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Old Dec 11, 2011, 07:46 AM
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Telemetry systems

I know nothing about Telemetry systems for R/C and wonder how a person flying an R/C model would ever be able to use these systems. It is dangerous and can be very costly to take your eyes off an R/C model for even a second. Visually reacquiring the airplane can be extremely difficult and in the short time of not seeing it, it can either fly out of sight; or, crash! Just to look down at my transmitter to see how Long I have flown seems dangerous enough to me!

I should think airspeed and altitude to be the information that would be the most popular. If it were just one or the other an audible tone could work, maybe one for each ear. Beyond this, it would almost seem to me that a second person is needed to relay information to the pilot.

Or, is telemetry only of interest to people involved in UAVs/FPVs?

I just don't see how the data transmitted on a telemetry system can be relayed to the pilot without risk to the airplane! Certainly, looking down at your cell phone to see the data won't work as your hands are both busy flying the airplane!
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Old Dec 11, 2011, 08:24 AM
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Upstate NY
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A lot of good points..

It is incredibly useful to know via telemetry, several simple things and this is from an electric glider guy:

1) Is my plane's receiver getting a "good" signal from the transmitter or is the signal level low (for whatever reason) and I am near limits? Many of these systems provide direct feedback to the transmitter regarding this and it does not require looking at the screen (tones are emitted). My planes are flown much further out than conventional planes in search of that elusive thermal. And once thermal is caught, the plane can go quite high. This is a really nice and safe feature which actually builds confidence.

2) How is my Lipo pack voltage doing? Electric sailplanes have a relatively huge burst of power to get up to say 500 feet, then you glide around for 30 min to an hour. It is really comforting to know that when gliding with no motor on that your Lipo pack voltage and/or ESC output is as expected. A stuck or failed pack/servo/etc drawing too much current stands a chance of being detected prior to ultimate plane failure.

3) There are additional sensors for GPS, prop speed, etc. I am actually in process of setting up an altitude sensor which right now is read when I land. It would be strictly used/read by buddy pilots as when the plane is high, I can't take my eyes off it or I will possibly not find it again.

Nothing in all of the above requires me to take my eyes off my plane as I agree with you, that would be unsafe. All of this is done to "help" me be more confident in my plane and how it is flying. (Except the altitude which is just curiosity).

Hopefully this helps?
Scott
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Old Dec 11, 2011, 01:40 PM
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Telemetry for RC Systems

Quote:
Originally Posted by Mode One View Post
I know nothing about Telemetry systems for R/C and wonder how a person flying an R/C model would ever be able to use these systems. It is dangerous and can be very costly to take your eyes off an R/C model for even a second. Visually reacquiring the airplane can be extremely difficult and in the short time of not seeing it, it can either fly out of sight; or, crash! Just to look down at my transmitter to see how Long I have flown seems dangerous enough to me! I should think airspeed and altitude to be the information that would be the most popular. If it were just one or the other an audible tone could work, maybe one for each ear. Beyond this, it would almost seem to me that a second person is needed to relay information to the pilot. Or, is telemetry only of interest to people involved in UAVs/FPVs? I just don't see how the data transmitted on a telemetry system can be relayed to the pilot without risk to the airplane! Certainly, looking down at your cell phone to see the data won't work as your hands are both busy flying the airplane!
1. The Aurora 9 with large bottom screen is easy to glance at
(holding TX up momentarily helps) without losing sight of model.
(see how large the letters can be for timer on attached jpg.)
There is also the Hitec Eclipse 7 Pro with a large screen at top of TX
which makes for easy reading.

2. For those who are slow to refocus, "Clip on" "HTS-Voice"
which gives a spoken update via speaker
(or headphones so as not to confuse others nearby)
and or use your I-Phone as HTS-Voice or even a Bluetooth & Android App.,
refer to Android Readout & Voice Video Demo ..

Much more under sub section "Telemetry" at
RC Groups > Vendors > Hitec/Multiplex USA > support page
"Aurora A9, Spectra Modules & Optima Transceivers " - FAQ & Undocumented Features.
- Mixes, Setups, Tips. {Individual Links often updated}


The Hitec AFHSS 2.4GHz system, and associated telemetry features,
is also being used in many Futaba, JR and other transmitters which
use similar modules, see also "Spectra" section on FAQ page above.

