# OTA Antenna Question



## leefarber (May 10, 2004)

Hello all,

I bit the bullet and orederd a 921 today to replace my 721. In advance of receiving the 921, I went out and bought a Zenith Silver Sensor indoor antenna that I intend to use for the OTA HDTV broadcasts (I live in an apartment in Los Angeles, so I'm keeping my fingers crossed that this antenna will suffice).

Just for the hell of it, I hooked up the antenna to the "TV ANTENNA IN" port on the 721. I was able to get a couple of channels, but it looks as static-y as my grandparents TV in Jersey did back in '79 (they didn't have cable, and were constantly adjusting the old "rabbit ears").

My question is this: is this indicative of what to expect when I TRY to get OTA HDTV channels once I receive the 921? Or is the 721 a totally different animal? I'm not worried as far as SD locals go, since I get those through the satellite, but it is important to me to be able to enjoy true HD. I'm totally ignorant of how antennas and OTA broadcasts operate, and now that "DTV" is thrown into the mix (as seen on antennaweb.org), I'm even more confused. If everything is working properly, should I be receiving SD broadcasts clear as day using the UHF antenna hooked up to the 721? And if I don't, does that mean I'm going to get lousy HD reception?

Thanks for being patient with a dumb-dumb.

Lee


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## oljim (Aug 6, 2002)

The 721 has no off air tuner and no reason to hook the ant to the 721 hook ant to TV and see how chs 14 and up look


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## xgrep (Aug 15, 2002)

oljim said:


> The 721 has no off air tuner and no reason to hook the ant to the 721 hook ant to TV and see how chs 14 and up look


True, but we can assume that the antenna signal was being fed through to the TV's antenna input, otherwise the possibility of seeing anything at all, static-y or not, would be zero! So if analog stations were coming in, but poorly, it's not likely they (or digital stations) would come in a lot better with the antenna connected directly to the TV's antenna input.

Now as to whether the 921 will be able to lock onto digital stations (and whether Lee was looking at UHF stations, which is what the Silver Sensor is designed to pick up) is another thing. In general, digital TV can work with a weaker signal than analog TV, but it's also more sensitive to multipath distortion - reflections off buildings arriving at slightly different times. In LA, multipath is probably going to be severe, and it's possible that reception of DTV will be very difficult, regardless of antenna. The Silver Sensor is moderately directional, so may be able to get some, but probably not all.

Please check to see how the Silver Sensor picks up analog UHF, and then let us know what happens when you try to receive DTV on the 921.

x


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## leefarber (May 10, 2004)

Thanks for the reply, X.

Actually, I fed the antenna through the 721's antenna port, which then passes directly out to the TV. I am dying to know what luck I'll have once I get the 921. It sounds like as of now, neither the 721 nor the Sony 34XBR910 have a digital tuner, so I can't receive DTV signals (even non-HD ones). When I get the 921, I'll see how the Silver Sensor handles the OTA HD broadcasts.

Basically, my apartment is on the 5th floor of a six story building, and it faces a courtyard. There aren't alot of tall buildings between me and the towers (LA isn't like Manhattan... most buildings are just a couple of stories tall), but I certainly don't have a clear line of sight (my dish is on a tripod on the balcony, and is JUST able to see the satellites... 119 much better than 110). From what I've heard, HD broadcasts are an "all or nothing" proposition, so either they will come in perfectly, or they won't. Guess I'll have to wait and see...


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## oljim (Aug 6, 2002)

Hook ant stright to TV input, no need to have cable from 721 to TV


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## Guest (Nov 12, 2004)

oljim said:


> The 721 has no off air tuner and no reason to hook the ant to the 721 hook ant to TV and see how chs 14 and up look


are you sure? my 721 has a tv antenna input and the book manual says it has one, and to use it the manual says you press the TV/VIDEO button, even though mine has never worked, as with alot of features of my 721


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## oljim (Aug 6, 2002)

You should use A/V cable and S cable from 721 to TV . No need for the RF cable


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## GoFish (Mar 30, 2004)

As stated it would be a more accurate comparison to connect the new antenna directly to the TV/connection vs. routing it though your 721 circuitry. Your 721 receiver tuners are not affected by the antenna signal (no OTA tuner in721). It's just a pass through for your TV. Viewing your signal strength while connected directly to your TV tuner will be a closer comparison to how it will look when connected to your soon to be delivered 921 receiver, since the 921 does have its own OTA tuner. Of course if your’ TV does not have a HDTV signal tuner I’m not sure that this will really be of much help in your assessment efforts.


