RE: [HDTV-in-SFbay] Re: Longely-rice predictions for KGO, main vs. aux antenna
So KGO has a higher ERP from the lower AUX antennas. Interesting.
From: HDTV-in-SFbay@yahoogroups.com [mailto: HDTV-in-SFbay@yahoogroups.com ] On Behalf Of Bob
Sent: Thursday, July 02, 2009 1:44 PM
Subject: [HDTV-in-SFbay] Re: Longely-rice predictions for KGO, main vs. aux antenna
ERP is 72 kW on the KGO Aux antenna. ERP cannot exceed 500 kW on the UHF Aux antennas because there are five stations on each of the UHF Aux antennas.
--- In HDTV-in-SFbay@ yahoogroups. com , "Swank, Richard (NBC Universal, KNTV)" <Richard.Swank@ ...> wrote:
> KGO digital (Aux antenna) provides SF with the minimum power level
> required in the city of license but my guess is that the ERP might be
> even lower than 24KW and 700' lower on the tower. I would probably
> guess that those 1000KW ERP UHF units are not 1000KW on their AUX
> antennas either.
- I would guess that the directionality is what generates the added ERP. That is, they wanted the higher ERP for their service area because they were lower down on the tower, so they use a carotid pattern to achieve increased ERP with the same transmitter PEP. That way they don't have to buy a bigger amp/transmitter for their auxiliary setup.
I'm not an expert on high powered VHF transmitters, but I would still be surprised if it would make sense to design one that you would need to increase transmitter power significantly when you wanted to use the auxiliary antenna.
--- In HDTV-in-SFbay@yahoogroups.com, "Swank, Richard (NBC Universal, KNTV)" <Richard.Swank@...> wrote:
> Must be at the lower AUX antenna center of radiation there is sufficient
> shielding by the terrain to allow a higher ERP in some directions.
> If there was no interference issues caused by them going to 75KW at the
> lower level they would not have had to go directional? To the west is
> not the problem. There may have been an antenna physical limit issue so
> they went directional to obtain a higher gain antenna at the center lobe
> and enable them to keep the transmitter power the same or near the same?