Alan T.
Alan's Hobby, Model & RC FAQ Web Links (quick search = Ctrl+F)
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Old Dec 11, 2011, 01:54 PM
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United States, IL
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The most useful telemetry features for me would be warning information to let me know how much capacity of a battery pack I've used, if I'm draining too many amps, the temp gets too high, or if the voltage drops too low in the form of audible alarms.
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Old Dec 11, 2011, 02:32 PM
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It is a common misconception of non-telemetry users that one has to use a display to make use of telemetry data.
This is not the case.
Any telemetry system worth it's money has a audio alarm for every parameter monitored.
On my Jeti system, I often do not have the display connected to my module at all.

I get different warning beeps for:
- signal weakness
- low voltage at the RX
- low voltage at the flight pack
- flight pack current too high
- the programmed amount of flight pack capacity has been used up

This way, I only have to deal with telemetry when something is wrong, or I have to land due to the flight pack becoming depleted soonish.
As long as no alarm goes off, I can rest assured that everything works just fine.

Think of it like a low voltage alarm every transmitter has. I have not heard anyone complain about this feature, and it surely does not distract the pilot during flight normally.

More advanced systems, like Graupner Hott, even have voice output for every parameter, which can be activated via switch.

Go to 1:20.

mx-16 erklärt von Ralf Helbing (6 min 18 sec)
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Old Dec 11, 2011, 02:37 PM
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I hold up my DX8 to look at the screen, I have a technique that works very well. You have to also use common sense. Sometimes it is not wise to look at the Tx.

VP
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Old Dec 11, 2011, 03:55 PM
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I too am interested in this whole telemetry business, but as use for post-flight performance data. Right now I am looking at Eagle Tree Systems that gives the seemingly necessary numbers (Altitude, temperature, amp draw, RMP, airspeed, etc) that is transferred to your computer as an aircraft instrument panel. Looks like a neat system for a decent price (approx $150) but would like any feedback from folks who have experience with this system before making a final decision.
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Old Dec 13, 2011, 05:52 AM
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Has anyone noticed any reduction in RC control range as a result of using on-board telemetry systems? I've seen a US$100 third party telemetry system with voice warnings that is supposedly compatible with standard 2.4ghz radios, but am concerned that having a telemetry transmitter so close to the control RX might not be too healthy.
Thanks.
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Old Dec 14, 2011, 07:09 AM
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I guess what I am interested in R/C is certainly a narrow partial in comparison to many of you! My focus is on building and flying of rag covered, piston driven airplanes of yesteryear! I check my batteries on the ground with my voltmeter, previous to flight and as long as I can see the airplane, I really have no interest; or, need for a down-link!
However, maybe it would be cool to say after a crash: "We've lost the telemetry"!!
I can see a variometer in a sailplane as being a real asset and would likely go for one, if I got more serious about flying sailplanes again.

As this is a multi faceted hobby and I am constantly astounded by the the diversity, I understand other peoples interest in telemetry. I just deal with technology enough in my daily life that I want my hobby to be less equipment manuals and more hands on, low tech stuff!
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Old Dec 14, 2011, 04:49 PM
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Quote:
Originally Posted by Levendis View Post
Has anyone noticed any reduction in RC control range as a result of using on-board telemetry systems? I've seen a US$100 third party telemetry system with voice warnings that is supposedly compatible with standard 2.4ghz radios, but am concerned that having a telemetry transmitter so close to the control RX might not be too healthy.
Thanks.
Sure. If you use a separate transceiver for telemetry (like a radio modem) of course it will conflict with another system on the same frequency (or potentially will, depending on how it uses the spectrum). In the case of FrSky or Spektrum, the same transceiver that is receiving from your signals is also replying with with telemetry data. There should be no reduction in range at all. The question would be though, does interspersing command and control packets with telemetry data impact latency? Because full duplex communication over a single shared medium will always reduce the total bandwidth.
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Old Dec 14, 2011, 06:21 PM
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Lakewood, Colorado
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I've used the built in telemetry with XPS, Jeti and FrSky systems, and in all cases,
the audio alarms for the two most basic things
1. low Rx battery voltage (XPS didn't have this, but the others have programmable alarm levels)
2. impending or total loss of signal (all 3 have some form of this, although XPS's was really primitive)
are the most useful to me.
As a slope pilot I might fly a plane for hours, and I want to know when the
Rx battery level reaches a programmed threshold. I fly until it beeps, and then land.
For someone flying an electric, you set it to monitor flight pack voltage instead
of Rx voltage, and do the same.

