Laurence, Dennis, LF, Good discussion has emerged since my first observation. I have had many constructive comments from various LF authors on here. Laurence has stated just what I have been thinking
Gents If the signals that are fading at different frequencies are from the same source, then you can determine the difference in path length from the null spacing. (assuming you can see signals over
Gary, Thats about it , the refraction is from a 'media' that's not stable so you will have differing propagation on adjacent frequency's One of the reasons these wide band data systems constantly out
Hi Rik & Graham, Thanks for the replies. All understood now, the screen shot certainly shows it up. I didn’t relate multi path fading to what I was seeing on the display as I am normally used t
Hi LF, Just made an interesting observation regarding QSB at 508KHz. For my own benefit I have started running a slow SpecLab showing 500 to 510KHz & capturing for evaluation. Occasionally the NDB &#
This was a very good write up - thanks - With the advent on "spectrum analyers" and panaraomic displays with the new SDR radios they provide a very telling visual fade pattern on even narrow FSK mode
Hi Gary! Yes fading seems to be very selective. Have you ever been listening to a distant AM radio station? Give it a try :) There it is often audible, that a "fading notch" travels through one sideb
Dear Gary, LF Group, Quoting from the Propagation chapter of the Admiralty Handbook of Wireless Telegraphy 1938 edition: "It is usually observed that the different frequency components of a modulated
Gary, I assume its selective fading , you can see it at 100 Hz separation at > add the shot with a few pointers ? G .. Nb .. check out the 500 band in those day's , no mal-adjusted cw signals right i
Good point. Forward thinking g3kev How about QRSS on three closely spaced frequencies at once, perhaps? 73, Dave G3WCB Dear Gary, LF Group, Quoting from the Propagation chapter of the Admiralty Handb
Graham & Roelof, Thank you for your comments, I must find some documentation on the effect & improve my knowledge on the subject. I have quickly benefitted from my wide & slow SpecLab display using t
Hello Gary, This phenomenon can be observed on many NDB's. I have been investigating thsi and it often heppens taht one sideband completely disappears, whilst the other is strong. It is similar to se
How about QRSS on three closely spaced frequencies at once, perhaps? 73, Dave G3WCB Dear Gary, LF Group, Quoting from the Propagation chapter of the Admiralty Handbook of Wireless Telegraphy 1938 edi
Hello Gary, LF, For a nice view of selective fading on 500kHz my grabber is currently showing the effect, and generally does at night, now that the Faroe AMBC station on 531kHz is radiating wideband
Jim, LF, I have the very handbook - Vol II "Wireless Telegraphy Theory" I didn't even think of looking there, a very good section on propagation. Probably many other things if I care to look. I only
Gary, if the QSB comes from multiple path propagation (where one of both of the paths is changing) QSB can be different on different frequencies. One could even use the QSB/frequency pattern to deter
