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post #8371 of 10450
Quote:
Originally Posted by TPeterson View Post

Nanny, with over a hundred TEI errors in a few minutes and that horribly fractured PID map, it's pretty clear that your reception is poor on the channel.

Hi,

Yes it is. Fusion was before the only tuner to be able to capture movies. My antenna is pointed in the wrong direction.

Darn HOA putting my attic antennas in a faraday cage making them unusable.

I had a long string of good captures until the fourth sub stream was added.

I guess giving up trying to use Fusion on the very last channel is what I must do.

SHF
post #8372 of 10450
Quote:
Originally Posted by dtvfan2012 View Post


I have tried TVfool, FCC map etc. to tune Clearstrem5 as well as DB4 antenna w/o success.

Those antenna models are not made for San Ramon reception conditions.
As you have pointed out, reception is not satisfactory.

There is like a 50% reduction of signal strength with antennas used in attic. = 50% Larger antenna needed.
Clearstream 5 is a good choice for strong areas that can be mounted on a Dish Network pole, Etc. .... A motorhome,.... boat, Etc. ...... You get the idea ?
DB4 is like a fancy UHF indoor antenna (4 loops) painted black for outdoor use.

Nothing less than a Winegard 7698 should be used in San Ramon.
If you want small, HD Stacker from www.dennysantennaservice.com
cuts the antenna in half, putting the UHF elements on the botton of the VHF Elements.
For quality reception, multi-element "Yagi" type antennas give satisfactory results in most cases.
Those models have been made for decades....... because they work.
post #8373 of 10450
I've heard of software-as-a-service, and a few other things -as-a-service, but this is the first I've heard of "antenna-as-a-service"..

http://arstechnica.com/tech-policy/n...ng-startup.ars

It will be interesting to watch how this plays out..
post #8374 of 10450
Quote:
Originally Posted by NxNW View Post

I've heard of software-as-a-service, and a few other things -as-a-service, but this is the first I've heard of "antenna-as-a-service"..

http://arstechnica.com/tech-policy/n...ng-startup.ars

It will be interesting to watch how this plays out..

So they must be set up very close to the transmitter site for these fingertip sized antennas to work. Is there enough internet bandwidth to serve potentially 1000's of users at the same time in one area, each with their own HD stream? Seems like an incredibly inefficient use of bandwidth.

Chuck
post #8375 of 10450
I got this idea to take some spectrum analyzer images and make animations of them in Photoshop to show how some signals vary. I have to post them at my own web site because the files are larger than allowed here (~1MB max size).

KGO at differing signal strengths.

http://images.aa6g.org/AVSForums/KGO_Animation.gif

When the KGO and KNTV signals are weak they are very non-flat and unstable. I think this may be due to the fact that they have to go through vegetation 3000' down the path. The stronger they get, the flatter and more stable they get. UHF from Sutro seems to be unaffected. The first image in the series had an SNR of 15-17 dB and the last image was SNR 25 dB.

This animation of KNTV is looks just like KGO when it's weak. KNTV was mostly too weak to decode. This is 10 sweeps taken over 60 seconds. KCBA is on the right.

http://images.aa6g.org/AVSForums/KNTV_Animation.gif

Here's KGO showing relative stability. Again 10 sweeps over 60 seconds. Those signals on the left sound like packet radio when I listened to them on my ham radio. KSBW is on the right.

http://images.aa6g.org/AVSForums/KGO_Animation-1.gif

And to show that signals can actually be pretty stable, here's KMMW just 14 miles away which never varies by more than +/- 1 dB. Again 10 sweeps over 60 seconds. That's KEXT analog on the left, a very strong signal.

http://images.aa6g.org/AVSForums/KMMW_Animation.gif

Chuck
post #8376 of 10450
dtvfan,

I checked and i can get 54.x channels even with an indoor antenna something cheap like artec. And yes you are right the kids channel is only on 54 and there is a world channel on 9.x PBS station.

Must be something in your specific location then.
post #8377 of 10450
Thanks for sharing the spectrum analyzer animations with us, Chuck. Interesting stuff!

NxNW... thanks for posting the link to the arstechnica site. I wonder how they're going to be able to handle to load. It'll be interesting to see how well it works out.

Larry
SF
post #8378 of 10450
Quote:
Originally Posted by Larry Kenney View Post

Thanks for sharing the spectrum analyzer animations with us, Chuck. Interesting stuff!

