Defective ESP-07

[MichelJasmin]

In my neighbourhood there is a WiFi router with a nasty name. While I was playing with my ESP8266 I saw it again.

The command AT+CWLAP (List Access Points) return the AP names, their MAC address and the RRSI: Received signal strength indication. I had immediately the idea to try to triangulate that nasty router. So I hooked up a PIC18F25K22 with a GPS module, a ESP8266 (ESP-07 with an external antenna) and an OLED colour display. Then I went for a walk...

Back home the data is dumped on my PC, imported in a MSAccess database (to simplify some maths) and a HTML file calling Google Maps is generated. The results are not perfect: my acquisition routine needed a few adjustments. I'll release the code in a few days. I must go for a walk again but the weather is too cold (-20C / -4F).



The router name in red is open. The yellow one is WEP or WPA_PSK or WPA2_PSK. The white ones are WPA_WPA2_PSK.



The red dots are the sampling points. The markers are the other routers. The red lines show the points that were used to trianglulate. The streets names and the MAC address were erased on purpose.



Stay tuned!

[rsocor01]

Ooh, I see. Also, it took me a while to see that the difference between the "Not Good" and "Perfect" boards was the crystal oscillator installed with the wrong orientation.

[Gevo]

@ MichelJasmin, would you share some BASIC code ? I still working on a LoRa 868MHz (RN2483) portable signal strength indication.

[Ioannis]

HI Gevo. Have you tested the RN2483 range?

Also, why did you chose 868 instead of the 434 band? I am sure it goes far away.

Ioannis

[Gevo]

Hi Ioannis,

I'm in located in Netherland and the LoRa network is here on 868MHz.

[Ioannis]

I believe that since we al are in Europe, LoRa is also legal, at 10mW, at 434MHz. The classic ISM Band.

Of course on 868 you may have up to 0,5 Watt legal transmission.

Have you done any range test?

Ioannis

P.S. @ MichelJasmin. We are tuned! And waiting!

[MichelJasmin]

@ MichelJasmin, would you share some BASIC code ? I still working on a LoRa 868MHz (RN2483) portable signal strength indication.

The ESP8266 gives the RSSI (Received signal strength indication) when you ask it to list all access points near by.

For the ones who wants to know how to triangulate, here it is:

Disclaimer: it's an approximate triangulation and the signal strength depends where is the source inside the home which impact the results.

To understantd how I did it, see the triangulation as vectors with differents signal strengths. Each one "pulling" with it's own strength.
All of the triangulation computing is done with some queries in the database. This saves A LOT of code.
The RSSI (Received signal strength indication) is an attenuation given in negative dB: -90db is less than -60dB and so on. To simplify things I work with positive numbers as a kind of signal strength:

Strength = (100 + RSSI)

Why 100? Because the RSSI given by the ESP never goes below -99dB.

Some simple math now. For a given Access Point (AP) I do a sum of all the measured signal strength: let's call it [RSSI_Sum]

Then for each sample (Strength @ coordinate) I compute a strength ratio (the vector "Strength"):

SignalRatio_@LatLong1 = Strength_@LatLong1 / [RSSI_Sum]
SignalRatio_@LatLong2 = Strength_@LatLong2 / [RSSI_Sum]
...
SignalRatio_@LatLong_n = Strengt_@LatLong_n / [RSSI_Sum]

Then I triangulate (ok, approximate a triangulation) the lat/long by doing a sum of... I don't know how to explain it in english...
for each GPS coordinate I do apply the SignalRatio of that coordinate then sum them all:

Latitude = Sum( Lat_n * [SignalRatio_n] ) 
Longitude = Sum( Long_n * [SignalRatio_n] )

It's a really rough triangulation because the planet is kind of round (Google "Mercator projection") but it's kind of OK for a few meters.

Finally a build a HTML file with some generated JavaScript for the Google Maps API. Kind of ugly but for a one time project it's OK.

If anyone want to know how I parsed the NMEA sentenses from the GPS let me know!

[Demon]

Ooh, I see. Also, it took me a while to see that the difference between the "Not Good" and "Perfect" boards was the crystal oscillator installed with the wrong orientation.

Darn, I missed that.

I thought he had disconnected one pin on the rightside chip. It looks like the lower rightmost pin has the solder removed.

(I didn't read the link, that would be cheating )


I don't live in Europe, but I was in France with my eldest back in September.

Allison doing her Titanic pose.


I HAD to see the track.


I had to return here and share with her Mont-Saint-Michel.


Can't go to France without seeing the splendor of Versailles.

[Demon]

For other Canadians:

3.6 Amateur Service

The amateur service will continue to have secondary status in the band 902–928 MHz throughout Canada. All types of emission are permitted. Amateur licensees are advised to consult with the Department to avoid operation on frequencies or sub-bands used by radio systems authorized on a primary basis in that area.

http://www.ic.gc.ca/eic/site/smt-gst...g/sf01054.html


So be careful what you buy off eBay or other sources.