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

Los Angeles, CA - OTA - Page 87

post #2581 of 9442
Interestingly, tonight's game (Wed) it started in HD with the announcers then switched to SD. Go figure!
post #2582 of 9442
Quote:
Originally Posted by andy.s.lee View Post

Attached is a plot for your location. The Mt. Wilson transmitters are within a 3 degree angular spread of each other.

Thank you for the plot map. Great info. Although I have some questions regarding that. So let me setup the first question. Here are the channels I receive without a problem (signal strength 80+ and no major breakups during bad weather)
KCBS
KTLA
KABC
KTTV
KLCS

Here are the stations that will break up a little in bad weather but mostly hang on to the signal.
KVCR
KCET
KOCE

Here are the stations that sometimes break up in good weather and all but dissappear in bad
KNBC - (The weakest of all)
KCAL
KCOP

Now I studied the plot that you attached and noticed that KNBC is broadcast at measly 296kW so I though perhaps that is why it comes in so weakly, however, KLCS is transmitted at an unbelievable 26kW and yet it comes in fine. On top of that KCOP is blasted at the highest kilowatt rating in the list 835 and yet I have a lot of trouble locking onto that signal. What could the explanation be for such erratic reception behavior?

My second question about the chart is what is Rx_dBm?
Quote:
Originally Posted by andy.s.lee View Post



Nope. That's another aspect of multpath that makes it such a challenge to clean up. Multipath is caused by the cumulative effects of attenuation, reflection, refraction, and diffraction of signals between the source and the destination. All of these properties vary with frequency (e.g., reflection coefficient on various materials will change as a function of wavelength). Although it's quite common for large solid objects to affect signals in a similar way (e.g., mountains, big buildings), there are many other multipath contributors that vary by frequency, hence the net sum at your antenna can be different depending on channel.

Self interference is only one of the side-effects of multipath. Another side-effect that engineers often need to contend with is fading. When multiple RF signals cross at a point in space, they may be in a state of constructively or destructively interfering with each other. This can cause narrow-band frequency selective dips in power, especially indoors or in urban environments. See Rayleigh fading on Wikipedia.

It suffices to say that when lots of multipath is around, it can have lots of detrimental effects, it is frequency selective, and it's exact behavior is unpredictable. These kinds of effects are nothing new nor unique to TV. These things also affect cell phones, GPS, WiFi, and a whole lot of other RF technologies we take for granted. The problem gets worse for indoor and urban environments and sometimes special measures must be taken (see Diversity schemes).




It is somewhat directional. It has a radiation beam width of about 60 degrees as seen here:


An example of an even more directional antenna is the Channel Master 4228 with a beam width of about 30 degrees as seen here:


In addition to beam width, another consideration is the front-to-back ratio (some antenna designs have narrow beam widths, but also have some gain going out the opposite side). This is another measure of how "selective" an antenna is. An antenna with very high gain in only one direction and very low gain in every other direction will have a better chance of picking out a specific transmission path.

A question about this antenna and my location. According to the chart I'm less than 30 miles from the transmission source and this antenna is very much a long range antenna. Is that going to be a problem?
Quote:
Originally Posted by andy.s.lee View Post

Rooftop is usually the best option. Signal strengths are usually stronger up there, plus you benefit by being above most of the multipath clutter caused by the buildings below. Once on the roof, it's also easier to switch to a larger, more directional antenna. When you add up all the benefits, it makes overcoming multipath a lot easier. Each situation is unique, so you might be able to do just fine with a more modest antenna setup.

The signal strengths in your area are quite strong, so your Silver Sensor may be a perfectly fine solution if you could just find the right location and orientation to make it work for all the channels all the time. If I were you, I'd start by experimenting with the antenna placed in different parts of the apartment or place it higher up. If you still can't find a satisfactory solution, then it might be time to consider something outdoors or more directional.

