Help with antenna selection in Wa?
 

Hi folks,

Here's my TV map: http://www.tvfool.com/?option=com_wr...60b56f2de6febd

Basically, I want to get the Vancouver stations from -9 to -16 NM dBm that are about 100 miles away.

Is that even possible?

Currently I have the V-shapped antenna, like from Radio Shack VU-190 or something pointed directly at those stations.

Before when they were in analog form, I could get channels 2, 6, 8, and 10. Now that they're all digital, of course I didnt expect to get them with my current setup since they are in UHF and their ERP is so much lower, though channel 43 CBUT is at 100kW.

The farthest I can get is channel 35 (12.1 KVOS) and KCBC 24 that is about 60 miles away.

I have RG 6 cable that is about 100 feet with combiners in between them serially.

Of course, I know I need to get an amplifier to eliminate the signal loss down stream...

So... back to original question.. can I get those channels with up to -16 NM dBm?

I read that the DB4 or DB8 has a gain of about 15 dbM, which would bring me to almost 0 dBm?

Or, that Lava 2605 (that famous 'get channels 150 miles away' advertising), where the spec they gave on their website is up to 30 dBm gain, which would bring me to +15 NM dBm.. is that for real, theoretically?

Another tidbit, that channel 22 with ERP 40 kW, on some days, my tuner would show a signal "blimp" for it, so that gives me hope that it faintly detects some signal with my current rig...

So , would a combination of amplifieri and new DB4/DB8 or that Lava 2605 antenna help me catch one or two Vancover stations?

I don't wanna move just to watch non-traditional TV.... :o

-Andrew

Tv Antennas and Reception
 

Read and understand about analog to digital transition of the USA and Canada , http://forum.tvfool.com/showthread.php?t=695 , http://www.tvtechnology.com/article/117022 , http://www.tvtechnology.com/article/105462 , http://www.user.dccnet.com/jonleblan...da_TV_stations. You can go to the forms of , http://www.digitalhome.ca , for update information. Also tvfool is being up dated. The pending applications that may not reflect the latest information shows , analog CBUT 2 , CHAN 8 , CHEK 6 . Digital , CHAN 22 , CBUT 43. In any event , if you will like to reach out for the Canada stations now or after the tvfool up date , at your location a Big Antenna will be needed. I recommend a Winegard HD7084P antenna or a Channel Master CM3671 and a Antennas Direct CPA-19 preamp. I recommend a dedicated antenna for the Canada stations.

Tv Antennas and Reception
 

You can connect a CPA-19 preamp to the VU-190 and see what can be received. Careful aiming of the antenna for Canada tv reception will help , turn the antenna to the left and right for the strongest signal. After reading the information about the Canada tv transition you now understand that Canada has a mix of analog and digital tv stations and will likely have for a long time in to the future. The complete tv analog shut down for the USA is 2015.

Yes, I understand about their switch to digital on Sep 1, 2011.

I even check out this site , which is fairly accurate:
http://members.shaw.ca/nwbroadcasters/tvpage.htm

.. that CM 3671 looks very similar to my current big antenna (though I dont know what its gain is).. I'm looking for the more compact and vertical one like DB4/DB8.

Also, my understanding about amplifiers is that it mitigates signal loss down the line to the TV, it does not "increase" the gain of the antenna itself, right?

Yes, I do understand those BC stations and which are digital (well most are, except for CHEK 6 analog on temp authority to stay there for the short future)...

Basically, with tvfool shows the direction of those stations I want and looking overlap with satellite map, I can see my antenna is pointed in that exact location.. of course I will adjust left and right ever slightly to be sure... for now basically I am fairly confident the channels I want are all UHF and digital (except CHEK 6)... and yes, I do intend to have dedicated antenna for those stations and another big antenna like VU-190 pointed south towards Seattle , which works all fine (I can get KBTC 27 just fine now with no pre-amp)...

As for that CPA-19... again, that only boosts signal downstream right, it does NOT increase my antenna signal gain, as I have read by another poster...

