*** Altimeter Watch Comparisons *** Sun Jan 1 11:05:25 1995 Message : #20323783 From: Nick Parker Address : nsparker@ingr.com Group : Usenet.rec.backcountry Subject : altimeter watch information (long) Org. : Intergraph Corporation, Huntsville, AL This year my wife gave me an altimeter watch (actually two, one of which I get to keep) as my Christmas climbing toy. Here's some specifications taken from the documentation that came with the watches, the results of some rudimentary comparison tests I made, and some other related info. This may be useful if you are in the market for an altimeter. Nick CASIO AVOCET 950 & 960 Alti-Thermo Vertech Alpine ---------------------------- -------------------- altimeter range 0 - 19,680 ft (negative) 0 to 60,000 ft neg. readings to -19,680 ft ) (to -4,000 ft) altimeter units 20 ft 10 ft altim. temp compen. no yes target altitude alarm yes, no preset altitude (up or down) alarms when you reach a barometer 13.55 - 32.45 inHg 28.84 - 31 inHg barometer resolution .05 inHg .01 inHg thermometer range -4 - 140F 0 - 122F thermometer accuracy +/- 3.6 F in range of -4 to +/- 4 deg F accuracy 0 deg F above freezing, +4 deg off for each 10 deg below freezing light yes no time alarms 5, plus hourly signal 1 time/date alarms none none day of week display yes (MON, TUE, etc.) none stopwatch functions up to 23hr 59min 59.99 sec, up to 23hr 59min 59sec, elapsed time, split time, splits, 20 split/lap two finishes, .001 sec groups, .05 sec resolution resolution countdown timer no yes, up to 23hrs 59min memory storage of 50 sets of data daily vertical, total (time, temp, date, altitude), vertical, max and avg auto or manual storage, max ascent rate, no data and min altitude storage function graphic display line chart of 26hr barometric none trend, bar chart of altitude change, line chart of progress toward target altitude water resistance to a depth of 300+ ft to a depth of 10 ft, detergents permanently damage sensor battery 2 year lithium, 2 year lithium, user replaceable, factory replacement low battery indicator only (mail to factory with $5.00), no low battery indicator Comparison Tests ---------------- I left both watches sitting side by side on my stereo cabinet overnight, so their temperatures would be stable and equal. In the morning I set both to an altitude of 700ft, which was my approximation of the elevation of my house (I don't have a topo map that shows my house). My house thermostat read 71deg, and the national weather service said the barometric pressure was 30.22 at the airport about 5 miles from my house, at a elevation of 620ft. The watch readings were: temp. alt. (F) (ft) ----- ----- Avocet 70 700 Casio 71.6 700 To test the efffect of a negative temperature change, I put both units outside for 30 minutes. My back porch thermometer (which is normally pretty accurate) read 43deg F. After the 30 minutes, the watch readings were: Avocet 48 690 (-10' fluctuation) Casio 47.2 780 (+80' fluctuation) I brought them back inside and gave them 30 mintes to come back to room temperature. To test the effect of a positive temperature change, I wrapped them in a towel, along with a ziplock bag full of 120degF water, for 30 minutes. [No, I didn't put the watches in the bag with the water.] After that time, the water temperature (measured with a mercury thermometer) was 111degF, and the watch readings were: Avocet 101 660 (-40' fluctuation) Casio 108 660 (-40' fluctuation) To see if the units would return to their original settings, I set them back on the stereo cabinet for 40 minutes, at which time the readings were: Avocet 69 740 (+40' fluctuation) Casio 73.2 720 (+20' fluctuation) To compare how the units would react to altitude change while being worn on the wrist, I put the watches on (and waited 40 minutes to make sure the watch temperatures had stabilized) then drove over to the airport and set the altitude of both units to 620ft, which is the airport altitude given to me by the FAA. I then drove up to a spot listed as 1620ft on the local topo map (exactly 1000ft higher than the airport). I would like to have tested on some higher mountains, but the local geography just wasn't cooperating. ;-) The watch readings were: Avocet 78 1670 (+50' discrepancy from map) Casio 81.4 1640 (+20' discrepancy from map) After returning home (I left the units with the altitude calibration I had made at the airport) and letting the watches sit on the table for an hour or so, the readings were: Avocet 70 750 Casio 74 780 Since the largest variation I'd seen in the performance of the two watches was in response to