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QRM or Band Condition changes, Ques 10m

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#1
Im hanging out alot on 10m doing what I can do and working band openings. Im new and educating myself as I go along enjoying my new hobby but I have a question on possible QRM or maybe the band conditions changing Im just not sure with the little experience I got so far.

Its seems daily at around 6pm 10meters goes south for me real fast like in the blink of an eye. I enjoy the low noise of 10m and do alot of data there but around 6pm give or take I go from a S0 on the meter to an S4-S5 of noise for no reason I can tell, kinda wiping out my JT65 for the evening all but for the stronger signals.

I just starting to realize a possible pattern but only today took note of whats going on I can also possibly show photos of before and after next time it happens. I am already aware of my known RFI sources or other anomalies and what they look like on my scope/waterfall, but this is mostly a whole band raise in noise level with a slight wave movement of the scope line. If interested can whip up a photo or video.

Wondering if there maybe an explanation out there? Am I looking at QRM or normal effects of day/night propagation changes?

Any help appreciated!
 
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#2
Sounds like normal propagation changes.

Propagation on 10 Meters is near the bottom of a 11 year Solar Cycle. For the most part, propagation is poor. But you also need to remember that 10 Meters is a daytime band. Once the sun goes down so does all propagation. And, yes, it can seem like someone flipped a switch. I have heard many long haul stations disappear in seconds.

But even when we are in a better part of that 11 year Solar Cycle, 10 Meters is still a daylight band. Once the sun goes down the band goes dead.

You can go batty trying to predict when a band is up or down. I use a very simple logic. 20 Meters is the middle of the road band. It seems to always be open, day and night. But the higher frequency bands (15 Meters) tend to be best during the day, for long distance propagation. I'm a daytime operator and prefer 15 Meters. On the other hand, the lower frequency bands (80/40 Meters) tend to be night time bands for long distance propagation..

Of course, you are only using part of your Technician privileges. It takes a lot of work, but you have CW privileges on 80, 40, 15 Meters. Just saying.

Martin - K7MEM
 
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#3
Thanks for the reply,

Yeah it does seem like propagation change just wanted to make sure. And it does certainly go off like a switch. I also notice my known RFI issues seem to be enhanced or stronger during that time, thats another battle Im trying to work on.

Yes I do work CW on other bands I have privileges from time to time, like the flex I have on 10 and 6m but have no 6m Antenna yet. Im working on General asap so I can have more elbow room, but enjoying so far.

Thanks Alot!

KG5PIO
 

N0IU

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Good luck with your General!

And not to be too nit-picky, but QRM is generally considered to be intentional interference and that certainly does not sound like what is going on in this case.

Either way, I agree with my esteemed colleagues that you are most likely experiencing typical 10 meter behavior.
 
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#6
Good luck with your General!

And not to be too nit-picky, but QRM is generally considered to be intentional interference and that certainly does not sound like what is going on in this case.

Either way, I agree with my esteemed colleagues that you are most likely experiencing typical 10 meter behavior.


Yes correct and thanks all for the info. also on the subject of interference is there a way to ID a source or cause by looking at its signal/waveform on the display? Some sort of reference that can be tapped into to help narrow down the search?




Thanks
 

N0IU

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...is there a way to ID a source or cause by looking at its signal/waveform on the display? Some sort of reference that can be tapped into to help narrow down the search?
Thanks
Not that I know of, but that really does not mean anything. If it is possible to record the noise as a .wav file (or some other format), that might help us identify what kind of noise it is.
 
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#8
Wondering if there maybe an explanation out there? Am I looking at QRM or normal effects of day/night propagation changes?
QRN, which is natural occurring noise associated with day/night propagation. This might be what you are experiencing.
Larry
 

Token

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Note the time pretty closely for a few days / weeks. Natural phenomena will not be rigidly fixed in time, even repeatable ones drift slowly in time, such as with sunrise / sunset times. Something that is rigidly fixed in time is almost certainly man made.

For example, every evening at 7 PM local time my noise floor on 40 meters goes up by 2 or 3 S units. One of my neighbors has a grow operation in an outbuilding and he apparently has grow lights programmed to come on at that time daily. The building is more than 800 feet from my antenna, but I still see the noise floor rise. In this case the noise floor goes up instantly, then over the next few minutes slowly goes down, ending up about 1 S unit above my normal noise floor.

T!
 

N0IU

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#10
QRN, which is natural occurring noise associated with day/night propagation. This might be what you are experiencing.
Larry
Well... um.... The "official" definition of QRN is, "Are you troubled by static?" or "I am troubled by static." QRN is generally associated with static caused by lightning.
 
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#11
Well... um.... The "official" definition of QRN is, "Are you troubled by static?" or "I am troubled by static." QRN is generally associated with static caused by lightning.
Wow. Thanks for the sarcastic, "official" reply. I'll make sure that I write it down and remember it.
Again, thanks.
 

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#12
Looks like the meaning of QRN may have changed over time. Originally, it appears to have referred to atmospheric noise in general, But, the meaning seems to have morphed into only referring to static.