Having a signal meter is a luxury that is probably not necessary for the majority of situations (it certainly wouldn't hurt if you don't mind spending the money). They can help with aiming antennas at transmitters, however, most situations are forgiving enough to allow for a +/- 10 degree slop in the adjustment (most antenna beam widths are even bigger than this) without a problem. If a system is so close to the edge of working that a signal meter is needed to get it right, that means there's very little margin for error and there's a good chance that the system will stop working once the weather gets bad or something else causes the multipath environment to change.

Outdoors is real easy. The problem is that we insist on bringing our TVs, cell phones, and other wireless gadgets indoors and into urban environments (how silly of us ). Multipath is a fact of life and we just need to do what we can (refer to diversity link above) to make our gadgets work in these RF challenged environments.

I guess the silver lining is that at least with your TV, you have the option of only moving your antenna to an "easy" spot while leaving the main unit in a convenient location for you to enjoy. Just try doing that with your cell phone.

Best regards,
Andy

I'm guessing that this chaos of transmitting signals at different angles and different kW is due to the fact that every station must do their own transmitting. Makes me wonder if it is technologically possible to transmit everything from a single tower, at the same angle, same kW.

Thanks Andy.
Rudy
post #2583 of 9442
Quote:
Originally Posted by ilopezc View Post

@Titan local noise maybe?

Thanks everyone for helping me. I made a crude directional antenna, but this was only designed for the VHF not the UHF band. I'm able to pick up about 6 broadcast channels with CH5 the best looking.

I also got Radio Mobile working and made a map for my location + overlayed it in google earth.

Now the VHF (ie 79Mhz) may come in just fine, but isnt path loss become greater with frequency and distance? Also I ventured on my roof, and I have some very tall trees greater than 20 ft. So while the VHF may get reflected about so I can get a nice signal (but no ghosting). Im worried that the higher UHF frequencies will get attenuated.

Also, has anyone experimented with passive repeaters?

Can you explain how you made that second image, please. The DTV-SJC2.jpg.

Thank You.
Rudy
post #2584 of 9442
Quote:
Originally Posted by twelvepbrs View Post

Andy, thanks a ton for the info, i already have a jensen indoor antenna with an amp (which is pretty crappy from what i've read on AVS), picks up KTTV, KTLA, KCBS, but kinda iffy on KNBC, and KCAL. The antenna is about as high and as close to my patio window as possible, but there is a large tree right in front of it, so i'm thinking of getting a tv-tuner card, and moving the antenna to my bedroom where my pc is and just recording video, and then playing it back to my tv; the view towards mount wilson is much less-obstructed from my bedroom (no tree), i noticed that the image you posted has almost all of the stations with an azimuth of 88º-90º, should this directly correspond to a compass reading? because antennaweb.org showed that all the channels have a compass orientation of around 75º for me; is it safe to assume the general rule of higher is always better for the antenna placement?
also, and this is a question for everyone, do the local stations vary their broadcast power throughout the day? so far it seems like signals are stronger during primetime (unless this has something to do with the atmosphere in the evening)
I'm getting ready to get rid of my dig-cable since my apt comes with free basic, and there are clear-qam for the local HD's but they seem to change/go in-out everyday, so i wanna get my OTA situ setup before i dump catv

Remember I ended up taking my Silver Sensor outside onto the patio. It is still under the roof but instead of being behind the window it is now in front of the window.
You'll need lots of patience if you are planning on undertaking this antenna pointing business. Lots of patience.

Good Luck.
Rudy
post #2585 of 9442
Quote:
Originally Posted by jimcrow21 View Post

Don't know what she means by "KCAL 9 will be availible in HD as well." I'm guessing she means news, unless they plan to broadcast everything in HD like PBS, though that is practically impossible.

I believe you are correct. The KCAL/KCBS HD News studio is to be ready about then. So both channels news will be HD about then.
post #2586 of 9442
Hello,

I live in Costa Mesa (92626) and have just ordered DirectV HD. One of the staions I will be losing is "THE TUBE NETWORK" and am wondering if I can pick it up with an OTA. It is currently available on the afflilate station KTLA-TV5 Digital Tuner 5.5 but when I searched my zip on Antennaweb i did not see the station listed. Is anyone here getting this station and if so which OTA are you using or would you recomend. I live in a single story house with no trees, buildings or hills.