cold temperatures, I decided to test that further by putting them in the freezer for an hour (along with my back porch thermometer). After that, the thermometer read 0 degF, and the watch readings were: Avocet 16 490 (-260' fluctuation) Casio -2.4 1040 (+260' fluctuation) After the units had been taken out of the freezer, and given a couple of hours to warm up to room temperature, the readings were: Avocet 70 730 Casio 72.6 780 My tests were by no means comprehensive, but they give the most direct comparison data I've ever seen. I had expected the Avocet temperature compensation feature to make a big difference in altimeter accuracy when temperature changes were experienced. However I found that neither unit was clearly superior in this regard. The Casio thermometer was generally more accurate than the Avocet. Misc. Notes ------------ There are other altimeter watches on the market, but as far as I know only the two models listed above can read up to, and above, 14,000 feet. Altimeters that can't even go to 14K don't seem like a wise investment to me. These units, like all altimeters, only give an approximation of altitude. The altitude readout will fluctuate with changes in barometric pressure. Reasonably accurate thermometer readings can only be taken when the watches are not exposed to external heat sources. This includes your body and direct sunlight. The Casio 950 and 960 differ only in the design of the case. The 960 has a rotating slide rule bezel that can be used to make mathematical calculations. The 950 does not have a slide rule, and is the model offered by most catalogs and retailers. I've never seen a 960. Casio's long history of watch making is evident in the comfort of their design. I found it much more comfortable to wear than the Avocet. Every corner of the Casio body and band has generous radii for comfort. The edges on the Avocet band and body (underside) are much sharper. The Casio band is much more flexible than the Avocet band. An elastic band is available for the Avocet, but I did not try it. The Avocet has a ski mode, which measures current descent rate, max descent rate, and number of runs skiied (run counter is automatically tripped by a descent of 150 feet). The Casio does not have this feature. Both units are easy to use, and have some type of graphic indication of what mode you're in (altimeter, stopwatch, etc). I could operate the buttons of either unit with gloves or mittens on. The LCD display of the Casio is about 25-30% larger than the Avocet display. The extra display size is put to good use. Both units are a little bulky, as compared to a regular watch. The Casio is a little wider (along the axis of your arm) than the Avocet. The Avocet is a little larger than the Casio in the other axis. The Avocet is a little thicker than the Casio. The Avocet looks less bulky, primarily due to the shape of the case, which has a narrowing at the "waist". All in all, they're about the same size. The Casio documentation goes into much more detail than the Avocet documentation, and I found the detail useful. The Casio graphic display of barometric trend is a good feature.With the Avocet you only get a + or - symbol telling you the current barometric trend, and a numerical value for the current pressure. The Casio gives you the current value, plus a line chart of what the pressure has been doing over the past 26hrs. Each dot on the line of the chart represents a barometric reading (recorded automatically at 2 hour intervals). This chart allows you to get an idea of the rate of change of barometric pressure, which may be valuable in judging how fast a front is moving in. Of course this data will only be meaningful if your altitude has not changed (overnight, for example), because barometric pressure changes with altitude. The Casio data storage function is a bonus. By pushing a single button, you can store the current date, time, altitude, and temperature. If you punch the button at important milestones (trailhead, high camp, during the climb, on top, etc.), you'll be able to later recall the data and see exactly how long it took you to go between the various elevations. Up to 50 sets of data can be stored and recalled. During recall the max and min altitudes are automatically noted with "max" and "min". The Casio also has a mode for automatically storing data at 15 minute intervals (12 hours worth). The Avocet has no data storage function, however it will remember max and min altitudes, and give an average ascent rate. The Avocet documentation specifically stated that detergents would permanently damage