Two nearby ASOS broadcasts on the same frequency: Why no squeal?

For some reason known only to the FAA, both Dunkirk, NY (KDKK), and
Wellsville, NY (KELZ), two small, uncontrolled airports in southwestern NY
state that are about 60 nm apart, share the same ASOS frequency.

For pilots flying to Dunkirk from the east, retrieving the current ASOS
broadcast is not possible until about 25nm east of the airport, due to the
more powerful KELZ broadcast. This is not so much a problem when
conditions are VFR, but when they are IFR I prefer to retrieve the ASOS as
early as possible in order to choose and prepare for a particular
instrument approach.

In any case, I am curious how it is possible for two transmissions to be
heard over an aviation frequency without the squeal (I forgot the
appropriate technical term for this).

--
Peter
























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Peter R. wrote:
For some reason known only to the FAA, both Dunkirk, NY (KDKK), and
Wellsville, NY (KELZ), two small, uncontrolled airports in southwestern NY
state that are about 60 nm apart, share the same ASOS frequency.

This is a classic situation to file a ASRS form.
Use this form to get action. It does work.

john smith wrote:

Peter R. wrote:
For some reason known only to the FAA, both Dunkirk, NY (KDKK), and
Wellsville, NY (KELZ), two small, uncontrolled airports in southwestern NY
state that are about 60 nm apart, share the same ASOS frequency.

This is a classic situation to file a ASRS form.
Use this form to get action. It does work.

After five months of flying to Dunkirk every Monday, I am ashamed to admit
that it finally dawned on me last week to do this.

Interestingly, I asked Buffalo Approach, who controls approaches into
Dunkirk, if anyone else had complained that it is not possible to retrieve
the ASOS from the east until very close to the airport because of the
Wellsville ASOS sharing the same frequency. The controller responded that
no one had mentioned this before.

--
Peter






















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Peter R. wrote:
For some reason known only to the FAA, both Dunkirk, NY (KDKK), and
Wellsville, NY (KELZ), two small, uncontrolled airports in
southwestern NY state that are about 60 nm apart, share the same ASOS
frequency.

For pilots flying to Dunkirk from the east, retrieving the current
ASOS broadcast is not possible until about 25nm east of the airport,
due to the more powerful KELZ broadcast. This is not so much a
problem when conditions are VFR, but when they are IFR I prefer to
retrieve the ASOS as early as possible in order to choose and prepare
for a particular instrument approach.

In any case, I am curious how it is possible for two transmissions to
be heard over an aviation frequency without the squeal (I forgot the
appropriate technical term for this).

They might just be lucky in that their transmitter oscillators happen to be
so closely matched that the beat frequency is subaudible. Good old AM
modulation!

"Peter R." wrote in message
...

For some reason known only to the FAA, both Dunkirk, NY (KDKK), and
Wellsville, NY (KELZ), two small, uncontrolled airports in southwestern NY
state that are about 60 nm apart, share the same ASOS frequency.


What makes you think it's known only to the FAA? Whatever the reason, I
would expect it to be known to the FCC. In fact, it may be better known to
the FCC than the FAA.

It's probably because there isn't another suitable frequency available.

"Steven P. McNicoll" wrote:

What makes you think it's known only to the FAA? Whatever the reason, I
would expect it to be known to the FCC. In fact, it may be better known to
the FCC than the FAA.

Remember the time not so long ago when you used to post meaningful answers
to poster's legitimate questions? I recall a few years back when even I
received some genuinely helpful advice from you.

These days it seems you respond for no other reason than to exercise your
extremely dry and bland wit.

It's probably because there isn't another suitable frequency available.

And why, assuming you can even take my question seriously, would there not
be a more suitable frequency available in a relatively quiet part of the US
(about 7 or so ASOS-equipped, uncontrolled airport in a 60nm mile radius)?

Of all the candidate ASOS frequencies (below 121.75 or so, perhaps?), what
would cause the FAA to choose the same one for two nearby airports?

--
Peter
























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Of all the candidate ASOS frequencies (below 121.75 or so, perhaps?), what
would cause the FAA to choose the same one for two nearby airports?

For that matter, why do Long Island's Easthampton and Montauk have the
same CTAF? (16nm apart) That's a real pain in the arse on a busy
weekend day... or under IFR... I know there are only so many freqs
available - maybe make MTP's PCL freq the CTAF? Just my .02

When airports are really close together its a good thing to share
CTAF frequencies... so you know what's going on at each place because
the airspaces basically merge. You really appreciate the situational
awareness.

There is a point though, when traffic is very heavy that it becomes
detrimental.

wrote:

Of all the candidate ASOS frequencies (below 121.75 or so, perhaps?), what

would cause the FAA to choose the same one for two nearby airports?

For that matter, why do Long Island's Easthampton and Montauk have the
same CTAF? (16nm apart) That's a real pain in the arse on a busy
weekend day... or under IFR... I know there are only so many freqs
available - maybe make MTP's PCL freq the CTAF? Just my .02

Recently, kontiki posted:

When airports are really close together its a good thing to share
CTAF frequencies... so you know what's going on at each place because
the airspaces basically merge. You really appreciate the situational
awareness.

While that may be true of CFAF in some cases, it's not true of ASOS. For
example, in my vicinity there are 2 towered airports (as well as a Class B
and another Class D about 20 nm away in opposite directions). One ASOS is
located on a lake shore (600 ft. ASL) and another inland 10 nm away at 900
ft. ASL. The conditions at one is often not the same as the other. If both
ASOS were on the same frequency such that one steps on the other, it would
not be good.

Regards,

Neil

The frequency of the squeal is equal to the difference between the
carrier frequencies. Many of the TV transmitters I work with are now
required the be within +/- 3 Hz of their assigned frequency. We do that
by locking the oscillators to a reference derived from a GPS receiver.
They could easily be doing the same thing.
--
Gene Seibel KB0NNN
http://pad39a.com/gene/broadcast.html
Because I fly, I envy no one.