Thanks in advance.
post #2587 of 9442
Quote:
Originally Posted by Kiwijonesy View Post

Hello,

I live in Costa Mesa (92626) and have just ordered DirectV HD. One of the staions I will be losing is "THE TUBE NETWORK" and am wondering if I can pick it up with an OTA. It is currently available on the afflilate station KTLA-TV5 Digital Tuner 5.5 but when I searched my zip on Antennaweb i did not see the station listed. Is anyone here getting this station and if so which OTA are you using or would you recomend. I live in a single story house with no trees, buildings or hills.

Thanks in advance.

I live a bit north of you in North Orange County, but in an area with hills and tall trees between myself and Mt. Wilson. The Tube comes in blazing strong for me.

I have two different antennas working HD at my house. One is an RCA VR-75 on my roof for my main TV. In my bedroom I have a Silver Sensor that I finally got set to the right point and KTLA never comes in at below 90 on my signal meter for either television.

The Tube kicks ass. It's like the MTV of my youth, only without Alan Hunter and Nina Blackwood ruining the goodness that was Martha Quinn, JJ Jackson and Mark Goodman. Oh yeah, and a much better selection of music too.
post #2588 of 9442
Excellent. Yeah "The Tube Network" is very cool especially if you are 40+ in age. I am watching videos of some of my favorite music that I did now even existed.

Do you think I would get away with a Silver Sensor in my Attic?
post #2589 of 9442
Quote:
Originally Posted by Kiwijonesy View Post

Excellent. Yeah "The Tube Network" is very cool especially if you are 40+ in age. I am watching videos of some of my favorite music that I did now even existed.

Do you think I would get away with a Silver Sensor in my Attic?

I have mine on top of an armoire, but I've read of lots of people using it in the attic to help with multipath issues. Just make sure you take a compass up there with you to set it pointing in the proper direction and then hold it down with something like QuakeGrip or some other tacky substance. Otherwise you run the risk of the thing moving around and getting off target.
post #2590 of 9442
Quote:
Originally Posted by RudyG View Post

I'm guessing that this chaos of transmitting signals at different angles and different kW is due to the fact that every station must do their own transmitting. Makes me wonder if it is technologically possible to transmit everything from a single tower, at the same angle, same kW.

Thanks Andy.
Rudy

When you design antennas in close proximity, they not only interact due to perturbations of the
antenna patters, but can also have intermodulation and even overheating problems from all of that
off-frequency energy being crammed down a waveguide and INTO the output tube that were
designed for an optimized VSWR at some other operating frequency....OUCH!!!!

The CN-Tower in Toronto, Empire State Building and other similar structures were forced to
address these problems head-on:
http://www.lnl.com/esbantennas.htm
However, note that they end up being extremely tall, co-linear stacks of many individual antenna structures.

BTW: DTV Transmit antennas must have much closer control of VSWR and frequently use a receiver
to monitor the transmitter's output and automatically generate compensating correction signals.
This is needed since reflections up and down the waveguide act as additional multipath, degrading
your ability to receive the signal....esp. tuners built more than a couple years ago....

========================================
Here's some photos of the Mt Wilson antenna farm with multiple FM/TV/DTV antennas per stick:
http://www.well.com/user/dmsml/wilson.html
http://www.earthsignals.com/Collins/0035/index.htm
and another antenna farm about 1/2-mile south, lower down on Mt Harvard.

It's something that has slowly evolved over the past 60 years, although some stations share the same tower.
What, you expect these fierce competitors to actually cooperate????
post #2591 of 9442
Quote:
Originally Posted by holl_ands View Post

.....
What, you expect these fierce competitors to actually cooperate????

I suppose that would be one option. Another option would be for either you or me to build the Master Tower and then lease the signal transmitting services to the networks.

