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Discussion Starter · #1 ·
I'm located in the SF East Bay in Livermore, which is a fairly bad area for reception considering its in a valley. I've had the CM4251 up on my roof for several months now, and I get spotty reception from Sutro in SF. I was able to receive ABC and CBS from Sacramento quite well, but only Fox and KQED came in from Sutro with any consistency.


Last weekend I put up the CM4248 antenna, and while I still have a few problems on some channels, my reception was MUCH better than with the supposedly superior CM4251. I figure this is mostly due to the CM4248 being better able to handle multipath, but what I can't explain is that on some channels my signal strength actually improved with the CM4248.


I still have a problem with CBS out of Sutro, but it's also my very best signal strength, so I'm thinking I may need to install an attenuator to turn it down a notch.


I'm also using the CM7775 preamp, which is required with both antennas or my signals really drop off.


Those of you in the East Bay and Tri-Valley areas should try out the CM4248 before investing in the CM4251. It's more wife friendly, and a hell of a lot cheaper. Speaking of which....anybody in the Northern California area looking for a slightly used CM4251?? ;-)


Chris
 

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That is about the same results I got in my tests. I think the 4251 might work best on a 100' mast on a flat plain in the middle of nowhere, 100 miles from the transmitter, since it gets killed by multipath in the city.


Glenn
 

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Quote:
Originally posted by R8der:
I figure this is mostly due to the CM4248 being better able to handle multipath, but what I can't explain is that on some channels my signal strength actually improved with the CM4248.
By signal strength, I assume you mean the meter provided by your receiver. (What kind of receiver is it anyway?) I don't think that meter really means "signal strength" but rather "error rate" or something like that. Can anyone tell me what those receiver meters really mean? In particular, I have an Echostar model 6000 and I'd like to know what that signal meter from the 8VSB module really means so I can use it to adjust my antenna arrangement properly. The E* web site is no help . . . you can't find anything on their site about the 8VSB module other than a December press release saying that they released it.

 

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Discussion Starter · #4 ·
Engine-Ear:


Yes, I have it all on a rotor. I was thinking that might be kind of obvious since I'm trying to pull in signals from two completely different locations....Sacramento and San Francisco...;-)


I agree that the 4251 is much more sensitive when it comes to signal strength, as evidenced by the Fox signal out of Sutro being significantly affected by a one degree movement of the antenna. The 4248 doesn't require nearly as exact a placement....which is much more convenient...particularly for stability during recording when I'm not sitting in front of the set!


Dagman:


Yes, I mean signal strength of the receiver. I used the Hipix card for this comparison. I don't believe the strength meter is for error rate....I believe it is for how strong the signal really is thats being received. We all know a stronger signal doesn't mean a better picture....however....the stronger the signal received, the better chance you'll maintain a lock continuously and not end up with audio/video dropouts for the duration of a show.


When doing my comparisons, I moved the antennas one degree at a time to see if a different heading would create a stronger signal for one or the other antennas. I don't know about the other STB's out there, but the strength meter on the Hipix sure seems to jump around alot....within a range of 10 on each station (i.e. 71-81, 55-65, etc.). This also might have something to do with my reception location. I do have a very large eucalyptus tree directly across the street from my house that may be causing some of my problems.


Regardless of the problems I had prior....I have a much more stable platform now with the 4248. I'm glad I invested the $35 (plus shipping) to give it a try!


Chris
 
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