So, back to my original question... if theory if the channels I want is say at -15 dBm , and I find that DB8 can get me a gain of 16 dBm, say, then my net gain is 1 dBm, and with amplifier, the input to my TV should be 1 dBm, right?

.. But I read elsewhere that I need at input to TV about 8-9 dBm to get a digital lock on my tuner to get a signal, right?

Tv Antennas and Reception
 

The CPA-19 will keep what signal is received and increased buy the 'antenna (gain)' strong all the way to the receiver. Signal loss happens in the coax and splitters down stream from the antenna. The Canada stations are very weak. As for the shake out of what Canada stations will be analog or digital and what stations will be VHF or UHF , Well.

Tv Antennas and Reception
 

As for digital lock , +8 and +9 are good target numbers. Some tv tuners , Sony or Samsung , can get lock , down to -10 or lower -15 NM (dB). The FCC and industry target number is 0 NM(dB).

Where can I find this CPA-19 amplifier?

On Amazon.com the reviews for Motorola amplifier is pretty good, along with some others like Winegard (sp)....

Yes, I know the Canadian stations have low ERPs, typically less than 50 kW, whereas the US stations are like 800 - 1000 kW. There's a separate thread for that. I dont know why that's the case... Are they trying to save electricity? heheh. or discouraging Americans from picking up their signals across the border? Or encouraging their folks to ditch OTA and get cable instead? (heh)

I've got an older Sony HDTV CRT (2006?) that can't pick up channel 44.1, while my newer DTV converter box (Artec) can, using the same cable. Must be because this Sony was older, so I am guessing newer Sony tuners are more sensitive.

I wonder if there's a list of DTV convert boxes rated by tuner sensitivity, because I have a variety.

Also, this Sony TV can pick up channel 6 (CHEK) while it's still on analog with my current poor setup, but the picture is static as expected, but watchable.

Stay away from Lava antennas, all of them. Total snake oil.

Ya, at first I was wary of those Lavas.. Yet, if you go to Amazon.com and read the hundreds of reviews, lots of them are quite favourable. I think Lava gets 4 out of 5 stars...

I was quite surprised when I read them. Of course there were few a few reviews saying they are junk too...

But a few of the good reviews say that they picked up stations 80-100 miles away with those Lavas. Which is what I need/want for my situation. Of course, I dont expect them to get any stations beyond that (eg, 110-150 miles away).

So I'm not sure what to make of them... can't believe all those good reviews are "fake."

Is KFFV the only digital station that your Sony can't receive or does not not receive any? If KTTV is the only station that you can't receive, then lack of tuner sensitivity may be the reason. If you can't receive any digital stations, then the explanation is likely the fact that older wide screen TV sets did not have integrated ATSC [digital] tuners. If this is the case, the you need an external tuner or converter box like your Artec.

No, KFFV (44.x) is the only channel my Sony (yes, it's HDTV with ATSC tuner) can't get. All the other digital channels it gets fine like the Artec DTV converter box.

So, like I said, I suspect because it's an older Sony model, its ATSC tuner is not as sensitive as the Artec DTV converter box I bought in 2009 as US went Digital.

Is there a listing of newer HDTVs ranked my tuner sensitivity so I know which model to buy for my next TV so I can pick up those weak Vancouver stations (get a better chance of digital lock on low NM values as listed in tvfool)?

Well here's the deal with Lava antennas....

1) Lots of people are selling these things, so padding review sites is not unusual

2) Many glowing customers unknowingly are in strong reception areas, so even a paper clip stuck in the tuner box can get them 40+ channels of Free TV.

3) Plastic! The only thing plastic on an antenna should be an end cap for waterproofing. When you get into structural parts in the design, you can expect early failure. Weather and the sun will do a number on plastic, especially cheap polystyrene which these antennas are made of.

4) The earth's curvature makes 100-120+ mile antenna claims suspicious. You would need a very large antenna very high up with an amp to get reliable reception.


Stick to the big boys that have been in the business for decades, Winegard, Antennacraft, Channelmaster, Antennas Direct.

