Cheap GPSDO-and-RTKlib-ready GPS module? (and warning) - Page 1
Forum section: electronics / projects

author: cdev
author_rank: Super Contributor
timestamp: March 16, 2022, 01:44:02 pm
content: This is for our GPSDO-builders..I saw recently that a ebay vendor (queens_land) is selling what look like pulls of the (RTKlib capable and timing friendly Ublox LEA-5T for $4) These are the 5 series modules, which have the sawtooth correction.(they also can be used for RTKlib using the ublox raw commands)Although its not a multi system GPS it is a timing friendly one that can deliver the raw data needed for RTKlib too (although most people setting up RTK base stations will probably want a multi system GPS (which LEA-5T isnt, its just GPS, no GLONASS or Beidou at all)) for their NTRIP base station)Several years ago I did this (set up a base station) and a lot of people were using my base station data.. It seems that in myfairlyveryurbanized area there were few other providers of it. If you're heavily into automation and robotics, and have a good sky view, especially I cant think of a better way to meet your other local robotics people than providing your raw GPS data to others. (This means providing your exact location, to a high level of accuracy). Its helpful because it makes it possible to using RTKlib derive the exact location of another mobile station by subtracting the errors caused by ionospheric variations from the known stationary base station data and interpolating the exact location. Typical accuracy should be under a centimeter. (with a good antenna, whose phase center is known)Providing GPS base station data is very helpful to others near you who are getting their feet wet using RTKlib.. which enables very accurate positioning of rovers, seehttps://rtklib.comand now, more recently,http://rtkexplorer.com/.The newer RTKlib binaries they provide are a convenient shortcut for users of common linux distros.From the queends_land ebay listingit appears what you get is the castellated module simply on a piece of PCB you seem likely to have to do the desoldering yourself which isnt easy to do without the equipment to do so.Maybe this should be in the robotics section, as RTKlib is the best way to precisely position mobile devices.. but difficult to use without the right setup.Many beginners will probably mess the desoldering part up. (I did, a few years ago, read below)Preheating (to well under the melting temperature) or Chip-Quik (to lower the melting points and facilitate safe removal ) is highly recommended. Dont use high temperature setting on your soldering iron either. This was a costly lesson that I learned trying to do this.Several years ago while trying to do this with a similar module I destroyed it- let the magic smoke out of a very cheap (so probably counterfeit) Ublox M8T module I was trying to extract from a badly made cheap GPS module intended for drone use.It happened very quickly and I definitely screwed it up.Now I have a preheater and Chip Quik in addition to my hot air gun. Use them wisely, meaning go easy on the heat.Its very easy to mess these modules up if you dont know how to handle them. Its also easier to mess up trying to desolder one than solder a new one to a PCB designed to receive one. So be warned.If you buy them new you will usually do okay. (but pay a lot more)The thing to avoid is having to heat the module for more than a second or so.Really, two is too long, even.