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post #14191 of 17914 Old 09-15-2016, 01:16 PM
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Well, my TERK HDTVa shifted a bit and KTVU VC 2 RF 48 was unwatchable at 2200 9/14/2016.

I see that it has taken two hits recently, September 15, 22016 at ~ 3 AM for 273873 missed packets and September 15, ~ 11 AM 314377 missed packets on Toast0's graph.

So I moved the antenna to the North East, the direction of KQEH RF 50 and KTVU RF 48.

With both KTVU RF 48 and KQEH RF 50 the Signal Quality % is shakily and there are dropouts.

EDIT: KTVU VC 2 RF 48 was mostly fine this Noon, a little worse at the end. KQEH VC 54 RF 50 continues to have more dropouts than I wish. Eyeball test later today.

Signal quality stays above the magic number 50 % most of the time for KQEH, I had hoped for perfect.

The fluctuations are numerous, trees moving or Airplanes?

---------------------------------------------------------------

The Reverse Auction Bidding is now at Round 5, 6, 7, 8, one post said perhaps into the next year. Times for up to Round 13 have been posted.

SHF

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post #14192 of 17914 Old 09-15-2016, 02:54 PM
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Originally Posted by SFischer1 View Post
The fluctuations are numerous, trees moving or Airplanes?

Trees: Pretty much a problem whenever the wind is blowing.

Airplanes: Stable reception most of the time with short periods (perhaps a minute at most) of instability.

Chuck
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post #14193 of 17914 Old 09-15-2016, 04:20 PM
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Trees: Pretty much a problem whenever the wind is blowing.

Airplanes: Stable reception most of the time with short periods (perhaps a minute at most) of instability.

Chuck
The South East Direction I tested before and got KTVU VC 2 RF 48 just fine has less trees.

The North East Direction has close tall trees and while the trunk is stable the limbs are moving more that any of the trees to the North West toward Sutro and right next to my CM4228HD. (Clear path to the North for the North East Direction close tall trees so the wind has a longer path.)

So, the North East Direction is unlikely to work for KQEH, back to the South East.

The trees close to my antenna and in the distance as normally not a problem. But one Noon KTVU and KPIX both were unusable due to the tall trees in the distance during a big wind storm.

https://www.avsforum.com/photopost/sh...hp?cat=2165469

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I still am trying to figure out the new (old) AVS photo albums.

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post #14194 of 17914 Old 09-15-2016, 07:03 PM
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The Reverse Auction Bidding is now at Round 5 6, one post said perhaps into the next year.
What is "perhaps into next year"? This reverse stage shouldn't last more than a month.

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post #14195 of 17914 Old 09-17-2016, 08:54 PM
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Hi Team, Am curious about what may be going on. I live in Pacifica and KRCB in Sonoma/Cotati frequently pixilates/vanishes on me. I love that station with all the cooking shows it has. What I am confused about is my Digiair pro meter on channel 23 shows absolutely no signal at all when measured at the antenna. The noise floor looks the same and on the surrounding channels at about 41.7DBmicroV and I don’t ever see a resolving signal pop up above this noise floor. But when I button up and scan for channels on my Tablo, KRCB gets picked up and the channel plays. It eventually pixilates enough to be annoying, and once in awhile reception is lost completely. (I have no splitters or amps playing with the signal after the antenna). Tablo says the channel is very good at 4 green circles what ever that means. So I am confused about how my meter does not detect it but the Tablo sees it and at least locks on it at least temporarily. Comments?
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post #14196 of 17914 Old 09-17-2016, 09:19 PM
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Originally Posted by j_iliz View Post
Hi Team, Am curious about what may be going on. I live in Pacifica and KRCB in Sonoma/Cotati frequently pixilates/vanishes on me. I love that station with all the cooking shows it has. What I am confused about is my Digiair pro meter on channel 23 shows absolutely no signal at all when measured at the antenna. The noise floor looks the same and on the surrounding channels at about 41.7DBmicroV and I don’t ever see a resolving signal pop up above this noise floor. But when I button up and scan for channels on my Tablo, KRCB gets picked up and the channel plays. It eventually pixilates enough to be annoying, and once in awhile reception is lost completely. (I have no splitters or amps playing with the signal after the antenna). Tablo says the channel is very good at 4 green circles what ever that means. So I am confused about how my meter does not detect it but the Tablo sees it and at least locks on it at least temporarily. Comments?
Please go to: http://www.tvfool.com/?option=com_wrapper&Itemid=29 and enter your exact address.

