or Connect
AVS › AVS Forum › HDTV › Local HDTV Info and Reception › San Francisco, CA - OTA
New Posts  All Forums:Forum Nav:

San Francisco, CA - OTA - Page 166

post #4951 of 10422
If you have severe multi-path, a new tuner is not the only fix. Different antennas have different reception patterns. If you can figure out the direction of the multi path, perhaps you can find an antenna that has a severe dip in its reception pattern in than direction. You might be able to missaim your antenna such that one of the dips aims directly at the multi-path and you still get enough signal to receive the channel you want.

But remember, the pattern changes with frequency.
post #4952 of 10422
DAP,

That fits my experience with multipath completely. I'm only looking for stations from Walnut Grove, but with 3 different tuners, tvs, and antennas, there is no single aim of any of the indoor antennas that will get all of the channels, unless conditions are absolutely perfect. Even with perfect conditions, better signal for various channels requires a different antenna aim. OTA reception is a participation sport.
post #4953 of 10422
Quote:
Originally Posted by Calaveras View Post

If anyone knows about a tuner that's been shown to have superior multipath handling above and beyond what I already have, I'd like to know about.
Chuck

I've got a Sony XBR4, Dish ViP622 and Dish DTVPal that all perform about the same when it comes to sensitivity and handling of multipath, but my Insignia D to A converter box with the LG receiver (same one used in the Zenith converter box) is much better. It can pick up weaker stations better, it can hold stations a lot longer when I swing the antenna, and it seems to receive more stations per antenna setting than the others. If I point the antenna at Sacramento, for example, I can still receive 3 out of the 4 stations from the South Bay - 14-36-48. (54 is too weak to come in unless the antenna is set right in the right spot.) The other receivers don't receive the South Bay stations with the antenna pointed at Sacramento.

As an aside, my first digital receiver, my Sony XBR2, has a real hard time picking up the South Bay stations even with the antenna pointed in that direction, and forget about anything from Sacramento on that one. Stations that come in perfectly on the others, are "No Signal" on the 8 year old Sony. So there has definitely been a major improvement in receivers over the years.

Larry
SF
post #4954 of 10422
Quote:
Originally Posted by Calaveras View Post

...I've noticed a couple of other problems. The very large antennas that used to be available for UHF and VHF are no longer made...

Winegard makes a very good highband VHF/UHF combo fringe antenna. It's 168" long, with I would consider large. It does not have the wide elements that were needed for lowband VHF chs 2 -6.

Quote:
Originally Posted by DEEPFRINGEGUY View Post

Something I've been wondering for a long time. Which TV's have the best tuners on the market right now?..

Based on anecdotal experience from living in a very hilly, deep fringe area, if I were buying a TV based only on tuner performance, I would get an LG.
post #4955 of 10422
Quote:
Originally Posted by dr1394 View Post

That signal looks fine to me. How old is your receiver? Anything that's more than a few years old won't have the best demodulator chip in it.

By comparison, here's a signal (KICU-DT) with much more distortion. It decodes perfectly (no errors) on a newer demodulator, but sometimes won't even lock on an older demodulator.

poses it.

Ron


I have 2 receivers, both seem to have similar performance as far as receiving OTA: Dish ViP722 and Sony KDL-42v4100. And I can receive signals where the multipath looks similar to the above picture.

Thing is, though, long delay multipath doesn't look like that. It isn't easily visible on a spectrum analyzer display. Taking a simple case, with just one reflection, the spectral nulls will be spaced at the reciprocal of the delay difference. So a difference of 10us will give nulls spaced at 100 kHz apart, which will merge into each other if the resolution BW of the analyzer is too wide.

As an example, here's the same KQED indoor signal that I posted before, but with narrower span and resolution BW:

http://www.petercripps.com/OTA_TV_sp..._multipath.jpg

It's certainly an interesting question as to whether a better receiver would pull this signal in. However, my original point was that, in this case at least, increasing TX power isn't going to help reception.

