edited by Calaveras - 1/6/14 at 4:18pm
post #9919 of 10423
Quote:
Originally Posted by Calaveras View Post

Quote:
Originally Posted by DAP View Post

As someone who has a VHFHI+UHF antenna mounted more than 30' above ground level on a hillside 500' above sea level aimed at an antenna 50 miles away with no obstructions (I have been able to see the antenna on a clear day standing at the base of my antenna mast), I can tell you that VHF High reception sucks (channels 7 and 11).
The problem in my case is that the signal must travel over cold water. Reception reliably fails every afternoon during the summer due to temperature inversions. UHF seems to survive okay following the same path.

I have another antenna (same model) at a lower elevation aimed at a different antenna (1edge) 50 miles away over land where VHF high is 100% reliable (channels 8 and 13).

One thing I have learned in the OTA DTV game is that you can find exceptions to every general rule. Nothing is 100%. There's always someone in an atypical situation where the rule doesn't apply. On the whole though, high VHF is better at the fringes than UHF.

DAP, I'm going to challenge your inversion idea. If there is any time during the day and year that inversions are least likely to exist is in the summer in the afternoon. The Bay Area fog marks the inversion boundary. The fog disappears in the late morning and afternoon because solar heating breaks the inversion. In the winter under high pressure like we've had for a month now, the inversion never breaks because the solar heating is too weak to do it. This is the cause of all those "spare the air" days and the dirty air trapped at low levels. Sounds to me as though your issue it may be exactly the opposite. You depend on inversions of some sort for reception. How do channels 7 and 11 do when it's raining, a time of no inversions?

Since we can't actually see the propagation path of the signals it's very difficult to know what's happening. Much of it is guesswork and we may never really know.

Chuck
Rain has never been a problem for reception, just summer afternoons.
post #9920 of 10423
Quote:
Originally Posted by DAP View Post

Rain has never been a problem for reception, just summer afternoons.

That just means we really don't understand what's going on in your situation.

Chuck
post #9921 of 10423
Quote:
Originally Posted by Calaveras View Post

On the whole though, high VHF is better at the fringes than UHF.
I'm going to challenge your inversion idea.

Chuck

It seems that way here.... VHF is king here for out of market reception..... The rocky east bay hills completely stop UHF from Walnut Grove.... VHF is (guessing) 65% stronger and works in NON-LOS landscape locations. KVIE / KXTV is always working here.
At my location here.... Low-VHF was supreme. (Based upon the analog reception here)
I don't know about Low-VHF now, because there are no full power stations to test and see.
I would expect choppy indoor reception with Low-VHF, and normal reception with a big outdoor antenna.

Inversions ?..... Nothing like the humid midwest..... with reception of tv stations 200+ miles common.
We have mini peaks twice a day with nothing substantial I've seen in a few years.

Inversion dropouts here mean your antenna system is "barely" working for our local tv market.
Edited by 888CALLFCC - 1/8/14 at 5:58pm
post #9922 of 10423
Quote:
Originally Posted by 888CALLFCC View Post

It seems that way here.... VHF is king here for out of market reception..... The rocky east bay hills completely stop UHF from Walnut Grove.... VHF is (guessing) 65% stronger and works in NON-LOS landscape locations. KVIE / KXTV is always working here.
Interesting... I have a 10 element VHF yagi and a CM4228 pointed at Walnut Grove, and I have more problems with the VHF stations than I do with the UHF. While KMAX 31 and KQCA 58 are almost always solid in here, KVIE and KXTV are not so reliable. They are often at or below the cliff edge. KOVR is more like the two VHF but comes in more frequently. KCRA used to be really good and solid, but KGO's translator interferes with it and it only shows up now when conditions are really good (or KGO 35 is off the air).

Larry
SF
post #9923 of 10423
Quote:
Originally Posted by Larry Kenney View Post

Interesting... I have a 10 element VHF yagi and a CM4228 pointed at Walnut Grove, and I have more problems with the VHF stations than I do with the UHF. While KMAX 31 and KQCA 58 are almost always solid in here, KVIE and KXTV are not so reliable. They are often at or below the cliff edge.
Larry
SF

When I lived near your neighborhood in the 1980's ...... I recall UHF reception from Sacramento........ The only clear ones were KRBK and KTXL...... Not sure of the wattages or transmitter locations back then.
But I do remember a serious fading problem with Sacramento stations ...... One hour clear.....Next hour fuzzy..... and a repeated cycle of that.

So possibly digital dropouts could be contributed to fading ?

