Definition of term?

[k9rzz]

Two terms frequently used around here seem to have pretty loose definitions: skip and ducting.

Anything heard beyond 'normal' is not necessarily "skip" or "ducting".

A skip signal has to be reflected/refracted off an overly dense cloud in the D, E, or F layer of the ionosphere. This doesn't happen at 800mhz nor will it yield in signals being heard 150 miles away.

Ducting is strong VHF propagation between point A to B. I think even the Wiki is off on this, it says:

"A low-level temperature inversion is a phenomena in which the temperature in the lower portion of the atmosphere, near the earth's surface, is considerably cooler than a layer further up in the atmosphere. This causes signals to be refracted thus resulting in a tunneling or ducting of the signals."

There can be tropospheric enhancement over a broad area that isn't necessarily "ducting". True, there is a layer of temperature inversion, but it's not restricted to a narrow path. Just because you have wires in your ceiling doesn't mean they are in a 'duct'. There can even be "local enhancement" where VHF signals are louder that normal out to maybe 100 miles, but anything further is not.

I just wanted to bring this subject up because often I'll see a message reporting some VHF weather band "skip" and I think "WOW!! That's awesome!" but then reading the text I find out someone heard a station 100 miles away (good, but not so awesome).

 

[RandyB]

I do agree that often the term "skip" is thrown around to easily when referring to a signal that travels an unusual distance, despite the reason. Most folks that aren't in the hobby and know little about radio communications have some idea of what skip is, but no idea what ducting or tropospheric enhancement is. I must admit that in the past, for the purpose of layman conversation, I've chosen to use the term "skip" rather than "ducting" or "tropospheric enhancement" for a phenomena that clearly is distinguishable.

There can be tropospheric enhancement over a broad area that isn't necessarily "ducting".

I certainly get what you're saying about "ducting" being a term that implies a restricted narrow path which wouldn't necessarily always describe episodes of distant propagation resulting from a temperature inversion over a broad area. So, I suppose in this case, simply saying "tropospheric enhancement" would be the best choice. Would you agree? Are there any other terms that would better describe this particular phenomena?

 

[k9rzz]

I like "tropo", "enhancement", or "enhanced". It's just when I read "ducting" again I react "WOW!!!" when really it isn't.

 

[fineshot1]

For the most part I never use the term "skip". Like K9RZZ I use "enhancement" or "band opening" and only use the term "ducting" when I know for sure it is such an event(we get them some times here on the NJ coast from Long Island or the CT coast over the water).

 

[kb2vxa]

OK, let's get a couple of things straight here. "Enhanced" VHF/UHF propagation is almost impossible to explain since to the best of my knowledge little to no scientific research has been conducted to study this often fleeting phenomenon. Since we really don't know the mechanics let's just say you may receive signals a little beyond your normal radius.

Tropo or ducting isn't like throwing a tennis ball into an air conditioning duct, the actual atmospheric duct can be a thousand miles wide and as long under the right (and rather rare) conditions. Simply stated it's when signals bounce back and forth between the ground and the atmospheric boundary layer (thermocline) created by a temperature inversion and can travel this way for hundreds of miles. Oh yes it IS a form of "skip" when you get down to it, it's like a flat stone repeatedly skipping off two ponds one inverted above the other.

Oh fineshot, if all you can get are LI and CT you don't know our famous coastal ducting. How does working from the Canadian Maritimes to Florida on 2M FM simplex with 50W into a 5/8 wave grab ya? Once I worked a friend in his mobile on the Delmarva Peninsula on 220 but that's another radio adventure story. (;->)

Now lets define skip properly, it's SO often misunderstood. The trouble is it's only the first word of the term skip zone where MF and HF signals bouncing off the ionosphere skip right over top of you and you DON'T hear them. In other words they go from transmission point A and take a bounce off the ionosphere to reception point C skipping you B in the middle. Don't forget multi hop in which there are two or more reception points and the equivalent number of skip zones.

When it comes to "skipland' DON'T even go there! (;->)

Lastly there is sporadic E propagation when signals bounce off ionized clouds in the E layer of the ionosphere and sporadic pretty much speaks for itself. This phenomenon is not caused by sunspots but rather by intense ultraviolet which is why it happens almost always in summer when the sun is overhead and independent of the sunspot cycle. It is most noticeable in the low VHF range but because it distorts FM so badly and FM also being so power hungry it's useless for propagating this mode. That's when CW and SSB shine so don't expect to hear anything usable or even recognizable as E on your scanner.