Peter
post #4956 of 10422
Quote:
Originally Posted by Larry Kenney View Post

I've got a Sony XBR4, Dish ViP622 and Dish DTVPal that all perform about the same when it comes to sensitivity and handling of multipath,

I have a VIP622 and the OTA receiver is pretty much useless here. It's about 4dB worse in multipath handling than my Sony SXRD or Pal DVR. That means I can almost never receive KCRA on it.

Quote:
but my Insignia D to A converter box with the LG receiver (same one used in the Zenith converter box) is much better.

Sounds like this is closer to my TV and Pal DVR experience. I have a friend with converter box that he says has a good tuner in it. Maybe I can get him to bring it down here as a test.

Quote:
As an aside, my first digital receiver, my Sony XBR2, has a real hard time picking up the South Bay stations even with the antenna pointed in that direction, and forget about anything from Sacramento on that one. Stations that come in perfectly on the others, are "No Signal" on the 8 year old Sony. So there has definitely been a major improvement in receivers over the years.

Larry
SF

I wonder if that's what my cousin's problem is, an older Sony. I'll have to ask what the model is but it's only 720P, not a 1080i set.

A increase of 2 or 3 dB in mutlipath handling would be a big deal for me.

BTW, July 15th is rapidly approaching. Still no work on Sutro?

Chuck
post #4957 of 10422
Quote:
Originally Posted by arxaw View Post

Winegard makes a very good highband VHF/UHF combo fringe antenna. It's 168" long, with I would consider large. It does not have the wide elements that were needed for lowband VHF chs 2 -6.

I guess it's big by today's standards but not what big used to be. It looks like only about 1/3 the boom length has hi VHF elements.

I've attached two images from a 1984 Winegard catalog. Take a look at that big VHF antenna, a 214" boom. I had one of those once. Granted it's low VHF too but it looks like the hi VHF elements spanned nearly the entire boom length. That would dwarf even the YA-1713. That's what I'd like to get today for hi VHF.

Quote:
Based on anecdotal experience from living in a very hilly, deep fringe area, if I were buying a TV based only on tuner performance, I would get an LG.

Do they make their own tuners or use someone else's? I know the Pal DVR uses Microtune but I don't know about anything else.

Chuck
LL
LL
post #4958 of 10422
Quote:
Originally Posted by dr1394 View Post

http://www.avsforum.com/avs-vb/showthread.php?t=1122271

A link explaining the constellation diagram.

http://www.digitalproceiver.com/mods...ing%208vsb.pdf

From reading that presentation, it would seem that the constellation diagram shows you all the effects on the signal, including multipath.

Ron

Thanks for the links. That's the sort of testing you have access to when you're in the business. The rest of us don't.

I still have a couple of questions. I didn't see anything in the slide show that mentioned using the constellation diagram to see multipath. Did I miss it? I still don't see how to tell the difference between low SNR caused by a weak signal or high multipath.

Can the equalizer compensate for more than one reflection? It looks like it picks equalization to maximize SNR which I guess implies one reflection.

Unfortunately multiple reflections are common, especially at my location.

I also thought it was interesting to see that there is a lot of error correcting going on once the SNR drops below 20 dB.

Chuck
post #4959 of 10422
Quote:
Originally Posted by Calaveras View Post

I guess it's big by today's standards but not what big used to be. It looks like only about 1/3 the boom length has hi VHF elements.

I've attached two images from a 1984 Winegard catalog. Take a look at that big VHF antenna, a 214" boom.

Yep, they're big. I wonder how much gain they had?

Those were popular for fringe viewers back before locals on satellite became available. Most people don't want such a huge monster in the yard if there's an alternative. Dealers don't want to stock them, due to limited space and shipping is outrageous. So, the market is probably small.

Quote:


Do they [LG] make their own tuners or use someone else's?

I'm pretty sure LG uses 6th generation LG tuner chipsets in their TVs.
post #4960 of 10422
Turns out if I had just looked at the Sutro Tower web page some of my questions would have been answered:

http://www.sutrotower.com/

The July 2 update certainly implies they will be working to replace the KGO antenna from July 3 - July 13.

