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Discussion Starter · #1 ·
Has anyone compared multipath rejection performance of these two units in an actual situation with severe multipath?


I have the RCA and live 17 miles from the transmitter with an intervening hill, but get no reception (WCBS-NY). I believe multipath is the problem and am curious as to how the Sony will perform. (I'll probably buy one and try it.)
 

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A seldom used landing approach to Kennedy Airport is between my house and the NYC transmitters. Some of the planes hit the right spot to cause a momentary interruption on the DCT-100. I got the Sony expecting it to do better. It does not. In fact the result is worse, the RCA will freeze frame the video for up to 2.5 seconds until it recovers. The Sony goes black and the "searching for station" banner is displayed until it recovers.
 

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I just got the Sony,. I have a station here in Denver that I had to use an outside antennae to get,.. I got 40% strength at best(ABC), but the DTC-100 locks that station at 40%, and never breaks up. I tried to pull in the same station with the HD-100, the HD-100 said that it had it locked at 94%, but the picture kept breaking up. I even tried moving the antennae,.. but It still wouldn't lock. So, I think the HD-100's DTV strength meter is not accurate, and it has a harder time,than the DTC-100, locking in on stations. Your mileage may vary.
 

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AlanS,


We've corresponded before; I'm in Short Hills and share some of your presumably multi-path problems. I get CBS, but not reliably.


I'm probably purchasing a Samsung OTA-only STB soon. I'll let you know if it is appreciably better than the DTC100.


br

c
 

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Good afternoon to all:


I have been reading the accounts of the Sony HD-100 reception problems, plus other DTV reception issues.


In most cases, the problem is multipath (although the Sony's difficulty does sound like PSIP errors). You can get a strong signal on a receiver, but with multipath, there may be enough dropped data or data errors to prevent the signal from locking up.


I have conducted some experiments with home-made antennas and found that improvements can be made to just about all UHF antenna designs. One of my designs (18" long, 5 elements) was used to pick up the Fox-27 DTV signal in the basement of the Hyatt-Regency Hotel in Atlanta. This particular room was below ground. The receiver was a Sencore AT984. No preamp was used.


The antenna was placed on a chair, and twisted slightly from horizontal. Numerous attendees at this conference (DTV 2000) witnessed this test.


The original design was built with $10 of parts from a local hardware store and about 1.5 hours on the workbench. It's ugly (PVC pipe boom), but it works very well.


This isn't to say indoor DTV reception is possible anywhere. What it does prove is there's more room for improving antenna designs for DTV.


This morning, I used a Silver Sensor, a new Zenith receiver, and no preamp to watch two Philadelphia DTV stations in my basement. The transmitter site was 25 miles away. The basement area was below ground. The signals also locked up on a Samsung SIR-T150 tuner.


I have also found that a good preamp makes a big difference. There are several preamps out there that are marginal performers. The Radio Shack UHF cartridge preamp is one of 'em. Channel Master's Titan 2 7775 is a good design and not easily overloaded. I use several of them at home and in my office.


At home, with stock Channel Master antennas, I can watch DTV signals from over 60 miles away reliably on the Samsung tuner. The antenna is a big part of the equation, but it appears that antenna "science" is an overlooked art.


By concentrating on antennas - and the rest of the system, including preamp and coax - I can now watch 14 different DTV signals from home, using a standard antenna rotor.
 

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Kelvin,

I couldn't help but notice you used a "new Zenith receiver". Is that by any chance the DTV1080? If it is, how is it? Many of us would love to hear some info on this unit since it doesn't appear to be available as of yet. I've heard it has a new generation chip and should have better performance.
 

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Discussion Starter · #7 ·
Kelvin:


Could you please post the plans for your antenna. There are lots of DIYers out here.
 

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Can anyone recommend a good on-mast preamp for use with both VHF and UHF? There are several on the CM web site. (Tried to get a UHF-only CM 7775 but failed so decided to try for VHF As well.)


I am replacing an old (17 years) Blonder-Tongue galaxy that is still working but probably has seen better days. I don't get all DTV channels reliably yet and am only 30 miles from Sutro tower in SFO.



Bob Smith
 

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Discussion Starter · #9 ·
Yes, I remember Claude. How are you? We discussed your antenna prior to your having it installed.


I can't even get CBS, but I get Philly cbs-hd (3-1 or 26) pretty reliably!

As you and others can see from my post, I think multipath may be the problem, since if I can get Philly from 70 miles, I would think that the NY signal at 17 miles and similar power is out there despite the intervening hill.


By the way, I have found that a Radio Shack attenuator (suggested by Bob Ross) inproves the DTC's reception on ALL (and I mean ALL) channels when it is set to MINIMUM strength. Remarkably, this includes the Philly station. So, I think there is a real multipath rejection issue with these signals.


Stay in touch and let me know if you get Philly too.


(Hey, you have the Sony projector, don't you? Do you like it?)

 
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