the pressure sensor. There was no such mention of detergent damage in the Casio documentation. It did say to clean the Casio band and case with water and a mild detergent. It also said that it is safe to immerse the unit in salt water, as long as it is rinsed in fresh water afterward. My Conclusions ------------- Both are nice, and both will do the basic job (tell the time, wake you up, and give an approximation of your altitude). Both units are about as accurate as I expected. You won't go wrong with either model. My initial choice (before I tested them, or completely read the documentation) was for the Avocet, primarily because it has a higher altitude range, and is temperature compensated. After looking into both units in detail, I decided to keep the Casio and send back the Avocet. I found that the temperature compensation feature, as implemented in the Avocet, didn't make it clearly superior to the Casio. The temperature compensation of the Avocet did appear to slightly increase altimeter accuracy in certain temperature ranges, but it didn't make any difference in other ranges. The Casio was more accurate in a head to head test of measuring an altitude change of 1000 feet, but only by 30 feet (which is not significant). The Avocet altimeter has a higher upper limit, and would be the best choice if you spend a lot of time over 19,000ft. Most, if not all, of my climbing will be within the range of the Casio. The graphic charts (altitude, barometric pressure, and altitude progress) and the data storage/recall system of the Casio will be of more use to me than the extended altimeter range of the Avocet. In addition, the Casio is much more waterproof than the Avocet, and IMO it's construction is much more robust. In general, the Casio has better timekeeping and alarm features (this is to be expected, Casio has been in the watch business for a long time). The omission of a light is a big flaw for the Avocet. A day of week display (MON, TUE, etc.) is a standard watch feature that not have been left out of the Avocet. All in all, it seems to me the Avocet was designed primarily for the skiier, and the climbing functions were a secondary consideration (this makes financial sense for Avocet, because the skiing market is huge compared to the climbing market). The Casio is designed specifically for climbers and hikers, and I feel it is the better instrument for climbing (up to 19,000ft). Wed Feb 1 10:38:38 1995 Message : #21551713 From: Nick Parker Address : nsparker@ingr.com Group : Usenet.rec.backcountry Subject : Re: altimeters Org. : Intergraph Corporation, Huntsville, AL kellyh@uranus (Kelly S. Harrelson) writes: I've used the Casio Alti-Thermo watch now for about two years. The thermometer portion of the watch isn't very useful. It's too sensitive to body heat. I have to take it off and attach it to the outside of my backpack to get an accurate reading. Heat from any external source, including your body and the sun, will affect the reading of both the thermometer and the barometer/altimeter. If your device (regardless of brand) goes from shade to full sun, or from your arm to your pack, you can expect the thermometer and altimeter readings to fluctuate. Some people have posted that they get very good results by keeping their watch in a coat or pants pocket, where the temperature is more stable. Extreme cold will also affect these little electronic devices. If you leave one out in the cold to get an accurate reading of the morning low, you may not be able to read the LCD display due to the effect of the cold. (This is probably only a problem in Really cold situations.) When the unit warms up the LCD display will be readable, at which time the temperature reading will have changed due to your warming the unit! If you own a Casio, you can get around this by turning on the automatic data storage feature before you set the watch out at night. In auto mode, it will automatically record the time, temp, and altitude every 15 minutes (50 sets of data maximum, which is 12 hours worth). The Avocet doesn't have a data storage function. The barometer portion though is fairly accurate and useful.... The altimeter, which somehow computes the altitude by measuring temperature and barometric pressure change, hasn't been much help. The altimeter and barometer are the same thing -- a (single) pressure sensor. The barometric pressure display shows inches or millibars of mercury, and the altimeter shows a conversion to feet or meters -- but it's the same data, coming from the same sensor. Some barometer/altimeters are temperature