Rudy

P.S. By the way some great pictures there.
post #2592 of 9442
Andy, I live in area code 91007 and from antennaweb.org, looks like i am within 8 miles of transmission. I am using indoor Silver Sensor antenna, philips phdtv1, guess what, it picked up 30 channels at one point(all sorts of them), BUT it did not get ABC,FOX,CHANNEL13. Do i need to go with terk antenna(indoor) or the higher version from philips phdtv3??

Thanks
post #2593 of 9442
Quote:
Originally Posted by RudyG View Post

Now I studied the plot that you attached and noticed that KNBC is broadcast at measly 296kW so I though perhaps that is why it comes in so weakly, however, KLCS is transmitted at an unbelievable 26kW and yet it comes in fine. On top of that KCOP is blasted at the highest kilowatt rating in the list 835 and yet I have a lot of trouble locking onto that signal. What could the explanation be for such erratic reception behavior?

Most likely, it's because of multipath. One of the ironies of OTA reception is that sometime stronger signals makes things harder to receive. When you are close to a strong transmitter, your house and everything around it are swimming in strong signals. This actually increases the number and strength of multipath reflections that might reach your antenna.

It's a little like the way you should avoid turning on your high-beams while driving on a foggy night. You can sort-of see ok with low-beams, but switching to high-beams causes increased light scatter and actually makes things harder to see.

Since multipath varies with frequency, the hot and cold spots may be at different locations for the various channels. You might get a "weak" channel to become "strong" and vice versa by moving the antenna around or pointing it in a different direction. Keep in mind that the signal strength meter on your receiver is probably not really a measure of true signal "strength", but rather a measure of signal "quality". All the signals in your area are pretty strong, but some of them might be prone to worse multipath interference than others. If you are still having a hard time fighting multipath, then it's probably time to consider moving the antenna higher and possibly to the attic or roof.

The reason for the variation between broadcasters is mostly because of the choice of directional antennas they are using (there's no point pumping a lot of energy into the Angeles National Forest and the mountains behind Mt. Wilson). Most of the broadcasters are transmitting with similar total power levels, but due to the antenna selection and exact orientation of the main lobe of the antenna pattern, you'll see slightly different power levels being sent in your particular direction.

Even through 296 kW sounds like a lot of power compared to 26 kW, it's only about a 10.5 dB difference (in power, everything is on a 10*log10 scale), which is why you see the ~10 dB difference in the Rx_dBm column. The total spread of all the channels is not that much (~20 dB), so I don't think the variations in transmit power you're seeing will actually matter much. The fact that all the channels are quite strong (above -70 dBm) means that the small differences in channel power will matter even less.



Quote:


My second question about the chart is what is Rx_dBm?

That is the predicted field strength of the signal at a hypothetical point in space (your receive antenna's coordinates). Knowing the transmit power of each broadcaster, their antenna pattern, and their frequency, we can compute the estimated signal loss over the terrain and through the air to reach you. The results are converted to dBm units, which is something you might read directly off a spectrum analyzer when looking at these signals.

Since these estimates are for a virtual point in space, the actual signal reaching your TV tuner depends on everything in your "RF chain", including your antenna's gain, any amplifier gains, cable losses, splitter losses, etc. The plots will tell you what's "in the air", and it's up to you to fill in the blanks for everything between "the air" and your receiver.

Based on my own experiences and the feedback from others who have used these simulations, I would generally categorize channels as follows:

- Channels above about -70 dBm are very strong and there's a good chance they can be picked up with an indoor antenna (although indoors is the most vulnerable location for multipath interference)

- Channels between about -70 and -100 dBm are where signals are getting weaker and the antenna will probably need to move to a better location (attic or outdoor) in order to receive it.

- Channels below about -100 dBm are getting difficult to receive and are best served by a rooftop or mast mounted antenna.