You will not be able to post the link so please change it so it just looks like text. We can figure it out. This is mine, your exact address is not shown.

xxxx__tvfoolish/?option=com_wrapper&Itemid=29&q=id%3de2cb4989f75b8 7

Your antenna type would also be helpful.

Pacifica has such varied terrain an exact TVFool report would be very helpful.

$360 meter??

SHF
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post #14197 of 17914 Old 09-17-2016, 09:57 PM
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Not sure if this is what you mean... Here is my information:

XXX_/?option=com_wrapper&Itemid=29&q=id%3de2cb3b582d36b c

Antenna = CM-4221HD Ultratenna 60 ->combined into a VHF dipole from amazon titled "VHF Retrofit Kit" to stablize my ch 7 &11.

-Eric
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post #14198 of 17914 Old 09-17-2016, 10:00 PM
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Not sure if this is what you mean... Here is my information:

XXX_/?option=com_wrapper&Itemid=29&q=id%3de2cb3b582d36b c

Antenna = CM-4221HD Ultratenna 60 ->combined into a VHF dipole from amazon titled "VHF Retrofit Kit" to stablize my ch 7 &11.

-Eric
Notice that the end of the link string has a space before the very last character. it should end like ...d36bc.

Not sure what caused the space between the b and c.

Thanks!
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post #14199 of 17914 Old 09-17-2016, 10:11 PM
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post #14200 of 17914 Old 09-17-2016, 10:46 PM
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Here is your link clickable:

http://www.tvfool.com/?option=com_wr...e2cb3b582d36bc

As expected, no better results than for ZIP 94044

KRCB is 2Edge which is bad news as the experts will tell you, usually no reception.

The only station LOS is KDAS-LP which is strange.

I am guessing that you have a hill / mountain to the North blocking Sutro and Mt. San Bruno (Sorry) but the signals are strong enough to be getting around it.

KRCB being further away is weaker and not able to get around as well.

As far as the difference between the meter and your Tablo, it's like my antenna installers $600 meter, I have a $90 ATSC tuner that gives better signal readings and proves that the station can be received. He did a great job pointing my antenna just by realizing what direction Sutro is.

Is your antenna cable RG6? My Stereo does just as well when the antenna is disconnected, well depending on what direction it is arranged.

SHF

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post #14201 of 17914 Old 09-17-2016, 11:45 PM
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Please be careful with the following.

Moving an antenna Up / Down, Back / Forward, Left / Right just two feet might produce better reception for KRCB.

Doing so on the top of a building may be very dangerous so make sure a helper is reading your meter, a readable signal level might appear if you are lucky.

And you may lose another station (or more) in a new position. It's the rules of multipath.

SHF
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post #14202 of 17914 Old 09-18-2016, 12:28 AM
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I went overboard on the cable and am using RG11. It is fatter copper with less loss for longer runs. Since my run is only 30 feet the advantage over using RG6 is about 0.3DB for at least 527mhz which may be helpful for on the fringe stations like KRCB.

Counting subchannels I am at 56 total. Of those, I receive 4 broadcasts that are rated 2Edge. FWIW, the LOS station only broadcasts at 40kw, is 68miles away, energy radiation pattern is away from me, and it being GOD tv, I am not crying over the loss.

Anyway, back to KRCB.If I understand you right, you seem to be saying that even extreme measures may not stabilize this channel. I guess I can accept that. Being able to rationalize why my meter shows no signal, but my tuner can lock on to it is the only thing that really bugs me.

Anyway, thanks for trying to help,
Eric
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post #14203 of 17914 Old 09-18-2016, 06:09 AM
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Being able to rationalize why my meter shows no signal, but my tuner can lock on to it is the only thing that really bugs me.
It's a limitation of your meter.