Larry
SF

I updated the first KGO animation with a 5th image since KGO was even stronger today.... and a flatter display. The SNRs now run from 16 to 28 dB.

Also I made an animation of KGO showing what I think is dynamic multipath, probably what we always called airplane flutter. You'll recognize when it shows up in this 32 frame animation.

http://images.aa6g.org/AVSForums/KGO_Animation-3.gif

Chuck
post #8379 of 10450
Quote:
Originally Posted by Calaveras View Post

I got this idea to take some spectrum analyzer images and make animations of them in Photoshop to show how some signals vary

Thanks for sharing this with us. I would be curious to see what KPIX channel 5.1 looks like from our location. That station can be a problem here sometimes even though it is supposed to be the strongest.
post #8380 of 10450
Quote:
Originally Posted by litildubey View Post

dtvfan,

I checked and i can get 54.x channels even with an indoor antenna something cheap like artec. And yes you are right the kids channel is only on 54 and there is a world channel on 9.x PBS station.

Must be something in your specific location then.

Yes, looks like my place has weak signal but in your area has good one.
Attached is the signal strength map from TVfool.
LL
post #8381 of 10450
I'm having trouble tuning in KTNC 42 on some of my tuners.

On some of them I get
42-1 KTNC-SF
42-2 KTNC-SA
42-3 KTNC-Th ("THIS" movies)
42-4 KTNC-Br with color bars

But on my two Sonys I get "No Signal" on 42-3 and 42-4 doesn't exist. Rescanning doesn't help.

Anyone else having problems with this channel? I know SHF mentioned that he was having trouble recording movies on 42-3, so maybe this is related to that.

Larry
SF
post #8382 of 10450
Quote:
Originally Posted by Larry Kenney View Post

Anyone else having problems with this channel? I know SHF mentioned that he was having trouble recording movies on 42-3, so maybe this is related to that.

I rescanned my Sony and I now get 42.1 thru 42.4. Don't these TVs drive you crazy?

Chuck
post #8383 of 10450
Quote:
Originally Posted by Larry Kenney View Post

I'm having trouble tuning in KTNC 42 on some of my tuners.

On some of them I get
42-1 KTNC-SF
42-2 KTNC-SA
42-3 KTNC-Th ("THIS" movies)
42-4 KTNC-Br with color bars

But on my two Sonys I get "No Signal" on 42-3 and 42-4 doesn't exist. Rescanning doesn't help.

Anyone else having problems with this channel? I know SHF mentioned that he was having trouble recording movies on 42-3, so maybe this is related to that.

Larry
SF

Hi,

My problem with KTNC-Th (ThisTV) was that program 5 went away completely. Now programs 1 - 4 with 4 consisting of Color Bars and tone.

But looking at KTNC right now, the fair signals are now poor and unusable! (3/7/2012 ~13:00.)

It may be the weather, transmitting down to the soup bowl we live in at sea level may be passing through an inversion layer.

Then again, because of their unresolved interference problems they might have lowered their power again, perhaps for testing.

Now at 13:18 I see the signal is back to fair, looking just a minute later very poor. Then back to fair and usable.

Signal Strength = ~ 82%
Signal Quality = ~ 60%
Symbol Quality = ~ 100%

This is what I call fair and usable if it is stable, it sure is NOT stable right now.

EDIT: Still not stable at 20:27 3/7/2010

SHF
post #8384 of 10450
The post above kind of provides a lead in to this one. I wanted to see how signals varied over a period of time so I recorded the signal strengths of 16 stations from Feb. 25 to March 8 on my spectrum analyzer. These are stations I normally receive including all the Walnut Grove stations plus samples from other transmitter sites. I took readings in the early morning, mid morning, afternoon and evening on most days. Attached is a summary of the 50 readings I took for each station. The readings are in dBm and show minimum, maximum and average signal levels plus the standard deviation.

The digital cliff is around -83 to -84 dBm on the analyzer as long as the station has a flat signal. If a station has a lot of variation the minimum decodable signal is higher. KGO is the worst at around -74 dBm. All stations can be decoded with their average signals.

I was able to reach some conclusions.

1) All signals vary over time. Close-by LOS signals vary so little as to be insignificant.

2) As the distance to the transmitter increases or you don't have LOS, they vary more. No surprise here.

3) Signals vary a little even under the most nominal conditions like rain.