That pretty much covers it and since auroral back scatter doesn't even apply here thus endeth the lesson, class dismissed. (cue bell sound, go to commercial)

 

[fineshot1]

Warren - you really need to get these alzheimers induced keyboard diarrhea rants under control.

For some unknown reason you like to take some of my comments and twist them.

I never said that was all I experienced - but you took it that way, why I don't know.

There have been so many propogation studies over the years it would be difficult to
site them all - but for some unknown reason you think its a black hole of knowledge.

OK - my rant is over now but from now on I will put you in my ignore list so I no longer
have to bother reading your toilet training trash.

 

[WayneH]

Ok folks, how about we all calm down now.

 

[RandyB]

Simply stated it's when signals bounce back and forth between the ground and the atmospheric boundary layer (thermocline) created by a temperature inversion and can travel this way for hundreds of miles.

The atmospheric boundary layer is the layer of the atmosphere that is influenced by friction from the earth's surface. It's a layer from the surface upward, so nothing bounces off of it.

 

[k9rzz]

""Enhanced" VHF/UHF propagation is almost impossible to explain since to the best of my knowledge little to no scientific research has been conducted to study this often fleeting phenomenon. Since we really don't know the mechanics let's just say you may receive signals a little beyond your normal radius."

Well, more research is needed then!

I've spent quite a few hours digging for FM BC DX the past few years and there are days (nights) when signals are with out a doubt louder than normal, but the range hasn't really improved. On those occasions I'll log the low power college stations in the area when I normally can't hear them at all.

That can be experienced on 2m SSB or FM as well. Louder than normal signals, but no additional range = enhancement!

 

[fineshot1]

I've spent quite a few hours digging for FM BC DX the past few years and there are days (nights) when signals are with out a doubt louder than normal, but the range hasn't really improved. On those occasions I'll log the low power college stations in the area when I normally can't hear them at all.

That can be experienced on 2m SSB or FM as well. Louder than normal signals, but no additional range = enhancement!

I call those "local enhancements" and have experienced that myself many times. Going out beyond that I would refer to it as a "regional enhancement".

 

[k9rzz]

Agreed !

 

[kb2vxa]

I don't know what it is with fineshot, he seems to take my elmering of you guys as some sort of personal attack. Oh well, I suppose that's how it is when you have a fragile ego but anyway...

"OK - my rant is over now but from now on I will put you in my ignore list so I no longer
have to bother reading your toilet training trash."

That's fine with me, frankly I'm glad the anal retentive finally pooped and got off my pot.

""Enhanced" VHF/UHF propagation is almost impossible to explain since to the best of my knowledge little to no scientific research has been conducted to study this often fleeting phenomenon. Since we really don't know the mechanics let's just say you may receive signals a little beyond your normal radius."

"Well, more research is needed then!"

I tell you what K9, apply for a government grant and live off taxpayer pork. (Sorry about the crack if you happen to be Jewish, hi.)

 

[fineshot1]

Well Warren - I was greeted with your response since I forgot to log in(i won't let that happen again) and thought you deserved a response.

Its your condescending posts that get me mad - which is what you call elmering - see below.

"OK, let's get a couple of things straight here."

"Tropo or ducting isn't like throwing a tennis ball into an air conditioning duct"

"Oh fineshot, if all you can get are LI and CT you don't know our famous coastal ducting."

These are all condescending statements above. If you are going to elmer someone as you
so call it you then you are going to have to change the way you talk to people via the keyboard.
Further more - I sincerely doubt that RandyB and k9rzz and myself need any elmering - not sure
why you always feel the need to try and elmer someone but if that's the way you go about it
then you can keep it to yourself. I for one do not need your type of elmering especially since
I have been working vhf/uhf band openings and the rare sporadic E while you were still a CB'er.
And - no you are wrong again as this has nothing to do with ego and more to do with simple
politeness and consideration.

 

[MOTORHEAD3902]

I wasn't going to post. Probably shouldn't this time, either.
Just suffices to say that the information, though it may be valuable, can be lost when delivered in a patronizing or sarcastic tone. Some may call it being a "straight shooter", or-as one of the mods here told me about himself- "blunt, get over it"...whatever the excuse, rude is rude and seldom funny.

If anyone is offended by my tone here, I apologize...

 

[kb2vxa]

Fineshot, stop making excuses for yourself. If you are the sum total of all knowledge then you are right, you don't need elmering. Please be reminded this is an OPEN forum where anyone aside from yourself may read and learn. Thanks for bloviating your vast wealth of knowledge and with it admitting your inflated ego problem. Now please for the sake of Radio Reference please abide by your word and ignore me.

Flame off; we now return you to your regularly scheduled whining and moaning, now get over it.