Most Helpful Customer Reviews
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81 of 83 people found the following review helpful:
4.0 out of 5 stars
You have to understand, January 26, 2005
I am a Professional Land Surveyor. I purchased a V7000 for my new vehicle primarily for the compass and exterior temperature. When properly calibrated, using the simple instructions, the unit is quite accurate. However, if you move the unit even a few inches, the calibration is lost. Decide where the unit will live, and ride around a while. Move it, if you will, and ride some more. Once you are satisfied with the location, go through the calibration steps. You will obtain a very accurate magnetic meridian. Then check the variation for you area using the included map or referenced web site. Unless you move the compass or the battery dies, it will reliably show your direction.
The outside thermometer, once mounted in the grille, agrees with the radio temperature (you know, when the man says, "It's 23 degrees in Miami today") within a degree or two, well within the variations in ambient temperature. And, if the outside temp is dropping, the flashing ICE message is a very helpful warning.
However, expecting the inexpensive barometer circuitry to accurately measure elevation is ludicrous. Reasonably close elevation measurement is beyond the capability of anything costing less than several thousand dollars. A 1" change in pressure results in a 1,000' change in elevation. Most cheap barometer do not compensate for the temperature fluctuations that affect their measurement, and thereby do not give reliable pressure readings. Since a change of 0.01" in pressure relates to 10 feet, and 0.10" is a hundred feet, the altimeter feature should be considered as useful for entertainment purposes only.
The "forecast" feature is a novelty at best. Traditionally, a falling barometer indicates bad weather, but if you pay any attention to your local weather forecast, it rains while the pressure rises and it rains while it falls. It's sunny while the pressure falls, and it's sunny while the pressure drops. The whole idea that a falling barometer means rain, and a steady or rising barometer means clear skys is pure bunk. And yes, hurricanes are formed by extremely low pressure centers, but they fall apart over land. While there is fault to be laid at the feet of PNI for including such a gimmick, anyone who really needs to know the forecast should listen to the radio or TV instead of depending on a $100 compass and temperature unit installed in the car.
As far as calibrating the pressure, forget it. The inherent error in the unit is so great as to make it a futile exercise. However, as you ride though the Rockies or the Catskills, you may be entertained as the readout increases (yes, increases) as you go downhill and decreases as you climb. What the heck, why do YOu need to know the elevation (oh, do NOT use this instrument to determine if you are in a special flood hazard area-- bad circumstances may result).
The LCD is bright under all light conditions, the auto-off feature and auto-on are very convenient, the auto-backlight is very nice, the unit is big enough to read easily and small enough to be inobtrusive. It's a shame other reviewers did not understand the limitations of using a cheap barometric sensor to determine elevation.
I'm satisfied with it.
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16 of 16 people found the following review helpful:
1.0 out of 5 stars
Extra Features Are Inaccurate and Not Worth The Money, January 13, 2004
As a compass, this unit appears to function properly. The additional features are a waste of money. The altimeter must constantly be adjusted (During the course of a drive from to NY to VT, it will be off by several hundred feet). If the car is turned off, the altimeter must be recalibrated. The Weather Predictor has always said SUN... never anything else. I made the mistake of hardwiring the power cable to my 12Volt power port myself (not purchasing the PNI wiring kit). This voided my warranty, and I could not return the unit. I wired it 2 months after I bought the unit, the problems were always there.
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20 of 21 people found the following review helpful:
2.0 out of 5 stars
Not Reliable, December 3, 2003
I found this compass disappointing. As a sailor I am use to the accuracy of Loran, GPS and marine compasses. I suspect that the problem is not the instrument itself, but the difficulty of compensating for the magnetic influences in a car. The PNI often gives erroneous directional information. My unit has developed a defect after less than 6 months of infrequent use. The 'off' button doesn't work. The unit eventually turns itself off. It is an interesting gadget, but a good road map is a better value.
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