RF Week: RF Day +1 (Day 5)

NP-G1.jpg
G1 Scan: BEFORE
RF - New G1 band
G1 Scan: AFTER

We were back at it again today trying to wrap up our campus RF transition. Today was a great education in RF courtesy of Luis Guerra, and the key phrase was Antenna System. Luis did some nice tweaks on all our antenna systems.

The photos here show a Before and After scan of our auditoriums in the G1 band. The scales aren’t quite the same and some of our frequencies have changed, but you can still see in the After scan that a lot of the low level RF noise that was present below the Digital TV signals is gone. This is because Luis adjusted are antenna system by lowering it closer to unity gain; the way we were running our antennas previously was too hot of a signal. When you look at the Before scan, the IEM signals are actually a lot stronger than the scan displays. By lowering the gain of our antennas, he was able to leave our signals at the same level while bringing down the underlying noise thus INCREASING our signal to noise ratio. We should actually be getting better performance now out of our antenna system, and if you are running powered antennas and never had the gain tuned I would suggest you do so.

Here’s another thing to think about it. If you put two transmitters close together you’re going to generate intermods between those transmitters. If the gain on your antennas is too high, you’re going to pick up a lot more of those intermods relative to the actual signals you want. This can come into play because typically it’s important to pay attention to 3rd order intermods, but a lot of folks will ignore the 5ths. If your antenna gain is too high, those 5th order intermods can actually be dangerous because their incoming signal levels relative to what you want might actually be equal or closer to equal. So get your antennas adjusted.

With the antennas adjusted, we spent the majority of the day programming everything on the campus that needs to run this Sunday. We had a small bump in there not being room for some of our in-ears, but we were able to negotiate a trade with KidStuf to swap some IEMs they had in another band. I left at the end of the day feeling pretty confident about things, but Sunday will still be the real test. I’ll be back with a final recap after Sunday.

David Stagl

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RF Week: RF Day +1 (Day 5)