Well, in the analog days, I was able to pick up those 100-mile stations in VHF fine (albeit static, but watchable)... yes, I know VHF has a longer distance than UHF.. and they had high ERPs like 100-300 kWatt.

Now these new UHF stations have less than 50 kWatt, so it makes it that much harder.

My other choice was to get either the DB4 or DB8 or those Clearstream C4 or C5, that Amazon shows good reviews as well.

Hopefully Amazon has a good return policy, such that I would just be out my "shipping cost."

You can try Solid Signal: http://www.solidsignal.com/pview.asp...lifier-(CPA19)



Just a few general comments:

>> The US went through some adjustments after the June 12, 2009 analog shutdown. The ERPs for several stations were increased as they fine tuned their new equipment and tried to improve reception. I suspect there will be some adjustment period for the Canadian broadcasters as well. You might see some ERPs go up as a result.

>> VHF stations will almost always be limited to ERPs below 100 kW. Even 50 kW is considered to be quite powerful for an ATSC (digital) signal in VHF. UHF stations can go over 100 kW, and Canada already has several of them (going up to about 470 kW).

>> Even in the days of analog-only television, I think we saw the same relative difference in Canadian vs. US ERPs. If everyone is simply trying to maintain the same coverage as they had before, then any analog ERP differences would naturally translate into equivalent digital ERP differences.

First point:

Ok, just to be clear, the "gain" listed for this pre-amp is downstream to prevent signal loss from the antenna to RF input of TV, right? It does NOT increase the actual signal gain of the antenna itself, correct?

I mean... suppose I have a UHF channel listed here at -5 dBm. This pre-amp claims to have +17 dBm gain for UHF. This does NOT mean I will get -5 + 17 = +12 dBm signal at the antenna, right?

Also, if I buy this from that site, what's their return policy in case it just doesnt work for me... am I just out "shipping cost?"

Second point:

Yeah, I noticed that.. US stations analog in VHF in Seattle was like at 800kW (see my earlier link), but now digital stations in VHF are like 50kw or so.. that's fine..

My grip is why Can stations UHF are so much lower than US... US UHF digital stations I see like 500 kW, but theirs is like 40kW, though CBUT 43 is at 100kW which is nice.. wonder why the other Vancouver stations not at 100kw.. :0

You're on the right track. A preamp can overcome loss in the cable and splitters that are connected to the output of the amplifier. No amplifier can remove noise or distortion from a signal and in fact, all amplifiers add some noise and distortion to the signal. So, no amplifier can do the job of an antenna which is to recover enough signal of sufficient quality so that noise and distortion will not mask or 'bury' the signal.

Your math is correct but incomplete, or based on a misunderstanding. The signal at the output of the amplifier would be +12 dBm... I suspect that you are referring to the noise figure however. (-5 dBm would be an extremely powerful signal level and virtually all consumer grade amplifiers are incapable of delivering +12 dBm output.)

If you are looking at a signal with a predicted NM of -5 dB (not dBm), the noise figure of the amplifier would be subtracted from the signal NM. For an amplifier with a noise figure of 3 dB the math would be {NM(-5 dB - 3 dB = -8 dB)} which means that there would be 8 dB more noise than a perfect or near perfect receiver could work with. The amplifier makes the net NM worse, not better.

The solution is to use an antenna with enough gain to produce a signal with a positive NM. Antenna gain is better than amplifier gain. Antenna gain adds to the NM of a signal, amplifiers subtract from a signals' NM.

FWIW: Measurement in units of dBm are referenced to one Milli-Watt (1/1000 Watt) of power. Signal power is commonly expressed this way. Noise margin can be expressed in dB, with the zero level (reference point) being the minimum signal/noise that a perfect or very nearly perfect receiver could recover. Signal power and NM are two different measurements and the units used are unique to each.

There is a low level of electrical noise generated by every atom in the universe. When we are dealing with very weak signals, noise generated by random electron movement in the antenna itself become significant noise sources.

Keep in mind that analog (NTSC) signals NEEDED much more power to achieve a clear picture. They need a fairly high signal to noise ratio (say roughly a 27 dB SNR) to produce a clean (like VHS tape quality) image.

