$25 GPS Solution

GrouchoDuke said:

Doesn't everyone have at least 5 FTDI's laying around already?

I recommend getting an FTDI with any U-blox GPS you decide to use (or maybe any GPS at all). For the U-blox ones (or U-blox clones), hooking it up to an FTDI & then U-center on a Windows PC (free) will make sure the GPS is set up correctly & working right. In many cases, you'll want to change the dynamics model anyway.

The modules work with NMEA or UBX protocols & you can change the configuration if you want. They're probably knock-offs, but they work & they're really small.

Definitely don't feed any electronics the wrong voltage - you'll let the smoke out!

Click to expand...

Mine are squirreled away in storage after a city sewer backup. The gist of it is if the module comes stock at 9600bps NMEA they'll be fine. Now the bit about being able to add a message like a ham callsign in the NMEA strings is another issue.
Ublox could conceivably have a "check" in their software to detect a counterfeit and or the counterfeit chipsets might not be able to add a message in the strings.
This is of import only in the 500mW 433Mhz units where being able to put a Ham callsign in would be convenient. In order to do this, might take a "real" Ublox GPS.

I still think the version 1 of the 3DR radios might be easier to convert than the version 2 but I'm going to see if I can get the board out of the case and feed power from the mini-usb side. Kurt

Ok I hacked this setup: https://www.aliexpress.com/item/201...c0-437c-90d2-5d4796b50d30&transAbTest=ae803_3

and when I plugged in the GPS: https://www.aliexpress.com/item/HAK...32799709822.html?spm=a2g0s.8937460.0.0.lWTIuU

The radios lost the lock, the steady green LED went to flashing. The GPS gave me a power on red LED and when it got a position lock, a flashing blue LED was seen.

I assumed 9600bps but I am going to have to diddle with the programmer to see if the GPS is at a higher rate than 9600bps. Could be.

If I had the RX/TX wires reversed, I think there would be no flashing LED so I think I got that right. Stay tuned. I might have to try and find my USB/serial interface and attempt to reprogram the module unless someone can confirm
it's 9600bps stock. Kurt

The weird thing is the ad for the GPS above says no LED on the GPS but mine has a red and blue one. They certainly behave like one would expect too.

My GPS (same as above) just arrived in the post yesterday. I guess I'll have try to hook it up on the weekend. Not sure if that will happen as I need to complete a 3D drawing of a nosecone base to get printed next week. If the drawing gets completed quick enough I should make it to the GPS if I am lucky.

Managed to wrangle some time and got the GPS connected to the airside telemetry unit. GPS spits out 9600 baud nicely. See the pics for the connections I have used. Red-Red, Black-Black, Orange-Green





Next step is to get the groundside happening...

I used the V1 ground station with the V2 generic 433Mhz radio because I could connect up the USB sockets to get 5V juice to the units. I followed this scheme from the GPS to the radio:
Connection diagram:
Black to GND
Red to +5V
Blue to TX
Orange to RX

I have the orange wire connected to the RX marking on the v2 radio. I get a flashing blue LED and a solid red.
The green LEDs are locked solid. I am wondering if I have the Rx/Tx swapped by mistake?
I suspect the blue LED comes on and flashes when there is a satellite lock or am I wrong there.

I'm totally disgruntled with the rx/tx markings on any GPS device because it becomes impossible to assume
what is what at times. I may swap the wires on the v2 tracker/transmitter or simply get out the v1 tracker
and connect as you show if you get data across the Rf Link. Once you get it going, please post the
3DR settings you are using (screenshot) once the NMEA strings are coming across.

Oh, I did some digging. Like others have pointed out, these cheap GPS units are not likely the programmable ones
where one could put a callsign in the strings. That would take a true 7N chipset as outlined here:
https://www.u-blox.com/en/product/neo-7-series

Boy, again for a true neophyte get a commercial tracking setup. This 3DR hacking is are real PITA. Unless
someone gets a perfect step-by-step, stay away.

Kurt

I suspect the blue LED comes on and flashes when there is a satellite lock or am I wrong there.

Click to expand...

Seems to be the case to me.

I'm totally disgruntled with the rx/tx markings on any GPS device because it becomes impossible to assume
what is what at times.

Click to expand...

Yep. What is in and what is out? Ambiguous. I tried a multimeter on the pins first to see if that would tell me which was which. No confidence there, based on trying to read the circuitry structure by resistance alone. I then applied the 5V power to both modules and scoped the leads, applying a resistor (use something between about 2k and 50k) to ground while observing the waveform. Digital outputs mostly don't change much in level with the additional loading (unless they are tristate:wink, but inputs do.