compensated, which means that an attempt has been made to compensate for the effect of temperature changes on the measuring device. The Avocet is temperature compensated, and the Casio is not. The effectiveness of temperature compensation varies with the implementation. I've heard (on the net, therefore it's meaningless) that the Thommen mechanical altimeter has a temperature compensation mechanism that works better than the electronic compensation of the Avocet. I tested the Avocet and the Casio Alti-Thermo side by side in various temperatures, and found that the Avocet implementation of temperature compensation did NOT make it clearly superior to the Casio. The altitude/pressure reading of both units fluctuated about the same amount in response to changes in temperature. The Avocet did read slightly more accurate for some temperatures, but it was no better than the Casio for others. IMO, the Casio is by far the better instrument for hiking and climbing due to some other features: data storage/recall (manual or automatic), display light, altitude alarm, graphical display of altitude change, graphical display of barometric trend for the past 26 hours, etc, etc. I also found it to be a Whole Lot more comfortable on the arm than the Avocet. I usually know the elevation changes of where I'm hiking from the topos. Plus, I wouldn't trust it's accuracy enough for anything serious (although for the areas that I've done, it's been fairly reliable). Unless you are making maps for the USGS, any of the units mentioned above should be plenty accurate. The readings of all barometer/altimeters will fluctuate with changes in weather patterns, and with temperature changes. To maximize the accuracy of the unit during a hike/climb, you should calibrate to a known altitude as often as possible, or at least once. Nick Parker - nsparker@ingr.com - Intergraph, Huntsville, AL Statements/opinions are my own, not necessarily Intergraph's. Wed Feb 1 10:38:38 1995 Message : #21551713 From: Nick Parker Address : nsparker@ingr.com Group : Usenet.rec.backcountry Subject : Re: altimeters Org. : Intergraph Corporation, Huntsville, AL kellyh@uranus (Kelly S. Harrelson) writes: I've used the Casio Alti-Thermo watch now for about two years. The thermometer portion of the watch isn't very useful. It's too sensitive to body heat. I have to take it off and attach it to the outside of my backpack to get an accurate reading. Heat from any external source, including your body and the sun, will affect the reading of both the thermometer and the barometer/altimeter. If your device (regardless of brand) goes from shade to full sun, or from your arm to your pack, you can expect the thermometer and altimeter readings to fluctuate. Some people have posted that they get very good results by keeping their watch in a coat or pants pocket, where the temperature is more stable. Extreme cold will also affect these little electronic devices. If you leave one out in the cold to get an accurate reading of the morning low, you may not be able to read the LCD display due to the effect of the cold. (This is probably only a problem in Really cold situations.) When the unit warms up the LCD display will be readable, at which time the temperature reading will have changed due to your warming the unit! If you own a Casio, you can get around this by turning on the automatic data storage feature before you set the watch out at night. In auto mode, it will automatically record the time, temp, and altitude every 15 minutes (50 sets of data maximum, which is 12 hours worth). The Avocet doesn't have a data storage function. The barometer portion though is fairly accurate and useful.... The altimeter, which somehow computes the altitude by measuring temperature and barometric pressure change, hasn't been much help. The altimeter and barometer are the same thing -- a (single) pressure sensor. The barometric pressure display shows inches or millibars of mercury, and the altimeter shows a conversion to feet or meters -- but it's the same data, coming from the same sensor. Some barometer/altimeters are temperature compensated, which means that an attempt has been made to compensate for the effect of temperature changes on the measuring device. The Avocet is temperature compensated, and the Casio is not. The effectiveness of temperature compensation varies with the implementation. I've heard (on the net, therefore it's meaningless) that the Thommen mechanical altimeter has a temperature compensation mechanism that works better than the electronic compensation of the Avocet. I tested the Avocet and the