You can't see the signal because your meter is too noisy. If your displayed noise floor is only 41.7 dBuV (-67 dBm), you're about 40 dB shy of measuring the noise floor for ATSC signals (-106.2 dBm). The threshold for ATSC reception is in the -85 dBm vicinity with a ~15 SNR and assuming a 6 dB tuner noise figure. With a noise floor of only -67 dBm, your meter about 20 dB shy of seeing the weakest receivable signals.

The solution is actually quite simple. Install an appropriate preamplifier to extend the meter's noise floor deeper. The fun part comes from trying to balance the received signal powers so any strong local signals will not overload the meter's front end and cause incorrect readings.
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post #14204 of 17914 Old 09-18-2016, 08:45 AM
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Originally Posted by j_iliz View Post
I went overboard on the cable and am using RG11. It is fatter copper with less loss for longer runs. Since my run is only 30 feet the advantage over using RG6 is about 0.3DB for at least 527mhz which may be helpful for on the fringe stations like KRCB.

Counting subchannels I am at 56 total. Of those, I receive 4 broadcasts that are rated 2Edge. FWIW, the LOS station only broadcasts at 40kw, is 68miles away, energy radiation pattern is away from me, and it being GOD tv, I am not crying over the loss.

Anyway, back to KRCB.If I understand you right, you seem to be saying that even extreme measures may not stabilize this channel. I guess I can accept that. Being able to rationalize why my meter shows no signal, but my tuner can lock on to it is the only thing that really bugs me.

Anyway, thanks for trying to help,
Eric

How much of the time do you receive KRCB?

I looked at the terrain profiles for a number of your stations. It looks like getting your antenna up higher could make a difference. 12' is very low. Try rerunning TV Fool with the antenna higher to see if the Noise Margin goes up. If it does then going to a larger antenna (DB8 or 91XG) and a preamp would help.

I'm not sure what you're looking at for your LOS station. TV Fool shows it to be KDAS-LP at 20 miles and 15KW but it only has a 11 watts in your direction which is the reason its NM is so low.

Chuck
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post #14205 of 17914 Old 09-18-2016, 01:07 PM
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From Mapping Fool (DeLorme Topo North America 9.0)

Actually the path to KRCB does not look horrible from ZIP 94044.



SHF
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post #14206 of 17914 Old 09-18-2016, 03:22 PM
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Hi ProjectSHO89 - What I call noise floor is when I turn on the meter without being plugged into any source and note the channel in question. At this moment it fluctuates between 41.1 and 41.5. I understand these numbers can drift through the day.

Anyway, I only assume that when I plug into a source that if there is a signal there, the amplitude at that channel will rise higher than what I call the noise floor. Is this assumption not correct or are you saying a tuner is able to resolve signals embedded lower than what I am calling that noise floor value. Here is what I see when the meter is unplugged from any source. Ch 23 is where the channel should be found:


Hello Calaveras - I can see a watchable picture 95% of the time I call up the station until the time it starts to pixelate and die . After sleeping on this issue, I am wondering whether I am having problems with the San Francisco Fog. FWIW - My house has been in the fog for many weeks straight. Luckly, this morning we have clear skys and the channel is now seems to be very stable. But like I mentioned above, I am not seeing the channel resolve on my meter.

Either the channel is broadcasted on a different frequency, or ProjectSHO89 is right that my meter does not do a good job at detecting noise floors very well. This is what it looks like when I am scanning across all channels simultaneously: Note the vertical bar where the channel should be:
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post #14207 of 17914 Old 09-18-2016, 07:41 PM
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Originally Posted by j_iliz View Post
Hi ProjectSHO89 - What I call noise floor is when I turn on the meter without being plugged into any source and note the channel in question. At this moment it fluctuates between 41.1 and 41.5. I understand these numbers can drift through the day.

Anyway, I only assume that when I plug into a source that if there is a signal there, the amplitude at that channel will rise higher than what I call the noise floor. Is this assumption not correct or are you saying a tuner is able to resolve signals embedded lower than what I am calling that noise floor value. Here is what I see when the meter is unplugged from any source. Ch 23 is where the channel should be found:


Hello Calaveras - I can see a watchable picture 95% of the time I call up the station until the time it starts to pixelate and die . After sleeping on this issue, I am wondering whether I am having problems with the San Francisco Fog. FWIW - My house has been in the fog for many weeks straight. Luckly, this morning we have clear skys and the channel is now seems to be very stable. But like I mentioned above, I am not seeing the channel resolve on my meter.

