Subj : More on wifi range - Pi PICO W Oil level sensor
To   : All
From : The Natural Philosopher
Date : Tue Dec 09 2025 10:47:16

First of all thanks to all those who responded on my first efforts to 
put a battery power Pi Pico W outside and have it phone home.

Having eliminated temperature and supply voltage as issues, I delved 
into wifi and router logs, and it was clear that it was sometimes 
getting a DHCP lease and even occasionally opening a TCP/IP connections 
and sending data. And might be dependent on where I parked the car and 
the weather.

I tried putting a tin tray behind the router and that made it worse.

Now the layout was that a ground floor router through the window and the 
garage was not very good at about 30m range.

Then I remembered I had put an Ethernet port in an upstairs bedroom by 
the window in case I wanted to use it as an office.

It was further away - 35m or so - but much less cluttered path. It just 
had to go through a corner of the garage.

Instantly the router reported about 8-10dB more signal and almost 
reliable comms resulted.

Now instead of 1 in 10 connections working,m I have one in ten 
connections *not* working.The limit seems to be about -93dBm reported on 
the Pi Pico and about -90dBM reported on the router/access point.

What seems to be the key is uncluttered line of sight for as much of the 
distance as possible. And wind and rain. There are trees /bushes behind 
and the last two days have been very wet and very windy. And I have seen 
good connections drop without sending data and reported signal levels 
up to 10dB worse.

On the plus side for those contemplating similar, the ultrasonic module 
seems flawless..

(HC-SR04) and the original one worked down to about 4V. I believe newer 
ones will do down to 3.3V.

Also the nano power timers (TPL5110) works OK. Although it needed 100uF 
across the output power rails to stop it oscillating :(

The whole thing seems to be accurate to a couple of litres in a 2500 
litre tank.

(I spent several hours trying to remember enough high school 
trigonometry to work out the area of a chord. )


All in all the reliability of the wireless is about the same as the old 
commercial (465Mhz)  sensor except that that needed the receiver where I 
could read it. The luxury of just looking on a web browser makes the 
whole thing worth while, as is knowing exactly when the batteries are 
running out. So far in about 6 weeks of battery testing the 3 x AAs have 
gone from '4.6V' to '4.4V' . Battery replacement does not need the whole 
unit to be removed. Simply a battery holder and cover with a simple 2 
pin battery plug.

The hassle of setting up the C SDK is worth it as there is much that 
Python cannot do.
And I am hoping never ever to have to spend two hours bleeding 60 metres 
of partially  air filled oil line when the tank runs dry (or is emptied 
by thieves)

There are apparently blue tooth solutions that talk to yiur mobile 
phone, but once again, the phone needs to be in range...

Anyway thanks to all who helped, and the upshot is that liquid levels 
sensing with battery powered ultrasonics and a wifi link is perfectly 
doable and depending on circumstance, very worth doing.

And I knew all that trig would come in handy one day :-)


-- 
No Apple devices were knowingly used in the preparation of this post.

--- PyGate Linux v1.5.2
 * Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)

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