GPS waypoint conversion

[jonnywake]

Greetings,<br /><br />I just bought a newer GPS and upgraded my handheld that dated back to 1996. I'll have to manually x-fer a handfull of waypoints to the new unit, but what do I do about conversion to the new format?<br /><br />The new unit has a three digit number in the last position of a Lat and Lon waypoint. Do I just enter a 0 for that third position for the legacy waypoints?<br /><br />For example a legacy waypoint reads N 35.56.57 W 078.39.32<br /><br />Thanks!

 

[dingbat]

Re: GPS waypoint conversion

The units on a GPS are configurable. Just switch the GPS over to the appropriate units of measure amd enter away

 

[jonnywake]

Re: GPS waypoint conversion

I tried that... there is no compatible format on the new GPS unit.<br /><br />I guess the legacy format is quite old and outdated.

 

[MajBach]

Re: GPS waypoint conversion

Do a search for a freeware program called 'G7toWin'. It can save to almost any format.

 

[AndyL]

Re: GPS waypoint conversion

If the last digit is in fact 100ths of a minute of arc that equates to 6 feet. If you need accuracy greater than that it must be a pretty fancy machine. Just as a test note down the position you are in at the moment on your old GPS then enter that as a waypoint on your new GPS without you physically moving. If that way waypoint and your present position co-incide then you know you are right.

 

[Drowned Rat]

Re: GPS waypoint conversion

jonnywake. Yes, just enter 0 for the 3rd digit on your new machine. As Andy points out, the 3rd digit (or thousands of a minute) is only a matter of inches and will not make any noticeable difference in the conversion.

 

[Stumpknocker]

Re: GPS waypoint conversion

johnnywake, I ran into the same problem as you are now experiencing. My friends have the Garmin 76 model (nice) and it used the same 3 digit format you mentioned. My Lowrance unit was configured in DMS mode or seconds. (25 15 23.5) We finally figured out what was going on by calling a technician at Lowrance and got all of our units on the same format so we could swap numbers more quickly. As we gained more understanding of the system we realized that all we had to do was toggle over to the new format and the unit did all the conversions.<br /><br />The two formats in question are DM and DMS. DM is the 3 digit system you are asking about. It stands for Degrees and Minutes. <br /><br />The three digits stand for fractions of minutes and of course 1 minute =1000 units. So, if you put in 29 Degrees, 15.500 minutes your older system would read 29 Degrees, 15.30 seconds. DMS means of course Degrees Minutes Seconds. 60 seconds = 1 minute in this format. 30 seconds = 1/2 minute and so on. <br /><br />So. If you transfer coordinates on your old DMS system and manually put them in your new DM formated machine you could have some accuracy problems. For example if you want to put in the waypoint for the "ole fishn hole".... and it reads 28 degrees 15 minutes and 45.5 seconds....the DM format would not be 28 15 455. It would be 28.758. Remember 45 seconds is 3/4 of 1 minute. 1 minute =60 seconds in the DMS format. The difference between the two formats is approx 1/3 mile. Way ugly. <br /><br />So, what I would do is to take the old numbers (DMS) and convert the seconds to fractions of minutes or DM format. Example again. Old WP= 25 degrees 15 minutes 30.5 seconds would translate out to 25 degrees 15.508 minutes. Divide your seconds by 60 to get DM or minutes/3 digit format. Hope this isn't to muddy. I'm pretty tired right now.<br /><br />Usually you will find under "setup" the format screen and you can toggle between DM and DMS at will. It will automatically convert seconds to the three digit format of fractions of minutes.<br /><br />If anyone disagrees with what I "think" I know here, please jump in and help me "correct" my logic. I am not all that great with these things, but I think this is a correct description of the two formats and their conversion.

 

[Drowned Rat]

Re: GPS waypoint conversion

Gil, you can have degrees/minutes/seconds, degrees/minuntes/tenths and hundredths of minutes, or degrees/minutes/tenths, hundredths, and thousands of minutes. It sound like from JW's post that his new machine is the latter and his old machine only goes to hundredths. If that is the case he can simply leave off the 3rd digit in conversion and add a 0. That would be no less accurate than his older GPS. Your point about knowing the difference between minutes and tenths of minutes / and minutes and seconds is a good one as they won't convert as easily. You can tell what format you have on your GPS by looking at the tic marks. If your GPS is set up in minutes and tenths of minutes it will look like this. 111*36.750'<br /><br />Minutes and seconds will look like this 111*36'45" Note, no decimal point, although some machines will give you tenths of a second or something like this 111*36'45.68" Also, obviously, the seconds will never exceed 59.99", whereas tenths of minutes will go to .999'<br /><br />Way overkill in my opinion <br /><br />I like to leave my GPS in the seconds mode as a distance conversion can easily be made in your head with no math. Knowing 1 degree of latitude equals 60 nautical miles, 1 minute of latitude equals 2000 yards or 1 nautical mile, 6 seconds equals 1/10th of a mile and so on. It's useful when using charts in addition to a GPS.

 

[Stumpknocker]

Re: GPS waypoint conversion

Drowned Rat, I too leave my unit in seconds mode. <br /><br />On the side of the DM format, the three digit mode is of coursed decimal therefore .125 minutes = 1/8 mile and so forth which is probably why so many machines are set to that format. Garmin is as far as I remember unable to toggle back and forth.... is that correct? My buddy has a 76 model and his inability to convert is what got this major learning curve underway. Although maybe he just didn't know where to look. I converted mine to hundreths so we were on the same page when loading numbers.<br /><br />I'm glad you mentioned the nautical mile. I had for some reason convinced myself that I read 1 minute = 1 statue mile. I went back through all of my resources and corrected that thinking. <br /><br />Do you measure in statute or nautical? If I remember correctly you are a guide for the rapids at the Canyon... using charts you probably stay in statute because of the legends involved. Correct?

 

[Drowned Rat]

Re: GPS waypoint conversion

Hi there Gil. Yes, the canyon does use statute mileage so the conversion doesn't fit quite as nicely. I've done it so many times though, I have the whole 300 miles saved as a track.<br /><br />I'm not sure about the older Garmins, but my e-trex does toggle. Perhaps they had too many complaints about the problem you describe with your friend's 76.

 

[paulrfrancisco]

Re: GPS waypoint conversion

First ensure the format on both units are the same.... DMS, or Degree, Minute, 100th or 1000th of a second.. As stated before, GMS is Degree Minute and seconds... 0-59 seconds... To get more granular that that you need to switch formats to the 100th or 1000th of a second...<br /><br />Converting the source to the same format as the destination first then outputting is one way to start off... or make the destination unit the same as the source...