XPost: comp.os.linux.misc   
   From: tnp@invalid.invalid   
      
   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.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)