- With high gain antennas (e.g., XG91, DAT-75, CM 4228) and a good installation (i.e., appropriate pre-amps, quality cables, etc.), it should be possible to receive channels down to about -110 dBm, give or take.

Of course, these are very rough estimates and every situation is different, so multipath, co-channel interference, adjacent channel interference, overload constraints, and a slew of other factors must be considered in order to understand the challenges facing any specific setup. The simulation software, the plots, and the tables are merely tools to help us make more informed decisions, but are by no means meant to be taken as gospel.



Quote:


A question about this antenna and my location. According to the chart I'm less than 30 miles from the transmission source and this antenna is very much a long range antenna. Is that going to be a problem?

I don't consider the Silver Sensor to be a long range antenna. It is directional, but the actual gain of the antenna is not that high. The antenna pattern plots are scaled to the highest gain point of the antenna, but do not actually show the total gain of the device. The Silver Sensor has a maximum gain of approximately 7 dBi, whereas an antenna like the CM 4228 has a maximum gain of approximately 16 dBi, which is more typical of what people think of as "long range" antennas.

In either case, I don't think there's enough gain in the antenna to cause any problems for you. The signals are indeed strong, so I would recommend that you DO NOT install any amplifiers in your RF chain. An amplifier could have overloading problems since it has to simultaneously amplify so many strong channels in the spectrum. Your tuner, on the other hand, should be fine with these power levels, since it only looks at one channel at a time, and any one channel's power is not high enough to cause any problems. Even a high gain antenna would not pull in enough signal to be a problem for your tuner.


Best regards,
Andy
post #2594 of 9442
Quote:
Originally Posted by csrini1 View Post

Andy, I live in area code 91007 and from antennaweb.org, looks like i am within 8 miles of transmission. I am using indoor Silver Sensor antenna, philips phdtv1, guess what, it picked up 30 channels at one point(all sorts of them), BUT it did not get ABC,FOX,CHANNEL13. Do i need to go with terk antenna(indoor) or the higher version from philips phdtv3??

See attached radar plot for analysis results.

My interpretation:

- KTTV (Fox) and KCOP are transmitting from just behind Mt. Harvard. Mt. Harvard actually blocks several of the Mt. Wilson transmitters, creating a shadow around most of your neighborhood. KTTV (digital on RF channel 65) and KCOP (digital on RF channel 66) are right behind the mountain, making it pretty difficult to receive. Since you only provided a zip code, I arbitrarily picked a point in the zip code for the simulation. You may get different results based on your exact coordinates and relationship to Mt. Harvard.

- According to the coordinates I happened to pick, KABC is not blocked and I would expect you to pick up KABC just fine. It should be very strong like the others, so you might be having difficulty due to multipath. You may be able to get this channel simply by moving your antenna around or pointing it in a different direction.



Since there is significant signal blockage in the area, you'll need to provide a more specific location to get more accurate results.

If the coordinates I used are pretty accurate, then I'd say that KTTV, KCOP, and possibly KABC are being blocked by Mt. Harvard. I would NOT change antennas. With this kind of blockage, I don't think you'll do any better with a different antenna. In fact, if you are really deep into the shadow zone, the only way you're likely to get these channels is with a rooftop antenna.

If you were just a couple of miles to the east, west, or south, you'd be out of the shadow and get all the channels, but with your current location, I'd say you're out of luck on a few channels. If you are willing to install a rooftop antenna, then you should be able to manage receiving a few more channels.


Best regards,
Andy
LL
post #2595 of 9442
Quote:
Originally Posted by andy.s.lee View Post

See attached radar plot for analysis results.

My interpretation:

- KTTV (Fox) and KCOP are transmitting from just behind Mt. Harvard. Mt. Harvard actually blocks several of the Mt. Wilson transmitters, creating a shadow around most of your neighborhood. KTTV (digital on RF channel 65) and KCOP (digital on RF channel 66) are right behind the mountain, making it pretty difficult to receive. Since you only provided a zip code, I arbitrarily picked a point in the zip code for the simulation. You may get different results based on your exact coordinates and relationship to Mt. Harvard.

