Bluetooth range for outdoor use

[tainanfish]

Hello everyone,
What is the Bluetooth range for outdoor use of the Wipy module ? Is it possible to specify the signal range in the settings and how can you do that?
Thank you for your help!
Philippe

[RichardTXD]

@tainanfish
Hi, I've been playing with BLE beacons for 2 years now and found that 'rannge' is very variable with BLE. We use kontakt beacons. They have 8 levels of power. Level 0 is maybe 5 metres open air line of sight, and level 7 is maybe 30 to 50 metres or more. That is with iPod/iPhones. The WiPy is less sensitive so range will be less.
I am not sure what your question is asking. However, if you are wanting any kind of accuracy you'll find it difficult with one beacon and whatever is in the area will affect the RSSI significantly. Beacon signals are absorbed by people, they reflect off many surfaces. It is not trivial to extract meaningful range information from Beacons.
We have found that decreasing the interval (ie making it send more often) improves the range accuracy of a beacon but lowers its battery life.
Hope that's helped - suspect it hasn't

[jmarcelino]

The WiPy and ESP32 chip that powers it is a Bluetooth Class 2 device (+4dBm transmit power) so maximum range is 10 meters (of course depending on antenna gain and any attenuation after the signal leaves the chip)

[RichardTXD]

@jmarcelino
Good comment.
I was more looking at the receive side.

[littlebat]

@jmarcelino

The ESP32 Bluetooth Radio and Baseband support the following features:
• Class-1, class-2 and class-3 transmit output powers and over 30 dB dynamic control range

Bluetooth LE Radio
RF transmit power - - +7.5 to +10 dBm

[jmarcelino]

@littlebat
Thanks for bringing up this topic :-)

Yes, the datasheet quotes +7 to +10 dBm TX power for Bluetooth LE and also the +4 dBm I mentioned for Bluetooth Classic, however I never got anything close to +7 dBm on BLE. In addition I understand the stack only supports operating in Dual BT Classic/BLE mode at this time - esp_bt_controller_enable(ESP_BT_MODE_BTDM);

This made me consider, perhaps incorrectly, that the lower value +4 dBm was all that's available at the moment.

Even in ESP-IDF there still isn't a way to know the actual Bluetooth TX power being used or to set it from when I asked back in Dec 2015: https://www.esp32.com/viewtopic.php?f=13&t=1052&p=9881 Actually this thread came up again very recently but with no solution yet.

Maybe you know a way?

[tainanfish]

@RichardTXD

Hi everyone thank you for your replies, I am not an expert but I will forward your answers to my technical partner who knows more than me about radiocommunications. We want to use Bluetooth to geolocalize (with triangulation) some assets stationed in a certain location and differentiate them from assets moving near this location. Our concept requires localizers that can detect beacons within a 10 to 20 m range, from what you say this might be difficult to do with Wipy. The wifi part would be used to send the collected info to the internet at regular intervals.
Best regards,
Philippe

[RobTuDelft]

@tainanfish Maybye you could also use Wi-Fi instead of Bluetooth to do this then?
Last week I measured the Wi-Fi signal strength at some intervals, using 60 probes (1 every 10 sec, for 10 minutes).
This is with the internal antenna. With external antenna it is more stable I've noticed.

[jmarcelino]

LoRa should also do well for that sort of (approximated) outdoor localisation and lower power than WiFi.

[tainanfish]

@RobTuDelft Thank you but we need something with low energy consumption, (the geolocalized Bluetooth beacons would be external, not included in cell phones), so wifi was not chosen for this reason

[tainanfish]

@jmarcelino Thank you, we thought about it but we need a pretty accurate geolocalization, with 1 or 2 meters accuracy (with triangulation), it seems Lora doesn't work well for this. GPS would work well but is much more expensive than bluetooth afaik

[jmarcelino]

@tainanfish
You might be surprised what LoRa can do (and remember in LoRa you CAN set the TX power) but if the question is just cost, then the GPS will be about the same ($8 for a GPS module, same as a LoRa module)

To me the problem with GPS is it's even higher power consumption than WiFi.