Either the channel is broadcasted on a different frequency, or ProjectSHO89 is right that my meter does not do a good job at detecting noise floors very well. This is what it looks like when I am scanning across all channels simultaneously: Note the vertical bar where the channel should be:

For some reason the links to your images don't work.

All the data on DTV reception is in dBm so let me convert 41.7 dB referenced to 1 uV to dBm. That is -67 dBm. The weakest DTV signal that normally can be received is around -84 dBm. Your meter can't see any signal below -67 dBm. That's due to the fact it has a very poor noise figure. ProjectSHO89 is correct, it's your meter. Sounds like that meter is designed to be used with a cable TV system and not an antenna. Put a 20 dB gain low noise figure preamp ahead of the meter and you'll see KCRB on 23.

It's not the fog that's causing your reception problem with KRCB, it's the temperature inversions that allow the fog to form. The transmitter is on a mountain above the inversion and the inversion prevents the already weak signal from reaching you. Today there's an off shore flow along the coast which wipes out the inversion so your reception is good.

Did you try different antenna heights in TV Fool?

Chuck
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post #14208 of 17914 Old 09-19-2016, 04:40 AM
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Back in 2009 when I got bitten by this bug, I bought a used Sadelco signal meter off eBay. I don't recall the model number, but I do recall that its signal display range was limited to -23 dBmV (-71 dBm) on the low side which made it useless for very weak signals unless I used a preamplifier. I quickly upgraded to a used Sencore 1454 and resold the Sadelco. Still use the 1454 for my occasional projects and experiments. It features a displayed noise floor of almost -60 dBmV (-108 dBm) and it easily resolved signals just above the displayed noise floor.

Just relating my experience so you can see that I've BTDT, got the t-shirt when it comes to an inadequate piece of test gear.
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post #14209 of 17914 Old 09-19-2016, 04:23 PM
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Hi SFisher1 - What tool did you use to create the terrestrial map ? That is really cool. I did almost the same but with Google earth but it just does not look nearly as cool as yours. Anyway, your path is kinda close. A more accurate one would have the signal exactly ride the water line heading along Ocean beach along SF.

Calaveras & SFisher - I am wondering whether there is some kind of delay in the posting of pictures. Here in my office by (Frys/Lawrance)the pics appear fine on a different laptop and network as they do at home. Can you not see the images I posted up?

Calaveras - Can you recommend a source I can study related to transforming uV to dBm ? My meter runs from 42 to 862mhz and I don’t believe it is intended to be used in any cable applications. A more updated version of my meter is being sold by Amazon and is here: https://www.amazon.com/Solid-Signal-...ywords=digiair

Previous posts said that if I place a pre-amp at the UHF antenna I would be able to see Ch23 popup on my meter. Then I would be able to play games for max Ch23 reception in relation to the other channels. Great ! Am willing to try it.

What would happen if I permanently left the pre-amp in place for my final system? Would pixelation be minimized based on the attenuation induced by my transmission cable, or does the SNR remain the same because I would also be amplifying the antenna reception noise floor in relation to the actual signal?

I have not told anybody as of yet but my 12ft antenna height is due to this being an attic mounted system. Am not interested in having a roof mount.

BTW - can somebody recommend a solid pre-amp to me? I like buying quality if that means anything.

Thanks Again,
Eric
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post #14210 of 17914 Old 09-19-2016, 04:31 PM
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Back in 2009 when I got bitten by this bug, I bought a used Sadelco signal meter off eBay. I don't recall the model number, but I do recall that its signal display range was limited to -23 dBmV (-71 dBm) on the low side which made it useless for very weak signals unless I used a preamplifier. I quickly upgraded to a used Sencore 1454 and resold the Sadelco. Still use the 1454 for my occasional projects and experiments. It features a displayed noise floor of almost -60 dBmV (-108 dBm) and it easily resolved signals just above the displayed noise floor.

