Liquivision???

[dmaziuk]

I'm only vaguely familiar with Liquivision, but this has me curious.

What is unique about the Liquivision transmitter tech?

Ultrasound.

 

[L13]

Ultrasound.

Not quite unique. Garmin uses ultrasound also.

 

[dmaziuk]

Not quite unique. Garmin uses ultrasound also.

More accurately, Garmin started using ultrasound five years after Liquivision stopped making dive computers. Coincidentally, another piece of dive gear utilizing ultrasound: the Buddy Watcher, was bought out by Dive Alert and quietly killed off -- as far as anyone can tell -- a year or two later. Kinda makes you wonder what is it about ultrasound, and how long Garmin can keep it up.

 

[Johnoly]

..Kinda makes you wonder what is it about ultrasound, and how long Garmin can keep it up.

One of the problems with ultrasound underwater is that battery life decreases exponentially when increasing the communication link distance. Combined that with a battery the size of a coin or even a piece of candy and you quickly see the challenge.

 

[RonR]

Everything is a tradeoff. In our testing of an ultrasonic transmitter, we get a line of sight transmission range of around 300' / 100m for tank data, allowing for buddy monitoring. We're getting 12-15 hours of diving on a charge. If you accepted less range (as Garmin does apparently) you could save battery power by using less transmission power. With the typical RF transmission your range might only be 10 feet or so, but the battery can last a long time. It would really depend on your goals, if that extended range is important to you for monitoring buddy tank pressures.

Liquivision also used the acoustic transmission for direction finding & buddy location. That's an option with acoustics, but not super easy to implement in practical terms.

Ron