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## Michael P (Oct 27, 2004)

The only reason the 721 has an OTA antenna "input" is for those set-ups that use the modulated ch 3/4 output (the worst choice for watching satellite - mono sound and NTSC RF artifacts). If you don't use ch 3 or 4 now, you did not even see the Silver Sensor's signal.

To echo earlier posts: Hook the "SS" directly to the antenna input on your TV!


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## TomCat (Aug 31, 2002)

xgrep said:


> ...if analog stations were coming in, but poorly, it's not likely they (or digital stations) would come in a lot better with the antenna connected directly to the TV's antenna input...digital TV can work with a weaker signal than analog TV, but it's also more sensitive to multipath distortion - reflections off buildings arriving at slightly different times. In LA, multipath is probably going to be severe, and it's possible that reception of DTV will be very difficult, regardless of antenna...


That's very true. Line of sight is the answer, and if you have that and a highly directional antenna you can normally cut through any multipath. From experience I can tell you that if you do not have LOS and are in a dense urban (lots of tall buildings) setting, even from 5 miles away DTV will be just a rumor. On the other hand, if you DO have LOS in such a setting, DTV can normally be received with no problem whatsoever, even through a narrow crack between buildings (but in that instance a highly directional antenna is important).

What xgrep says is true...if you generally have bad reception on analog OTA, you will likely have problems with digital channels. One distinction is that "static-y" can be interpreted as low signal (lots of video snow) or ghosty (lots of multiple images) or both. The distinction is important, because SNOWY analog OTA does not mean digital channels will be a problem, but GHOSTY analog OTA means you will have a serious problem.

If you can receive digital channels, they will be perfect. Generally there are three options, one of which applies to any given location...perfect reception all of the time, no reception at all, or if you are right on the edge, perfect reception marred by moments of digital breakup. Welcome to the "cliff" effect.

Antenna placement isn't as effective a strategy as with analog, either. With analog, sometimes you can find a node where multipath will be minimized, but with digital, you must have LOS, and at that point moving the antenna around from location to location really doesn't help much. IOW, if you try it from a single location and it doesn't work (highly directional antenna well-aimed with LOS) you're probably at the end of your options.

Incidentally, I get perfect 8VSB reception with the free antenna they throw in when you buy a FM receiver...a simple twinlead dipole with only 3 dB lobes basically attached to an inside window with packing tape. I'm 21 miles away from the towers, but I have perfect LOS. I haven't needed to, but if you try this and it works but one channel is not as good as the others, you can cut the length to optimize it to that frequency (they are normally optimized for 98 MHz...the center of the FM band).

BTW, while the Siver Sensor is a great antenna, it is not really all that directional and might not be enough for an iffy location. Check out antennaweb.org, which is a great place to start when considering an OTA antenna.


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## andrews (May 8, 2002)

You may not realize it, but turning on the receiver blocks the "antenna" in all the units I have worked with. Try turning off the unit. Are the channels still "fuzzy"?

I noticed that recently when I hooked up my 522s and use the built-in channel 3 output rather than my own multiplexer. When I had the receiver on, all the over-the-air channels were horrid. Turning the receiver off brought them back to normal. The unit must be masking the antenna signal when the unit is on.

The only case this would be good is for the channel the unit is outputting to. Otherwise, the unit should just pass the antenna signal through as well, but this appears not to be happening.

Does this make sense?

Brad


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## scooper (Apr 22, 2002)

andrews - See the TV/Video button on your remote ? when you want to watch OTA, pressing that once passes through the antenna signal, and pressing it again turns SAT back on. Just like the TV/VCR button on a VCR. Powering off your satellite receiver accomplishes the same thing.


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## andrews (May 8, 2002)

scooper said:


> andrews - See the TV/Video button on your remote ? when you want to watch OTA, pressing that once passes through the antenna signal, and pressing it again turns SAT back on. Just like the TV/VCR button on a VCR. Powering off your satellite receiver accomplishes the same thing.


I hadn't thought of that, but that would probably work as well. Still, they should only mask the antenna signal on the channel they are outputting on, not the whole spectrum. 

I just mix my modulator and antenna later in the process. This seems to work well for me and eliminates such problems. Though I would now like to find something to completely strip a channel from the antenna feed. 

Brad


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