<html><head></head><body><div><br></div><div><br></div><div>On Fri, 2017-01-20 at 14:56 -0600, Craig Huff wrote:</div><blockquote type="cite"><div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Fri, Jan 20, 2017 at 12:57 PM, Gary Buhrmaster <span dir="ltr"><<a href="mailto:gary.buhrmaster@gmail.com" target="_blank">gary.buhrmaster@gmail.com</a>></span> wrote:<br><blockquote type="cite">A couple of quick thoughts:<br>
<br>
First, be aware that no consumer device is calibrated,<br>
so the readings are perhaps "in the ballpark", but not<br>
accurate. If you want accurate readings, you need to<br>
use a (calibrated) meter.<br>
<br>
As I recall, the specifications require the devices to<br>
support roughly -12 to +15 dBmV ("ideal" is 0dBmV),<br>
and to decode 256QAM at a CNR of at least 33<br>
(there is no limit, but in practice you do not see<br>
numbers more than around low 40's except in<br>
very tight plants).<br>
<br>
It is *strongly* recommended in practice to avoid<br>
being near the edge ranges of any of those numbers<br>
because real world plants have some variance<br>
(a few dBmV changes across the year is not unheard<br>
of). And since you are using consumer equipment to<br>
measure, it is even more important to stay well<br>
within the middle of the ranges.<br>
<br>
A high quality amp, and/or a high quality splitter<br>
(with appropriate cabling and connectors) should<br>
really not be introducing ~2dB SNR noise. And a<br>
high quality splitter is usually closer to -3.5dB<br>
than a 4.7dB loss. Whether is is an artifact of the<br>
measurement or the splitter/amp/cables is unknown.<br>
Something feels wrong there.<br></blockquote><div> </div><br></div>Gary,<br><br></div><div class="gmail_extra">My EE experience hasn't been near RF in decades, so it's all rusty, but yeah I agree with all you had to say. I just don't have anything better than the data the Ceton provides. I guess I'll try the splitter for now and maybe see if one from a Comcast customer service office is any better.<br><br>Most welcome would be the suggestion of a suitable amplifier (with or without a splitter incorporated) to use in place of the dinosaur that came from Radio Shack a couple of decades ago. Brand? Model? Vendor?<br><br>--<br></div><div class="gmail_extra">Craig.<br></div></div>
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</a></pre></blockquote><div><br></div><div>my knowledge is not much in this area, but having used a few different signal amplifiers, i get the best result with this:</div><div><br></div><div><a href="http://www.3starinc.com/aska_am-125_uhf_vhf_fm_22db_distribution_home_amplifier.html">http://www.3starinc.com/aska_am-125_uhf_vhf_fm_22db_distribution_home_amplifier.html</a></div><div><br></div><div>but i am using it for ota with 2 hdhomerun tuners and it is way better than the radio shack and channel master ones i used before. </div></body></html>