GroundUrMast is correct. The only defense against a co-channel interfering signal is to use a directional antenna to favor the desired broadcast. Using the spatial selectivity of the antenna, you can increase the signal strength of the desired broadcast, and decrease the signal strength of the undesired broadcast, as seen by your receiver.
If you are not able to do this, then your receiver is going to be getting a mixed version of both signals, at which point, it might be impossible to separate the two.
Digital TV signals require a theoretical minimum signal-to-noise ratio of about 15.2 dB in order to just barely function. To avoid occasional breakups or signal loss, you need to have some safety margin above this (more is better).
Right now, you have WXMI coming in at around -59.6 dBm and DW19BA coming in at around -62.2 dBm (these are just estimates based on propagation modeling). This means that without any selectivity from the antenna, you are starting with only about a 2.6 dB SNR advantage for WXMI. The way analog and digital signal power is measured is different, so in reality, you more likely dealing with a true SNR somewhere between 5-9 dB.
To get the minimum 15.2 dB SNR or more, you will definitely need a directional antenna to suppress the detection of DW19BA. Sorry to say this, but I think your best bet really is to use a highly directional antenna on a rotator.
Quote:
Sidebar (for the technically curious)
Analog TV signal power varies according to what picture is being shown, and the FCC regulates their broadcast power according to the maximum ERP allowed. An "all-black" picture will cause an analog transmitter to send out the most amount of power, and an "all-white" picture will send out the least. An "average" picture will be somewhere in between.
Digital TV signal power remains roughly constant no matter what picture is being shown. Due to the differences in signal structure, the FCC regulates broadcast power for digital transmissions according to their average ERP.
Since analog broadcasts are processed according to their maximum ERP values, the calculated dBm values should represent an upper bound on the amount of signal power received. Digital broadcasts, on the other hand, have a nearly constant power output, and the calculated dBm values should represent the average signal power received.
|