WOAI fades in NW SA

[DAndyRock]

Can someone with a better technical understanding of broadcasting explain a reception issue I have with WOAI-AM 1200?

I often here talk of the fact that WOAI can be heard all the way to Kansas at night etc etc, but why is it that during the day, I get pretty much static while driving on 1604 between Culebra and about Bandera Road. I do know that thier are some radio toweres out on Galm Rd which may have some impact, but I have expereinced similar problems along Portranco Rd between 151 and Culebra.

Am I just driving too close to the overhead electrical lines, or should I move to Kansas?

 

[eepstein]

As a former Kansas resident, I can tell you that with few exceptions, WOAI came in very strong late at night. I have also received WOAI relatively well in Colorado Springs, Phoenix, Tampa, Chicago, Twin Cities--I also would receive WOAI occasionally from my old college town of Turlock, CA (central valley). Im not sure why there are some reception problems in the SA area. Up here in the Austin area, it is clear as a bell night and day.

> Can someone with a better technical understanding of
> broadcasting explain a reception issue I have with WOAI-AM
> 1200?
>
> I often here talk of the fact that WOAI can be heard all the
> way to Kansas at night etc etc, but why is it that during
> the day, I get pretty much static while driving on 1604
> between Culebra and about Bandera Road. I do know that
> thier are some radio toweres out on Galm Rd which may have
> some impact, but I have expereinced similar problems along
> Portranco Rd between 151 and Culebra.
>
> Am I just driving too close to the overhead electrical
> lines, or should I move to Kansas?
>

 

[longhorns360]

> Can someone with a better technical understanding of
> broadcasting explain a reception issue I have with WOAI-AM
> 1200?
>
> I often here talk of the fact that WOAI can be heard all the
> way to Kansas at night etc etc, but why is it that during
> the day, I get pretty much static while driving on 1604
> between Culebra and about Bandera Road. I do know that
> thier are some radio toweres out on Galm Rd which may have
> some impact, but I have expereinced similar problems along
> Portranco Rd between 151 and Culebra.
>
> Am I just driving too close to the overhead electrical
> lines, or should I move to Kansas?
>

How long has this been going on? I have noticed that WOAI is sounding weaker than normal here in Austin.

That one tall tower I believe you are referring to on Galm Rd. is an FM site and wouldn't be causing interference at that range of frequencies nor would any other VHF/UHF sites.

Other AM single or multi-tower arrays will interfere, but you will have to be sitting on or in front of the property.

Yes, it could be interference from nearby aerial power/telco lines or other powerful sources of electrical noise.

 

[grantchester]

> > Am I just driving too close to the overhead electrical
> > lines, or should I move to Kansas?
> >
>
OAI's transmitter is at least 50 miles away, to the southeast.
There's an antenna farm for 1160, the former KENS radio on the northwest end of town. There could be ground-wave issues once you get up in the hills. Just guessing. Their little stand-by transmitter at 6222 I-10 might have been on instead of the big blowtorch near Elmendorf.
g

 

[radiotex2]

KRDY 1160 is located at Braun Rd and 1604. Their signal saturates everything in the area and does overlap onto 1200 close to the transmitter. Add IBOC hiss into the mix and you get reduced reception.

I live in this area and I used to have WOAI on my old clock radio so that I could listen when I was getting dressed in the morning. Not anymore. I can still get it early before sunrise just like I used to. But when WOAI fires up the IBOC OR KRDY switches to full power, bye bye WOAI. It seems it's been like this for about a year so I suspect that it is more IBOC related.

As for Austin reception, As dry as things have been the past few months ground conductivity is down. This is common in drought periods. Most of Austin's reception of SA AM stations is reliant on a good solid ground.

 

[longhorns360]

> As for Austin reception, As dry as things have been the past
> few months ground conductivity is down. This is common in
> drought periods. Most of Austin's reception of SA AM
> stations is reliant on a good solid ground.

Good point, I didn't think about that. Ground conductivity and terrain in Austin is normally trouble to even local reception anyway.

