I've been playing with Lady Heather and an old Magellen Explorist 210. I wanted to see how good I could do with elevation, given some averaging. It's not bad, but some other interesting things showed up. The most interesting is that the reported time can be off quite a bit. Apparently, the 210 has some internal quirks where the time isn't updated properly, and it can drift off by many seconds over time. Only a full reset can get it back in sync. I've seen it off by up to 15 seconds in the past. I think the error is also reflected in Lady Heather, but haven't proven it yet. There's also some timing problem, as I get continuous red tics on the chart. Not sure why, but the legend for the chart always gives the elevation in meters, but labels it as feet.
Of all the inexpensive modules on the 'bay, can anyone suggest something troublefree that I can eventually set up as a GPSDO of decent quality? At the moment I'm a bit lost in the woods because there are so many options.