I also questioned how many stations would share antennas.

http://www.sutrotower.com/conversion.html

"The existing analog antennas at the top of the tower will be removed and replaced with six new digital main antennas. One will serve four stations, one will serve three stations and the other four will serve one station each."

So there is going to be two community antennas. It will be interesting to see when that is completed how many people have trouble with one or more of the stations on the community antennas.

Chuck
post #4961 of 10422
Quote:
Originally Posted by Peter124 View Post

I have 2 receivers, both seem to have similar performance as far as receiving OTA: Dish ViP722 and Sony KDL-42v4100. And I can receive signals where the multipath looks similar to the above picture.

Thing is, though, long delay multipath doesn't look like that. It isn't easily visible on a spectrum analyzer display. Taking a simple case, with just one reflection, the spectral nulls will be spaced at the reciprocal of the delay difference. So a difference of 10us will give nulls spaced at 100 kHz apart, which will merge into each other if the resolution BW of the analyzer is too wide.

As an example, here's the same KQED indoor signal that I posted before, but with narrower span and resolution BW:

http://www.petercripps.com/OTA_TV_sp..._multipath.jpg

It's certainly an interesting question as to whether a better receiver would pull this signal in. However, my original point was that, in this case at least, increasing TX power isn't going to help reception.

Peter

My best long-distance stations are the 1000kW variety. I'm very confident that increased signal strength helps my reception. It's not the only variable, but it helps.
post #4962 of 10422
I noticed today that KICU 36.1 is broadcasting in 720P 16:9. I haven’t seen any 16:9 HD programs yet. There is also a new 36.2 sub channel.

The signal today is much stronger than I’ve seen before. By aiming the CM Quantum 1160 antenna I’m getting 90-95 on the DTVpalDVR. The best I got before was about 65.

If the signal holds maybe I can watch Monk tomorrow.
post #4963 of 10422
Quote:
Originally Posted by Selwonk View Post

I noticed today that KICU 36.1 is broadcasting in 720P 16:9. I haven't seen any 16:9 HD programs yet. There is also a new 36.2 sub channel.

It's been like this for awhile. 36.2 is a Korean channel:

http://en.wikipedia.org/wiki/KEMS
post #4964 of 10422
Quote:
Originally Posted by Selwonk View Post

I noticed today that KICU 36.1 is broadcasting in 720P 16:9. I haven't seen any 16:9 HD programs yet. There is also a new 36.2 sub channel.

The signal today is much stronger than I've seen before. By aiming the CM Quantum 1160 antenna I'm getting 90-95 on the DTVpalDVR. The best I got before was about 65.

If the signal holds maybe I can watch Monk tomorrow.

KICU seems to be stronger here too starting this past week. I wonder if they finished their antenna raising project? I have no way to confirm that. I'm taking a wait and see attitude if the signal holds up in the long term.

Chuck
post #4965 of 10422
Quote:
Originally Posted by Peter124 View Post

I have 2 receivers, both seem to have similar performance as far as receiving OTA: Dish ViP722 and Sony KDL-42v4100. And I can receive signals where the multipath looks similar to the above picture.

Thing is, though, long delay multipath doesn't look like that. It isn't easily visible on a spectrum analyzer display. Taking a simple case, with just one reflection, the spectral nulls will be spaced at the reciprocal of the delay difference. So a difference of 10us will give nulls spaced at 100 kHz apart, which will merge into each other if the resolution BW of the analyzer is too wide.

As an example, here's the same KQED indoor signal that I posted before, but with narrower span and resolution BW:

http://www.petercripps.com/OTA_TV_sp..._multipath.jpg

It's certainly an interesting question as to whether a better receiver would pull this signal in. However, my original point was that, in this case at least, increasing TX power isn't going to help reception.