And no matter what I'm flying, I like to know if there's some reason I might
be losing the signal. It could be due to bad antenna orientation, blocked by my own
body or someone else's, external Rf, a damaged or missing Rx antenna (happens more
often than you might think), or damaged Tx antenna (fatique due to repeated bending
or turning). The low or loss of signal alarm tells me all that. I even get a different
audio alarm if power is lost to the Rx and restored in the air (brownout).

It's also incredibly useful for locating downed planes. With very simple body blocking
techniques you can use the low or lost signal alarms to pinpoint the exact location
of a lost plane (quite common on the slope, and not unheard of at RC fields) to within
a couple dozen feet (closer with a live RSSI display). I even found one of my
slope planes *inside* someone's garage after I landed at the bottom of the hill, and
a nearby resident picked it up and took it home. Imagine their surprise when, after
my puzzled 10 minute search I showed up at their door and told em I was pretty
sure my plane was in their garage. Lots of excuses. Can't imagine they'll do it again.

Heck, I even have a little 1S lipo strapped to the side of one of my FrSky 6ch telemetry
Rx's that I power up by itself, and throw into my FPV plane. The FPV plane
has a completely different control system, but should it go down somewhere
out of sight I can narrow its general location down by reviewing the last
received video, and then when I'm within a half mile or of it so, I throw my FrSky
Tx module back in the radio, and use the same direction finding techniques
as above. If I want more range or to pinpoint the direction more easily, I throw
a 12dB Yagi antenna on the Tx module. The Rx only draws about 30-40mA sitting idle
so a 160mAh lipo will power it for a couple hours above the low voltage cutoff.

With the addition of a telemetry display one can monitor the signal strength in real time to
evaluate your Tx and Rx antenna placement and orientations. See where there
are problem Rf areas at a given location. Monitor voltage from multiple
batteries, current to the motor, and so forth. I rarely ever need to look at
the display, but given a choice between a tricky slope landing and re-launch to
check something, versus a quick glance at the display, it should be obvious
which is the safer option.

ian
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Last edited by Daemon; Dec 14, 2011 at 06:28 PM.
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Old Dec 14, 2011, 11:43 PM
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You might find useful my matrix spreadsheet:
http://www.rcgroups.com/forums/showthread.php?t=1529962
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Old Dec 15, 2011, 01:32 AM
Dean
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Ian, the other day a friend took my glider up almost out of sight and trimmed it for a gentle turn while I was looking away. I was then able to locate the glider by pointing the *dead* end of the antenna around the sky while looking straight down the antenna and listening to the beeps like we do with the body blocking method. He of course kept his eyes on the glider while standing behind a few of the guys so I couldn't see where he was looking.
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Old Dec 15, 2011, 08:05 AM
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Is Telemetry A good thing or a Gimic

I am a bit frustrated with the telemetry thing. Got BIG bucks invested in Spektrum (2 DX8, boat load of Receivers and a large number of TM1000s, sensors, etc.) so I am not likely to be switching systems and starting over.

I want real time data while I am flying. Not crazy about beeps and vibrates. I know I would get confused trying to count long and short beeps, etc. to figure out what is going on

I have tried gyrations of holding up the box to see the screen just below the airplane / heli in the sky. Goofy and uncomfortable at best for me

I really thought that the Spektrum I-Phone / I-touch interface was going to be the magic bridge .... I've been told that that the Spektrum Engineers didn't think to include any kind of an audio interface.

Saw the HiTech audio interface - seems that would be the answer to all my issues.

Is there such a magic box for Spektrum?

Has anybody really figured real-time telemetry flying out?

Deeply appreciate any help I can get
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Old Dec 15, 2011, 08:31 AM
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What I am looking for is an audible alarm when my aircraft exceeds 400' aside from that I wouldn't mind being able to down load GPS and altitude readings to my computer for midnite review of the previous days flying... Just what would I need to accomplish this? I'm thinking of getting a new Dx8, but don't know what else would need to be purchased.


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