- According to the coordinates I happened to pick, KABC is not blocked and I would expect you to pick up KABC just fine. It should be very strong like the others, so you might be having difficulty due to multipath. You may be able to get this channel simply by moving your antenna around or pointing it in a different direction.



Since there is significant signal blockage in the area, you'll need to provide a more specific location to get more accurate results.

If the coordinates I used are pretty accurate, then I'd say that KTTV, KCOP, and possibly KABC are being blocked by Mt. Harvard. I would NOT change antennas. With this kind of blockage, I don't think you'll do any better with a different antenna. In fact, if you are really deep into the shadow zone, the only way you're likely to get these channels is with a rooftop antenna.

If you were just a couple of miles to the east, west, or south, you'd be out of the shadow and get all the channels, but with your current location, I'd say you're out of luck on a few channels. If you are willing to install a rooftop antenna, then you should be able to manage receiving a few more channels.


Best regards,
Andy

Thanks andy for the quick response.
post #2596 of 9442
Thanks for the explanation about Mt. Harvard. I get all digital stations except KCOP which I do not get at all. However digital channels KCBS, KABC, and KTTV on a bad day might break up occasionally.

I previously got KCOP but one October, I believe in 2005, it suddenly stopped coming in. I was told that KCOP at that time moved their transmitter to be co-located with KTTV which is owned by the same company.

I live in a difficult OTA area but I have a chimney mounted Winegard 8200 UHF/VHF antenna with a Winegard 8275 UHF/VHF preamp.

Rick R
post #2597 of 9442
Quote:
Originally Posted by Rick_R View Post

Thanks for the explanation about Mt. Harvard. I get all digital stations except KCOP which I do not get at all. However digital channels KCBS, KABC, and KTTV on a bad day might break up occasionally.

I previously got KCOP but one October, I believe in 2005, it suddenly stopped coming in. I was told that KCOP at that time moved their transmitter to be co-located with KTTV which is owned by the same company.

I live in a difficult OTA area but I have a chimney mounted Winegard 8200 UHF/VHF antenna with a Winegard 8275 UHF/VHF preamp.

Rick R

If you provide specific coordinates and antenna height (you can send it via private message if you prefer), I can run an analysis for your location as well. Mt. Harvard should only be an issue for people living pretty close to the mountains like around Sierra Madre or Arcadia. You might be faced with a different kind of obstruction. Let me know if you're interested.

Best regards,
Andy
post #2598 of 9442
looks like ABC has started stretching the 6.30pm evening news, which looks just awful, in my opinion.

Dont they understand that if you wanted to stretch it, you can do it yourself, but you cant unstretch it???

I also find it hard to believe that anyone actually thinks it looks better like that!

If they feel like they must fill the widescreen, why dont they zoom/crop, preserving the original aspect ratio, instead of stretching and having everyone be fat and short?

rant over...

KABC - 818-863-7468

I tried calling, but this is now a fax#

anyone have current contact info for them, please?

Thanks
post #2599 of 9442
Would someone mind saving me several hours reading the first 43 pages of this thread and tell me what I should expect as far as OTA HD reception goes for my new condo. It's in Marina del Rey and has facing SW, so I can only see the ocean/marina and directly south. I'm guessing Mt Wilson is on the other side of the building...
post #2600 of 9442
Quote:
Originally Posted by benway View Post

KABC - 818-863-7468

I tried calling, but this is now a fax#

anyone have current contact info for them, please?

Thanks

Maybe we should send them some complaint faxes. Really wide ones.

KABC has never had true 4x3 on 7.1 though. They've been stretching (perhaps unintentionally) to 3x2 for as long as I've had access to HD. But you're right . . . looks like they've joined the nincompoops at KTLA in 14x9 land, and that's gotta be a deliberate act of sabotage by some management buffoon.

