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Discussion in 'DIRECTV HD DVR/Receiver Discussion' started by kevinturcotte, Feb 1, 2012.
Why can't they just make a super powerful omni-directional antenna? lol
Why couldn't they take something like this though: http://www.solidsignal.com/pview.asp?mc=03&p=DB8&d=Antennas-Direct-DB8-UHF-HDTV-TV-Bowtie-Antenna-(DB8)&c=TV%20Antennas&sku=853748001088 and just connect 4 of them together into 1 large antenna (With 1 output)?
Basically because they would cancel each other out, since there is no way to eliminate ALL the signal from coming in from the sides and back.
Now, you COULD use the same type antenna used to TRANSMIT the signal at the TV station, but they are about 30-40' tall, and weigh several tons. They would, however, give you the gain you are wanting, and are onmidirectional
Hmmm-wonder if my local NBC would notice if their's suddenly went missing? lol
They also have very narrow bandwidths, so you won't get many channels with one, even if you could afford it, cancelling out the advantages of it being omnidirectional.
If you have a $1000, you can buy one of these: http://rf-links.com/newsite/pdf/ap806.pdf
For $4000, you could stack them for onmidirectional coverage.
And for about the same amount of money, I could probably also throw up one of those 1.8 meter Hawaii/Alaska Directv's dishes and pretty much eliminate rain fade lol
You sort of have to understand multipath to get this. Multipath is identical signals coming from different directions at different times; something 8VSB abhors. When a TV signal bounces off a watertower or building, the main signal arrives earlier than the reflected signal, and the bits all mix together, flummoxing the decoder. It would be like two people saying the exact same thing to you, but one is delayed by a second or two, which means you might not be able to understand either of them. The decoder doesn't know if the bits it sees coming in are arriving in the proper order or not, and if they are mixed with reflected signal it can't tell them apart, and so loses the ability to decode.
The two solutions to multipath both rely on minimizing the reflected signals. Tuner technology does active EQ to find and suppress echoes, and antennae can be built to have directionality, meaning the signals reflecting from different directions will be suppressed.
If you take multiple antennae that are directional and simply combine them, what you are doing in effect is creating an antenna array that has less directionality than either of the two antenna components, and that is exactly what you want to avoid.
That is why combining antennae is always a compromise and must be done in very specific ways to be effective. There are ways to increase directivity by combining antennae in an array, spacing them a quarter wave-length apart, and pointing them all in the same direction. You also have to make the leads exactly the right length to get the signals to combine rather than cancel. But there is no way to pick up from different directions using multiple antennae without increasing the probability of more multipath interference.
I have an AM21 tuner that I bought in 2008 that I used to have hooked up to my H20 series receiver. That had the option of searching for the over the air channels.
Now I have an HR34-700, and an HR24-500 and I can't get either one of them to work with the AM21. How do you get it to search for the digital OTA channels? It just doesn't even recognize that I have it hooked up.
Any help is appreciated.
Have the AM21 disconnected from the sat box. Do a menu restart on the sat box. When it powers completely down (the front panel lights will go off), pull the AC plug from the wall. Plug the AM21 back in as required. Plug the power back in on the sat box. Let it boot up.
It should recognize that you have the AM21 connected at this point.
Go into Menu > Setup > Antenna Setup and configure the OTA setup with your primary zip code, etc.
You should be good to go after that.
The H20 had a built-in OTA tuner and did not use a AM21. Your current setup will not scan for channels but uses a database. Follow hasan's suggestions to get it going.
Great advice guys! Directions for hookup worked great!
My old receiver I needed the AM21 on was either an HR20-700, or an HR21-100, can't remember for sure.
Anyway, it works great now!
Really appreciate the help with this!