This article at Wikipedia refers to the ITU-R. Since viewing the ITU-R requires payment, we are dependent on sources which refer to ITU-R and not the document itself.

The ARRL, which I know is not the ultimate authority, lists the meaning of Q codes for net operations in FSD-218.
 

W9BU

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#13
I enjoy the low noise of 10m and do alot of data there but around 6pm give or take I go from a S0 on the meter to an S4-S5 of noise for no reason I can tell, kinda wiping out my JT65 for the evening all but for the stronger signals.
I don't think this was mentioned in the the responses, but it's possible that your noise is man-made. Since it occurs at a particular time each day, maybe what you are hearing is an appliance or electronic device in your house or your neighbor's house that is turned off all day until the household routine changes at a particular time of day and the noise source is turned on.
 

N0IU

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#14
Wow. Thanks for the sarcastic, "official" reply. I'll make sure that I write it down and remember it.
Again, thanks.
That was not meant to be sarcastic at all. I have been licensed for nearly 25 years and I have never heard QRN as something associated with "natural occurring noise associated with day/night propagation". I can quote several sources that back up my definition, can you?
 

Rred

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All of which is why Q signals were born for and intended to remain with telegraphy, where "short" was vital. Customers also paid by the word, and a "Western Union Word" was defined as five characters plus one space, or six characters, regardless of the actual word count.

Not voice communications and not web posts.

In written and spoken communications, even the ARRL and the FCC will tell you that Q signals are simply jargon. Jibberish used by a clique to make sure that "outsiders" can't understand them.

Some, come on guys, Stop arguing over the Q signals, or stick to telegraphy.
 
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#16
Appreciate all the help and input from all but yeah nevermind on the Q thing not a huge deal and a mistake on my part. I dont mind being corrected when Im wrong its part of learning. Anyway on the conditions or interference having now really looking at it the noise does seem to be more random happened again yesterday at 3pm right before my eyes and this morning I turn on gear at 11am and the noise is already there. When I did witness it it was like something was just switched on, so now Im thinking it maybe something outside the house. I know its not in my house.

This is one of those things thats gonna be hard or a pain to find I will see what I can do to track it down I maybe better to find out during the week where it seem to be around 6pm perhaps someone coming home and turning on a device I can better look out for it, seems like weekend its too random.

Anyway most likely cant do nothing about it with the winners I have living around me. I do have video of a different interference I like to link here on next post to see if anyone can recognize it maybe a new post will be better. This interference is outside for sure and all over HF at various intensity and bandwidth, its more of a annoyance than stopping me really but it would be sure nice to figure this one out and end it if I can.
 

N0IU

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When I did witness it it was like something was just switched on, so now Im thinking it maybe something outside the house. I know its not in my house.
Not being sarcastic at all I assure you, but how did you determine that it is not something in your own house? The only way to know (that I know of) to be absolutely 100% sure would be to kill the power to your house and operate your radio off of a battery. If the noise goes away, then it is something within your house. Then comes the real challenge; finding the device(s) that are causing the noise.
 

Token

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#18
That was not meant to be sarcastic at all. I have been licensed for nearly 25 years and I have never heard QRN as something associated with "natural occurring noise associated with day/night propagation". I can quote several sources that back up my definition, can you?
Not that it matters, but I have been licensed for almost 50 years, and in that time I have often heard QRN associated with natural noise or static (from any natural source), and QRM most often, but not always, associated with man made noise.

Loosely put, when static is high, such as in the event of high solar noise or in the event of lightning, the QRN is said to be high.

From RECOMMENDATION* ITU-R M.1172 QRN = "are you troubled by static" or "I am troubled by static".

From https://web.archive.org/web/20120906015123/http://jcs.dtic.mil/j6/cceb/acps/acp131/ACP131F.pdf the same definition.

And from the ARRL the same definition http://www.arrl.org/files/file/Public%20Service/fsd218.pdf

I have often heard new hams ask the difference between QRM and QRN. That can be hard to define, since QRM simply means you have interference, without defining the source. But QRN is specific to either atmospherics (atmospheric noise) or static, depending on which source you quote. And so I can remember my Elmer giving me the loose guidelines of, if it is another transmissions hammering you or you know it is man made it is QRM, if it is noise or static it is QRN.

And the diurnal cycle most definitely can cause the natural noise floor to go up or down, some bands have a higher natural noise floor, or perceived static level, at night, others have a lower one at night.

T!
 
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#19
Not being sarcastic at all I assure you, but how did you determine that it is not something in your own house? The only way to know (that I know of) to be absolutely 100% sure would be to kill the power to your house and operate your radio off of a battery. If the noise goes away, then it is something within your house. Then comes the real challenge; finding the device(s) that are causing the noise.
I guess I cant be 100% sure I do know its not a device someone is turning on manually can be something going on off by itself but can imagine what right now. I did turn off the house electric to see what it does already I know its effects or what kind f noise the house is generating but this is something new or not noticed before since it happens when it happens.

I will get another battery and try it again and look out for this particular event.

Thanks
 
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