This morning at 11.00 I moved SD from test system (Pi Zero 2W) to main system (Pi 3B) and swapped dongles at the same time. All good it seems but just noticed this:
The step coincides with me moving stuff about, and I did initially forget to swap the dongles.
Is it a problem? I’m not in a busy area and the Zero 2 seems to be coping
(Overall CPU at around 9%, temp 43°C) Pic is of the Zero 2 system
Is there a corresponding flip in the Signal Level on the Pi3B system?
From your description, the first part of the graph is from the Pi3B system, card swap, then the lower performance of the Pi Zero 2W system. With neither system being CPU limited, the SD card swap is probably not the issue. I would suspect the dongle changes, assuming the antenna/cable connections remained with the initial Pi boards. One way to test could be to swap the dongles back again and check the graphs again.
Any spare dongles you can use?
The signal level abrupt shift looks like a one associated with a gain change. Left to right, higher gain shift to lower gain.
No spare dongles, although the way I’m going with this stuff it’s only a matter of time before a buy something else (I’m hooked!!)
The dongles stayed with the SD cards (after initial cock up)
Based on the second graph from the Pi3B, no significant change at all in the signal levels.
Ok, Hmmmm, So the first graph from the Pi Zero 2W shows the signal strength dropped. Recheck the cable connections at the antenna and particularly at the dongle. I had this happen to me a while back and needed a few more turns on the cable connecting to the dongle. I was doing the same kind of thing you did, testing an idea and swapping parts around. It might make a difference, or something else is affecting your signal strength. The investigation continues…
Thanks. Yeah, it’s odd. Nothing else has changed, even the crappy internal antenna mag’d onto an ancient DVR on the top shelf has not moved. Hang on… I did tidy the cable from the antenna to the dongle, folded the loops back up and put a wire tie around it. No sharp bends but a change nonetheless. I wonder…
Interestingly I was reading the home made antenna thread and was going to check the length of the internal antenna but noticed that both of the ones I have actually have a coil in the centre so I planned on knocking something up tomorrow. Oh well, it’s all interesting stuff though.
How tight?
Coax doesn’t like to be pinched.
Pretty loosely, they’re no actual kinks. I’ll play tomorrow but as for today both systems (main and test) look to be on track for high numbers, strangely. Just goes to show how fickle this can seem to be.
I realise I shouldn’t be changing more than one thing at a time but having left the cable still coiled I’ve replaced the original stick antenna with a 67mm long homebrew job (thin copper wire soldered to a threaded brass stud) and this had a minor effect (09.30 onwards on graph) of a slight increase in gain. -36db to -33. Whether or not this will be reflected in more aircraft ‘seen’ is still to be decided!
Guess I better untidy the cable now.
Tim
I really, really wish I had a taller tower/mast.
How high is it now? What’s stopping you?
Following on from @victorbravo77 comment, how much difference in height is needed. If my antenna (base) is currently sat at around 3 meters off the ground attached to the gable end of the house, will adding a couple of extra meters make much (any?) difference. I’ve bought the pole and fixings so hoping for a strong “yes” here! In a semi urban environment, but still getting out well to the SE, usually maxing out at 200NM+
The goal is really to clear as many nearby obstacles as possible. The geometry of more distant objects requires a much larger local change to effect a measurable result at range.
As an example, my neighborhood is mostly single family homes with two stories. If I plant a pole in the middle of my back yard and mount my antenna so that it’s 3 feet off of the ground, it would be like putting that antenna in the bottom of a bowl - completely surrounded by obstructions up to an angle of at least 45 degrees.
But if I take that same pole and mount it 3 feet above the peak of my roof, now the antenna is 3 feet above everybody’s roof and it has a clear line of sight to the horizon, more or less. There are some individual trees in some directions, but the obstruction angle is now more like 10 degrees.
This kind of result isn’t necessarily possible in all cases, or even in all directions, but the idea is to maximize what is available to you.
Another thing to consider is where the planes actualy are in relation to your antenna. I have mentioned before that my station is about 100 miles inland from the Pacific Ocean. Based on my antenna location and the geography to my west, I should be able to “see” planes out to 100+ miles offshore. Problem is, planes don’t really fly 100 miles offshore in my area. I easily see planes out to 200-225 miles north and south, but I have some 4,000 foot mountains about 40 miles east of me. This limits my range in that direction, and I am certainly missing planes that way - but I would have to raise my antenna by 100 feet or more to see any kind of difference.
Point being, maximize what you can, but remember that you won’t see planes that aren’t there.
Roughly 35 feet (~11 meters) AGL.
Fear of heights. Lack of materials.
…now I’m just making excuses. 
“… will adding a couple of extra meters make much (any?) difference”
Yes, @jafrank says it quite well. Taller is much better. Obstructions and the gentle curve of ol’ Mother Earth limit your signal ability (all other things like power level, freq, etc. being equal).
Let us know how that project goes!
35 feet is a pretty good height depending on how tall things are around you. Hopefully that at least puts the entire antenna length above the peak of the house. I am at 30 feet, and it serves me pretty well in most all directions but I’m still developing a materials plan on how to get maybe 5 or 6 feet higher. I base everything off of a single Rohn tower apex section that touches the ground next to the house and I have the apex pipe socket clamped to the eve of the house. From there everything pushes up in manageable pipe sections of 10 feet or less, so I don’t end up climbing any higher than the eve of the house roof which is about the same 9-foot height of the Rohn apex section of tower. This design keeps you off the roof. We don’t want you to fall and spoil your good looks.
Place I lived once was right on top of a hill, albeit in an urban environment. I was into CB in those days and strapped an 18’ (27MHz?) dipole onto the chimney stack. Got out rather well and in the right light it looked like a sword fixed to the roof. All went well until a lightning bolt brought what I’m sure was ball lightning into the spare bedroom. As you can imagine, some damage was done!
Back to original subject - I’ll max out the current antennas height and see what happens, only way to be sure. I don’t expect wonders because of my local environment, live in single storey house and surrounded by two storey ones, plus hills pretty much all around. All fun though.
Wondering what your “Coverage Graph” looks like. What is your current ranking so maybe I could take a peak?
@CraigWoodThomas - assume you mean on the stats page, it’s 11864
Interested to see what you see!
So, I had a look at your coverage there out of Bournemouth, England and it appears you have a lot of untapped potential for aircraft to the Northwest and Northeast of your location there on the coast. Appears you have a good view to the south over the water but aren’t getting much of a look to your North.