I'm deeply opposed to all distortion or cropping of 4x3 TV pictures. Hate it, hate it, hate it. Please, oh TV stations, leave them 4x3 when you upscale them. Or at least give us a true 4x3 option on a subchannel. Jeez.
post #2601 of 9442
Quote:
Originally Posted by benway View Post

looks like ABC has started stretching the 6.30pm evening news, which looks just awful, in my opinion.

I noticed that the other day and, like you, cringed! What are they thinking? Do they believe that it looks "good"? That people with short squat fat heads look good?

Tonight I could hardly contain myself, finally getting around to watching "America's Next top Model" from Wednesday night on my TWC DVR. Well first, it started about 7 minutes late because of some stupid basketball game (yes, that really bothers me... just as KTLK radio's preemption of progressive talk radio during basketball and hockey season because of Clippers and Kings games bothers me), so that the end of the show was not recorded. I now have to record/watch the last 10 minutes of Sunday night's rebroadcast.

But the real problem was that just like ABC, KTLA-DT broadcasts 4:3 SD content in 14:9 stretch-o'-vision!!! THIS SHOW WAS UNWATCHABLE! I wonder if Tyra knows the presentation was butchered here in LA like this?

These guys that run the networks, like TNT-HD, KTLA-DT, ABC-DT... do they really not watch the stuff they put on the air? What in the world is wrong with broadcasting in human-friendly 4:3 OAR??? It's not 16:9 content and they know it. Do they honestly believe with their own eyes that 4:3 stretched into 14:9 is good looking???

I am PISSED! I've written an email to the station manager, but who knows if it';; just fall on deaf ears (the same ones that actually put it on the air that way in the first place).
post #2602 of 9442
Quote:
Originally Posted by StephenMSmith View Post

Would someone mind saving me several hours reading the first 43 pages of this thread and tell me what I should expect as far as OTA HD reception goes for my new condo. It's in Marina del Rey and has facing SW, so I can only see the ocean/marina and directly south. I'm guessing Mt Wilson is on the other side of the building...

See the attached radar plot to see what's "in the air" at Marina Del Rey. Things would be easy if you could put the antenna on the roof. Otherwise, I guess you'll just have to try it and see how "transparent" the building is (to RF energy, that is).

Best regards,
Andy
LL
post #2603 of 9442
post #2604 of 9442
Threads merged.
post #2605 of 9442
re ABC stretch

try KABC-TV.MAYOR@abc.com

attn Cheryl Fair / News Director I wrote to her before when their 5.1 sound had no center channel.

or http://abclocal.go.com/kabc/story?se...nfo&id=1642694
post #2606 of 9442
Quote:
Originally Posted by andy.s.lee View Post

See the attached radar plot to see what's "in the air" at Marina Del Rey. Things would be easy if you could put the antenna on the roof. Otherwise, I guess you'll just have to try it and see how "transparent" the building is (to RF energy, that is).

Best regards,
Andy

Well, the roof is not an option. I'm hoping for a repeat of the indoor antenna miracle (for me at least) I got in my current apartment -- I'm completely surrounded by tall buildings and have no clear view of the sky in any direction. Yet I get everything that LA has in OTA HD just fine.
post #2607 of 9442
Quote:
Originally Posted by andy.s.lee View Post

If you provide specific coordinates and antenna height (you can send it via private message if you prefer), I can run an analysis for your location as well. Mt. Harvard should only be an issue for people living pretty close to the mountains like around Sierra Madre or Arcadia. You might be faced with a different kind of obstruction. Let me know if you're interested.

Best regards,
Andy

My problem is that directly in my line of sight to 35 mile away Mt Wilson is 2714' Rocky Peak that is 3 miles away. I have a Winegard 8200 UHF/VHF antenna with a Winegard 8275 UHF/VHF preamp. My antenna is 25' above ground level and my zip is 93063.

Rick R
post #2608 of 9442
Quote:
Originally Posted by Rick_R View Post

My problem is that directly in my line of sight to 35 mile away Mt Wilson is 2714' Rocky Peak that is 3 miles away. I have a Winegard 8200 UHF/VHF antenna with a Winegard 8275 UHF/VHF preamp. My antenna is 25' above ground level and my zip is 93063.

