4.3 U SER I NTERFACE The user interface & associated keypad is responsible for user interaction and communication of environmental parameters to the unscrambler. It provides the means by which the gas and environmental parameters of the unscrambling operation can be changed. The HLB Unscrambler gives the user full control over the setup and updating of each of the parameters relating to unscrambling the helium speech. If unscrambling is deemed unnecessary, for example when the HLB depths are near 0 msw, the unscrambler on/off switch can be switched to the off position and no unscrambling will take place. Turn the unscrambler on using the round push-button switch on the user interface section of the front panel marked “UNSCRAMBLER”. The “UNSCRAMBLER” pushbutton will illuminate blue when the unscrambler has been switched on.
15 CO-OM-6605 R0 Chapter Fig 4.1 shows the User Interface and Keypad Fig 4.1 User Interface & Keypad There area number of user interface pages which can be viewed and/or adjusted. The power up page is shown in Fig Fig 4.2 User Interface Power up Page After power up the user interface defaults to the homepage which displays the depth at which the depth pot is set at. Fig 4.3 shows the user interface home page.
Chapter 4 CO-OM-6605 R0 Fig 4.3 User Interface Home Page All user interactions are by means of the four direction buttons ↑ ↓ ← →, the select button (centre) and the depth control potentiometer. The LCD provides feedback to the user and prompts them for the appropriate key selection to either scroll to the next field or to edit the displayed field. The depth control potentiometer can be adjusted at anytime and updated parameters will be transmitted automatically to the Unscrambler DSP. There is also areal time update to the LCD which displays a digital readout of the depth at which the potentiometer is set. The user interface operates in two modes, a scrolling mode whereby the ↑ & ↓ buttons will take the user through the environmental fields (PPO 2 , Temperature & Pitch Reduction) and an editing mode where a nominated field can be incremented or decremented. Depth and PPO 2 are the dominating parameters in the operation of the unscrambler. The depth parameter is expressed in meters of seawater (msw) and operates over a range of 0 to 500 msw. The depth adjustment is the controlling factor behind the unscrambling operation and can be operated on its own without any interaction on the user interface to successfully unscramble helium speech. Fig 4.4 Depth Potentiometer
17 CO-OM-6605 R0 Chapter The gas mixture (PPO 2 ) is defined by the normalised ratio of the partial pressures of the helium and oxygen components of the Heliox atmosphere. No other gas components are considered in the software algorithms. The default PPO 2 value is 0.8 atm and it can be adjusted over a range of 0.0 to 2.0 atm. Fig 4.5 shows the user interface PPO 2 page. Fig 4.5 User Interface PPO 2 Page To adjust the value, the select button (centre) should be pressed and upon doing so the user interface enters edit mode, this applies to each page that can be edited. Fig 4.6 shows the PPO 2 page after the select button is pressed. Fig 4.6 User Interface PPO 2 Edit page Pressing the ← or → buttons on the keypad changes the PPO 2 value by increments of 0.01 and pressing the ↑ or ↓ buttons changes the PPO 2 value by increments of Pitch Reduction Ratio (PRR) refers to a reduction in the pitch of the unscrambled speech and can improve the naturalness of the divers voice, but may not necessarily improve intelligibility - it may make long term listening less tiring. The default PRR value is 1.00 and it can be adjusted over a range of 0.6 to 1.00. Under normal circumstances PRR can be left in its default state. Pressing the ← or → buttons on the keypad changes the PRR value by increments of 0.01 and pressing the ↑ or ↓ buttons changes the PRR value by increments of Fig 4.7 shows the user interface PRR page. Fig 4.7 User Interface PRR page
Chapter 4 CO-OM-6605 R0 Temperature also has a minor effect on the unscrambler function although under normal circumstances is usually left in its default state. The default temperature value is 18 o C and it can be adjusted over a range of 0 o C to 30 o C. Pressing the ← or → buttons on the keypad changes the temperature value by increments of 1 and pressing the ↑ or ↓ buttons changes the PPO 2 value by increments of Fig 4.8 shows the user interface Temperature page. Fig 4.8 User Interface Temperature page