OverTheTop said:

Managed to wrangle some time and got the GPS connected to the airside telemetry unit. GPS spits out 9600 baud nicely. See the pics for the connections I have used. Red-Red, Black-Black, Orange-Green

View attachment 326652

View attachment 326655

Next step is to get the groundside happening...

Click to expand...

What model is that scope?

What model is that scope?

Click to expand...

It is a Siglent SDS1102X-S. My trusty old CRO (Tek 7623A rackmount, 100MHz analog storage) died and while I was fixing it (shorted tantalum cap on the +15V line) the Siglent came on special. $880AUD including the serial decode function and 25MHz arbitrary waveform generator. Seemed like good value for a modern scope for home use, especially with the added features. I actually work for Agilent but I can't get the Keysight (formerly Agilent) scopes at anywhere near that price unfortunately.

Seems like the special is still active:
https://www.triotest.com.au/store/siglent-oscilloscopes/737-siglent-sds1102x-s-digital-oscilloscope-100mhz-1gsas-2-channel-with-awg.html

I have the Rcv/Transmit lines reversed (I think) and am going to switch them out this weekend.
I'm going to have the com speed set at 9600bps and the Air at 24kpbs. Something about error correction cuts
the effective air link in half. Using MavLink. Does that sound correct? Am still going to try the "mixed"
system. V1 ground station and a V2 (air or ground) transmitter/remote.

Gotta marry off my daughter today so it will have to wait! (Don't worry, great situation and the groom is
a very nice young man) Kurt

Reprogrammed the radios so they communicate. Will be ready for when I switch the Rx/Tx wires on the GPS. Am going to try this setup as I've got it programmed in.
Comments? Leave ECC on? They say it cuts the rate in half hence I chose 24kps as opposed to another number. Any drone/fliers/programmers out there?



Kurt

ksaves2 said:

Gotta marry off my daughter today so it will have to wait! (Don't worry, great situation and the groom is
a very nice young man) Kurt

Click to expand...

Congrats! Was just at a family wedding last weekend myself. Always great to see a couple that's good for each other.

Leave ECC on? They say it cuts the rate in half hence I chose 24kps as opposed to another number.

Click to expand...

Make a choice. ECC on improves probability of a good packet. Slowing the baud rate improves probability of a good packet. Either way probability of successful packets goes up, as does power consumption. Personally I would go ECC if it is available, but I have not based this on anything but a hunch. Depends on how many bit errors per packet it can correct for.

OverTheTop said:

Make a choice. ECC on improves probability of a good packet. Slowing the baud rate improves probability of a good packet. Either way probability of successful packets goes up, as does power consumption. Personally I would go ECC if it is available, but I have not based this on anything but a hunch. Depends on how many bit errors per packet it can correct for.

Click to expand...

Anybody, post your Mission Planner setting if you get this to work. Mixing v1 and v2 radios might be a total bust. I have the V1 receiver paired via B/T to a computer or Android by an HC-05 B/T module.
I have a v2 tracker module being used as a tracker with the GPS pictured and connected as shown in #184 above. Funny thing, is when I had tx/rx reversed from what's shown, I get a flashing blue LED
and a solid red no matter what. If the unit hasn 't been on for awhile, it takes a short time for the blue LED to start flashing.

No dice. Has anyone got one of these 3DR rigs operating? If so, post your connections and Mission Planner radio settings. If not, is this a $50.00 dead end? Perhaps only v1 radios are workable?
Again, this is like mixing. Don't figure is will save you money if it doesn't work and you have to spend a lot of time an money to see a return. Kurt

Still have not received the Ublox M8N module, so in the meantime I've been working on my sanding, priming, paint techniques on a test boilerplate rocket.

I found an alternative radio configuration program that is very similar to the Mission Planner GUI radio screen. This however, also generates a command line screen, that shows all the little details of the radio communication setup. Might be useful for debugging or diagnoses of problems. I found the program at this link:

https://www.ardupilot.co.uk/ardupilot-software.html

It looks to have a lot less CPU overhead than the full Mission Planner, as it addresses the radio configuration only.

Here is a screenshot of what it looks like when the windows are expanded. Again, I found I had to disconnect the power to the GPS in order to use the "load settings" button. No big deal as it currently is just a matter of unplugging one wire from a Dupont connector. At some point, if I cannot get this resolved, I'll wire in another mini-Molex type connector for the GPS power during flight conditions, as those snap together solidly.


