More on wifi range - Pi PICO W Oil level sensor

Interesting.

DOES show a number of "cells" ... but not the ESSID of my extender for some reason.

In theory, this sort of data could be used by a relatively simple daemon to switch back and forth to the 'best' signal. The old CL stuff is fine ... but can sometimes be replaced by half a dozen lines of more-comprehensible Python.

Somebody said something interesting ... that the effect of the Big Red Truck on the wifi signal kind of turned it into a radio proximity sensor. Ya know, THAT might be useful ......

As for The Project ... with enough interesting input The Project might change ... to something More Interesting :-)

Hmmm ... My stuff gives off wifi, and there are a few neighbors too. MIGHT be I could sample signal strength and come up with certain 'fingerprints' - like of vehicles driving by or, more important, the Amazon truck pulling into my driveway ... BEEP !!!

See how little stuff can spawn bigger ideas ? :-)

Yeah. You can get maybe 50kbps out of 27MHz Probably enough fir a very low res cam.,

Short to medium wave the best, as used in ADSL.

Er no, Not bars.

Take more LSD

No,. it just needs setting up. I looked into ot and decided life was too shoryt

Yes. unfortunately that is not how *most* wifi works ]

That may be spoofing someone elses... Try' iwlist wlan0 scanning' on its own

Ther is a lot more info

Its called 'network manager' but its not very good.

That was in fact how Radar was born. Engineers noted that HF radio was affected by planes flying overhead.

Chain Home was built to run between 20MHz and 55MHz.

The Germans sent a Zeppelin to investigate,m but they spotted it miles away and switched it off.

Germany thought the frequency was too low for proper radiolocation. They thought it was probably a LORAN style system for navigation.

At that time I don't think a radio valve (tube) was much uses over about

It is certainly doable at 2.4 GHz.

Build a directional mirror - parabolic, and send a wifi signal up it.

Point it away from a similarly equipped receiver, and wait for something to reflect it back.

Or just spend $2 for one already built ready to hook up to your Pi.

I have a bunch of Ubiquity UbiFi access points around the house with wired backhaul to the router. They can also work with wireless backhaul, but we were having the house rewired so putting a load of CAT6 in, and a POE switch, was a no-brainer.

They do exactly that. As a device moves between areas with different APs the APs detect which has the best signal and the one with the lower signal strength drops the connection. The device then reconnects and picks the one with the stronger signal.

They've been in place about four years, now, and seem to work well.

Aha. So that's how they do it. No intelligence required in the client

So they talk to each other 'my client needs to be your client.'

That only happens with me when they go out of range completely.

It's very clever.

I set up one PI3 to do that, it was in an outbuilding and prone to be moved around. As I recall it was easier to do with older versions of Deb/PI-OS.

I *think* you could set a threshold, so they didn't jump over a momentary interruption.

GOTTA look that stuff up again ... alas didn't make any copies of the old setup. It DID work though. I can ALMOST see the config file ... almost ....

That's the fault of your client software. Thunderbird threads correctly even if the subject changes. I don't know what you are using :-?

You mentioned thieves stealing fuel. You can also monitor for that. You would need a fuel flow meter on the fuel line, or a sensor telling when the furnace is working. Compare with the tank level decreasing rapidly.

Two ideas.

Some routers can steer the signal horizontally; the technology is called "MIMO"

Then you can replace the antena on the router or the remote with a directional WiFi antena. Home made with a box of Pringles. just google for "pringles wifi antenna". I made one and it actually works. But maybe they are sold, too.

...

You can calculate it numerically on a computer, by calculating the aproximate integral ;-)

The problem is that the sensor I built on the tank has no power except batteries: So it only wakes up occasionally and draws nanoamps in between. I have completed the warning software that looks for low oil levels, loss of communication, a failing battery and unexpected changes in oil level, BUT it cannot do that in real time as the unit is only powered up for a minute or so every couple of hours.

Depending on how long the batteries last I may increase the frequency of operation. But it can never be 'real time'

Worth trying to send the data as UDP rather than TCP? if it fits in a single packet,the receiver doesn't have to track the position within a stream ...

I sorta tried that without huge success, In fact I am getting up to 12dB variation in signal due to who knows what?

The setup is all somewhat experimental. At least for now the software is more or less stable - I have a few hanging daemons if the link goes down mid message - but that is easily fixed .

Huh? it can be as exact as your measurements are. No 'approximations' here...

diameter= tankDepth - offset; radius = diameter * 0.5; y = echoDepth - offset -radius; theta = asin( y / radius); x = radius * cos(theta); pie= radius * radius * theta; delta = x * y; area= (M_PI * radius *radius)/2 - (pie + delta); volume=(area/(M_PI * radius *radius ))*tankVolume;

That is about ultimately three days of work. It is redundant but I think gcc can optimise out the intermediary variables that I used to make sure even I could understand it.

What has been encouraging is the pinpoint accuracy of the measurements. Once in a stable environment the ultrasonics are very precise. something like a mm or two in a couple of metres. Probably more precise than the speed of sound in air of variable pressures would justify, or indeed the expansion of the oil in warmer temperatures.

LOL.

Maybe I have built the world's most complicated barometer.

Well the daemon runs under xinetd...for sheer laziness. I guess I could make it UDP.

But I don't know what problem that would solve.

Ah.

What about a small solar panel and rechargeable batteries?

What antenna on the router?

It's just a wifi bridge with an internal something or other.

That gets complicated. I am trying easy s*it first :-)

P Pico W doesn't have an 'antenna' either. Just some PCB traces.

Everything is possible. I am lazy. I do what is necessary to achieve desired result and no more.

For now I seem to have adequate connectivity.

The data would arrive if a single packet got through the fog, whereas with tcp at least dour packets on sequence need to make it (or get retried) with UDP you could afford to spray each packet half a dozen times and if one of them makes it, you're good ...

Yes. That is in the 'lemme think about that' pile... Not that there is much sun here..

At this time of year.

And where the tank it is likely to get overgrown or shat on by birds