Peter

Ah-ha, I get it now. But your spectrum analyzer photo shows nulls spaced around 10 kHz which would be approximately a 100 us echo. Unfortunately, I don't believe there is any demodulator chip on the market with an equalizer that can handle a 100 us echo. The ATSC A_74 receiver specification only covers -25 to +50 us.

However, that long of a delay suggests a geometry that should be easy to overcome with a directional antenna. That is, the multipath direction is either off to the side or behind the antenna.

Ron
post #4966 of 10422
Quote:
Originally Posted by dr1394 View Post

However, that long of a delay suggests a geometry that should be easy to overcome with a directional antenna. That is, the multipath direction is either off to the side or behind the antenna.

Yes, 100us represents a path difference of 30km! Maybe a reflection off the East Bay hills ... I'm on the peninsula.

When I had the 91xg up on the roof, I was getting Sutro signals from all sorts of funny directions, none of them good enough to decode the signal. Many of the reflections were stronger than the 'direct' signal.

But, at that time I didn't do the narrow resolution BW measurement, and I'm now tempted to try again and see if I can find a direction that gets rid of that long delay interference.

Anyway, interesting discussion, thanks for the observations, Ron.

Peter
post #4967 of 10422
Kudo's to KRCB and it's Create channel for airing Barbecue University all day long yesterday. I thoroughly enjoyed it and thought it was most appropriate for the 4th of July. Good programming!
post #4968 of 10422
Quote:
Originally Posted by dr1394 View Post

However, that long of a delay suggests a geometry that should be easy to overcome with a directional antenna. That is, the multipath direction is either off to the side or behind the antenna.

Ron

Your comment got me to thinking about my multipath situation and just exactly where it's all coming from. I think when you're blocked to the transmitter but you receive strong reflections, that it's very difficult to overcome the problem.

Peter mentioned he was using a 91XG and I looked up that antenna on the HDTV Primer page to see it's pattern and compare it other UHF antennas.

http://www.hdtvprimer.com/ANTENNAS/comparing.html

The 91XG has the best pattern of any of the antennas reviewed. The response over the back 180 degrees or more of the antenna is running around -30dB in both the horizontal and vertical planes. No other antenna comes close.

In an earlier post Peter showed us the spectrum analyzer displays for KQED on the direct path and the reflected path. The latter was 10 dB stronger! I don't think it's surprising that even a 91XG isn't good enough to reject the reflection enough to allow reception. And who knows how many other peaks in reflections there might be.

I decided to take look at the Walnut Grove stations for signal strength on the direct path and rotate my antennas to look for other peaks. Walnut Grove is almost due west of here and I know from past experience that I have a lot of reflections from the east. There's a range of 3500' - 4500' mountains that span NE through SE of here. I've been up on one of the peaks with a battery operated TV and all the analog stations were very strong up there. I remember pointing my antennas in that direction and although the analog stations were strong, the pictures were completely scrambled. It was impossible to make out anything.

I'm using a pair of 91XGs as anything less simply doesn't work here. Here's what I got looking at the AGC value on my Sony plus the SNR value when on the direct path. (Lower AGC = Stronger signal)

Station - SNR - AGC Direct - AGC Back

KCRA - 19 - 24 - 24
KOVR - 25 - 24 - 24
KSPX - 29 - 23 - 25
KMAX - 19 - 26 - 28
KTXL - 17 - 37 - 33 (weaker than average)
KQCA - 26 - 27 - 34
---------------------------
KVIE - 24 - 26 - 25
KXTV - 24 - 25 - 25
---------------------------
KMMW - 31 - 24 - 38

I was stunned to see such strong signals coming from the east on most stations. Even worse though was that the lowest numbers stayed fixed with antenna headings from 60 - 120 degrees for all the Walnut Grove stations. That's 60 degrees of strong reflections while on the direct path the strongest signal was only over 10 degrees.

KVIE and KXTV are both VHF and for those I use a pair of ch 7 - 13 log periodics. I know the F/B on those channels is >20 dB.

