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Thank you. Are USGS triangulation station markers described in some other database then?

Hi. On the following page I have documented the location of a long-gone Fire Lookout Tower: http://wythe.us/content/tiki-index.php?page=High+Rock+Lookout+Tower At the tower site I came across a USGS reference mark named "HIGH ROCK" stamped 1948. There is also a USDA Forest Service marker #191, initialed in pencil "LRE 4-22-04". Those seem to be somewhat rare - I posted about that USDA marker here before. Both are pictured on the page I referenced above. My main question is that the USGS reference mark is not listed here or on the NGS site. There nearest benchmark is another fire tower several miles away. What does it mean when a USGS mark is not listed? Thanks!

I have found one of these as well, and this thread is practically the only google hit on these types of survey marks. This marker is numbered 191. It is also close to 4000 feet elevation. The year was not marked. It is on Jefferson National Forest, but not along the border of the forest. The forest boundary is about a mile to the north at the base of the mountain. Here is a picture: http://wythe.us/content/tiki-download_file...=43&preview That is not my writing in pencil. It reads "LRE 4-22-04". I'm pretty sure it says "04" but it could possibly be "09". The number seems to match the other 4 though. Certainly seems these were being logged judging by the pencil mark. Approximate location: N 37.10867 W 80.97048 Oh, and there used to be a fire lookout tower at this location (which is why I was there). It was about 100 feet to the south of the mark. Directly under where the tower used to be is a USGS Reference Mark, but it does not point to the USDA marker.

I have maps I've custom-made that I use with my Garmin eTrex Venture (hydrology, contour, land-cover, etc). Are they compatible with the Nuvi? Does it also use Mapsource? Wal-mart has the Nuvi 200 on sale tomorrow (black Friday) for $99, and I'm considering grabbing one for the car.

20 meters is a bit extreme - typically you should be within 10 or so. Keep in mind that the accuracy of the GPS used to place the cache is also not perfect. So the error of your GPS combined with theirs could either balance out, or make things worse.

I use MetroGuide for detailed streets, and have my own custom-made topo maps for my home area. When I travel outside the range of my custom maps I really start missing the extra information, especially hydrology, but the elevation contours are useful too (even while driving). Dan

Nice! Dan

Here's a thread with power consumption measurements on a Vista HCx and a Venture Cx. Neither saw any substantial difference in power consumption with WAAS on or off. As expected, the backlight is the massive power consumer, more than tripling power consumption when used on high compared to off. Dan

BTW, I saw no difference with WAAS on or off. Dan

tomc61, were you using Alkaline AAs or rechargeable? We can't compare device to device without knowing the voltage you were using. Here are the values of a Venture Cx using rechargeable batteries at 2.77V. I provided values in both milliamps and milliwatts. The milliwatts should be used for comparing device to device, because wattage is a measure of power which is independent of voltage. Milliamps can only be compared if the voltage is exactly the same. My batteries are Rayovac Hybrid rechargeable. They are rated 2100 mAh, so I provided the (theoretical) battery life I would get with these batteries. Radio on: Backlight off: 77.4 mA (214 mW) (27.1 hours) Backlight medium: 144 mA (399 mW) (14.5 hours) Backlight high: 220 mA (609 mW) (9.5 hours) Radio off: Backlight off: 48.6 mA (134 mW) (43 hours) Backlight medium: 108 mA (299 mW) (19.4 hours) Backlight high: 185 mA (512 mW) (11.4 hours) So, backlight at medium doubles power consumption, which would halve the battery life. Backlight at high more than triples power consumption, cutting battery life to less than 1/3 compared to no backlight. The user manual states a maximum 32 hours battery life. My measurements show 27 hours with these particular batteries, so that is in the ballpark. Garmin would probably have used the highest mAh AA batteries available in order to state the longest possible battery life. Dan

My prediction was pretty close: I haven't had a chance to test my Venture Cx up. It has the older receiver, so the differences with the radio on and off will probably be different. Dan

Not really, that's just your way of seeing it because you don't use auto routing, in fact if you look at the price of the Yellow eTrex and Yellow eTrex H you see they are the same, therefore there is no charge for the H chip. I don't follow you. The Venture Cx does autorouting too. I have used it, I just don't need to use it regularly. The only difference I see between the Venture Cx and Legend HCx is the high sensitivity receiver, which I said "The Legend HCx is currently around $25 more than the Venture Cx at Amazon.com, so for so little extra it would be worth it." The fact that the bottom-end devices cost the same price doesn't really mean anything. It just indicates that they can't reduce the price of the original eTrex any lower or they would be losing money. It cost them a certain amount to manufacture those devices when they were made a number of years ago - probably the exact same amount it costs to make the new eTrex H now. That's just the way technology manufacturing goes. The margin on the low end device must be tight, so they don't have room to reduce it further. To me, it shows they made too many of the original eTrex and demand for them hasn't been strong. Dan

Hard reset instructions are here. I'm not sure how much more power it consumes. If I have time later today I'll hook my GPSr up to the multimeter and check the amperage under various conditions. My hunch is that it at least doubles power consumption under full brightness. Dan

I think it is speculation that it uses extra battery life. My manual says nothing to that fact. Dan

The backlight isn't a single light, but is actually multiple white LEDs, which basically never wear out and are shock proof (since they are solid state). On my eTrex they can be seen by looking up into the top edge of the display. There are 4 of them. You either have a loose connection between the display and mainboard, or conceivably a software glitch, since the backlight is of course software controlled. A hard reset might be in order, if you have things backed up and can easily restore. Rolling back the firmware would be another thing to try, if that is possible. If it still doesn't work then it is probably a physical problem. In that case I would think bumping or jarring the unit would cause the backlight to flicker on and off. Dan

