Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Pinging the Ionisphere  (Read 463 times)
NU0R
Member

Posts: 408




Ignore
« on: May 16, 2007, 02:52:51 PM »

WB2WIK "Steve" wrote   "I can tell if the band's open or not even if nobody's using it, just by how the noise sounds, what kind of lightning static I'm hearing, where it's peaking...and whether I can reflect a "ping" off the ionosphere using my own station, and hearing the ping." --- Steve, I am not
doubting your word in any way, but can you explain "pinging". That is a new concept to me and I am not about to pass up an opportunity to learn from you. You are my hero and my Elmer. Kinda like E.F. Hutton, when you speak I listen.  Thanks Bruce
Logged
N6AJR
Member

Posts: 9879




Ignore
« Reply #1 on: May 16, 2007, 03:23:31 PM »

me too, I want to play
Logged
N5EG
Member

Posts: 244


WWW

Ignore
« Reply #2 on: May 16, 2007, 03:42:44 PM »

We used to do this back many years ago. At the time, a separate Tx and Rx, separate antennas (tube Rx).

Send a string of 'dits' on 80 meters, and hook up an oscilliscope to the IF output of the receiver. You can see the RF emitted by the transmitter, and then the echo off the ionosphere a few milliseconds later.

The presence or absence of echos, and the amplitude envelope of the received echos would tell us a lot about the ionosphere that night.  The Tx->Rx delay is double the distance to the reflection point.

Modern solid state rigs may need some form of protection for the front end. You also need to be
able to access the IF on the receiver. A narrow filter
in the receiver may add up to a millisecond of delay,
so it's best to use a wider filter, or tap the IF in front of most of the selectivity. You can calibrate out nominal delays. Yaesu FT-1000MP has too much T/R delay to be used by itself (about 14 milliseconds), with the receiver not recovering unitl after the echo has already gone.

  -- Tom, N5EG

Logged
WA9PUL
Member

Posts: 9


WWW

Ignore
« Reply #3 on: May 17, 2007, 08:40:44 AM »

Or just use this if you don't have the requisite equipment?

http://137.229.36.30/cgi-bin/digisonde/latest.cgi

Paul
WA9PUL
Logged
WB2WIK
Member

Posts: 20537




Ignore
« Reply #4 on: May 17, 2007, 09:06:02 AM »

With a QSK rig (very fast turnaround T-R) and the AGC "off," tune to a clear frequency, tune up for as much power as you can run, and send a high-powered "dit."

The ping return happens pretty fast, but with my Jupiter (for example) set to zero QSK delay and the AGC "off," I can hear it, when it's there.  Doesn't even take a string of dits, just one will do it, if you're going to hear it.  If you're not sure, send another one.

When a band's open, I've never failed to hear the return ping any time I've operated at a big-gun contest station (usually 1500W, big beams on high towers, quiet location), although down on 80m or 160m that can be quite a challenge due to lack of antenna gain and too high noise levels.  I understand the truly "big guns" on those lower bands can do it, though -- just not me.

I can hear the ping easily on 17m or 20m even at this point in the cycle, when the muf's high enough.  With 100W and a dipole, no.  With a kilowatt and a beam, yes.

WB2WIK/6
Logged
KT8K
Member

Posts: 1490




Ignore
« Reply #5 on: May 17, 2007, 09:23:45 AM »

I have heard my own signal ping a few times over the years - apparently during extraordinary propagation conditions - and I run 5 watts on HF.  

In one case I was able to hear multiple pings from my 40m "dit", indicating returns from multiple paths.  (That was a one-time observation in my 29 years as a ham.)  I'm sure the phenomenon can be much more easily (and more frequently) observed at higher power levels. Fun!  
Happy propagation sleuthing, and don't forget to "CQ" if the band is quiet but you're hearing pings.  You might be the first on the band to snag that rare one.  73 de kt8k - Tim
Logged
N3OX
Member

Posts: 8852


WWW

Ignore
« Reply #6 on: May 17, 2007, 11:01:02 AM »

"WB2WIK "Steve" wrote "I can tell if the band's open or not even if nobody's using it, just by how the noise sounds, what kind of lightning static I'm hearing, where it's peaking..."

Although the pinging is probably the coolest bit, we've established that it's pretty rare for the 100W and modest antennas station...

I've heard it a few times with 100W and a tribander on a hill on, say, 15m when the band was good and I lived in a very quiet location.

However, all the other stuff is something any of us can do unless we have a very high local manmade noise level...

The sound of an open band with no one on it is one of my favorite things... you know it's open to *somewhere* but you don't really know where until you call CQ or tune around to find that weak DX CQ...

73,
Dan
Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
K8AG
Member

Posts: 345




Ignore
« Reply #7 on: May 17, 2007, 12:39:27 PM »

That's my QSL card!!!! Wink

Everybody on HF is pinging the ionosphere.

73, JP, K8AG
Logged
K7PEH
Member

Posts: 1125




Ignore
« Reply #8 on: May 17, 2007, 06:48:07 PM »

Such a ping of the ionosphere would be about a 3 millisecond interval plus or minus 2 milliseconds depending on height of layer you are reflecting off of.

But, hearing your own signal that takes the long path is about 130 milliseconds or so which should be discernable.

So, how do you know you are hearing a NVIS type ping or a long path signal?  Also, on a near vertical ping, I would think that there would be multiple bounces that are possible which might stretch the interval out to maybe 10 to 20 milliseconds but even this is a very small period of time for the average ear.

Or, am I off on a completely different track.
Logged
N3OX
Member

Posts: 8852


WWW

Ignore
« Reply #9 on: May 17, 2007, 07:17:40 PM »

"Such a ping of the ionosphere would be about a 3 millisecond interval plus or minus 2 milliseconds depending on height of layer you are reflecting off of."

If you're talking the round trip for hearing your own backscatter off the point where your signal first hits the ionosphere, it would be quite a bit longer.

You're not ever going to get a NVIS ping from the F-layer on 20m ...

Dan
Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
K7PEH
Member

Posts: 1125




Ignore
« Reply #10 on: May 17, 2007, 08:04:55 PM »

>>>
If you're talking the round trip for hearing your own backscatter off the point where your signal first hits the ionosphere, it would be quite a bit longer.
<<<

I guess I don't understand the kind of path that the signal takes.  Are you talking about a long path circumnavigating the globe or something else.  You say it would be quite a bit longer on this backscatter reflection but I don't think I understand the kind of path you are referring to.

I agree that a signal that makes a longpath trip can be heard by someone who is listening and the conditions are right.  But, if the signal is taking a much shorter trip, say under 50 milliseconds, then instruments of some sort must be used as I just don't think the human ear can detect that quick of a signal response.  Of course, I can always be surprised.
Logged
N3OX
Member

Posts: 8852


WWW

Ignore
« Reply #11 on: May 17, 2007, 08:22:03 PM »

"Are you talking about a long path circumnavigating the globe or something else. You say it would be quite a bit longer on this backscatter reflection but I don't think I understand the kind of path you are referring to. "

Some RF comes straight back at your station even if you're hitting the ionosphere at an angle.  

It's a very small amount  compared to that which continues on the path, which is why you need a lot of effective radiated power or good conditions to hear it, but it's there.  

So it would be 1 hop worth of delay... out to the ionosphere where the signal reflects and continues on its way but with a little scatter making that trip back to you.

Dan
Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
K7PEH
Member

Posts: 1125




Ignore
« Reply #12 on: May 17, 2007, 08:37:53 PM »

Dan, OK.

But, it seems to be a rather tenuous method to test for propagation performance.

73,
phil, K7PEH
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!