OK, so I've been limited in my flight time here in the PNW, but I did manage to get a few test flights in with several different GPS modules.
Clear sky, sunny day, 12 midday flights. Please note that the drones were turned on for about 10 minutes, left sitting at the launch area, turned off, and then turned back on again. Each drone was then flown straight up to about 380ft AGL, would hover there for about 10 minutes before being brought back down. Each drone has the Rev 2 shield from 3DR. Flight area faces North with no large obstructions in the way, however to the East and West there are large buildings and tree's, to the South there is a very large hillside covered in tree's that probably goes up to about 500ft.
Rev A: Not going to bother putting on back in a drone for testing just because they are so god awful. Previous experience had me waiting 5+ minutes for a GPS lock IF I got one at all.
Rev B: Would get about 12 -13 Sats with a 1.1 HDOP. 2 and a half minutes lock on time though.
MRO Original: Surprisingly got 18 sats with .08 HDOP. Was quite impressed. However did take about 1 minute to get enough sats to take off.
MRO new version: Fluctuated between 19 and 20 sats with a .06 HDOP however, it did take about 30 seconds to get a sat lock before flight was available.
HERE GPS: Hit 19 sats with a .06 HDOP, however unlike the MRO, it achieved lock pretty much after hitting the power button which was pretty darn impressive.
I did notice that will all the drones, there was some slight drift when up in the air hovering. It wasn't terrible but if I had been recording a time lapse at the time, it would have been quite obvious. It wasn't windy or gusty that day so maybe it's just as good as any of the GPS modules get.
For me the winner was the HERE GPS. Maybe because the mast raises it above the body, but the near instant lock was a welcome feature (it also looks pretty sweet).
I didn't get to do a more in depth test as I was freezing parts of my anatomy off at the time, however I'm thinking of setting up a cable cam and having the drone fly about 400 ft left, return, 400 ft right, return and watch the HDOP and number of sats. I'd also like to run this test again but on an overcast day just to see how things go in not so optimal conditions.
With each drone, still had to land manually as once it was nearer to the ground the GPS signals became erratic and the drones would drift left, right, forwards, backwards... with manual control I was able to compensate though. Again, this is more geography based PITA (pain in the a**) than a fault with the GPS (wasn't someone supposed to be working on an optical sensor for us to help overcome this one?).
Overall thoughts are this. If you live in an area with poor GPS signal, you'll want to upgrade to the very best GPS system there is, but realize that you're still going to have issues every now and then. However, if you don't live in an area with poor GPS, then you could get away with a Rev B board easily. Although since the cost of upgrading is cheap, you might as well go ahead an upgrade.
On the upgrades available themselves....
The original MRO chip was an easy plug and play solution, however it did lack a USB socket with which you could connect to it for fine tuning, making changes etc. Not so with the new MRO! Now it's got a USB interface that you can plug directly into............ providing you haven't put it in your drone. You see the little enclosure that the GPS chip fits into has a back wall, and three struts (one left, one right, one front!). However due to the way the MRO chip fits into the drone the front strut sits right in front of said USB connection and renders it unusable while in the drone (unless you want to start cutting off parts of your drone, but then you'll want to probably replace that front strut with two other struts on either side.... and who wants to do that modification...). Point being you'd think a chip made for a 3DR solo by someone who used to work at 3DR would have taken this design issue and maybe offset the USB interface so it was actually accessible.
The HERE system does require a bit of DIY. I believe Jesters Drones used to supply a custom GPS cover with the here system but then stopped doing so (cost, or time of customizing?). As a result, you will be required to do a slight modification do your drone's GPS cover (ie. drill a hole in it and then smooth the edges out). It wasn't difficult with the help of my trust Dremel, but I can see some people maybe having issues doing this (look, if they can't follow instructions for doing a very very easy software upgrade, do you really want to trust them with power tools?). Also if they don't smooth out the holes, it's possible the soft wires that connect the Here to the Solo could get frayed. Shouldn't be an issue if you're leaving the GPS in place, but if you're taking apart your solo on a regular basis or having vibration issues..... who knows?
So hey, if you have a solo, want to upgrade it, the GPS is a worthwhile place to start, but for the love of god, don't pay $80 for a Rev B upgrade (saw one for about that price on Ebay), you're just being ripped off!