Just relating my experience so you can see that I've BTDT, got the t-shirt when it comes to an inadequate piece of test gear.
ProjectSHO89 - I feel honored to be following in your footsteps. Thank You for the BTDT experience for it saves me quite a bit of my personal time. I should be able to now waste my time elsewhere ! ;-)
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post #14211 of 17914 Old 09-19-2016, 04:53 PM
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Can you recommend a source I can study related to transforming uV to dBm ?
Present the query "convert dBuV to dbm" to Google and watch the magic!
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post #14212 of 17914 Old 09-19-2016, 05:14 PM
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Present the query "convert dBuV to dbm" to Google and watch the magic!
I did not mean my previous post to come off flippant in any way. I apologize if you took it that way.
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post #14213 of 17914 Old 09-19-2016, 07:02 PM
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Hi SFisher1 - What tool did you use to create the terrestrial map ? ...
"DeLorme Topo North America 9.0".

Smart Phones have taken over the World. At Target the other day I had to wait 20+ minutes while someone failed to pay with one. My Ice Cream melted.

Garmin has taken over DeLorme and I cannot find a link for Topo 10. All I can find is the offering with the PN-60 handheld hiking GPS which I have. $300 Others are offering Topo 10 for ~ $80.

https://shop.delorme.com/OA_HTML/DEL...?section=10460

----------------------------------------

Are using the insert Image icon? I add pictures to attachments and right click to get the shortcut.

https://www.avsforum.com/forum/43-for...mage-post.html

----------------------------------------

"attic mounted system." Do not pass "GO", do not collect ($20???). Go directly to JAIL.

Doing anything likely will not make you happy.

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post #14214 of 17914 Old 09-19-2016, 07:19 PM
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Originally Posted by ProjectSHO89 View Post
Present the query "convert dBuV to dbm" to Google and watch the magic!

Here's all you have to do:

dBm=-108.75 dBm + dBuV

In the case above:

-108.75 dBm + 41.7 dB = -67.05 dBm

Chuck
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post #14215 of 17914 Old 09-19-2016, 07:38 PM
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Originally Posted by j_iliz View Post
I have not told anybody as of yet but my 12ft antenna height is due to this being an attic mounted system. Am not interested in having a roof mount.

BTW - can somebody recommend a solid pre-amp to me? I like buying quality if that means anything.

Thanks Again,
Eric

You should have told us this. I would never recommend an attic antenna to someone with 2 edge stations. 1 edge maybe. The DTV system was designed assuming an outdoor gain antenna at 30'. An attic antenna puts you at a huge disadvantage. Unfortunately the antenna you need is dictated by what stations you want to receive, not where you want to place it. You're probably okay for the transmitters on Sutro Tower but not KRCB. If you want KRCB then an outdoor antenna with a preamp is a must.

TV Fool lists KRCB with a NM of 7.8 dB. Take a look at my article on Interpreting TV Fool Noise Margins and my comments for each level.

http://www.aa6g.org/DTV/Reception/tvfool_nm.html

I think my comments for the 0 to +10 dB level fits your experience exactly.

Chuck

Last edited by Calaveras; 09-19-2016 at 09:36 PM.
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post #14216 of 17914 Old 09-19-2016, 08:36 PM
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BTW - can somebody recommend a solid pre-amp to me? I like buying quality if that means anything.
I believe the best out there is the CM 7778. I've used one (actually I have 7777) for at least 15 years. It has been rated as one of the best available forever....

https://www.amazon.com/Channel-Maste...&keywords=7778

Bobby 

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post #14217 of 17914 Old 09-19-2016, 10:35 PM
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Hi Team, Am curious about what may be going on. I live in Pacifica and KRCB in Sonoma/Cotati frequently pixilates/vanishes on me. I love that station with all the cooking shows it has. What I am confused about is my Digiair pro meter on channel 23 shows absolutely no signal at all when measured at the antenna. The noise floor looks the same and on the surrounding channels at about 41.7DBmicroV and I don’t ever see a resolving signal pop up above this noise floor. But when I button up and scan for channels on my Tablo, KRCB gets picked up and the channel plays. Comments?
I also own the "Digiair pro". You may have the overload step attenuator on ... and not even know it .... Turn it off for true readings.
On a few rare occasions, I had to re-boot the analyzer. ... Plus it gets very hot after 2+ hours of continuous use.
It is actually very accurate.

