Caratteristiche del prodotto Delta P VRX C54

Delta P VRX C54:

VPM and VGM ALGORITHMS

The Leader in Technical Dive Computers releases the VRx - the latest addition to the VR range of dive computers:

- NEW SHAPE - More Compact
- RECHARGEABLE BATTERY
- USER ADJUSTABLE DECO
- VGM Variable Gradient Factor Model

The new VGM decompression algorithm incorporates the best of Gradient factors, bubble models and Haldane dissolved gas models

The VRX is the latest in dive computing technology.

· Built in torch

· Range of colours

· Low profile design

· High resolution graphics

· Military specification available

· Enhanced ergonomic functionality

· NEW - Variable Gradient Model (VGM) algorithm

· Rebreather interfaces, 1 or 3 cell monitoring as options

· Replaceable, Lithium Ion rechargeable battery system/4 year battery warranty!!

· ROHS compliant (ensures we manufacture to the highest environmental standards)


The new battery system is a step towards reducing the burden on the environment. It is rechargeable, long life (4 year warranty), andreplaceable at factory. Battery charging options 240v, 110v, 6v and even a solar source.

The new VGM decompression algorithm is the culmination of 10 years of expertise in the field and is the most practical and flexible decompression planning system available.

The new VRX is simply the most advanced and complete decompression planning aid available for today and tomorrow.

Torch

The VRX is fitted with an LED torch. The control for this is found in the Dive options screen. There are three settings:

N = torch always off
Y = torch is always on when the VR is on
A (option) = torch turns on when the VR is on and turned face down. The torch stays on for 10seconds after the VR is returned to a non-face down position. This function is only available with the accelerometer option.


Note: The torch is intended as a last resort backup when diving, and should not be considered as an alternative to a good dive torch.

Battery

The VRX is fitted with a rechargeable Lithium-ion battery. A multi-voltage charger is supplied, that will recharge a completely flat battery in approximately 3 hours.

The battery level is shown in percentage on the main front dry screen. A full battery will give the approximate performance:

Total sleep time without use = 6 months
On time with backlight on = 10 hours
On time with backlight off = 20 hours
On time with torch and backlight on = 8 hours
The battery comes with a 4 year warranty. The lithium battery can also be serviced and replaced at the factory. Do not take the VR apart or change the battery yourself. Warranty is void if the VR has been opened or tampered with.

VGM overview
VR Technology announce their new Variable Gradient Model Decompression Algorithm.
Haldane theory has long been and still is the basis of many of todays decompression algorithms, from simple dissolved gas models through to complex bubble growth systems.
Using this and their own extensive track record in dissolved gas and bubble growth modeling, VR Technology has again pioneered a new decompression algorithm utilising the benefits found in all of the current systems whilst implementing some new techniques. The new algorithm allows the basic user a simple series of options to select an algorithm suitable for their style of diving while still allowing the experienced user the ability to customise their profile based on their own experience, equipment in use, gas type and dive depth.
It has long been accepted that most algorithms heavily penalise the diver for using large fractions of helium. VGM takes into account that rebreather use with high helium content is becoming the norm for Technical Diving and hence allows the experienced user to extensively customise their profile through a range of defaults or user selectable setups. It also allows for the fact that divers are individuals and not everyone fits the physical and metabolic profile of the standard human diver. The new system allows customisation of the deep to shallow stop ratio and the overall stop time at each level to cater for this and other levels of experimental diving.
The default setting built into the system simulates the well established decompression profiles of our VR range of computers. Adjusting the algorithm to reduce the default profile may for some divers increase the risk of decompression illness and should be undertaken with extreme care and decisions to do so should be based on previous experience and/or controlled trials.
The new system will exclusively be included in our new VRX dive computer and will also be launched with a new VGM PC based decompression planning system.


Display modes
In display modes there are two additional features:

Automatic display flip (option)
The A option for the Flip mode causes the screen to be automatically flipped over if the VR is turned upside down. This means the display will auto rotate to show the information the right way up, even if you have turned the VR upside down.

Twist mode for mini screen jumping (option)
Setting Twist mode on allows the user to skip through the mini screens in the main dry screen by twisting the VR to the right 90degrees or to the left 90degrees. The unit has to be held for half a second or so to trigger the mini screen change. A twist to the right will be equivalent to a short right button push, so the mini screen will change to the next one as though a short press of the right button had been performed. A twist to the left is equivalent to a short left button push and will change the mini screen accordingly. A twist down (version 1.1) will navigate to the current mini screen.


VGM implementation in the VRx dive computer

Automatic tissue tolerance adjustments
To allow the VR to give realistic decompression and no stop times across the 10m to 120m range the VGM algorithm automatically modifies tissue tolerances in line with accepted decompression schedules based on stochastic data.

Tissue over pressure tolerances (M values) begin to be modified from standard VR Buhlmann settings above 30m bottom depth and 30min bottom time.

User adjustments
Extra changes to the default values can be achieved using the Fast, Mid and Slow tissue tolerance percentages. Positive percentages give more stop time. Negative percentages reduce stop times.
A warning screen is displayed when exiting this screen if negative values are set.

