Reading Wireless Air Transmitter using Arduino

[Robbyg]

I have not been here in almost a year but wow it's nice to see that you guys did pick up the torch and have figured out the details.

I look forward to seeing when someone gets a receiver made that can be dipped into the water and get readings from multiple transmitters.
Personally I feel like that would be a very useful device to have on board a dive boat. Even with limited range it opens up other possibilities like a BC mounted repeater that can amplify the signal. It would be briliant if the captain of the boat could actually monitor a whole group of divers.

 

[Robbyg]

So did anyone ever go the extra mile and make something?

 

[Timmyjane]

So did anyone ever go the extra mile and make something?

Reckon not. Seems like the project died.

 

[Pearlman]

This topic is out of my league but I got curious about the magnetic field and compasses that divers wear. Some googling led me to this: NFC and Compass discussion

The NFC field is very strong within a sphere of about 10 cm round the antenna, which is usually near the back of the phone (often it forms part of the battery), and falls off very quickly after that...

…even a fairly brief direct contact between your phone and a weak magnet such as a compass would be enough to demagnetise the compass (I don't think it would normally reverse the polarity but the compass just wouldn't settle). The solution is to turn off NFC when you aren't using it ..l

In a normal diving stance underwater the compass location (wrist mounted) is far away from the transmitter therefore nothing untoward is expected. But what happens if by chance on the boat a divers compass arm is touching the tank valve while he shuts it down and the transmitter is on? Now the compass is within 10cm of the magnetic field - is there a risk of the compass getting demagnetised and never settling thereafter, making it unreliable and useless?

 

[tursiops]

This topic is out of my league but I got curious about the magnetic field and compasses that divers wear. Some googling led me to this: NFC and Compass discussion




In a normal diving stance underwater the compass location (wrist mounted) is far away from the transmitter therefore nothing untoward is expected. But what happens if by chance on the boat a divers compass arm is touching the tank valve while he shuts it down and the transmitter is on? Now the compass is within 10cm of the magnetic field - is there a risk of the compass getting demagnetised and never settling thereafter, making it unreliable and useless?

No. The NFC radiated field is not similar to the 38kHz radio transmission from the pressure transmitter.

 

[acahir]

I read this post with interest a year or so ago, and decided to revisit it out of curiosity. Amazing work decoding the swift transmissions, was really fun to watch the progress through the posts.

I'm curious if anyone has seen any similar reverse engineering with Garmin's SubWave transmitters? I've searched around a little, but never found anything.

 

[tursiops]

Reckon not. Seems like the project died.

That's not really accurate. The original project did not die; it ended successfully. The goal of decoding the signal was achieved; see posts 131 and 163. Some folks wanted to go beyond the original goal and try and build some kind of receiver/transmitter and that progress has indeed been slow. Hey, it took a year and a half just to work out the decoding!

 

[mikkelking]

What would you be looking for on the chip? We already know the transmission frequency....

It's likely that they use a standard bluetooth chip, and you'll be able to find specs for it

 

[tursiops]

It's likely that they use a standard bluetooth chip, and you'll be able to find specs for it

The design (1995) predated BT(1999) and does not use anything like BT frequencies or protocols. You should read the entire thread and not just respond to early posts that are now OBE.

 

[Timmyjane]

It's likely that they use a standard bluetooth chip, and you'll be able to find specs for it

It’s sound. I had no idea either. Pretty wild stuff.