Our VHF then was ok, .... but KNTV had a ghost problem that nothing would fix..... But when 65 came on the air in the 1980s from the same transmitter location .... It was weaker but more clear..... practically ghost free.
So that was kind of weird.
post #9924 of 10423
Quote:
Originally Posted by Larry Kenney View Post

Interesting... I have a 10 element VHF yagi and a CM4228 pointed at Walnut Grove, and I have more problems with the VHF stations than I do with the UHF. While KMAX 31 and KQCA 58 are almost always solid in here, KVIE and KXTV are not so reliable.
Larry
SF

One of the techniques I noticed back then in San Francisco...(1980s)... is that I saw a triple-stack of VHF antennas specifically for KNTV.... (Then out of San Jose)
The upper two were pointed to Loma Prieta..... The lower one was off alignment ..... ( to cancel out a multipath signal)

Unless you have a spectrum analyzer ..... you'll never know what is happening to those VHF stations in San Francisco.
post #9925 of 10423
KEMO Sold

KEMO filed a Consummation Notice with the FCC today. Una Vez Mas has sold the station to North Star Media. San Francisco is not in the UVM list of stations.

http://northstar-media.com

I cannot find any published news on this yet.

North Star Media does not appear to be a supplier of Spanish language programming. Might be worth keeping an eye on them to see if the programming changes.

Chuck
post #9926 of 10423
Quote:
Originally Posted by 888CALLFCC View Post


Unless you have a spectrum analyzer ..... you'll never know what is happening to those VHF stations in San Francisco.


I did that. I recently had the pleasure of visiting Larry and of course I brought my spectrum analyzer. First let me say that the Sacramento stations are very weak there.

I thought that because he is so close to Sutro tower that maybe the Sacramento stations had reasonable signals but that the TV was being blasted by all those high power stations on the tower. This did not turn out to be the case.

To my amazement the stations on Sutro were no stronger for the most part than the better signals I get from Walnut Grove, 54 miles away and 2 edges. KUVS at 14 miles away is 15 dB stronger than his strongest station. How could this be?

Using Google Earth and the FCC database, I determined that Larry has a 18.5 degree look-up angle to the antennas on the top of Sutro tower. The ERP of the stations is greatly reduced at such a large angle. Attached is an image showing the vertical antenna patterns of all the UHF stations on Sutro tower. I pulled these from the original applications filed by the stations when they were constructing their final DTV stations and made a spaghetti graph. The plots only go out to 11 degrees below the horizontal. I extended the plot to 20 degrees and extrapolated what looked like an average of the patterns with the black line. The cyan line goes back to the response which is about 1.5%. Converted to power for a 1 MW station that's a little more than 200 watts ERP. Certainly the various signals will vary above and below that. 200 watts is 37 dB below 1 MW. Larry's TVFool shows stations with around 80 dB noise margin. Taking into account the reduction due to elevation pattern, the number goes down to 43 dB noise margin. We performed a noise margin tests on several stations and found the highest station to be 52 dB. Other stations were in the 40's.

It's nice that you can be near a tower and not have your TV completely overloaded by super strong stations. But there are a couple of problems. Turns out that when you're far off the main lobe, the frequency response of the antenna can be very uneven across the 6 MHz channel. This results in minor to major amplitude variations in the signal. You can get very non flat signals. Attached are two images, KGO on 7 and KPIX on 29, showing very non flat responses. KPIX was about average for variations. Some stations were much better, some were much worse. Fortunately amplitude variations don't affect the SNR much unless there are serious dips.

Unfortunately multipath is still an issue and some of Larry's signals had rather low SNRs. There are many sources of multipath in the City. One possible source is reflections of the main lobes off of other antennas on the tower. It would't be hard to imagine 1 MW ERP reflecting reflecting a few 10's of watts down to Larry's antennas to mess up the 200 watt ERP main signal.

Larry has commented that he's never been able to use a preamp at his location. Looking at the strength of his signals he should be able to as long as the gain wasn't too high. But I noticed that my spectrum analyzer was getting overloaded unless I used about 10 dB attenuation at the input. I suspect that there is a lot of other RF getting in and overloading the analyzer and any TV preamp. San Francisco is a notoriously very high RF environment. In order to use a preamp in the City I suspect you'd have to have tight bandpass filters around high VHF and UHF to reject all the other RF.

Larry did pass along a couple interesting tidbits; 1) Pictures were ghosty in the analog days and 2) SNRs are much higher when the stations are on the auxiliary antennas. I would assume that's because the lookup angle is less and the vertical patterns of the auxiliary antennas are broader.

Chuck

post #9927 of 10423

Hi,

 

Very interesting, someone too close to Sutro being visited by someone too far away.

 

In looking at the graph I seem to be seeing that the max signal is one (1) degree below horizontal which means most of the signal is passing over all our heads.

 

 Given the height of Sutro  is it possible that all of SF has the signal passing way over the top thus some of the problems reported in the city.