I agree that ‘OAI’s IBOC may be playing a role in the interference problems, but, your proximity to that 1160 array may be more of a problem. Since the AM IBOC mask has most of the ‘digital’ energy on the sidebands of 1200kHz, it may cause more problems for those folks trying to listen to 1160 and not 1200. Even then, 1160 is far enough away to be suffering from interference unless you happen to be driving east on I-10. Yes, there is evidence of WOAI causing interference to DX stations on 1190 or 1210.


The digital noise level at 1200 is well below the carrier. It is also possible that any multi-pathing may be exaggerated by the presence of the digital signal by when the carrier is null, the digital will fill it in.

 

[Doctor_Technical]

> OAI's transmitter is at least 50 miles away, to the
> southeast.

As someone who hails from the once-small town of Baton Rouge, *everything* in San Antonio seems at least 50 miles away

Good call on receiver de-sensing, but there is something else going on as well. Check out WOAI's omnidirectional pattern at
http://www.radio-locator.com/cgi-bin/pat?call=WOAI&service=AM&status=L&hours=U

Doesn't look very omni, eh? It was explained to me that the hinky groundwave coverage toward SA is due to the signal running into a conductivity break at the Balcones fault. I'm not so sure about the signal hitting Old Austin Highway and turning straight up, but we from South Louisiana know that localized conductivity changes (i.e. that big band of Yankee silt known as the Mississippi River) can cause AM reception weirdness.

Paul E. Burt, Chief Engineer
BMP Radio of San Antonio

 

[radiotex2]

> Doesn't look very omni, eh? It was explained to me that the
> hinky groundwave coverage toward SA is due to the signal
> running into a conductivity break at the Balcones fault. I'm
> not so sure about the signal hitting Old Austin Highway and
> turning straight up, but we from South Louisiana know that
> localized conductivity changes (i.e. that big band of Yankee
> silt known as the Mississippi River) can cause AM reception
> weirdness.
>
> Paul E. Burt, Chief Engineer
> BMP Radio of San Antonio
>
The Balcones escarpment does affect AM groundwave from San Antonio and always has. This is where 1200 always had an advantage with the Franklin. Still is unimaginable to me that they would switch to a conventional antenna. The skywave for WOAI was famous all over the northern hemisphere. I'll bet they lost alot of coverage after the change.

 

[longhorns360]

> >
> The Balcones escarpment does affect AM groundwave from San
> Antonio and always has. This is where 1200 always had an
> advantage with the Franklin. Still is unimaginable to me
> that they would switch to a conventional antenna. The
> skywave for WOAI was famous all over the northern
> hemisphere. I'll bet they lost alot of coverage after the
> change.
>

yep, as I recall, the Franklin was installed with the sole purpose of getting a city-grade signal into Austin. I believed it failed in noticeably improving Austin ground-wave coverage and instead the site was moved north to where it is now.

 

[Doctor_Technical]

> the site was moved north to where it is now.

Just to satisfy my own curiosity, can anyone point me to the location of the old main site?

Long before I moved here I got the impression that the site was still usable, perhaps with a simple 1/4-wave antenna. While driving down around Elmendorf I have found no likely candidates.

In December I heard what sounded like both signals on at once (clue being that audio from the IBOC is delayed ~5 seconds). Pretty spectacular, and I'm curious how they did it.

AFAIK the studio-site STL tower is no longer driven as a backup; when I visited there circa 2000 you could still see the cuts in the parking lot for the ground radials.

 

[daypart]

> yep, as I recall, the Franklin was installed with the sole
> purpose of getting a city-grade signal into Austin. I
> believed it failed in noticeably improving Austin
> ground-wave coverage and instead the site was moved north to
> where it is now.

If that's still a goal, wouldn't a simpler solution would be to move the transmitter and antenna north, say to San Marcos?

 

[TampaTV]

FYI- I can pick up WOAI here in Tampa at night!
<P ID="edit"><FONT class="small">Edited by TampaTV on 01/25/06 11:46 AM.</FONT></P>