I used to live near the Fairmont district of Pacifica back in the 1980s. From my memory there, KRCB and a few other stations had "fading" problems in about a 2 to 3 hour cycle.
Analog crystal clear one hour, snowy two hours later.
You can only lessen that impact with a maximum sized UHF only yagi-style antenna.

This is actually the worst time of year to be adjusting / upgrading your antenna.
The hot weather brings signal enhancement above "normal" reception conditions. Even wimpy antenna systems work now.
On a wind-less rainy day, reception should be near normal, and your meter readings should be true accurate.
You can find a outdoor elevation that works, lessen signal nulls, and gang antennas together, ..... with the analyzer.
You will sometimes find, the roof of a backyard shed, works better than the main house roof, ... for reception. Same goes for some "fence" or tree installations.

With a attic installation, ... expect weird results on UHF.
Such as simply walking below creates temporary multipath & dropouts only when you walk around, etc.
Usually I find it best if the antenna has a blue-sky path towards the transmitter. Hills within say 5 miles will create UHF reception problems.

Ben
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post #14218 of 17914 Old 09-20-2016, 04:40 AM
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The tip about the attenuator sounds spot-on. Didn't know the meter even had one.
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post #14219 of 17914 Old 09-21-2016, 01:52 AM
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I'm back from my two week trip to Europe. I had a great time, except for the day I was in bed with the flu.

The recent discussion on reception of KRCB was interesting. Here in San Francisco their signal varies quite significantly over the course of the day. Sometimes it's solid, while other times it's below the cliff edge. I was surprised that someone in Pacifica could receive it.

This afternoon I was scanning the channels and noticed the weird phenomenon again where 6, 10 and 31 were stronger than usual, but KQCA 58, which is usually the strongest station from Walnut Grove, was below the cliff edge. KMAX 31 was up to 26.5 dB SNR. Haven't seen it that strong in a long time. Even KOVR 13 was coming in at 19 dB and I almost captured 64. KQCA was just 13.5 dB. I wonder if the height of the antennas is causing this and the inversion layer is causing the signals of most to go up while 58 nose-dives. I not familiar with the height of each stations antennas up there.

Larry

My complete SF Bay Area DTV Station Lists: http://www.larrykenney.com/sfonair.html
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post #14220 of 17914 Old 09-21-2016, 08:27 AM
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Quote:
Originally Posted by Larry Kenney View Post
I'm back from my two week trip to Europe. I had a great time, except for the day I was in bed with the flu.

The recent discussion on reception of KRCB was interesting. Here in San Francisco their signal varies quite significantly over the course of the day. Sometimes it's solid, while other times it's below the cliff edge. I was surprised that someone in Pacifica could receive it.

This afternoon I was scanning the channels and noticed the weird phenomenon again where 6, 10 and 31 were stronger than usual, but KQCA 58, which is usually the strongest station from Walnut Grove, was below the cliff edge. KMAX 31 was up to 26.5 dB SNR. Haven't seen it that strong in a long time. Even KOVR 13 was coming in at 19 dB and I almost captured 64. KQCA was just 13.5 dB. I wonder if the height of the antennas is causing this and the inversion layer is causing the signals of most to go up while 58 nose-dives. I not familiar with the height of each stations antennas up there.

Larry

KMAX/KCRA/KQCA use the same antenna so the height is the same. I see the same variance in signal strength so it must have to do with frequency. KOVR, KTFK and KXTV are on the same tower with KOVR the highest, KXTV about 5m lower and KTFK about 15m lower still. The KTXL antenna is stacked on top of the KVIE antenna on a third tower.

I've always found it curious that KQCA is your strongest Walnut Grove station while KOVR is much weaker when it's exactly the opposite everywhere else that I've been able to check. I thought maybe it was just how it is in your general direction but that's not true either. Attached are the spectrum analyzer displays for KOVR/KTFK and KQCA in Walnut Creek showing KOVR 10 dB stronger there.

Chuck
Attached Thumbnails
Click image for larger version

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Name:	KQCA.gif
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ID:	1672953  

Last edited by Calaveras; 09-21-2016 at 08:30 AM.
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