FRSky Telemetry out of range?

Ockert · Post by **Ockert** » Mon Jan 30, 2012 8:07 pm

Hi guys
Having a fully modded TX and RX on the way to my doorstep (thanks to Rob), I've been reading up on as much as I can get my hands on. This might sound a complete weird one, but has anyone tested or compared the transmission range from the RX units (telemetry range) and how does it compare to that from the TX (One way control range)?

The reason I am asking is that I have all sorts of plans other than flying my models with the kit. It is easy to get the TX to control a huge radius since it is optimised for range, but if you rely on the telemetry to reach all the way back to base(coming from the RX), things like RX antennae design and setup might play a role. You might control something up to the max distance, but telemetry feedback might fail half-way.

Is this anything to be concerned about at all?

Also, if you bound a TX and RX unit, can I reliably keep them alive for days/weeks/months?

Thanks
Oks

Post by **Rob Thomson** » Mon Jan 30, 2012 8:33 pm

Range is in my experience very good... but obviously most of my experience it airborne range.

Thing with 2.4g is that is is a narrow frequency so it does not go round corners well! So direct range over land is really something to try and see!

Knowing where you live - I reckon it is so flat you should go a long way!!

Hope the tx arrives in good order after its global voyage.

Ockert · Post by **Ockert** » Tue Jan 31, 2012 6:41 am

It is flat enough out here to set some new range records, for sure.

However the reason I am following this train of thought is to figure out what failsafes there are on the RX and maybe to introduce a feedback loop which, if broken, can indicate "telemetry out of range" in stead of running into garbage and invalid readings.

Post by **cre8tiveleo** » Tue Jan 31, 2012 6:56 am

are you relying on telemetry on the tx for you to fly your plane back?

I use copilot and the home feature failsafe , so if at any time my rx has a signal loss , copilot kicks in with the various other dohickies and starts flying the plane home. When the signal returns i can regain control, otherwise my plane will continue home, then just circle gently around until the voltage drops ... Then return to earth...

(maybe in one piece)

Myself, could care less whats displayed on my radio, i'm watching my plane, either on a monitor for fpv(all data is on screen) or just watching it, flying and enjoying aerobatics, chasing birds...etc. Never look at the controller while flying.I record all the telemetry on sd in the plane.

---
I am here: http://maps.google.com/maps?ll=44.056212,-79.476230

Ockert · Post by **Ockert** » Tue Jan 31, 2012 7:23 am

cr8tive_leo wrote:are you relying on telemetry on the tx for you to fly your plane back?

I use copilot and the home feature failsafe , so if at any time my rx has a signal loss , copilot kicks in with the various other dohickies and starts flying the plane home. When the signal returns i can regain control, otherwise my plane will continue home, then just circle gently around until the voltage drops ... Then return to earth... (maybe in one piece)

Myself, could care less whats displayed on my radio, i'm watching my plane, either on a monitor for fpv(all data is on screen) or just watching it, flying and enjoying aerobatics, chasing birds...etc. Never look at the controller while flying.I record all the telemetry on sd in the plane.

True, but if your RX setup is not optimal and you only have telemetry within a 200m range your SD will contain only sections of the flight. So why record it at all?

More importantly though telemetry consists of informational data AND critical data (which is not displayed). Think of voltage alarms.They will be useless if you are gliding a sloapy up there in the clouds. You will have full control yes, but blissfully unaware that your knowing your alarms are useless. If you eventually come in range without enough juice to battle a bit of wind, it might be enough to lose a plane.
I know it is a c**p example, but the point is, why have telemetry if you cant trust it the full range?

Post by **Rob Thomson** » Tue Jan 31, 2012 7:43 am

The TX does already receive a signal back from the RX to tell it when range is low - this can trigger an audible alert to warn you of that situation.

Not sure if that is what you are trying to establish?

Ockert · Post by **Ockert** » Tue Jan 31, 2012 7:55 am

rob.thomson wrote:The TX does already receive a signal back from the RX to tell it when range is low - this can trigger an audible alert to warn you of that situation.

Not sure if that is what you are trying to establish?

Exactly what I am after. Good to know it is in place. Have you though of including it in your sound & haptic feedback?

Post by **Rob Thomson** » Tue Jan 31, 2012 8:05 am

Currently it is a module function only.

You can set the signal strength at which the alarm triggers - but the sound does not come down the wire to the tx.

Mike may know better.. but I do not believe there is a way to bring this to the tx yet?

Rob

Post by **cre8tiveleo** » Tue Jan 31, 2012 12:34 pm

Ockert wrote: True, but if your RX setup is not optimal and you only have telemetry within a 200m range your SD will contain only sections of the flight. So why record it at all?

More importantly though telemetry consists of informational data AND critical data (which is not displayed). Think of voltage alarms.They will be useless if you are gliding a sloapy up there in the clouds. You will have full control yes, but blissfully unaware that your knowing your alarms are useless. If you eventually come in range without enough juice to battle a bit of wind, it might be enough to lose a plane.
I know it is a c**p example, but the point is, why have telemetry if you cant trust it the full range?

My sd card is in my plane, everything is recorded, like a black box. No range restrictions at all.

\
*it is a c**p example...*

I see your point, but being in the hobby for close to 30yrs, you learn what the limits of your equipment is, and you improve on it.

I have a redundant power supply in some of my more valuable models. Dual bec with second battery. Once the first battery is dead, or low, the bec automatically switches to the other power source.

(best $20x4 I spent)

It's all good, I don't slope soar, each variant of the hobby requires it's particular needs. I love this firmware!

simplyfly · Post by **simplyfly** » Thu Aug 16, 2012 10:26 pm

So what is the range of the return telemetry link?? is it equal to the range of the control transmission?

Post by **Kilrah** » Fri Aug 17, 2012 5:09 am

Yep, +/- a little sample variation of course.

Post by **cre8tiveleo** » Fri Aug 17, 2012 11:34 am

simplyfly wrote:So what is the range of the return telemetry link?? is it equal to the range of the control transmission?

Welcome to the Dark side! Muuuahahahahahahaa!

Winston · Post by **Winston** » Sat Aug 25, 2012 2:58 pm

simplyfly wrote:So what is the range of the return telemetry link?? is it equal to the range of the control transmission?

In a thread somewhere on RCGroups I read that disassembly has revealed the same transceiver chip is used in both the airborne rx (actually transceiver) and the unit you install within the 9x, so the range should be identical for both control and return telemetry. In other words, as long as you have control, you should have telemetry. I also read that the FrSky tx power for both the airborne and control transceivers was 100mW in v1, reduced for some reason to 60mW in v2. I wonder if they did the same with the control tx in the non-telemetry version.

Post by **Kilrah** » Sat Aug 25, 2012 10:05 pm

100mW was including the gain of the antenna (60mW + 2dB = ~100mW). I don't think they changed anything on the hardware, but only changed the way they specified it.

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