Clear sky, sunny day, 12 midday flights. Please note that the drones were turned on for about 10 minutes, left sitting at the launch area, turned off, and then turned back on again. Each drone was then flown straight up to about 380ft AGL, would hover there for about 10 minutes before being brought back down. Each drone has the Rev 2 shield from 3DR. Flight area faces North with no large obstructions in the way, however to the East and West there are large buildings and tree's, to the South there is a very large hillside covered in tree's that probably goes up to about 500ft.
Rev A: Not going to bother putting on back in a drone for testing just because they are so god awful. Previous experience had me waiting 5+ minutes for a GPS lock IF I got one at all.
Rev B: Would get about 12 -13 Sats with a 1.1 HDOP. 2 and a half minutes lock on time though.
MRO Original: Surprisingly got 18 sats with .08 HDOP. Was quite impressed. However did take about 1 minute to get enough sats to take off.
MRO new version: Fluctuated between 19 and 20 sats with a .06 HDOP however, it did take about 30 seconds to get a sat lock before flight was available.
HERE GPS: Hit 19 sats with a .06 HDOP, however unlike the MRO, it achieved lock pretty much after hitting the power button which was pretty darn impressive.
I did notice that will all the drones, there was some slight drift when up in the air hovering. It wasn't terrible but if I had been recording a time lapse at the time, it would have been quite obvious. It wasn't windy or gusty that day so maybe it's just as good as any of the GPS modules get.
For me the winner was the HERE GPS. Maybe because the mast raises it above the body, but the near instant lock was a welcome feature (it also looks pretty sweet).
I didn't get to do a more in depth test as I was freezing parts of my anatomy off at the time, however I'm thinking of setting up a cable cam and having the drone fly about 400 ft left, return, 400 ft right, return and watch the HDOP and number of sats. I'd also like to run this test again but on an overcast day just to see how things go in not so optimal conditions.
With each drone, still had to land manually as once it was nearer to the ground the GPS signals became erratic and the drones would drift left, right, forwards, backwards... with manual control I was able to compensate though. Again, this is more geography based PITA (pain in the a**) than a fault with the GPS (wasn't someone supposed to be working on an optical sensor for us to help overcome this one?).
Overall thoughts are this. If you live in an area with poor GPS signal, you'll want to upgrade to the very best GPS system there is, but realize that you're still going to have issues every now and then. However, if you don't live in an area with poor GPS, then you could get away with a Rev B board easily. Although since the cost of upgrading is cheap, you might as well go ahead an upgrade.
On the upgrades available themselves....
The original MRO chip was an easy plug and play solution, however it did lack a USB socket with which you could connect to it for fine tuning, making changes etc. Not so with the new MRO! Now it's got a USB interface that you can plug directly into............ providing you haven't put it in your drone. You see the little enclosure that the GPS chip fits into has a back wall, and three struts (one left, one right, one front!). However due to the way the MRO chip fits into the drone the front strut sits right in front of said USB connection and renders it unusable while in the drone (unless you want to start cutting off parts of your drone, but then you'll want to probably replace that front strut with two other struts on either side.... and who wants to do that modification...). Point being you'd think a chip made for a 3DR solo by someone who used to work at 3DR would have taken this design issue and maybe offset the USB interface so it was actually accessible.
The HERE system does require a bit of DIY. I believe Jesters Drones used to supply a custom GPS cover with the here system but then stopped doing so (cost, or time of customizing?). As a result, you will be required to do a slight modification do your drone's GPS cover (ie. drill a hole in it and then smooth the edges out). It wasn't difficult with the help of my trust Dremel, but I can see some people maybe having issues doing this (look, if they can't follow instructions for doing a very very easy software upgrade, do you really want to trust them with power tools?). Also if they don't smooth out the holes, it's possible the soft wires that connect the Here to the Solo could get frayed. Shouldn't be an issue if you're leaving the GPS in place, but if you're taking apart your solo on a regular basis or having vibration issues..... who knows?
So hey, if you have a solo, want to upgrade it, the GPS is a worthwhile place to start, but for the love of god, don't pay $80 for a Rev B upgrade (saw one for about that price on Ebay), you're just being ripped off!