Based on the attached map, it looks like some parts of this zip code are shadowed and other parts are not. Using the zip code alone for the basis of a channel receivability analysis might give a false sense of what you can really expect to get. If you would like to evaluate your exact location and see just how "deep" you are in the shadows, I'd need a more precise coordinate. You can send that info via a private message if you want to keep it off the forum.

Best regards,
Andy
LL
post #2609 of 9442
I'm trying to add some OTA HD to my recent Dish HD upgrade. After reading forum threads for some time and checking antennaweb and Google Earth, I'm a little concerned about reception and which antenna to try first. GE shows a hill a little over 2 miles away that gets to just over 1000' while my house is at around 360'. Antennaweb shows no digital channels for my specific address but about a quarter mile south shows them all. If I put a decent antenna on the current mast it will be about 22' high. Zip is 92821 - cross streets Brea Blvd and Lambert.

I actually tried with current really old antenna and 300-ohm wire - couldn't get any HD channels other than 4.1 which dropped frequently. Any advice or experience with this area appreciated.
post #2610 of 9442
Quote:
Originally Posted by jammer13 View Post

I'm trying to add some OTA HD to my recent Dish HD upgrade. After reading forum threads for some time and checking antennaweb and Google Earth, I'm a little concerned about reception and which antenna to try first. GE shows a hill a little over 2 miles away that gets to just over 1000' while my house is at around 360'. Antennaweb shows no digital channels for my specific address but about a quarter mile south shows them all. If I put a decent antenna on the current mast it will be about 22' high. Zip is 92821 - cross streets Brea Blvd and Lambert.

I actually tried with current really old antenna and 300-ohm wire - couldn't get any HD channels other than 4.1 which dropped frequently. Any advice or experience with this area appreciated.

Jay,

See attached radar plot for the analysis of your location. Longer bars represent stronger signals. Details about each transmitter is listed in the table to the right.



My interpretation:

- The bad news is that you're definitely in the shadows of the hills above Rowland Heights. If you'll notice in the table under "Path", every single channel is either single or double edge diffracted ("1Edge" or "2Edge") as opposed to line-of-sight. The LOS path for most of the channels (see under "LOS_h") passes about 65 meters over your head! But not to worry... too much...

- Height helps, but there's no point in going to extremes (more expense, more trouble, slight improvement). I usually recommend going with a 10 foot pole on the roof using a chimney or tripod mount since that's about as much height as you can get with minimum effort. If you're able and willing to go higher, that's up to you.

- The semi-good news is that there are still a fair number of channels that should be receivable if you get a high gain antenna (e.g., Channel Master 4228, AntennasDirect XG91, or Televes DAT-75). You'll also want to get a low noise-figure pre-amp (e.g. Winegard AP-4700 or Channel Master 7775) in order to minimize signal loss due to cables and splitters. You'll probably be able to receive everything above -100 dBm (under "Rx_dBm") relatively easily and you may actually be able to receive things down to about -110 dBm, give or take. However, as you get close to the lower limits of the system, there will be less margin for variations and errors (e.g., bad weather, multipath, antenna movement, etc.).

- I don't recall off hand whether any of the current digital channels will be moving to VHF in the future, so perhaps someone else could check on this.

- A quad-shielded RG-6 cable is ideal, but standard double-shielded RG-6 should also work just fine if you include one of the pre-amps above. Having extra shielding only helps if you need additional noise immunity due to nearby RF emissions. If the existing cable is something worse, like RG-59, then it should be replaced. RG-59 is more lossy (although that shouldn't matter with the pre-amp) and is more prone to noise ingress.



Although your situation is a bit tougher than average, I still think that a well installed system will get you a good number of the Mt. Wilson digital channels.



I hope this helps. Good luck!



Best regards,
Andy
LL
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 › Los Angeles, CA - OTA