Divers can change conservatism up or down, based on their own knowledge of what suits their body chemistry and physical ailments or attributes. The Normal or Default value is 0%. Negative percentage is less safe. Positive percentage is more safe. The Bar Graph of tissue over pressure tolerance compares the current values to the standard default settings. The bar graph transitions from Fast tissues to the left (mainly relevant to deep stops) through to Slow tissues to the right (mainly relevant to shallow stops). Mid range tissues are in the middle!

Fast Tissues can be adjusted between -15% to +40%. The effect of the fast safety setting reduces linearly from Fast to Mid range tissues.

Mid range Tissues can be adjusted between -15% to +40%. The effect of the Mid setting reduces linearly from both mid range to fast, and from mid range to slow.

Slow tissues can be adjusted between -15% to +40%. The effect of the Slow setting reduces linearly from slow to mid range.

No less than a total of -20% across all tissue can be set.

To achieve the same setting for all tissues use the same percentage setting for Fast, Mid and Slow.
Custom settings allow precise decompression matching to users known requirements or expectation for the next planned dive.

Mid range tissue adjustment is an extra feature compared to standard gradient factor adjustments. From stochastic dive data, Mid range tissues appear to require longer decompression after prolonged bottom time and/or extreme depths. VGM has a built in system for adjusting this, but the diver may wish to adjust the setting manually as well.

Use Diveplan to check settings for next dive. Fine tuning of Fast, Mid and Slow tissues can be used to achieve user specific decompression profiles.

Preset conservatism settings (0% = normal standard safety value)


Extreme exposure dives
VGM also modifies mid range tissues separately to fast and slow tissues, achieving adaptation of mid range stops separately to deep or shallow stops. Extended mid range stops are a common technique used on deep dives to allow surfacing with a lower bubble count than would otherwise be expected - Britannic 1998 exploration is an early example of this technique.


Algorithm selection
The Setup screen shows the active algorithm and allows it to be changed from VGM, Buhlmann with micro bubble stops, and VPMB with Buhlmann. If changed to VGM, then when exiting setup the user is shown the Algorithm Safety Bubble Control screen.

Diveplan and diving
Diveplan screen allows change of preset settings for VGM if VGM algorithm active.



VGM - Decompression philosophy
The VGM algorithm has been built on recent practical dive planning and diving techniques as well as the scientific and theoretical understanding over the past 100 years. It combines better theoretical understanding of bubble physics together with known diving practices that help decompression and well being during and after decompression diving.

VGM also gives the user the ability to change the conservatism of the decompression to make it more conservative, but also more aggressive. Some technical divers find they feel good after a decompression with less in water time than others. The equivalent gradient factor for the VGM setting is displayed for comparison with other dive planning software and computers.

We feel the default settings will suit many experienced divers, and it is the input of real technical divers in the choice of these settings that has made VR Technology and its team at the forefront of technical diving product design for over 20 years.

Decompression is a physiologically complicated event. There are many factors that affect how well the human body decompresses and how well it is able to withstand pressure exposures. All dive algorithms have been devised to combine the complexity and risk of staying in the water with the risk of decompression sickness after surfacing. Things like hydration before a dive, and rest and hydration and even oxygen after a dive all help reduce the risk of DCS. So bear in mind that as with all decompression planning there needs to be a balance and understanding of the risk of reducing decompression times and the impact of DCS. Please refer to your training agencies- information and advice on these issues.

VGM incorporates 5 main features:

Haldane decompression model, based on Buhlmann ceofficients
Modification of tissue over pressure tolerances or M values for the faster tissues to create a decompression profile similar to a bubble model like VPM
Further modification of over pressure tolerances for deep or long exposure dives, especially in the fast and middle order tissues
Automatic adjustment of the above parameters to allow the default settings to give common decompression and No Stop times across the range of diving from 10m to 120m
User adjustable parameters so the diver can use his/her experience to further modify the decompression to that which suits him/her. The equivalent gradient factors are displayed for a particular dive for ease of comparison with other dive computers and dive tables, although because this system goes beyond gradient factors certain adjustments may only give an estimate of the nearest GF equivalent.
A basic version of PC dive planning software VGM ProPlanner is available free from the web site. This allows a quick way to see what decompression the VRx dive computer will give and allow specific conservatism factors to be tried out on the PC before choosing the right ones for a dive on the VRx. The PC software also gives print outs and an output in common spreadsheet style format for use in creating back-up tables.

The VRx gives an Equivalent Gradient Factor (EGF) after a dive. Because it is an adaptive variable system, the gradient factor cannot be calculated until after decompression has started. The expected EGF is displayed in the dive summary screen accessed by using a long press of the right button from the main dive screen. It is the screen displayed after running through the decompression stop look ahead. The EGF is also shown on the DivePlan exit screen and the dive log in the VRx.

Summary

VGM is able to adapt to the dive actually dived - the gradient factor is essentially adjusted on a dive by dive basis automatically. The safety factors can be adjusted from the default settings to adapt a decompression to the required profile based on the diver-s experience though.