My FrSky telemetry project

Telemetry is the new "big thing" in RC systems. If you've got something to say or a question to ask, do it here.

Re: My FrSky telemetry project

Postby JimmyJ » Sun Jul 11, 2010 4:10 am

Bruce:
Just read your most recent article on the FrSky telemetry project.
You write: "It is my intention to extend this functionality to add speech synthesis and an earplug connection so that all the required information can be reported without the need for the pilot to take their eyes off the model while flying." I fully appreciate the need to keep our eyes on the models and would also like to hear information via speech synthesis. There is one other thing I would like in addition to the speech synthesis. The ability to see the telemetry information projected onto my sunglasses. An American company named Microvision may have the technology for incorporating/projecting telemetry information onto a pair of sunglassses: http://www.microvision.com/wearable_dis ... obile.html. Microvision calls it Mobile Device Eyewear. I realize you are still in the building and testing stages of your telemetry project, but a pair of sunglasses that project the telemetry information in a kind of "heads up display" while your are also listening to speech synthesis or alarms is the way to go. Hopefully in the near future, we will have a telemetry option like this offered.
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Re: My FrSky telemetry project

Postby JimmyJ » Sun Jul 11, 2010 4:33 am

RCModelReviews wrote:Damn, mine are still stuck on the slow boat from China -- it's now been in the air for over a week.

As for fuel -- simple level sensors are fine if you're not doing a whole bunch of aerobatics but if you fly 3D like me... well that's going to require the addition of some accelerometers so that the system knows which way up your model is at any given time. Hmmm.. that sounds like a fun project (for later!).


Glad there's others thinking about fuel (fuel tank) consumption and how to measure it for telemetry! Seems to me, next to receiver battery voltage, fuel tank level/consumption is next in line...for glow n gasoline fliers.
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Re: My FrSky telemetry project

Postby RCModelReviews » Sun Jul 11, 2010 11:44 pm

Good news... my FrSky telemetry system has finally made it to NZ -- just waiting for it to clear customs and be delivered now (that can't take more than another week -- given the state of our internal post/courier services) :-)
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Re: My FrSky telemetry project

Postby vane » Mon Jul 12, 2010 12:32 am

Didn't buy any lipos with it did you bruce? haha

Unfortunately I don't think I will be able to afford to get the frsky telemetry system for a while :s unless I get a bit of discount through giant cod!

I need a job :S

Also, hoping to get that himodel 5.8ghz video set for my 18th in 8 days :D anyone recommend a good budget camera?
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Re: My FrSky telemetry project

Postby mr.sneezy » Mon Jul 12, 2010 2:18 am

RCModelReviews wrote:Good news... my FrSky telemetry system has finally made it to NZ -- just waiting for it to clear customs and be delivered now (that can't take more than another week -- given the state of our internal post/courier services) :-)
Bruce, I got my new set last week, and in between other pressing matters (like being laid off) I got to do some RF bench testing done on the new version. All good so far, power output is great, transmission scheme is multichannel FHSS just like the test version, 'range check' power reduction was 32dB. Binds great in both Telemetry mode and V8 compatibility mode.
Martin
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Re: My FrSky telemetry project

Postby suchislife » Mon Jul 12, 2010 11:54 pm

Looking forward to making one of these. Well done so far, Bruce.

I am wondering would it would be possibe, given that you will have airspeed, to set up a voice synthesised "stall warning?" Or would AoA be needed to make it reliable? Could prevent some of my... less elegant landings. Also a "terrain, pull up" based on rate of descent and alt?
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Re: My FrSky telemetry project

Postby jet760 » Tue Jul 13, 2010 1:45 am

hi bruce how has the flight test gone. Any luck with the weather
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Re: My FrSky telemetry project

Postby RCModelReviews » Tue Jul 13, 2010 4:17 am

I have decided to use the production telemetry system (now that it's in my hands) but this means I'll have to make some changes.

On receipt of the development system I requested that FrSky use TTL signal levels for the serial-connection on the receiver rather than true TTL levels -- since true RS232 requires an extra set of circuitry (level converters) and was also totally unnecessary. My telemetry hub connects to the development system through a TTL-level connection which bypasses the level-converters.

Unfortunately, FrSky seem to have stuck with the true RS232 levels which means I've now got to add some level-conversion circuitry to both the airborne telemetry hub and the dashboard. You can't just plug a microcontroller into an RS232 signal -- the voltages are way too high -- you have to add a converter to reduce the voltage going into the microcontroller and raise the voltage the microcontroller puts out to reach RS232 levels.

It's a shame -- because it actually increases the component count on the dashboard by about 20% and by 40% on the telemetry hub -- for no gain at all. I guess they weren't listening or had some other reason for sticking with true RS232 levels. An odd way to go, because it increases the price of the module, receiver and any hub/dashboard that you might want to add. The only upside is that it means you can connect an RS232-capable computer to the transmitter -- although I don't see that many folks will wander out to the flight-line with a laptop strapped to their hip when flying their model -- so is there really a need for true RS232 -- indeed, wouldn't USB be better if it's the ability to connect to a PC that you're trying to deliver?

Still it's a minor thing -- just means I'll have to make up a couple of small PCBs to do the conversion and wait for some components to arrive.
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Re: My FrSky telemetry project

Postby hillflyer » Tue Jul 13, 2010 8:06 am

Hi Bruce,
would it be possible to just bypass the RS232 converter instead of doing this TTL-RS232-TTL conversion stuff?
Of course it would mean opening up the Rx case, soldering to the input pins of the converter chip etc.
Unfortunately not a good idea if you are keen on the warranty...

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Re: My FrSky telemetry project

Postby RCModelReviews » Tue Jul 13, 2010 8:54 am

I've got to give FrSky credit for providing excellent support -- I emailed them with my concerns and they responded within an hour advising that the receiver doesn't use true RS232 levels at all so that won't be an issue.

If I remove the ability of the dashboard to set the module's own alarm levels then I can use a simple resistor/diode setup to convert the transmitter module's true RS232 levels to something approximating TTL as well. This just means that users will have to connect the module to a PC with the serial cable supplied and use the FrSky software also supplied, when they want to set the internal alarm levels.

One thing I'll be doing straight away is modding the telemetry transmitter module to allow for a plug-in LED that can be clipped to the transmitter's handle or installed on the transmitter front-panel. The LED on the module changes color to indicate the signal strength but it's utterly impractical to keep turning the radio over to look at the back of it when you want to see that LED.

I'm proposing the use of a small phono jack that will allow the external LED to be plugged in (which will automatically disable the internal LED). This (of course) assumes that you're not using a dashboard (which I suspect most people won't) but want an indication of the signal strength "at a glance" while in-flight.
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