Quote:
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But I am curious if anyone knows why the reception is different during the day versus the evening.
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Although Fox and ABC have their antennas on the same tower at about the same height, their transmitting frequencies are different which can create differences in propagation. Other possible causes:
1. Temperature inversions
2. Fox antenna polarization is horizontal 1000 kW ERP; ABC is 1000 kW horizontal and 600 kW vertical
http://www.rabbitears.info/tvq.php?r...ms&facid=74137
http://www.rabbitears.info/tvq.php?r...ms&facid=56549
3. Trying to "split the difference" with antenna aim makes the received signal more susceptible to multipath reflections. The most favorable ratio of direct signal to reflected signals is when the antenna is aimed directly at the transmitter.
Switching to an antenna with greater horizontal beamwidth doesn't always work. Sometimes it is necessary to have a separate antenna for each direction for best results.
TiVo tuners are known to be more susceptible to multipath interference than TV set tuners as forum member
mulliganman found out with his Roamio. If your TiVo has a Diagnostics Screen, monitor not only signal strength, but also SNR and uncorrected errors when adjusting antenna aim.
thread:
question regarding overamplification
http://forum.tvfool.com/showthread.php?t=15025
posts:
before improvements
http://forum.tvfool.com/showpost.php...8&postcount=15
after improvements
http://forum.tvfool.com/showpost.php...6&postcount=21
His solution was to move his C2V to a better location where there were fewer multipath reflections and more direct signal.
4. ABC is on real channel 48, making it more likely to be affected by 4G LTE interference from cellular transmitters moving into frequencies previously used by TV transmitters in the channels above 51.
5. Your signals are extremely strong. If the attic loss is minimal, there is the possibility of partial overload which can create spurious signals from IMD (Intermodulation Distortion) in the tuner that can affect signals that are weaker than your strongest signals.
WCMH has a Noise Margin (outside and in the clear) of 73.6 dB before adding antenna gain; which is overload territory.
Interpreting Noise Margin in the TV Fool Report
http://www.aa6g.org/DTV/Reception/tvfool_nm.html
6. You have some strong local FM signals that
might interfere with TV reception.
http://www.fmfool.com/modeling/tmp/1...1/Radar-FM.png