I included data for KMMW since it's low power (250 w in my direction) and LOS. It acts like you expect for an LOS station, high SNR, strong signal, and comparatively weak in every other direction. The reading of 38 was only at one specific heading, much higher numbers in all other directions.

Peter could try a pair of 91XGs. That made a big difference for me but I wouldn't want to put money on that fixing his problem.

What people with lot of multipath need is an antenna that can reject all far off main lobe signals by around 40 dB. I don't know of any antennas that can do that.

Chuck
post #4969 of 10422
Quote:
Originally Posted by Calaveras View Post

I have a VIP622 and the OTA receiver is pretty much useless here. It's about 4dB worse in multipath handling than my Sony SXRD or Pal DVR. That means I can almost never receive KCRA on it.

(snip)

BTW, July 15th is rapidly approaching. Still no work on Sutro?

Chuck

I think you need a new Dish receiver! Mine has very good OTA receiver sensitivity... and pretty much matches the results I get with the DTVPal. The Insignia beats both of them though.

I took a walk by Sutro. They started working up there Friday, but as far as I can tell they haven't removed anything yet. KGO's antenna and a side mounted antenna... I suspect KBCW's... are laying on the ground next to the tower ready to go up.

Larry
SF
post #4970 of 10422
I'm still getting better signal strength on KVIE and KXTV from a reflection at approximately 257 degrees than I do from the direct signal. Only trouble is, it's not reliable. It varies a lot more than the direct signal.

The Sacramento/Stockton UHF stations don't seem to have any reflections that are strong enough to pick up. KMAX is the only one I receive 100% of the time here in San Francisco.

Larry
SF
post #4971 of 10422
Quote:
Originally Posted by Larry Kenney View Post

I'm still getting better signal strength on KVIE and KXTV from a reflection at approximately 257 degrees than I do from the direct signal. Only trouble is, it's not reliable. It varies a lot more than the direct signal.

The Sacramento/Stockton UHF stations don't seem to have any reflections that are strong enough to pick up. KMAX is the only one I receive 100% of the time here in San Francisco.

Larry
SF

How do you get KQCA(46) Larry? It's multiplexed on the same antenna as KMAX(21), but about 125kW less power. I'm thinking we're diametrically opposed. I get KQCA(46) great; it's one of my best stations, but, although I did recently get a brief lock on KMAX(21), it's not coming well enough for me.

I talked to Bob Hess, and he thinks it's the 91XG having a little lower gain in the lower end channels compared to the old 4228. That chart that Chuck put up earlier is the one I like to use for comparisons. I think Bob might be right.
post #4972 of 10422
Hello Everyone,

I currently have DTV with Sacramento locals for my area. I live in between Sacramento and San Francisco. But I would like San Francisco locals since I work in that area. I don't know too much about OTA besides antennaweb shows I need a "violet" marked antenna. I am in Fairfield, 94533 and it would be great if I'm able to get KTVU-2 and KRON-4. Any help would be greatly appriciated! Thanks!
post #4973 of 10422
As of Friday I was able to receive KTSF (Channel 26) with no problem with a Terk amplified indoor antenna for nearly a year. Since then the signal has changed from a steady reading in the 40s and 50s to a reading that bounces from the 60s to zero every few seconds, and the station is unwatchable. Has anyone else noticed this? What could be causing it? I use a DTVPal DVR (and have used it for about two months with virtually no problems with this channel). The only change - on Saturday we replaced our 20 year old Mitsubishi TV with a Samsung plasma. We do not use the tuner on the new TV and all of the other stations that we used to receive continue to work just fine. Oddly, KTEH is in the 90s, even though it broadcasts from Fremont and KTSF is in San Bruno. We don't have line of sight to any tower, but there is not much in the way (the houses on our street and our own house) as we are several hundred feet above sea level. Any thoughts would be appreciated. I have called and e-mailed KTSF. Also, it appears they may be operating at only 220 kW and have an application in for over 800 kW - but that is not clear. Thanks.
post #4974 of 10422
Quote:
Originally Posted by OaklandOTA View Post

As of Friday I was able to receive KTSF (Channel 26) with no problem with a Terk amplified indoor antenna for nearly a year. Since then the signal has changed from a steady reading in the 40s and 50s to a reading that bounces from the 60s to zero every few seconds, and the station is unwatchable. Has anyone else noticed this? What could be causing it? I use a DTVPal DVR (and have used it for about two months with virtually no problems with this channel).

