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Old Dec 15, 2011, 08:12 AM
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Hong Kong, Hong Kong Island, Central And Western District
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I understand that there COULD be conflict, but I'm just wondering what the real world experience has been. Part of the problem is that the various suppliers (Spektrum / Futaba) are not very clear about how it solves the conflict (either by having the radios talk at different times, different frequencies, wider spread or digital encoding.) This shouldn't be a difficult to solve, compared, say, to cleaning a much higher bandwidth signal from an FPV video transmitter.

I was wondering if anyone has any usage experience of telemetry transmitters and RX combinations that don't like to play with each other?

Thanks.

Quote:
Originally Posted by caseih View Post
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 15, 2011, 09:13 AM
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Illinois
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Originally Posted by JimMcWhorter View Post
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.
It's not that it wasn't thought of - it was from Day 1, but making it to market on time meant that not all features were included in the first release. This is standard practice anywhere you find software - start small, add features over time.

I think you're going to like very much the features coming out for the STi over the next few updates ...

Andy
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Old Dec 15, 2011, 09:15 AM
AndyKunz's Avatar
Illinois
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Originally Posted by Franco2fly View Post
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.
Buy the DX8 packaged with the TM1000. Purchase the Spektrum Altimeter SPMA9575. If you buy from a local shop, a lot of times you can get them to bundle them a little cheaper for you.

In the DX8, configure it to alarm at 400'.

Go fly!

Andy
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Old Dec 15, 2011, 09:18 AM
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Originally Posted by caseih View Post
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.
Not at all for Spektrum. With the DX8 it will remain at the same high speed (very close to DX7SE) whether you use telemetry or not.

Andy
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Old Dec 15, 2011, 09:53 AM
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Originally Posted by AndyKunz View Post
Not at all for Spektrum. With the DX8 it will remain at the same high speed (very close to DX7SE) whether you use telemetry or not.

Andy
I have noticed the tight response of the DX8 to be the same with Telemetry.

VP
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Old Dec 15, 2011, 07:58 PM
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Like Mode 1 said, I too am a builder of our planes of yesteryear. I guess as hokey as it may sound, the telemetry thing excites me in that it looks like it gives unfortunate folks like myself a virtual cockpit sort of thing. I don't know, maybe I'm way off the mark...wouldn't be the first time, nor do I suspect it would be the last
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Old Dec 15, 2011, 08:28 PM
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Originally Posted by DeadByDawn View Post
Like Mode 1 said, I too am a builder of our planes of yesteryear.
Me too! A couple recent builds:

Micro Bridi T-20: http://www.rcgroups.com/forums/showthread.php?t=1553198
Micro Mach One: http://www.rcgroups.com/forums/showthread.php?t=1397143
Micro Kaos: http://www.rcgroups.com/forums/showthread.php?t=1380102

What have you built lately? I'd love to see pix!

Along the thoughts of your "virtual cockpit" comment, that's very true!

I found telemetry extremely helpful, but very scary at first since I found several of my models were skating on the edge of power problems. Had to spend money updating BECs, cleaning up linkages, and tossing out crappy servos.

Andy
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Old Dec 16, 2011, 05:26 AM
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Originally Posted by AndyKunz View Post
Me too! I found telemetry extremely helpful, but very scary at first since I found several of my models were skating on the edge of power problems. Had to spend money updating BECs, cleaning up linkages, and tossing out crappy servos.

Andy
So, your saying telemetry has allowed a sort of tune-up of the radio system, by it's use? That makes me interested a little bit more in these systems! Still, this makes me wonder how I was ever successful flying R/C back in the old days of my old Kraft radios?!? Without all the new gadgets, R/C was most certainly an extremely dangerous hobby!!
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Old Dec 16, 2011, 09:09 AM
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Illinois
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And do you remember how much crashing we did back then??

One of the big differences between then and now is that analog systems degrade as power declines. You may lose performance with the radio system as your batteries wear down.

In modern (digital) systems, performance appears rock solid or nothing at all. Digital electronics stop working when the voltage hits a certain point, whereas with analog it slowly degraded. That's why we didn't see power brownouts as an issue.

This is also true with digital transmission. Back then the analog cell phones and old walkie talkies would get static long before they stopped working, and RC stuff would get glitchy. With modern cells and radio systems, you have crystal clear performance and then you get out of range and --- ABSOLUTELY NOTHING.

That's what PCM would do too, remember? You had a warning with an regular PPM system that things were going downhill, but with PCM you didn't know you had any problems until you had no control.

Same idea.

That's how telemetry has helped me personally. I use it in all my models that are big enough to carry it.

Andy
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Old Dec 16, 2011, 01:37 PM
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Julez's Avatar
Germany
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I use it in all my models, since all modern telemetry systems have it directly included in the recievers.

Thankfully, my systems of choice do not need more power or a higher voltage than old radio gear, so I never encountered a single power problem in any of my planes.

It appears to me, that currently the Graupner Hott system offers the most advanced telemetry options, and it additionally logs the data on a memory SD card for later review. With the included voice output, it has everything one could ask for. The only exception is a small electro module, like the stamp-sized Jeti MUI 30.
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Old Dec 16, 2011, 03:34 PM
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Quote:
Originally Posted by AndyKunz View Post
And do you remember how much crashing we did back then??

One of the big differences between then and now is that analog systems degrade as power declines. You may lose performance with the radio system as your batteries wear down. Andy
No, I don't remember crashing more, as I didn't crash more than, than I do now and my Karft equipment WAS Digital Proportional. Analog proportional was only around for a pretty short time and it was before I got back into the hobby in 1976, I believe.
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Old Dec 16, 2011, 04:03 PM
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Illinois
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Your Kraft receiver was an analog device. Digital referred to the PPM data stream. The NE5044 was an analog encoder, the RF decks were analog, the receivers were analog, the NE5045 was an analog chip, the NE544 servo amps were analog.

PCM was done using digital encoders and decoders, but the RF path was still analog technology.

Now all those analog functions are carried out by micros or digital RF.

Andy
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Old Dec 16, 2011, 07:03 PM
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Andy, I bow to your superior knowledge! My Kraft radios were certainly refered to as Digital Proportional, that is all I know for sure about them.
I've never owned a Pulse Code Modulated anything. and I still believe the amount of crashing that was done back in the late 60s, 70, 80s and 90s was really no different than today, excepting the period of time when we switched from the old frequesncy system to the channel system when manufacturers were sorting out narrow banding.
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Old Dec 16, 2011, 07:33 PM
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Illinois
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I think the crashing was partly related to what was possible at the time. I know I had no trouble at my house with my World on AM 27.045 but getting near the US route made it terribly unreliable. That was probably due to AM. I also had to clean servo pots, clean the dust out of gimbals (never thought about protecting the tx from balsa dust!), and really poor rechargeable NiCd cells.

I learned, I hope!

Andy
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Old Dec 17, 2011, 06:53 AM
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The only 27 Mhz equipment I ever had was in a sailboat, which was the right way to use 27 Mhz! That and "10-4 Good Buddy, what's your 20".
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