Tablet Ground Station via Bluetooth Telemetry Bridge

We've been experimenting more and more with tablet ground stations here at Event 38 and have had a lot of success using the DroidPlanner app. The software has been working well for us but we found our ground station setup was really cluttered, the opposite of what we were going for when switching to tablets. My main complaint was having the ground side telemetry radio dangling from my phone or tablet. Not only was it a hassle and prone to coming unplugged, it was also hard to keep it in a good position for radio reception.

Following Arthur Benemann's instructions, we set up a bluetooth bridge that would let us at least set the radio down and move freely with the ground station tablet. A huge improvement, no doubt, but still a little rough around the edges, even needing power from a laptop. So we added a nice case and a single cell LiPo battery to power it all. This worked even better, and looked pretty nice as well!

It still had some power management issues but it worked well enough for our purposes. At this point we're thinking about running a Kickstarter campaign to run a production scale build of these but we'd like to get some feedback from potential users before we solidify the specs. I'd appreciate any/all comments on what kind of features you'd like to see on something like this, if any, besides the telemetry bridge to Bluetooth. Right now we're planning on including the following:

Internal LiPo battery, rechargeable by USB
Battery status LEDs
433 and 915MHz variants to be compatible with any 3DR Radio
~20m Bluetooth range
~1km telemetry range
5-6 hours battery life
A durable plastic enclosure

Is there anything else we should consider adding to improve the functionality or usability? Do you think this would be priced fairly at $139? Let us know what you think!

Here's some photos showing my 9x with the 3dr radio to bluetooth bridge integrated inside. This has the same functionality of the box proposed by Jeff without the need to carry arond another box/battery. There's a bunch of other mods in here but you should be able to pick it out. The bluetooth module and the 3dr radio are powered off the 5v from the regulator on the top PCB on the transmitter front. The 3dr aerial goes out through the Thr. Cut switch hole. This switch has been hot glued inside the case (not used). The 5v gets powered up when the transmitter is turned on. I've considered setting up a switch to turn the bridge on and off but I use it pretty much all the time and it doesn't appear to drain a lot out of the battery. Only potential issue is the load on the 5v reg but no problems there so far!

I think this is a great set up as I don't have to carry another box around, charge another battery or have the 3dr radio module hanging off my tablet. Bluetooth range is never a problem because I always have the transmitter and tablet with me.

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Comments

Chris Onyando January 6, 2014 at 5:03am

The link above now works
Chris Onyando January 5, 2014 at 2:22pm

Hi Guys,

I successfully tested a bridge that i set up using an android device hosting the telemetry module and an app called mavcell.

I wrote about it on this blog post.

The blog post is still waiting approval. Incase the url changes, I will update accordingly.

Cheers.
Shawn McCracken December 7, 2013 at 9:19pm

Which tablets have you tested this with? I am most interested if it works with Samsung Galaxy Tab 3 7" that does not support USB OTG.
LTMNO October 23, 2013 at 7:55am

Thanks Richard... much appreciated... I will test that.... I have to setup the test bench when i get a chance to work that out... I was going to go out and get an Android Tablet for this... but I read somewhere a IOS version... in Beta Testing and not released to public yet... i might hold out for that... thanks again.

Cheers
LTMNO October 23, 2013 at 6:28am

Thanks, I am going to test bypassing the FTDI / USB adapter and just connect to the tx/rx/5v/gnd pins... see what happens there... fingers crossed... from the looks of it, the USB board with FTDI is attached to the original Telemetry Radio.
Jack Stewart October 22, 2013 at 11:06pm

@LTMNO

As Richard indicated it is this telemetry set here:

http://store.3drobotics.com/products/3dr-radio-telemetry-kit-433-mhz

I'm not sure if there's an equivalent in 915mhz. I'm sure if you hunt around you'd find something. I bought a separate USB version to plug into my PC and you can have both the PC and the tablet connected and receiving telemetry at the same time if you want.
Jeff Taylor October 22, 2013 at 2:03pm

Love that setup, Jack!
LTMNO October 22, 2013 at 6:15am

Jack, great idea... for those of us that have mod'd the radios with all the fixings.. whats one more... my problem is finding enough room in there with all the other upgrades I have done. Did your 3dr Radio originally have the USB attachment on it? Or is this a different Transmitter?
Jack Stewart October 22, 2013 at 12:31am

Here's some photos showing my 9x with the 3dr radio to bluetooth bridge integrated inside. This has the same functionality of the box proposed by Jeff without the need to carry arond another box/battery. There's a bunch of other mods in here but you should be able to pick it out. The bluetooth module and the 3dr radio are powered off the 5v from the regulator on the top PCB on the transmitter front. The 3dr aerial goes out through the Thr. Cut switch hole. This switch has been hot glued inside the case (not used). The 5v gets powered up when the transmitter is turned on. I've considered setting up a switch to turn the bridge on and off but I use it pretty much all the time and it doesn't appear to drain a lot out of the battery. Only potential issue is the load on the 5v reg but no problems there so far!

I think this is a great set up as I don't have to carry another box around, charge another battery or have the 3dr radio module hanging off my tablet. Bluetooth range is never a problem because I always have the transmitter and tablet with me.
Jeff Taylor October 18, 2013 at 7:59am

Thanks again for the feedback!

We haven't had problems with data drops, we're also using the RN-42 Bluetooth module. It will probably be a single cell 1000mAh but we'll make sure that lasts at least 5-6 hours first.

We did get about 20 meters range on Bluetooth as well and this is where the only problem we've seen so far comes in - if you go out of range then walk back in, our devices didn't automatically reconnect by Bluetooth at first. I installed an app called Bluetooth Auto Connect and this does the trick of automatically reconnecting to previously paired BT devices when they're in range.

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