Personally, I would take the expandable storage over the high sensitivity receiver any day. I make my own maps which can be quite large, so storage is critical. Also, I wouldn't consider the new Venture HC as the next step up from the Venture Cx. I would be choosing between the Venture Cx and the Legend HCx. The difference is only $25 or so, and basically represents the cost for the high sensitivity receiver. Dan

Ahh, I stand corrected. I knew there wasn't a Venture HCx, but did not know about the HC. The Venture Cx supports autorouting. I seldom use it, but it definitely works. I don't know whether the HC model supports it - perhaps they disabled it to further cripple the device. "Pack more detail into your adventure with the eTrex Venture Cx. This popular handheld navigator has a bright color screen and microSD card slot for expandable memory, and it can route you on roads or off, for wherever your travels take you." Dan

I wish I could manually mark Geocaches as found, without having to go through the whole Find geocache / enter the compass navigation spiel. I know I can simply change the icon itself for the waypoint, but that will not make a calender entry or put the found date and time in the waypoint notes. So basically I want a button on the Waypoint screen saying "Found" if it has the not-found geocache icon. Dan

The user manual makes a rather confusing remark - that WAAS can both increase AND decrease accuracy. So I think the ability to turn it off simply allows you to ignore the WAAS system in case something strange is going on with it. To me, it indicates that Garmin isn't comfortable with WAAS as a core or required part of the system. I doubt battery life would be affected. The receivers stay on trying to acquire GPS satellites constantly, and the WAAS signals are just mixed in with the bunch. The backlight would have far greater impact on battery life than receiving a WAAS signal. Dan

I have this GPSr, and it's worked really well for me. I use it hiking, driving, geocaching, benchmarking hunting and while riding on my dual sport motorcycle. I bought it for $176 at Amazon which included free shipping. At this point in time the biggest decision you'll have to make is whether to go with the new high-sensitivity receiver models, like the Legend HCx. That device is the same as the Venture Cx except for the receiver. There are times when hunting Geocaches in heavy tree cover that the H model would certainly be nice, because my position is floating all over because of the poor signal. The Legend HCx is currently around $25 more than the Venture Cx at Amazon.com, so for so little extra it would be worth it. Note that the Venture product line was identical to the Legend line except for the accessories included in the box. It looks like Garmin did away with that silliness and the Venture model is not available in the new high-sensitivity product line. Dan

Garmin uses letters to indicate some of the device features. C means it has a color display. X means it supports expandable storage (Micro SD Cards). H means it has the new high-sensitivity receiver technology. In my case, CX was mandatory. Color screens are simply a must for me, because color can be used to convey additional map information on the small screens. External storage was also a requirement, because otherwise you are forever limited to the tiny internal storage. Also, some models come prepackaged with some accessories. For example, the eTrex Venture Cx and the eTrex Legend Cx are the exact same device (except the Venture is yellow). The difference is the Legend comes with a small Micro SD card and a USB cable, while the Venture does not. MicroSD cards are very inexpensive ($20 for 2gigs), and many people have USB cables of that type, so for some it wouldn't be worthwhile for pay extra for the Legend over the Venture. Dan

Don't just walk into a retailer like Wal-Mart and plop down some cash on one of their GPSrs. I looked at several stores, and most had old GPSr devices for high prices. Dan

My Venture Cx has reported accuracy of +/- 5 ft a number of times. However I take that with a grain (or actually a whole shaker full) of salt. Keep in mind that the difference between a single digit precision (ie the difference between N50° 00.000 and N50° 00.001) can be a dozen feet or so depending on your latitude. Also, the algorithm the GPSr uses to estimate the accuracy is based on known factors, like how many satellites the GPSr is currently receiving, the position of those satellites relative to one another, and how much atmosphere lies between the GPSr and each satellite. Unknown factors, like the reflection of signals off of buildings, or the bending of signals through atmospheric conditions (like large temperate gradients) cannot be accounted for by a normal GPSr. In Amateur Radio there is a phenomenon known as tropospheric ducting, which affects high frequency radio waves that are normally line-of-sight only. That can result in the bending of radio waves so that they stay in the atmosphere and follow the curve of the earth, and in extreme cases allow reception of signals thousands of miles away. So just remember that, on average, your GPSr is probably pretty accurate. However determining exactly when it is being accurate is difficult. Dan

You're probably aware of what happened to James Kim and his family. It is awful he died, but it is more amazing that his wife and children survived - they were extremely lucky. As an amateur radio operator, I don't travel anywhere without a handheld transceiver. In my case I use a Yaesu VX-7R, which is a small, rugged, waterproof handheld radio that can transmit on 4 different bands, and receive everything from TV to CB to shortwave, including AM, FM and weather radio. Mine is modified to allow transmission on any frequency the radio can physically transmit on. In a life or death situation I would (and could legally in that instance) transmit on any frequency to make contact. My point is if you travel in remote areas, especially during dangerous weather, obtaining an amateur license and a $300 radio would provide arguably the highest likelihood of communicating for help. Dan

Pretty much any card should work fine. It is possible that the card might be formatted with a filesystem that the GPSr can't read, but that can be remedied by reformatting the card in a PC or laptop that can read SD cards. That is a good price for that card. Dan