EDIT Addendum: Using the above program, I switched a window to "Terminal" screen. Then, on a whim I hooked the power back up to the GPS module, while the radio was active. This lit up the terminal screen with all the streaming GPS NMEA packets immediately. There is also a window with scrolling radio signal strength. I may be able to install this program on the XP laptop as it appears to be a legacy from the same author as Mission Planner, in which case I'll be able to effect radio programming with that device. See screenshot with the terminal interface screen scrolling the NMEA packets.

Here are some shots of the setup I am bench testing. I'm using a v1 receive station and a v2 generic unit.
I program through the HC-05 with the GPS removed from the v2 generic unit. I have the connections like
ecarson shows. The system seems stable and I think ecarsons depiction works with the v1 setup.
I'm not getting any strings coming across though. I like the fact that a "native" v1 setup is getting packets
across. I'm only doing this "bench" setup as one can see everything is completely independent.

I strongly suggest one try for as few interconnect cables as possible. A USB cable gets jostled and the system goes down. I've triapsed around with the EggFinders and a B/T connection between my mapping app and the Eggfinder
receiver (LCD) and it is rock steady once setup.

I'll whip out and modify my v1 "remote/transmitter/tracker" and I might have better results doing v1 to v1 link via
B/T as opposed to v1 to v2 link as shown in the photos.

On the other hand, I might have the radios incorrectly programmed for the GPS. So far, beware if trying to mix
v1 with v2 radios.

The USB connections above are only supplying 5V to their respective units. The receive station is the v1 "receiver" with an HC-05 module wired to the "Hope-like" RF board and the
v2 is the remote/tracker. The green LED's are solid, the B/T module shows it's locked but nothing is seen. This "mixed marriage" might be incompatible and I have a v1 module
I can pair and work with along with my B/T v1 receiver. That's to follow. If ecarson is getting
strings across, I should be able to pair my v1, B/T receiver with its v1 transmitter/tracker
module and see some streams.

He notes that the v1 tracker/receiver can't be programmed with the GPS attached. This might
mean one will need a pure "battery harness" to program the v1 tracker and then a "GPS harness" to plug-in to the tracker when wanting to track. Kurt

Messed with it some more. I like that program in message #194 better. I tried using two
generic 433Mhz transceivers. Those are the v2 rigs like the one I show in the foreground above in #195. I've come to the conclusion my baud rate on the GPS chipset I have is not 9600bps
or my switching the rx/tx wires for the v2 rig was wrong. Well I have two more GPS units coming and will try again with the v1 3DR set since ecarson has strings coming across.

Again, if one is in a hurry, buy a commercial tracker or they may end up in the rut I'm in. Stuff happens when hacking these things. Kurt

It's the stupid GPS! With the https://www.ardupilot.co.uk/ardupilot-software.html software I can get the devices to communicate and give me "signal" information and I get this screen:


The one on the left is the "signal quality" I believe The one on the right is with the terminal open and nothing comes across.

Wonder what got messed up there. Kurt

OK, here is what the "RSSI" or signal strength screen looks like when everything is working the way it is supposed to. I hit "connect" on this screen, and soon the packets come in and are compared in what looks like relative S/N ratio.

If I can get this to install on the XP laptop this afternoon, this might be very useful for analyzing in the field when I travel away from the transmitter with the laptop in hand (or in vehicle).

Something is amiss on your system for sure. I did find that when using the FTDI cable, the GPS was correct on RX/TX cable. It seemed to be the air transmitter that had the TX/RX reversed. I hooked my GPS module up to my oscilloscope, and verified this. I got the pulses from the yellow (orange?) wire on the GPS while it was in operation status (red solid and blue blinking).



Edit: to add it took me less than 10 minutes to get this program running on my XP laptop, and it functions exactly as it does on the new OS systems. This is very good! I now have radio programming, GPS configuration, and general GPS legacy programs all working on my field laptop.

ecarson said:

OK, here is what the "RSSI" or signal strength screen looks like when everything is working the way it is supposed to. I hit "connect" on this screen, and soon the packets come in and are compared in what looks like relative S/N ratio.

If I can get this to install on the XP laptop this afternoon, this might be very useful for analyzing in the field when I travel away from the transmitter with the laptop in hand (or in vehicle).

