Time of flight module

Hey there,

I was wondering if there any Wifi or BLE modules with time of flight (TOF) facility for Arduino boards, where I can verify distances of other contacting devices, e.g. the distance between Arduino board and Android smartphone?

Any hints?

Thanks in Advance,

Your Android phone has GPS data, and there are GPS shields or boards for Arduino. So you could calculate the distance between them. I can't help you with the programming tho. I would have to do loads of research for that. But it's definitely possible. Do a Google and YouTube search.

I wish you allot of success with your project,

Mike

I give the android as an example. I'm interested in the Arduino part. I need to find a wireless module with TOF facility. Using GPS limits the use of devices. For example, I can't use Laptop with Arduino, and even GPS is not recommended for generic solutions.

Even if a TOF radio module were available for Arduino, how would that help to measure the time taken from an Android phone (or other device) ?

To use TOF to measure distance from the Android phone you would need to know within a few hundred nS exactly when the signal was sent.

I need to find a wireless module with TOF facility.

Good luck!

You can’t measure the time it takes for a signal to reach somewhere because you don’t know when it was sent. Think about it, exactly how is it going to do that?

Is this your idea or has some one sent you to the stores for some Sky hooks or a long stand?

To the nay-sayers, TOF is becoming a "thing" in WiFi.

Intended uses are e.g. to aid inertial positioning inside buildings, like shops, so more stuff can be marketed at us :o

See: Robust WiFi Time-of-Flight Positioning System

from the short article:

Our system uses COTS APs with customized firmware operating in the core of the 802.11 MAC state machine of a low-cost WiFi chipset (cost per unit of less than three dollars). The system can estimate the position of 802.11 standardcompatible devices, such as smartphones

Yours, TonyWilk

See: Robust WiFi Time-of-Flight Positioning System

Interesting advertisement, but there is no useful information in the article.

TonyWilk:
To the nay-sayers, TOF is becoming a “thing” in WiFi.

Really, apart from quoting a page from a article that says very little, what evidence do you have for that ?

srnet: Really, apart from quoting a page from a article that says very little, what evidence do you have for that ?

I was peripherally involved in a feasibility study to track things in a very large building, this might be a good introduction: Location Tracking Approaches

As of c. 18months ago the base kit to do this (and the 'management system' sold by the likes of Cisco) ran to, well, lots of money.

Havn't looked into it recently, but WiFi routers already have RF beam forming (so there's a vector) and with some time-of-flight capability for distance... well, once this gets down to even twice the price of a standard WiFi access point then tracking everyone by their phone within buildings will be commonplace.

Marketing types love this sort of thing: Our new expensive widget sales point - how long did people look at it? did the same people come back? Where else in the store did they go? What did they end up buying? What credit card did they use? Are they already in our database? etc. etc. etc.

Yours, TonyWilk

You can already buy Pozyx, which actually works indoors, but the price is a good indicator of how far we have yet to go before hobbyists will be seriously interested.

That link is an academic paper, like most academic papers it is not designed to tell you anything but to say later "we did that first". Spent 21 years as an academic so I know how it works.

At a guess it is not so much a time of flight but a time of turnround, that is send a ping and see how long it takes to come back. Keep doing this and variations in the turnround time could indicate distance. A rock solid algorithm I don't think. Mind you the marketing men won't worry about it actually working just that they can get a number.

However the OP is asking about these things TODAY not in one or two years time, so the answer today is forget it. The answer in a few years might be different. I wonder if he can wait that long.

Grumpy_Mike:
However the OP is asking about these things TODAY not in one or two years time, so the answer today is forget it. The answer in a few years might be different. I wonder if he can wait that long.

Not so far away as you may think:

Wi-Fi CERTIFIED Location

…but I suspect the products they list are a bit pricey.

So, yeh, you’re right - practically the OP ain’t going to get WiFi location hardware from BangGood for $5 any time soon :slight_smile:

Yours,
TonyWilk

Grumpy_Mike: You can’t measure the time it takes for a signal to reach somewhere because you don’t know when it was sent. Think about it, exactly how is it going to do that?

Is this your idea or has some one sent you to the stores for some Sky hooks or a long stand?

How can you claim this? It seems you do not know how RADAR systems works or other similar systems. Look at ToF-based distance bounding protocols and then you know how to measure that.

Radar works by bouncing a signal off an object, with wi-fi nothing bounces off anything.

srnet: Even if a TOF radio module were available for Arduino, how would that help to measure the time taken from an Android phone (or other device) ?

To use TOF to measure distance from the Android phone you would need to know within a few hundred nS exactly when the signal was sent.

Simply, the ToF-enabled device send a challenge to the other device. The other device has to respond to this challenge as fast as possible (In other words, the processing time should be a very small fraction to neglect it). Once the response arrive the ToF-enabled device, it can measure the time needed for that signal to arrive by calculating the propagation delay through dividing the ToF by 2. Other aspects have to be taken into account, but this is the idea in simple way.

Simple but wrong. Read all the answers here.

Grumpy_Mike: Radar works by bouncing a signal off an object, with wi-fi nothing bounces off anything.

You are right, I meant the idea in general. For distance bounding protocols, You send a challenge through a wireless medium to the other object, if this object responds within a threshold of time, then it is in vicinity. Otherwise, it is far away. That's why ToF module is needed because such kind of measurements would never give a good accuracy without a dedicated hardware.

Grumpy_Mike: Simple but wrong. Read all the answers here.

How come? tens of paper are published since 1993 addressing this issue, and I've already demonstrated it myself on an AVR microcontroller with IEEE.802.15.4 transceiver with ToF facility enabled in it and got a resolution up to 2ns, this means 30 cm. Since in Arduino there is an AVR MCU too, I wanna try it over there with another type of wireless communication.

Ma7moud: How come? tens of paper are published since 1993 addressing this issue, and I've already demonstrated it myself on an AVR microcontroller with IEEE.802.15.4 transceiver with ToF facility enabled in it and got a resolution up to 2ns, this means 30 cm. Since in Arduino there is an AVR MCU too, I wanna try it over there with another type of wireless communication.

But that's something different to your original post.

Would it be possible to do this on custom hardware at either end, then yes is probably the answer. That you cannot buy modules on eBay suggests its not as easy as you might think.

However your original suggestion was between an Arduino and a Android phone.