I moved a week ago. I had Comcast in Maryland, with the 6416 box. Getting into the diagnostic menu, the signal always read ~21dB. The picture was good and I had already amplified it, so I never messed with it.

Comcast came out and set me up here in PA on Sunday. The tech did a good job setting me up through all of the cables, and the box had decent picture. I checked the signal, and again found ~20-21dB. The tech had split the cable four ways, so that meant a -7dB loss to the HD box. Figuring that the I could use the nice amp I had used at my old house, which also split four ways and gave a 7dB gain, I went ahead and swapped the splitter with the amp. The amp definitely got power, but the box signal still showed the same readings, ~20-21dB. The tech had another amplifer for the "rest of the house" down-stream of the four-way split, which claims to add 4dB, so I plugged in down there instead. The signal did not change.

So, I went anywhere from -10.5dB to +7.5db, but the box never registered any change, and the TV did not have any major variation in quality from what I could see...other then the added noise of running after two amps. Does the box only take in so much signal? What am I missing?

43 views, and no input?

I read your origional post and appeared to make sense that the Motorola units have a circutit to limit the incoming signal strengths so as to prevent overload of the digital tuner and therefore nonreception but I have no knowledge if that is actually true.
Also I have never seen any previous refrences of overload to any make/model of digital cable tuners.

....Getting into the diagnostic menu, the signal always read ~21dB....Which diag screen are you viewing? d04 INBAND STATUS? A digital channel is being viewed prior to entering the diag menu, correct?

To find out for sure it would be necessary to measure the signal level coming out of the cable before it goes into the box using a signal level meter (SLM). If you can't borrow one, maybe you could ask the next tech to use his to measure the signal level.

Sencore says you need to keep the digital signal level between -15dBmV and +15dBmV:

http://www.sencore.com/uploads/files/AchieveGoodHDTV.pdf

Which diag screen are you viewing? d04 INBAND STATUS? A digital channel is being viewed prior to entering the diag menu, correct?

Yes, d04. I tried it with digital, HD, and other channels.

To find out for sure it would be necessary to measure the signal level coming out of the cable before it goes into the box using a signal level meter (SLM). If you can't borrow one, maybe you could ask the next tech to use his to measure the signal level.

Sencore says you need to keep the digital signal level between -15dBmV and +15dBmV:

http://www.sencore.com/uploads/files/AchieveGoodHDTV.pdf

Well that makes me feel better. I have read that closer to 30dB is better, but obviously that was misguided. Thanks!

The prescribed -15dBmV to +15 dBmV range in the Sencore article, which is not very sophisticated, seems to be for broadcast 8VSB. FWIW, 64 QAM and 256 QAM usually need stronger signal levels and higher signal-to-noise ratios than does 8VSB.

Is it possible that your cable box is displaying the signal to noise ratio, rather than the signal strength? Signal to noise ratio is expressed in dB. Signal strength is commonly measured in dBmV or dBm.

The Moto boxes display signal to noise ratio, SNR, on the d04, INBAND STATUS, diag screen. My DCT6200 generally indicates "POOR" for less then 30dB and "GOOD" for greater than 33dB with "FAIR" falling in between. That screen also indicates uncorrectable and correctable errors. Any uncorrectable or high correctable counts will always result in video breakup.

In a general sense, if a number of channels, on different carriers, are exhibiting POOR SNR and high error counts, then I would suspect low signal level at the stb. If channels on a single carrier are exhibiting this problem with adjacent carriers not, then I would suspect the cable headend having a problem with that carrier.

The Moto boxes display signal to noise ratio, SNR, on the d04, INBAND STATUS, diag screen. My DCT6200 generally indicates "POOR" for less then 30dB and "GOOD" for greater than 33dB with "FAIR" falling in between. That screen also indicates uncorrectable and correctable errors. Any uncorrectable or high correctable counts will always result in video breakup.

In a general sense, if a number of channels, on different carriers, are exhibiting POOR SNR and high error counts, then I would suspect low signal level at the stb. If channels on a single carrier are exhibiting this problem with adjacent carriers not, then I would suspect the cable headend having a problem with that carrier.

It said "good" regardless of the setup, so I guess I am good to go. The picture was not bad, I just was not sure if it could be a bit better. Thanks for clearing it all up for me. :cool: