AWOS Power Output Reduction

[TWinter]

Our local airport just had the AWOS reworked with what they claim as new top of the line equipment, however, all of the local pilots including myself have noticed a BIG decrease in the reception. It is literally a radius of about two miles max. Today I was already setting up for landing when it finally picked up. Several of us have mentioned it to the FBO Manager and he said the FAA has recently mandated that the power output be reduced to a lower wattage (2.5 watts) compared to the old 4 watts.. Something like along those numbers. Apparently the FAA will be ordering a reduction in all AWOS transmitter output over a transition period of ? time.

Anybody heard of this? I really think this is a bad move..Altitude was not a big factor in the reception. Still very poor and nearly useless no matter how high.

 

-Tom

[takair]

Maybe this is the beginning of User fees.  To get more miles, we will have to buy premium service.  I had not heard of this and it seems like they did not think it through.  Wonder what the regs are?  This would be worthless in an IFR environment. Mi can imagine ATC asking to "advise when you get the weather".....we would have to request an overflight.  

[TWinter]

Just now, takair said:

Maybe this is the beginning of User fees.  To get more miles, we will have to buy premium service.  I had not heard of this and it seems like they did not think it through.  Wonder what the regs are?  This would be worthless in an IFR environment. Mi can imagine ATC asking to "advise when you get the weather".....we would have to request an overflight.  

They just finished working on it Friday. When I was on the ground departing Friday I thought nothing of it, other than the fact it was nice to have it up and going since it had been down most of the winter. The broadcast sounded different, but no big deal. When I was returning I flipped to our AWOS frequency and heard nothing at about 5 miles out..kept listening, getting closer and still nothing. I started checking my frequency thinking I might have hit a key and was off channel.  Finally as I'm announcing my inbound intentions and nearly to the field I finally start to hear the broadcast..It's useless as is. I am planning on calling the FBO City Manager tomorrow and following up. The FBO manager did send all the local pilots a email stating the AWOS was up and certified last week. He also mentioned the lower power settings per the FAA.

[RLCarter]

Doesn't sound right, even in a C-150 you wouldn't have enough time 1 mile out, IFR would be damn near impossible 

[carusoam]

What would be normal distance to begin listening to the AWOS?

I try to pick it up from about 20 miles away to be used in the next ten minutes.

Best regards,

-a-

[takair]

FAAs own AC 150/5220-16D says it should be good to 25 nm.

 

[TWinter]

Here is the email sent out..Something obviously not right.

Good Morning…

 

KDYR AWOS telephone service is now fully functioning.  Also, the new AWOS Radio broadcast has been tweaked to 2.4 watts increasing reception range about 20%.  The old AWOS wattage was almost 4 watts.  This has been reduced at all stations by FAA/FCC (???).

 

Just as a reminder, Summer FBO hours starting Monday April 3 is 7 am- 7 pm Monday-Friday.  Sat., Sun., and holidays 8 am-5 pm.

 

Thanks,

 

[carusoam]

Typical Mooney pilot response...

The antenna must not be connected properly.

Clean and reassemble the new broadcast antenna.

After that, José always knows the radio questions...

Best regards,

-a-

[RLCarter]

Current AC If management can't get it corrected give your FSDO a call

[N601RX]

I don't think the power being reduced from 4 to 2.4 watts would cause the range reduction that is being described. 

[N201MKTurbo]

So I found an on line field strength calculator and put in 2.4 W of transmitter power with an antenna gain of 2.4 db. I put in a distance of 10km and wrote down the field strength. I increased the transmitter power to 4 W and I had to increase the distance to 12.75 km to get the same field strength. 

So there is about a 27% increase in range going from 2.4 watts to 4 watts.

[1964-M20E]

Reducing  transmitter power output would not increase range but I'm just an electrical engineer and when asked one day how FM radio works I simply said freaking magic.

 

Class B ATIS I can generally pickup 60 to 80 miles out at most altitudes above 5000.  Smaller ATIS and AWOS stations generally 20 to 30 miles you can pick them up at 2000 AGL.  You should be able to pick up a WX broadcast at least 25 miles out so you can set up for the approach even in VMC. JMHO

 

 

[ArtVandelay]

Try disabling squelch and see if you pick it up from farther out.

[TWinter]

I've tried the squelch on the 750 and even kicked it over to the old radio and still not picking up any better. The email the FBO sent out was sent as a generic email to all local pilots even before I mentioned it. So it's not just me having the problem. I think they have had a few pilots reporting bad reception and short range. I'll be curious if it changes or they get the feds back out to check connections. I was actually more curious if any other folks noticed a reduction in range. Just an observation...I can live with it, I know something is not right, but thought it was worthy of a topic post.

 

-Tom

[Mooneymite]

Funny this topic would come up....there's an airport where I go to buy fuel.  It just got an AWOS, but it is so weak, I thought it was out of service until I got within about 5 miles of it!  I talked to the fellow who runs the FBO and he said, "Yeah, they've cut the output back".  I"m hoping this is just an antenna problem with the new AWOS, but maybe it's a systemic thing?

4 miles really isn't much range when you're making aeronautical decisions!  Some days, 100 miles isn't enough for me!  

[Bravoman]

When flying  down to St Augustine from Atlanta I can usually pick up KSGJ ATIS at well over 100 nm out if I am up at least 13k ft.

[thinwing]

This sounds like an Antenna miss match or connector problem.2.4 watts pep ground to air ,unobstructed line of sight 120Mhz should provide at least 10 mile range.Maintance needs to connect an SWR meter between antenna and output and look for greater than 2/1 mismatch

Edited April 5, 2017 by thinwing

[thinwing]

All it takes is a glob of elec. contact grease bridging center to shield

[Yetti]

A VHF signal from a 5 watt walkie talkie ground to air will go 20 miles easy.  2 watts should also go that far.

Sloppy install.  Probably the antenna coax.  Installers probably don't even know what a swr meter is.  Sometimes you actually have to tune the antenna to the frequency.

In the car antenna world this was done with a pair of bolt cutters to the antenna

The cut off part of the antenna sharpened made a great punch.

Lots of things forgotten from several summers of installing two way radios to put myself through college.

 

 

[thinwing]

8 hours ago, Yetti said:

A VHF signal from a 5 watt walkie talkie ground to air will go 20 miles easy.  2 watts should also go that far.

Sloppy install.  Probably the antenna coax.  Installers probably don't even know what a swr meter is.  Sometimes you actually have to tune the antenna to the frequency.

In the car antenna world this was done with a pair of bolt cutters to the antenna

The cut off part of the antenna sharpened made a great punch.

Lots of things forgotten from several summers of installing two way radios to put myself through college.

 

 

Plus that range is from a 1/4 wave rubber duckie on hand held with zero ground plane and human body counterpoise.Assuming at least a full wave vertical installed with good ground radials,20 mile ground to air nominal on a good install.Is this setup currently transmitting thru a dummy load?

[Yetti]

Doubt it would be a full wave.  That would be 48 inch antenna.  Probably a 5/8 wave.

Could be all sorts of things.  Coax to antenna.  I have replaced alot of coax and connectors to make things better.

 

SWR meter tells all.

Edited April 8, 2017 by Yetti

[thinwing]

468/fmz equals a 4 ft vertical ...pretty std for an airport awos

[tigers2007]

Verify the condition and quality of all antenna connections. Clean them with Deoxit D5 aerosol spray and then treat/brush on with Deoxit D100 (in the nailpolish style container). Both available from Amazon. This stuff works miracles. I use this on everything now. Keep in mind that even a single strand of the dense woven copper shielding will cause significant problems. Like The Yetti says - visually inspect ALL of the connections (even up at the antenna).


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[cliffy]

Only the FAA guys can get access to the ASOS stuff.  IIRC