I have a DTVPal DVR too and the lowest reading for a stable signal is 58. At 56 the "Low Signal" message appears. I'm puzzled as to how yours is giving a viewable picture in the 40's and 50's. I have seen times when a signal in the low 60's becomes unstable jumping from 0 to say 61 because of trees blowing about or other things causing rapid signal fluctuation. Something must be causing your signal to change rapidly but it's hard to say what that could be.

Chuck
post #4975 of 10422
Quote:
Originally Posted by DEEPFRINGEGUY View Post

Kudo's to KRCB and it's Create channel for airing Barbecue University all day long yesterday. I thoroughly enjoyed it and thought it was most appropriate for the 4th of July. Good programming!

I agree. Had it on all day with the sound off but closed captioning running so I could listen to music. I wonder what he does with all the food he grills. I'd like to drop in on him and do some tasting.
post #4976 of 10422
Quote:
Originally Posted by Calaveras View Post

I have a DTVPal DVR too and the lowest reading for a stable signal is 58. At 56 the "Low Signal" message appears. I'm puzzled as to how yours is giving a viewable picture in the 40's and 50's. I have seen times when a signal in the low 60's becomes unstable jumping from 0 to say 61 because of trees blowing about or other things causing rapid signal fluctuation. Something must be causing your signal to change rapidly but it's hard to say what that could be.

Chuck

Good point. I was using strength numbers from a converter box I used prior to obtaining the DTVPal DVR. I rarely checked the readings before this problem cropped up but I think they were usually in the 60s and stayed there, rather than this strange oscillation.
post #4977 of 10422
Quote:
Originally Posted by Nuz View Post

Hello Everyone,

I currently have DTV with Sacramento locals for my area. I live in between Sacramento and San Francisco. But I would like San Francisco locals since I work in that area. I don't know too much about OTA besides antennaweb shows I need a "violet" marked antenna. I am in Fairfield, 94533 and it would be great if I'm able to get KTVU-2 and KRON-4. Any help would be greatly appriciated! Thanks!

Have you looked at TVFool?

http://www.tvfool.com

I entered your zip code and it looks like a decent rooftop antenna should work but you should enter your exact address and antenna height for more accurate information. I'm pretty sure there are other people in Fairfield watching SF stations.

Chuck
post #4978 of 10422
Quote:
Originally Posted by Calaveras View Post

Have you looked at TVFool?

http://www.tvfool.com

I entered your zip code and it looks like a decent rooftop antenna should work but you should enter your exact address and antenna height for more accurate information. I'm pretty sure there are other people in Fairfield watching SF stations.

Chuck

Thank you Chuck! I'll check the site.
post #4979 of 10422
Can anyone explain this to me..

After the digital transition, KICU plans to relocate from channel 52 back to channel 36 with additional power. As a result, KTVJ will no longer be able to operate on channel 36 and will need to relocate to a different channel.

I thought Digital Ch 36 was on a diff frequency then Analog Ch. 36
post #4980 of 10422
Quote:
Originally Posted by DEEPFRINGEGUY View Post

How do you get KQCA(46) Larry? It's multiplexed on the same antenna as KMAX(21), but about 125kW less power. I'm thinking we're diametrically opposed. I get KQCA(46) great; it's one of my best stations, but, although I did recently get a brief lock on KMAX(21), it's not coming well enough for me.

KQCA is watchable about 50%-70% of the time while KMAX is watchable 100% of the time. I wonder why our results differ so much?

Larry
SF
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Local HDTV Info and Reception
AVS › AVS Forum › HDTV › Local HDTV Info and Reception › San Francisco, CA - OTA