Digital (ATSC) signals can produce a clean (like DVD quality) image while using less signal power (roughly a 15 dB SNR).

The lower power of digital broadcasts does not make it harder to receive. The power was reduced to maintain roughly the same amount of coverage as the old analog systems. Since the threshold for reception has been reduced, it takes less power to get to that threshold. The high ERPs with analog stations was mostly out of necessity due to the spectral inefficiency of that signal format (developed in the 1940s and 50s).

In general, ERP is a bad way to look at station effectiveness because it does not take into account the signal type (ATSC vs. NTSC) and it does not take into account the frequency (high frequency channels require much more power than low frequency channels). For example, a 50 kW digital station on channel 7 will cover the same area as (actually even more than) a 5000 kW analog station on channel 51.

Yes, you're correct.. when I said signal of -5 dBm, I mean that's the NM value I get here in Tvfool when it shows channels for my specific location.

So back to my actual problem that I started for this thread.

The channels I want show up to -16 dB NM value. Then I need to find an antenna that is spec-ed/claimed to be +16 dB gain or higher , right so that I can get above the 0 dB threshold to get a signal lock?

That Lava antenna claims +30 dB gain (but not sure if they meant that is for the pre-amp gain and not the antenna gain itself).

The DB8 antenna I see in various sites show a gain of +16 dB, which would get me to this 0 dB threshold... but looks like I need more gain to get signal... would I have to string 2 DB8s together or something like that (would look unslightly)...

Ah, ok, got it... ATSC requires less power than NTSC...

And yes, I knew about VHF signals go further in distance than UHF, which is why I was disappointed to know that those Vancouver stations went from VHF to UHF.

For example, I was able to receive analog channels 6, 8, 10 ERPs like 200-300kW (fuzzy, but watchable) at 100 miles away with my current antenna system... now they are at UHF at 40Kw... So I am just disappointed that it will take another big antenna in any hope of receiving these signals.

But like I said in my earlier post, I had Artec DTV box and once in a while, I would see a "signal" blip in its signal meter on channel RF 22 (CHAN) at 100 miles and 40kw... and my location shows it is at -9.8 dB NM.

This gives me hope to pick up this channel somehow if the best GAIN UHF antenna (either DB8 or Clearstream 4?)

Closed or open loop?

Another question... I have an ohmmeter so I can measure the RG6 cable, the inside and outside shielding... Once I connect my RG6 cable to antenna leads via twin-lead to coaxial adapter, and I measure for ohms across the terminal of either the RG6 itself or directly on the antenna leads, is it open (infinite resistance) or closed (some ohm readings)?

Tv Antennas and Reception
 

http://forum.tvfool.com/showthread.php?t=1999. This can go on for ever. I will provide no more information

What's frustrating is now legitimate sites like SolidSignal are starting to sell scam antennas, shame on them.

If the prediction is 100% accurate, and if there is never any fading, and if there is no interference, and if you have a perfect receiver, then reception of a signal with a NM of -16 dB would require an antenna that has 16 dB of gain on the channel of interest plus the additional gain needed to overcome the noise figure of any amplifier used. That equates to antenna gain of 19 dB in theory (assuming a preamp NF of 3 dB).

In the real world, a 10 dB 'fade' margin is cutting it quite close. Engineering for a margin of 15 dB is not overkill by any means (IMO). So I'm suggesting an antenna with 29 to 34 dB of forward gain. (I know of no such antenna on the consumer or commercial market.)

Reception of a signal arriving at a NM of -16 dB is going to be impossible in some cases, unreliable in others. In a few cases, you'll get lucky and find that the prediction was off in some way.

It may be more practical to find a friend in Bellingham or Lynden who would allow you to operate a HTPC or Slingbox remotely.

Ya, I noticed that too on their website.

What's funny is that I can get CHEK 6 VHF analog and they show NM of -10 dB. Heheh...

As for that slingbox idea, yeah, I thought about that.. wonder why there's not a website that would do something like this? I guess it would be a copyright issue, huh?