4) Signals vary the most with strong temperature inversions. Again, no surprise here. We had 2 days of that last week which accounts for almost all the Min/Max signal levels.

5) Not all signals from one transmitter site go up and down in unison. I saw cases where just one signal was up or down and the others unaffected. VHF and UHF can have different behaviors at the same time.

Monitoring signals like this doesn't capture the brief dropouts that I experience most often. I saw one of these on KOVR and one on KSBW where there was a 20 dB + signal fade over just a few minutes and then came back. It appears that just about any station that is not close-by can have this happen and especially if they're not LOS. Changing temperature inversions are responsible for these huge dips in strength. I did not see any equally brief swings on the plus side.

Chuck
LL
post #8385 of 10450
Going into those 2 days last week without inversions, I was getting all stations from Walnut Grove with a single aim indoors. I had been for about 2 weeks. Without inversion, KVIE dropped to a black screen while all others were fine give or take. The solution for KVIE was to lower the antenna about 2 feet and give it a slightly different aim. I'm back to the old aim now.
post #8386 of 10450
Quote:
Originally Posted by Calaveras View Post

5) Not all signals from one transmitter site go up and down in unison. I saw cases where just one signal was up or down and the others unaffected. VHF and UHF can have different behaviors at the same time.
Chuck

This is one thing that has surprised me. I'd expect all of the signals to go up or down together, or at least all of the VHF would behave the same and all of the UHF would behave the same, but no... that doesn't always happen.

Often ALL of the stations will be better or worse than "normal", but I've seen some stations way above their "normal" level while, at the same time, others have been low and others remain at "normal". I haven't been able to find any rhyme nor reason for this.

Occasionally KMAX and KOVR will be 6 to 8 dB stronger than usual while KQCA and the two VHF stations will remain at normal level. Other times just the VHF stations will be better than normal while the UHF's will be at the usual level. I figure it might have something to do with the frequency in those cases.

Another point of interest... often when the Walnut Grove signals are up, the South Bay signals are down, or vis-versa, when Walnut Grove signals are low, the South Bay will be better than usual. I don't usually see much change on the signals from KRCB 23 and KEMO 32 even though they're 45 to 65 miles away.

Ain't RF fun?!?

Larry
SF
post #8387 of 10450
Today confirmed something I've noticed a couple times prior with a Mohu Leaf. I'm trying it in a 3rd location. In the first two locations, wind has meant trouble for uhf signals. That's been true for all indoor antennas I've tried. However, in this 3rd room, the only one with a correct facing window, uhf is being enhanced by wind. This is a first for me. For example, KCRA doesn't reach the word good on the Zenith converter on calm days. Today, and with the north wind event we had prior, the meter was pegging 2 letters under good. Very strange. I like it though.
post #8388 of 10450
I've been curious for some time as to how the signal levels vary over the course of a day but it's hard to be around to monitor a station for a whole day. Yesterday (3/10) looked to be a dead day for me so I decided to give it a try. I planned to take a reading every 15 minutes and plot the results. I chose KCRA because I know it goes up and down a lot.

After about an hour it became obvious that I was missing huge short term changes in the signal with 15 minute sampling. I decided to take an image every 1 minute for an hour to get a detailed sample when KCRA was having large swings in the signal.

I ended up with two results; one attached here showing the graph from 5 am to 9 pm, and a second showing an animation of 1 hour worth of changes.

KCRA for 1 Hour (7:30 to 8:30 am)

http://images.aa6g.org/AVSForums/KCRA_Animation.gif (5.3 MB)

Not only does the signal go up and down but it tilts a lot. KCRA has always had a problem with the high end being lower than the low end. KXTV is the same way. KTFK is the opposite. KTXL is always flat. I was surprised to see that sometimes KCRA is flat. You can also see the audio carrier of KACA analog 34 which hardly changes at all and part of KICU which changes as much as, but not in sync with KCRA. The SNR of KCRA as shown by the TV varied from 18 to 28 dB over the hour.

The graph shows the signal as very unstable in the morning and then becoming relatively stable after noon. I see this pattern often. Sometimes the early evening dip is severe.

Unfortunately this sort of variation is what I see all the time although I believe it's much less on rainy days. I should verify that this week during the upcoming storm. I highly suspect that anyone without LOS to their stations, or even if they're just far away, puts up with these variations. This would account for most of the reports of intermittent reception problems.