Something is amiss on your system for sure. I did find that when using the FTDI cable, the GPS was correct on RX/TX cable. It seemed to be the air transmitter that had the TX/RX reversed. I hooked my GPS module up to my oscilloscope, and verified this. I got the pulses from the yellow (orange?) wire on the GPS while it was in operation status (red solid and blue blinking).

View attachment 326774

Click to expand...

Yeah, something is amiss. I'm using the v2 radios and totally screwed up. I reversed the TX/RX back and forth and actually got the solid red lock and flashing blue LED on the GPS both times. I totally recommend that utility you found
for 3DR programming because it can tell you the signal quality between the Local and Remote station. I didn't see that with Mission Planner.

When I get to working with the v1 radio, I'm going to configure the radios first. I created a battery harness I can plug into the remote "just" to provide regulated 5V power with no GP attached. Once I get them communicating,
I'm going to wire the GPS exactly like you show in message 184 above. I'll just connect the red + and black - (no brainer there of course) and do the orange to green signal wire and leave the other wire disconnected.
I might have scrambled the GPS chipset when I left is attached while doing some programming.

So, the orange wire is the "received GPS signal going OUT the wire". That is going into the "transmit line" for the 3DR radio. Hmmmmmmmm, maybe I shouldn't have connected the other two wires.

This is why the lines should be labelled transmit "out" and receive "in". Some GPS boards are marked that way.

The only programming I did with my v1 3DR radio was adding the B/T module to the receiver and configuring the Rf link to the transmitter/remote without a GPS attached to it. It should be fine.

Oh, one IMPORTANT thing I did find out with the v2 radios. Note this well people. When using the micro USB for Data and power, no problem. I tried my battery harness to apply 5V through that JST-SH (or whatever) socket (my v2 radios are 4 pinned sockets) and the only thing that happened was the red LED lit and not the green one. Seems like power can ONLY be input from the micro USB socket and regulated 5V comes out of the the 4 pinned JST-SH socket which is where the data comes in
to be transmitted. Hopefully, the two GPS's will arrive soon and I can jump on getting that set up and running like ecarson has. Me suspects, the B/T module on the receive end will allow data to be piped via B/T to different tracking apps.
Nice not to have an easily jostled USB cable to dislodge. Kurt

P.S. I've just thought I've been connecting all four wires coming off the GPS chipset to the 3DR radio. Stupidhead here is going to "cut" the blue wire which is used to "program" the GPS chipset. In reality for a tracker, only the received signal "out" from the
GPS which ecarson has determined to be the orange wire and has valid NMEA strings to prove it, along with the + and - wires need to be attached to the 3DR radio technically to telemeter the strings. The blue wire serves on purpose for us and
I have a hunch might be messing things up here for me. I'm going to try again later. There's still a chance I messed up the GPS chipset by trying to program the radios with it attached. Stay tuned.

with all the info in this thread i was able to purchase hookup and test the 433mhz 500mw unit . it really is simple. Thanks corzero.

i did buy the 100mw 433mhz unit too but it was shipped with the wrong antenna the seller sent me a new antenna and just received it Friday. will put together that one this week.

Danh said:

View attachment 326801

with all the info in this thread i was able to purchase hookup and test the 433mhz 500mw unit . it really is simple. Thanks corzero.

i did buy the 100mw 433mhz unit too but it was shipped with the wrong antenna the seller sent me a new antenna and just received it Friday. will put together that one this week.

Click to expand...

You bet! I thought a simple, cheap system would help some folks out. I did some ground range testing with my car last week. I set the transmitter on someones real estate sign on a state road here in Tampa and drove off holding my receiver and phone out of my sunroof. I lost signal at 1.2 miles and that was with a slight bend in the road presenting an obstruction. Very promising for our line of sight use. This test was with the 100mW 915 radios at full transmit power.

Weather permitting, I'm going to fly the GPS in a giant field I found north of Tampa tomorrow. I'm using an (29mm) Estes D-Region with a big CTI F motor that should reach about 11 to 1500 feet or so. I will be using a large, 36" parachute to allow it to drift as far as possible to get as much data as possible with the short flight. Android GNSS commander has a log function in which I can save NMEA data. I can transfer that file to my laptop and .kml it into Google earth for 3D flight path image. I'll post screen shots tomorrow night.

ksaves2 said:

Yeah, something is amiss. I'm using the v2 radios and totally screwed up. I reversed the TX/RX back and forth and actually got the solid red lock and flashing blue LED on the GPS both times.

So, the orange wire is the "received GPS signal going OUT the wire". That is going into the "transmit line" for the 3DR radio. Hmmmmmmmm, maybe I shouldn't have connected the other two wires.

