Quote:
Originally Posted by videobruce
Now, having said that, there is a fine line (almost literally) between just have tight a filter/trap is. Frequency and cost come into play. The 'math' is above my pay grade, but since I have 20+ years of tuning traps (as I call them), it's not just a 'art', but a major math problem. It's a classic case of "Robbing Peter to pay Paul" between attenuating an adjacent channel while trying to persevere the wanted channel. It really can't be done fully, it's all compromises.
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At the present time, are you able to receive 17 that is adjacent a much stronger 16? That would seem impossible for a TV tuner to handle.
Quote:
The receiver should meet or exceed the thresholds given in Table 5.2 for rejection of first adjacent-channel interference at the desired signal levels shown above the columns therein.
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Wouldn't it be difficult to design a filter to attenuate 16 without doing damage to 17?
http://www.tinlee.com/MATV-Bandstops.php?active=3
CR7-HT Series: Adjacent Friendly UHF Bandstop or Sharp Notch
CR7D-ch.# HT, CR7T-ch.# HT
Bandstop (CR7D-ch.# HT) “Adjacent Friendly” Rejection Filter
TV Bandstop available for ch.14 to 69, NTSC or ATSC
Highly Selective stopband with 20-45 dB attenuation can pass adjacent channel (3-4 dB loss at 1.5 MHz from stopband)
CR7D-HT contains 4 notches which can be combined for deep and wide notch or 4-6 MHz stopband. Example graph 2 shows video carrier notch, 1 Mhz wide. Example graph 3 shows 6 MHz stopband.
http://www.tinlee.com/PDF/CR7-HT%20s...info%20sht.pdf
Ignoring cost, would that work, or is there still too much difference in strength between 16 and 17?
Is there a filter design that would work better?