Chuck
LL
post #8389 of 10450
Quote:
Originally Posted by Larry Kenney View Post

This is one thing that has surprised me. I'd expect all of the signals to go up or down together, or at least all of the VHF would behave the same and all of the UHF would behave the same, but no... that doesn't always happen.

I've given up even trying to understand how it works. Every time I think I see a pattern in the signals for a few days it changes into something completely different. The signals I see from Sutro are especially perplexing. The only thing that seems consistent is that 7, 9, 32 and 44 come in the most often and all the others rarely. This morning was a rarely day as almost every Sutro station that is possible to receive in my location was coming in. Even KCSM which I see only a few times a year was coming in. Almost all signals from all directions were good this morning.

Chuck
post #8390 of 10450
Quote:
Originally Posted by Calaveras View Post

I've given up even trying to understand how it works. Every time I think I see a pattern in the signals for a few days it changes into something completely different.

When you figure it out, you can submit your PhD thesis. Check out the following study:

The propagation of VHF and UHF radio waves over sea paths
Sim, Chow Yen Desmond
Doctoral Thesis, November 2002
University of Leicester

Abstract:
https://lra.le.ac.uk/handle/2381/7444

202 Page Thesis, 6.78MB pdf file:
https://lra.le.ac.uk/bitstream/2381/...mond%20Sim.pdf
post #8391 of 10450
For me.
During warmer weather (summertime) I lose kntv. kgo comes and goes. Kpix drops occasionaly.
During the winter, I get everything from sutro pretty much all the time.
post #8392 of 10450
Quote:
Originally Posted by Calaveras View Post

Not only does the signal go up and down but it tilts a lot. KCRA has always had a problem with the high end being lower than the low end. KXTV is the same way. KTFK is the opposite. KTXL is always flat.
Chuck

Tilt is a new subject that I'm not familiar with. What causes the signal to tilt... is it something in the transmitter or is the atmosphere doing it? How does tilt affect the picture?

Quote:
Originally Posted by Calaveras View Post

The signals I see from Sutro are especially perplexing. The only thing that seems consistent is that 7, 9, 32 and 44 come in the most often and all the others rarely. This morning was a rarely day as almost every Sutro station that is possible to receive in my location was coming in. Even KCSM which I see only a few times a year was coming in.

It occurred to me that the physical placement of the antennas on Sutro Tower seem to affect whether or not you see a station's signal. 7 and 44 are on the southeast tower. 9, 32 and 60 are on the northeast tower. The stations that you don't receive... 2, 4, 5 and 20 are all on the west tower.

I wonder why you can't get 38 (RF 39). It's running 1 MW ERP and is on the same tower at 9, 32 and 60, which are all running less power. There's nothing transmitting on 39 over your way that I know of.

Larry
SF
post #8393 of 10450
Quote:
Originally Posted by deltaguy View Post

... uhf is being enhanced by wind.

I bet it's the leaves on the trees near your home that are causing the change. The movement of the leaves in the wind seem to be enhancing the signals for you. It's a form of multipath.

Larry
SF
post #8394 of 10450
For iitywygms, or anyone else in the Santa Rosa - Winsor - Cloverdale area...

According to this month's new station report, which I receive in the digest of the Worldwide TV-FM DX Association, there are two new digital stations on the air licensed to Santa Rosa. They are K02QO transmitting on channel 2 and K03IC transmitting on channel 3. Both are low power stations running 300 watts, transmitting from Cloverdale just southwest of the intersection of US101 and CA128 and their signals are beamed southeast from there right down 101.

Also, KDTV's translator is supposed to have gone digital on channel 28 up there. It transmits with 3.7 kW from near Robert Louis Stevenson State Park west of Highway 29 north of Calistoga.

I wonder if anyone has received these stations. I'd like to confirm their existence before I add them to my DTV channel lists.

Thanks.

Larry
SF
post #8395 of 10450
KDTV-CD has been around for a while. It was on SiliconDust before it went down back in October. http://www.silicondust.com/hdhomerun...lineup_7391435

- Trip
post #8396 of 10450
Quote:
Originally Posted by Larry Kenney View Post

For iitywygms, or anyone else in the Santa Rosa - Winsor - Cloverdale area...


Also, KDTV's translator is supposed to have gone digital on channel 28 up there. It transmits with 3.7 kW from near Robert Louis Stevenson State Park west of Highway 29 north of Calistoga.