T

Click to expand...

This is true with all GPS units I purchased. These are plug and play with drone flight controller systems, so I'm not sure there are too many units out there that are shipped with incorrect wiring.

I'm not sure why you're having problems with your radios, but I've been known to be easily confused. Hope it works out for you.

CORZERO said:

Weather permitting, I'm going to fly the GPS in a giant field I found north of Tampa tomorrow. I'm using an (29mm) Estes D-Region with a big CTI F motor that should reach about 11 to 1500 feet or so. I will be using a large, 36" parachute to allow it to drift as far as possible to get as much data as possible with the short flight. Android GNSS commander has a log function in which I can save NMEA data. I can transfer that file to my laptop and .kml it into Google earth for 3D flight path image. I'll post screen shots tomorrow night.

Click to expand...

I'm looking forward to seeing some flight data from it. I'm really curious what the range is.

ecarson said:

Still have not received the Ublox M8N module, so in the meantime I've been working on my sanding, priming, paint techniques on a test boilerplate rocket.

I found an alternative radio configuration program that is very similar to the Mission Planner GUI radio screen. This however, also generates a command line screen, that shows all the little details of the radio communication setup. Might be useful for debugging or diagnoses of problems. I found the program at this link:

https://www.ardupilot.co.uk/ardupilot-software.html

It looks to have a lot less CPU overhead than the full Mission Planner, as it addresses the radio configuration only.

Here is a screenshot of what it looks like when the windows are expanded. Again, I found I had to disconnect the power to the GPS in order to use the "load settings" button. No big deal as it currently is just a matter of unplugging one wire from a Dupont connector. At some point, if I cannot get this resolved, I'll wire in another mini-Molex type connector for the GPS power during flight conditions, as those snap together solidly.
View attachment 326731

EDIT Addendum: Using the above program, I switched a window to "Terminal" screen. Then, on a whim I hooked the power back up to the GPS module, while the radio was active. This lit up the terminal screen with all the streaming GPS NMEA packets immediately. There is also a window with scrolling radio signal strength. I may be able to install this program on the XP laptop as it appears to be a legacy from the same author as Mission Planner, in which case I'll be able to effect radio programming with that device. See screenshot with the terminal interface screen scrolling the NMEA packets.

View attachment 326733

Click to expand...

Good find! Definitely a lighter-weight program. I love the RSSI function as well. Mission Planner was a good starting point but is designed for drone flight controllers and accompanying systems. This radio-specific program definitely suits our use much better.

Danh said:

View attachment 326801

with all the info in this thread i was able to purchase hookup and test the 433mhz 500mw unit . it really is simple. Thanks corzero.

i did buy the 100mw 433mhz unit too but it was shipped with the wrong antenna the seller sent me a new antenna and just received it Friday. will put together that one this week.

Click to expand...

Which exact system did you get? v1 or v2? I tried mixing a v1 "receiver" with a B/T module with a v2 transceiver and I succeeded in dorking a GPS. I found out if you lose
the settings for the "air" module on the v1 unit you are screwed. It won't sync with your base and unless you have the time to go through all the settings, you will be SOL.

This setup is very dicey unless one follows the instructions exactly. If you forget to "push" the settings of the receiver to the v1 "air" module (the one corzero suggests in the first post), you will be treated with no easy method to recover the v1 air module. If you get the flashing green LED on both the v1 air and base modules you are screwed.

I you get the combination transceivers or v2 rigs: https://www.aliexpress.com/item/F19...-TX-Telemetry-w-OTG-for-APM2/32782098117.html . You can connect them up separately and reprogram them to the same net and parameters and recover them seperately. Only problem with the v2 radios is
that they only accept power in from the micro GPS socket. You can't treat a v2 transceiver by feeding 5V through the micro JST-SH socket in parallel with your gps chipset.
I tried it already and just got a red LED. Version 2 radio is a no-go unless you are wanting to use it as a USB only base station.

Nonetheless, one needs to keep track of their settings on the v1 radio because if you lose the solid LED lock between the two units, if you don't remember the exact settings
for both units, you are shafted.

I may have to resort to a USB serial board to see if I can get the "air" unit to connect to the program and put some default settings in there to get it back. A real PITA.
Whatever you do, be careful.

Danh, you might have been lucky. You get the system stable, don't change it. I want a Bluetooth link on the receive station to send the NMEA strings across at 9600bps on a
Bluetooth link so just about any tracking app can monitor it live. The v1 radio looks like it can do it but like I said, be absolutely certain you send any changes to the air module
before you exit out or log your prior settings. The program won't do that for you. If you get the flashing green "LED of death" you could be SOL as I discovered.