I can still see a couple of analog Canadian stations here in Seattle. They're quite noisy (snowy). Analog kept working when the signal got weak. OTA DTV has quite a bit of forward error correction ability engineered into the ATSC standard so it looks perfect right up to the point where the receiver can no longer decode valid data. Digital signals are prone to that phenomenon, referred to as 'cliff effect' where, when close to the minimum, a slight decrease in signal to noise will produce a dramatic increase in error rate.

Wow... you're just down the road from me? Nice... Do you have any good recommendations for antenna installer? Or have you done any yourself?

Basically I'd like to do a J-mount (under-the-eave mount) so as not to alter the roof itself, plus I'm afraid of heights. ;)

The only BC station (lower mainland) that is still analog is CHEK 6 that I know of... the fact that you can get it in Seattle (maybe you live on Queen Anne hill).

Using consumer grade (priced) equipment, you best hope for seeing any signals from Canada would be an Antennas Direct XG-91, their CPA-18 or CPA-19 preamp, mounted on a 5' tripod + 10' HD mast at the roof peak.

I would expect that you would see some signals, at least intermittently, weather and atmospheric conditions would often rule.

Mounting at eave height would likely rob you of precious signal.

(From Canada, I now see only CHEK-6)

Sorry, I don't have a recommendation for antenna installers.

A while back you asked, It depends on the matching transformer design. Many will have low resistance from center conductor to shield. There are designs that appear 'open', virtually infinite resistance.

Bamboom http://bamboom.com/

http://arstechnica.com/tech-policy/n...n-new-york.ars

Thanks for the links! I'll check it out!:)

Just last night, I got a good signal on CHEK-6 (less snowy than normal).. so just for fun, on my Artec box, I scanned on BC's DTV 17, 22, and 26 and got a 'signal' blimp, meaning some signal on it... gives me hope!

Yes, I do intend to get that XG-91 model, that seems the best UHF gain antenna (they claim 16.7db gain) to pick up deep fringe , which is my situation.

Once I order it, I can do a quick test by just putting it in my 2nd story room and aiming it outside my open window and connecting it with a 6 feet RG6 cable directly to my TV tuner (hence no need for an amplifier just yet, since I really dont have any signal loss downstream)...

SO, here's the deal.. currently my antenna is mounted on a fence post about 12 feet high that bypasses a big tree towards the direction of those BC stations.

If I mount it on the house rooftop, the big tree (about 50-60 feet tall big tree) will be in direct line-of-sight of the house and the stations. d'oh...

.. so which is better? Lower height, no tree, or higher height, but big tree with leaves about 30 feet away?

Which mounting option is best... you'll need to try both to know for sure.

In the winter with all the leaves off the tree, I'll bet a cup of coffee on the shot through the tree.

It's funny. Using tvfool's map, I zoomed into my lot, placed my marker on my current fence post antenna at 10feet, and got CHAN to show at -6.8 dB.

Then I put the marker on my roof , about 30 feet high), and it shows CHAN at like -7.5 dB.

So, it's almost like better to keep it at my fence post antenna location than going on the roof the house... weird...

Also, I played with the height setting at the fence post location and if I set it to 20 feet, my dB when down to like -7.2 dB...

Weird, eh? Guess in *some* rare situation it's better not to have a higher antenna... oh well...

some of this "picking up signals" is an art-form and not so much science (though most is science and math). eheeh...

The mathematical model used by TV fool is only able to predict based on the information is has access to. It does not have an absolute picture of every tree, building, rock, etc. The terrain data is finite in resolution.

Yes, in some cases, you'll get better reception close to the ground. That's the exception, not the rule, in the real world. Simulation is a valuable aid but the real world is where it happens.

Per TV Fool:(Emphasis added)

Yup.. understand those points...

... next, I picked up what looked like a DB4 antenna off Craigslist. All the V-shaped elements are quite rusted. Given this antenna claims a -13 dB gain... with all that rust, how much gain did I "lose?" Maybe -5 db ?