I wonder if anyone has received these stations. I'd like to confirm their existence before I add them to my DTV channel lists.

Thanks.

Larry
SF

I was not able to see anything from Cloverdale. My antenna is pointed in the exact opposite direcction so I am not suprised.

I did pick up KDTV. It is a spanish station. So you can add that to the list.
post #8397 of 10450
Quote:
Originally Posted by Larry Kenney View Post

Tilt is a new subject that I'm not familiar with. What causes the signal to tilt... is it something in the transmitter or is the atmosphere doing it? How does tilt affect the picture?

I suspect it has to do with differing attenuation over the terrain the signal has to refract over. It shows up in all sorts of ways; tilts, dips, or a ragged looking trace. As far as I can tell the SNR is reduced to whatever the weakest part of the signal is but it doesn't cause multipath.

Quote:


It occurred to me that the physical placement of the antennas on Sutro Tower seem to affect whether or not you see a station's signal. 7 and 44 are on the southeast tower. 9, 32 and 60 are on the northeast tower. The stations that you don't receive... 2, 4, 5 and 20 are all on the west tower.

It's true that 2, 4 and 5 are poor here, although 5 is somewhat better than 2 and 4. 60 is the worst, even weaker than 34. But I cannot receive 34 because of co-channel analog KACA.

20 is actually about equal to 9 but very hard to receive because of adjacent channel KUVS which is often 50 dB stronger even in an antenna null. See the attached image of KOFY and KQED and you'll see the problem.

Quote:


I wonder why you can't get 38 (RF 39). It's running 1 MW ERP and is on the same tower at 9, 32 and 60, which are all running less power. There's nothing transmitting on 39 over your way that I know of.

I receive KCNS on occasion but it's pretty weak. One would think that over a 110 mile path that there would be no detectable difference between any station from the different locations on Sutro Tower but there is. I do have KMMD-LD on Mt. Toro to contend with on RF 39 but it's usually very weak when pointed to SF.

You can see on the KOFY/KQED image that the signals are not flat but they're not that bad.

Another problem is not being in the main lobe of the antennas. The ERP often changes with frequency which is another cause of non flat signals. I see this on KMMW, KCBA and KSMS. The grossest example of this is KCSO which I've posted another image of. There's a 20 dB swing in it's ERP across the its signal. That ugly signal still produced an SNR of 25 dB when I took the image using an FM antenna. I think that image is proof that you cannot trust the published FCC antenna patterns at least if you're not in the main lobe of the antenna.

Chuck
LL
LL
post #8398 of 10450
Thanks for the info on signal tilting. Interesting!

I can see that KOFY just squeaks past KUVS.

I'm surprised a low power station on Mt. Toro could bother a 1 MW station from Sutro Tower, but you seem to have a terrific path down to the Salinas-Monterey area. I think in your previous signal posts, KSBW 8 is your strongest station. That's amazing! How far are Fremont Peak and Mt. Toro from your location?

Larry
SF
post #8399 of 10450
Quote:
Originally Posted by Larry Kenney View Post

That's amazing! How far are Fremont Peak and Mt. Toro from your location?

Fremont Peak is 115 miles and Mt. Toro is 132 miles. Sutro is 110 miles. Fresno is 99 miles.

I took some images this morning with the antennas in the 4 directions of the VHF stations and made a composite image in Photoshop so all the signals are at their peak strength for comparison. You can see KSBW and KVIE are essentially equal. All stations could be decoded except KNTV which is too weak without tropo help.

It's interesting to compare KSBW and KCBA which are on the same tower. KSBW is using an omni antenna and 20.6 KW ERP. KCBA is 25 dB weaker. This means KCBA effectively has 65 watts in my direction. This is why I'm concerned about a 300 watt channel 7 with an omni antenna showing up on Mt. Toro. It could be 6 dB stronger than KGO and I already can receive KCBA much of the time when pointed to Sutro. KGO could go bye-bye. UHF signals from Fremont Peak or Mt. Toro are not nearly so strong.

I included the faded trace showing KAIL from Fresno. It's too weak to decode especially with KGO underneath but I can see it on the analyzer.

It might be fun to do this on the UHF band. I'd have to take a somewhat different approach to make a composite image.

Chuck
LL
post #8400 of 10450
Very interesting - thank you Calaveras.
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