I gotta find that stupid serial/USB board like this one: https://www.sparkfun.com/products/12731 I have one somewhere in 5V but 3.3v might work to get this working again.

Anyone who flies drones and gotta method to reset the "air" module post it cause if you lose it, it might be gone and not easily recovered. Kurt

ksaves2 said:

Anyone who flies drones and gotta method to reset the "air" module post it cause if you lose it, it might be gone and not easily recovered. Kurt

Click to expand...

"Upload Firmware" updates and reprograms the radios to the newest firmware version. Click "Copy to Remote" to program transmitter. See buttons below.



I highly doubt you have damaged any of your components. I have yet to experience any of the issues you mention, but I'll be sure and post my experience and solution if I do.

I re-verified that signal pulses are coming off the orange GPS wire. Nothing from blue wire while in normal operation. This is a screen shot from
the oscilloscope. I finally got the square wave edges well defined. I had wanted an oscilloscope since 1969, and finally got one earlier this year.
Hantek DSO5202P. It will take me years to learn all the stuff this thing can do, so waiting 48 freaking years was not so bad.

kurt my air module is V1.0 i assume the ground module is as well.

i dont know about being lucky i just bought everything in the links. and didn't try to do anything that wasn't in the first post. i dont know much about electronics just read the threads and got it to work. i did directly solder my gps wires to my air module only to find out later you need to unhook the gps in order to adjust settings. so i cut them and use the good ole twist and tape method for for testing until order actual connectors now that i know it works.

i ran my gps for 4 hrs on an 1s 800 mah battery. still was running when i shut it off

tomorrow i will get some screen shots of my settings and show how i have it hooked up

CORZERO said:

"Upload Firmware" updates and reprograms the radios to the newest firmware version. Click "Copy to Remote" to program transmitter. See buttons below.

View attachment 326806

I highly doubt you have damaged any of your components. I have yet to experience any of the issues you mention, but I'll be sure and post my experience and solution if I do.

Click to expand...

is there a reason your frequency's are not the same on both settings?

CORZERO said:

View attachment 326805

This is true with all GPS units I purchased. These are plug and play with drone flight controller systems, so I'm not sure there are too many units out there that are shipped with incorrect wiring.

I'm not sure why you're having problems with your radios, but I've been known to be easily confused. Hope it works out for you.

Click to expand...

I think I whacked the GPS when leaving it connected to the tracker while programming. I have a couple of GPS sets coming and another v1 radio. As I mentioned above, I lost the settings to my
v1 "air" unit and there is no easy way to bring it back to stock. The net ID is I guess important but I used the stock 25, 35 and I believe I tried 34 as a net ID and I get nothing but a flashing
green LED of death when I tried to restore it.

With the v2 radios: https://www.aliexpress.com/item/F19...-TX-Telemetry-w-OTG-for-APM2/32782098117.html one can plug them in separately
through the micro USB connection, fire up the programming utility and put in identical settings and save them. You then can plug them in as a complete unit and the rig plugged into the computer
directly becomes the "local" and the "remote" will also appear. They will bond if the settings are the same as programmed separately. I use a battery with a USB 2.0 plug to micro USB plug to provide 5V power to the v2 "remote" (through the micro USB socket) to call the "pair up" together. Problem is with the v2 radios I can't find an easy way to isolate to 5V+ and ground off the micro USB socket to power the thing for flight. I wouldn't trust a USB cable for power during a rocket flight.

If one wants to fly with 3DR, only use the v1 3DR radio that corzero put up in the first post. A Bluetooth module can be added to the "receiver" and programming can be accomplished through the B/T link
but is a real PITA due to the stupidness Winblows attaches to B/T links. I think the smart thing (now) is to disconnect a power cable for the B/T module and program through the USB 2.0 plug. Once everything is programmed can plug the B/T module back in and use it to get the positions into a tracking program

Also, if one wants to be able to "reprogram" the remote/flight module of the v1 radio, it behooves one to make the GPS connection easily removable. I did some reprogramming with a GPS attached to a v2 radio
and I suspect I made an $8.50 mistake and scrambled the GPS. Disconnect any GPS to the v1 flight module before reprogramming and always, always send the new parameters to the remote and save them. Don 't forget them like me so now I gotta try and see if a FTDI serial card might get the thing back.

Kurt