 

I guess I just do not understand the elevation pattern, is there a distance from Sutro that is the ideal distance.?

 

SHF

post #9928 of 10423
It was great meeting Chuck and I certainly learned a lot during his visit!

It's nice to know that we're not being blasted by all that RF from Sutro. It's interesting that the signals I receive from Sutro Tower, just 3/4 mile away, are about the same strength as the signals he receives from Walnut Grove stations 54 miles away. The signals are like a beam from a lighthouse shooting toward the horizon, and we're only getting a small amount of them. As a result, I'm able to receive the much weaker signals from a distance.

As he said, my signals from Walnut Grove are very weak, but a few are strong enough to be received most of the time, especially KMAX 31 and KQCA 58. KOVR and the two VHF stations are not so reliable. We were only able to receive 31 and 58 when Chuck was here. The rest of the stations were below the cliff edge. He noticed two spikes in both channel 9's and channel 10's signals, but we have no idea what the spikes are. They were stronger than the TV signals. Maybe that's why I have more trouble receiving them than I do the UHF stations.

It was interesting to see how bad most of the signals from Sutro looked on the spectrum analyzer. Chuck showed you two, most were worse. KQED's signal looks like a rocky mountain range with lots of peaks and valleys, and that explains why I have more trouble with that station than any other. I get the cleanest signal for KQED off the back of the antennas that are pointed at Walnut Grove. The stations with the smoothest signals are the ones that produce the highest signal to noise ratio on my TV.

We checked the signals received with my indoor rabbit ears/UHF loop and they looked a lot cleaner, but I can only receive Sutro stations and a couple from Mt. San Bruno on that antenna, and any movement in the room causes the signals to fluctuate greatly. When Chuck raised his arm and moved it back and forth, you could see the signals on the spectrum analyzer changing in response to his movements.

Distant stations looked good and were quite flat. KICU 36 and KEMO 50 looked exceptionally good here.

Thanks for the very interesting and informative day, Chuck!

Larry
SF
post #9929 of 10423
Quote:
Originally Posted by SFischer1 View Post

Hi,

Very interesting, someone too close to Sutro being visited by someone too far away.

In looking at the graph I seem to be seeing that the max signal is one (1) degree below horizontal which means most of the signal is passing over all our heads.

 Given the height of Sutro  is it possible that all of SF has the signal passing way over the top thus some of the problems reported in the city.

I guess I just do not understand the elevation pattern, is there a distance from Sutro that is the ideal distance.?

SHF

The signals are not going over your head in Sunnyvale. That would be true true if the Earth was flat but the curved Earth rapidly lowers the apparent height of the tower. Many stations have their downward tilt adjusted so that the center of the main lobe hits the Earth at about 60 miles out. 60 miles is about the horizon for an antenna at 2000'. How far from Sutro is Sunnyvale? About 45 miles? You'd probably find that Sunnyvale is about in the center of the main lobe for the Sutro stations.

Us up here in the foothills have a problem where we're above the main lobe for the Walnut Grove stations. At 54 miles the main lobes are 2500' below me so I'm down the slope of the main lobe on the upper side. To solve that problem the stations need to use lower gain antennas with wider main lobes to deliver more ERP to us. It's been documented over on the Sacramento OTA thread that KMAX/KCRA/KQCA have the most dropout problems because they have the highest gain antenna. OTOH almost no one has a problem with KVIE because they have the lowest gain antenna.

Chuck
post #9930 of 10423

Hi,

 

But I am a fully paid up member in the flat earth society. :D  :o

 

Both "DeLorme Topo North America 9.0" and TVFool report that I am 36.4 miles from Sutro (KGO).

 

I sure live in the right place, perfect for a signal from Sutro and just right for Mt. Allison and Monument Pk  to be in the little lobe of my CM4228HD.

 

My antenna installer who said "He knew where Sutro was" and just pointed the antenna in that direction remarked about the little lobe being in the right place.

 


 

Your results for Larry's location suggest the words in the e-mail about Sutro Auxiliary antenna operation as the Aux antennas must also go out over the local residents even closer to Sutro.

 

9/10/2012

Quote:

Since analog TV operations ceased at Sutro Tower in 2009, there is very little difference between the measured radio frequency emission levels in the neighborhood between Main and Aux antennas.

 

9/24/2013

Quote:

However, unlike the days when both analog and digital TV were being broadcast simultaneously from Sutro Tower, the emissions from Sutro Tower are much less that they were in the past, and the auxiliary antenna emission is only a few percent higher than normal main antenna operation.

 

Mark your calendars for 9/??/2014 for Sutro Auxiliary antenna operation.

 

Again I ask if anyone is willing to back me up to receive and post the Sutro Aux antenna operation notices. I do not always check my e-mail as often as needed.

 

SHF

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