Hi All I bought an hx4700 a while back because it was reportedly one of the best of its generation with regards to sunlight readability. But quit frankly once I had it installed and wired I discovered its readability during flight is still not adequate. I previously flew with a low cost GPS and then a Palm V mounted in the cockpit which also had their display limitations so I have experienced this before. The information provided by XCsoar is so useful, I would never fly without the hx4700. It is just sad that sometimes when I scan the panel I miss some of the details on the PDA.
Now I am considering upgrading to the Dell Streak, and actively looking for alternatives, because the Dell is reported to have significantly better sunlight readability than the hx4700. But when I read the reports, it is obvious that sunlight readability is very subjective. What looks good in the shop and during a casual walk outside does not always cut it when you mount the device is in a glider cockpit and go flying. So I figure we should design a means of evaluating sunlight readability so we can compare our experiences in a semi-scientific manner. I took my hx4700 out into the sun yesterday and danced around with it a while and came up with the following: PROCEDURE FOR EVALUATING SUNLIGHT READABILITY OF A PDA DEVICE FOR GLIDING PURPOSES: 1) Requirements: - PDA, PNA, Tablet Computer, smart cell phone or other device to test, with enough battery charge. - XCSoar software, loaded with terrain maps and turn points, or alternate mapping software, like Google maps. - An outdoor location with direct, bright sunlight. - Gliding sunglasses and optionally a gliding hat or peaked cap. 2) Preparation: - Start up a XCsoar on the device, demo mode may prove useful if it is not located in an area covered by your maps and connected to a GPS. (Otherwise use alternate mapping software like Google Maps). Make sure you have some coloured features, like terrain markings, as well as some text details, like turn point or street labels, clearly visible on the screen. - Ensure that the PDA backlight is on full brightness and will maintain that setting for several minutes during the evaluation. - Put on your sunglasses and optionally your hat. 3) Test Positions: Take the device out into the sun and assess it in the following 5 positions. In each position the device should be held at arms length, with the screen pointing directly back at your eyes. Position A: Sun shining over your shoulder such that the shadow of your head falls just to one side of the device and the device is in full sunlight. If it has a reflective screen, the reflection of the sun should shine on your neck or chin, just below your eyes. Position E: Hold the device up in front of the sun so the shadow of the device blocks the sun from shining directly into your eyes. Be careful not to look directly into the sun. Wearing a gliding hat or peaked cap allows you to shade your eyes from the sun with the brim of your hat while you are positioning the device. Position C: Rotate your arms in an ark to a point midway between point 1 and point 5. Hold the device at right angles to the sun so that it shines across the screen and small adjustments would put in in either shade or sunlight. Position B: Rotate your arms in the ark to a point midway between Position A and Position C. There should be direct sunlight falling on the screen. Position D: Rotate your arms in the ark to a point midway between Position C and Position E. The screen should be in shadow. Note I have described the positions in an order which easiest to understand. Once you know what you are doing it is very easy to go through them in alphabetic (ie positional) order. 4) Test Procedure: Line up the device in the required position and then tilt it slightly to minimize the effects of reflections etc. Move it up to 15 degrees left or right and/or up or down while maintaining the relative positions of the sun, your eyes and the device until you have the best visibility. Hold the position and look away at some details on the horizon for several seconds. Then glance back at the device for 2 seconds. Read some black text details, like turn point labels (or street names) on the map, and then look at colour features like terrain shading. Assign a score from 5 down to 1 for the visibility of the details. The score should be similar to the 5 to 1 score one uses to report on a radio test transmission, ie: 5: Clearly visible 4: Some distortion, but still clearly visible. 3: Significant distortion, but still visible. 2. Lots of distortion, barely visible. 1. Total distortion, information not discernible. Separate scores should be assigned for black text and colour features. Finally make a note how high the sun is above the horizon. This will give others an indication of how bright the conditions were during your assessment. To test the above I tried it with the following devices: - My HP Compaq hx4700. - A college's htc Desire smart phone. (Google shows that this phone came out with two models of screen, AMOLED and SLCD. There is no definitive way to determine which is installed. The original packing does not state AMOLED, which suggests it is SLCD but the test results indicate otherwise). - My well used Nokia 6110 Navigator cell phone. - My Casio black and white digital watch. (Top of the line for a plastic digital watch, but still not an exotic watch). I logged these results: Colour visibility Position A B C D E hx4700 5 4 2 2 1 htc Desire 1 4 3 3 2 Nokia 6110 nav 1 3 2 2 2 Black/white visibility Position A B C D E hx4700 5 4 2 2 1 htc Desire 1 4 3 3 2 Nokia 6110 nav 4 3 2 2 2 Casio digital watch 5 5 5 5 5 This was in sunny but winter weather in Cape Town with the sun about 35 to 40 deg above the horizon. The most interesting comparison is Position A, with the sun shining directly onto the screen. My hx4700 reads 5, but the htc is a 1. My Nokia goes black and white. In position B both the hx4700 and the htc are clearly visible. The "shade" positions, C, D and E test the strength of the back lighting. The htc is better than the others. Clearly the limitation of the hx4700 is the strength of the back light when it is contrasted with a very bright sky as a background. As a comparison I tested my Casio black and white digital watch. It scored "5" in every position for black text (but obviously no colour scores). Interestingly when the face was in shadow it was just as legible as in sunlight - but it looked different, as if the white background has the ability to reflect ambient light even when in shadow. I would appreciate it if others could attempt the above test with different devices. Please give feedback on the devices you test as well as comments and suggestions on the test procedure. It would be very good if people could test multiple devices and give feedback on them so that the relative sunlight readability of different devices can be accessed. If others see the usefulness in this idea, I am happy to post it up on a wiki somewhere. We can keep a log of test results on the same wiki. Thanks Ian ------------------------------------------------------------------------------ EditLive Enterprise is the world's most technically advanced content authoring tool. 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