Article 45538 of sci.geo.satellite-nav: Date: 03 Sep 1997 08:18:00 +0200 From: guido@gps_gear.mayn.de (Guido Lenz) Newsgroups: sci.geo.satellite-nav Message-ID: <6dBJhYNConB@gps_gear.mayn.de> References: <340C2F36.4375@cww.de> Subject: Re: Speedlimit Garmin 45XL X-Newsreader: CrossPoint v3.11 R/B18139 Organization: GPS GEAR GmbH Lines: 93 Path: matra.meer.net!news.spies.com!news.sgi.com!nntprelay.mathworks.com!news.mathworks.com!newsfeed1-hme1!newsfeed.internetmci.com!193.174.75.126!news-was.dfn.de!news-kar1.dfn.de!news-stu1.dfn.de!news-mue1.dfn.de!news-nue1.dfn.de!wuff.mayn.de!gps_gear.mayn.de!guido Xref: matra.meer.net sci.geo.satellite-nav:45538 On 02.09.97 you (Werner Vogel ) wrote with the subject "Speedlimit Garmin 45XL": >Does anyone know of a fix that will allow the 45XL to operate at >speeds greater than 99 knots? >-- >Werner Vogel >N 51° 25` 21`` >E 06° 53` 24`` HTH, HAND Guido ======================Reply Separator====================== ## Copy of message dated 08.07.96 ## Origin: /archiv-gps ======================Reply Separator====================== On 03.04.96 Tim Hogard wrote the following: > ## Nachricht am 09.04.96 archiviert > ## Ursprung : /sci/geo/satellite-nav > > Larry Soo (Larry_Soo@mindlink.bc.ca) wrote: > : > >In article <4jicme$bmt@mujibur.inmind.com>, thogard@inmind.com > : > >(Tim Hogard) wrote: > : > > : > >:This is a just a quick note to say that I jsut got back from > : > >a short :trip in a Piper seminole where my modified GPS45 was > : > >tracking just fine :above 90 kts. The plane was going up to > : > >165kts and the GPS45 tracked :just fine. > : > >: > : > >:I'll be providing more details in the near future. > : > > > : Um, is this an April Fool's joke? > > Uh, no. Maybe the bit about more info in the near future but I'm > going on weekend vacation soon and don't have time to do a good > writeup so... > > Yes, I do have a GPS45 that works above 90kts. > > I'm working on unit #2 right now. Now I remember why the 45 is > going to be such a pain and why I had planed on fixing a 40 next > but the case is open and well and I have use of a 90 this weekend > and I would like to make a comparison between the two. > > What I did was pulled the rom off and disassembeld parts of it. I > found the check aginst 90 kts, (it's 46.3011 m/s). It also does a > check with 514 m/s (thats 999kts) as well as 18000m and -1200m so > it will only work to 60,000 ft. These constants are intel 8087 > single format. Change these constants and fix the checksum (the > unit checks for a byte sum of 0 as good) and put the rom back in. > The rom that is used is a 27lv020 which can be reprogramed but you > can only change ones to zeros. Replacement parts are almost > impossable to get so with some creative work, the existing rom can > be reused. Once the right bits are in the rom, then it can be put > back on. I used a microscope because the parts are real small. > Even with the microscope it was hard to tell if the pins were > soldered correctly. I could push on the pins with a probe and if > it moved then it needed work. > > Once the rom was reattached, I applied power and it beeped properly > when turned on. It even had a track log from months ago when the > power (and chip) was removed. I guess the backup battery will keep > memory for a long time. I put the unit in NMEA mode an used a > display program I wrote for my GPS25 and took it up in the > airplane. It was reading upto 165kts before the clouds got too low > and we had to turn back. At least the plane would go fast in > circles. I'll put the track log on my web page just as soon as I > have time and can get it back in grmn mode (the GPS45 isn't the > easist to use GPS without a display) > > I intend to have a gps38 without the 90kt speed limit for sale for > $300 in the near future. Anyone interested? So it's overpriced, > and isn't water proof but it will work in airplanes. > > Also one question for thouse that want to do this at home... Is it > ok if it won't work at exacly 90 kts? Above and below will work > fine but exactly 90.0022 kts it will display an error but I suspect > that it would be years of flying at 90kt to hit that point. This > tradeoff will require just two bits to be changed in the rom as > opposed to several bytes... > > -tim > http://www.abnormal.com/~thogard GPS, VW and Usenet topics. -- GPS GEAR GmbH, Berliner Platz 11, 97080 Wuerzburg, Germany Phone +49 (0)931 321 94-0, Fax +49 (0)931 321 94-11