The Heads-Up-Display (HUD) is an optional attachment to the DS-1 Digital Display. Its function is to keep the diver aware of his approximate PPO2 level at all times. The HUD gives basic information only, for accurate PPO2 levels the diver should check his DS-1 Digital Display.

The HUD consists of a mouthpiece mounted housing with two LED's, one red, one green. When this is fitted, the diver selects their desired setpoint in the calibration menu of the DS-1 Digital Display, and the HUD indicates PPO2 information to the diver based on voting logic from all three sensors. A green flash indicates PPO2 is close to setpoint, a red flash indicates low PPO2, and a double red flash indicates high PPO2. This method was chosen as it is simple, green is good, red is bad.
The HUD can be swapped from the left eye to the right eye by simply reversing the mounting bracket.

Why the limited indication?

There are a number of HUD's available on various rebreathers out there, and they all have either a different number of LED's, or employ them in different ways. Some use a complex code of flash counting which gives accurate PPO2 levels for each sensor. It's good point is that it conveys lots of information to the diver, but it's bad point is that it conveys lots of information to the diver! If the diver ever gets into a stressful situation, he is likely to either forget how to decode the flashing, or more likely, may not have time to concentrate on it.
With our HUD, the diver knows whether his PPO2 is good, low, or high, that's it. If it's not green, then check your digital read out.

Why two LED's?

We chose to use two LED's for safety reasons. Using a single bi-colour or tri-colour LED saves space, but if the LED fails, you lose all indication. Using two LED's, in the event of one LED failing, the diver can still get a valid indication. If the green LED fails, the diver will still be alerted when the PPO2 is high or low via the red LED. Conversely, if the red LED fails, the diver still knows his PPO2 is good via the green LED.