Casio Alti-Thermo side by side in various temperatures, and found that the Avocet implementation of temperature compensation did NOT make it clearly superior to the Casio. The altitude/pressure reading of both units fluctuated about the same amount in response to changes in temperature. The Avocet did read slightly more accurate for some temperatures, but it was no better than the Casio for others. IMO, the Casio is by far the better instrument for hiking and climbing due to some other features: data storage/recall (manual or automatic), display light, altitude alarm, graphical display of altitude change, graphical display of barometric trend for the past 26 hours, etc, etc. I also found it to be a Whole Lot more comfortable on the arm than the Avocet. I usually know the elevation changes of where I'm hiking from the topos. Plus, I wouldn't trust it's accuracy enough for anything serious (although for the areas that I've done, it's been fairly reliable). Unless you are making maps for the USGS, any of the units mentioned above should be plenty accurate. The readings of all barometer/altimeters will fluctuate with changes in weather patterns, and with temperature changes. To maximize the accuracy of the unit during a hike/climb, you should calibrate to a known altitude as often as possible, or at least once. That's my opinion, here's some others: Related articles from rec.climbing & rec.backcountry ---------------------------------------------------- From: tvervaek@col.hp.com (Tom Vervaeke) Subject: Re: Altimeter/Temperature watches Date: 13 Oct 1994 19:37:22 GMT Mitchell J. Lieberman (mjlieber@moose.uvm.edu) wrote: : I saw a really good description of one of the Altimeter/temperature : watches here a few weeks ago, If the author still has the text lying : around, could you send it to me or repost it? I am considering a watch of : this type, and I am looking for feedback or experiences. The Casio looks : good but it seems very bulky, as well as not having the timed rate of : decent feature. Any comments? The Avenir(or Avocet?) seems less bulky. I : also heard that LL Bean is selling one under there own name, which one ? : The uses will include but not be limited to biking/sking(both) & snowshoing. Mitch: The Casio Alti-Thermo watch ($125 @ REI) is a temp & alti watch that is quite popular. It does have a time rate-of-ascent/descent recording feature. It's a little big on the arm, but doesn't look out of place. It fits nicely under the cuff of my shirt. Perhaps you're thinking of another Casio? ------------------------------------ From: shanew@utxvms.cc.utexas.edu Newsgroups: rec.climbing Subject: Re: Altimeters Followup-To: rec.climbing Date: 1 Mar 94 03:00:32 CST In article , reiser@pmafire.inel.gov (Steven Reiser, P.E.) writes: > I have a Thommen dial type altimeter I used in the Andes. However,this > last Christmas I received an Avocet Vertech which is digital and has a > watch built in and straps onto your wrist. I has a zillion functions I > rarely use also. > > I cost $130, has a resolution of 10 feet, but must be set at a known > elevation and is of course affected by changing weather as they all are. > I've used the Vertech several times this winter (I love the solitude of > winter mountaineering) and it is really handy on the wrist. > It's upper limit is 60,000 feet - far above any mountaineers requirements. I also own a Vertech and have seen them as low as $75 which is a steal as far as I can tell. As for the zillion functions that are worthless, I tend to use quite a few of them. For one, when I go out in the wilderness, and absolutely have to be up at a certain time (say to stay ahead of the sun) it has an alarm. It has a countdown timer and stopwatch useful for cooking things, figuring out how long it took to climb that last hill, etc. It can give you average rise in alt. per hour and if you you aren't moving at all, gives you change in barometric pressure, plus temperature, both useful for weather forecasting. All in all, I've been pleased with mine which I've used hiking mountains in Vail and just backpacking in various places. I'll admit I haven't taken it climbing yet, but somehow I don't think I'd look at it a whole lot on the side of a rock to see how high up I was. Seems too much like looking down on a tightrope to me. Hope all that helps. ------------------------------------ From: dveale@nwcl.nwcl.net Newsgroups: rec.climbing Subject: Re: altimeters? Date: Fri, 16 Dec 1994 16:44:18 -0800 On Wed, 14 Dec 1994, Mark Wright wrote: > Just want to ask people further afield what their experiences and > recommendations are as to altimeter watches? So far as I know, Avocet is the only brand which is temperature compensated which can be a big plus. I'd go with them. ------------------------------------ Fri Apr 14 17:10:33 1995 Message : #24772706 From: Nick Parker Address : nsparker@ingr.com Group : Usenet.rec.backcountry Length : 223 words Subject : Re: Casio Altimeter watch Org. : Intergraph Corporation, Huntsville, AL Don't know specifics about Casio, but Avocet will replace the battery and re-calibrate for $5 and two days. Not bad. I would expect about the same from any maker. Make sure to insure package! Actually, with the Avocet you *have* to send the watch back to the factory (with $5) to get the battery changed -- this is in the Avocet owners manual. I prefer to be able to change my own batteries, and avoid the cost and inconvenience of shipping -- yet another reason I went with Casio. I don't know what Avocet's policy is, but conceivably you could void your warranty by trying to change the battery yourself, since the documentation clearly states that it has to be sent back to the factory for a battery change. I've been using my Casio "Twin Sensor" for a number of years and haven't had any problems with it. Aside from the altitude limitation, it seems to work well and is reasonably accurate. I haven't seen a posted (rec.cli, rec.bac) report of a Casio Alti-Thermo failure, but the Avocet failure post count stands at 9. -- Nick Parker - nsparker@ingr.com - Intergraph, Huntsville, AL Statements/opinions are my own, not necessarily Intergraph's. (Nick Parker) Fri Apr 14 10:24:05 1995 Message : #24759285 From: Nick Parker Address : nsparker@ingr.com Group : Usenet.rec.backcountry Length : 113 words Subject : Re: Casio Altimeter watch Org. : Intergraph Corporation, Huntsville, AL "Karen M. Bayne" writes: ...In each case they had to replace the band relatively quickly (not such a big deal) and all but one watch has also been replaced (by Avocet) due to failure. We stopped carrying it, even though people liked 'em while they worked; and perhaps the failure rate has been improved by now. The comparison I did between the Avocet and the Casio (which was posted around new years) is now on the Waddington Gallery, at http://debra.dgbt.doc.ca/waddington/ The specific page is: http://debra.dgbt.doc.ca/waddington/gear/watches/watch.html Nick -- Nick Parker - nsparker@ingr.com - Intergraph, Huntsville, AL Statements/opinions are my own, not necessarily Intergraph's. (Nick Parker) *** Avocet Alti-Watches *** Tue Jun 13 12:16:02 1995 Message : #27328621 From: Tyler Stewart Address : tstewart@utkvx.utk.edu Group : Usenet.rec.backcountry Length : 317 words 1945 bytes Subject : Re: Casio Triple Sensor Altimetre/Barometre/Compass query.. Org. : University of Tennessee, Knoxville I have had a bad experience with Casio altimeter/barometer watches. I owned their first altimeter watch, but the sensing mechanism broke after 6 months. Also, it's a PAIN to change the watch battery. If you touch the wrong thing when replacing the battery, the sensor can short circuit.That is what happened to the second Casio altimeter watch I owned. Right now, I'm on my third Casio altimeter watch right now, and I've had it for for 3 years without any problems. I guess I'm just incredibly stupid for continually buying these things. As for temperature compensated altimeters, YOU WANT a temperature compensated altimeter. My experience has shown that there can be significant discrepancies in altitude readings if the altimeter does not compensate for temperature. The only temperature compensated altimeter watch I know of is made by Avocet. There are two model: The Alpine and the Hiker. They sell for around $120-$130. They also include a thermometer. I have a friend who owns the Hiker, and he has nothing but good things to say about it. One day when we went hiking, we set the altitude on our watches at the same time and at the same place. Later on in the hike, we checked the 7.5 min quad and found that the Avocet's altitude readings were right on. My Casio's was very far off. My friend also takes his Avocet when he flies and says that it is just as accurate as the altimeter in the Cessna he flies. I've always regretted not buying an Avocet altimeter watch. My advice is take back the Casio and buy the Avocet. The Avocet is much cheaper than the Casio, but it doesn't have a compass. Use the money you'll save and buy a nice Silva compass too. If you don't know where to buy the Avocet, email me, and I'll give you some numbers. Tyler Stewart -----------------------------