Espritmodel.com Telemetry Radio
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Old May 02, 2012, 08:04 AM
AndyKunz's Avatar
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Take a look at the Min/Max screen. That tells you what your low rx voltage was.

If you wiggle several servos at once, it will give you a better idea, since that's more like real flying. Do this with a half-discharged (as half as you want it to be) battery.

Set your alarm a point or two lower. As your battery discharges, the internal resistance increases. This will be evident by servo movements causing the voltage to dip lower than they were with a medium-charged battery.

Andy
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Old May 02, 2012, 08:12 AM
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Quote:
Originally Posted by AndyKunz View Post
Take a look at the Min/Max screen. That tells you what your low rx voltage was.

If you wiggle several servos at once, it will give you a better idea, since that's more like real flying. Do this with a half-discharged (as half as you want it to be) battery.

Set your alarm a point or two lower. As your battery discharges, the internal resistance increases. This will be evident by servo movements causing the voltage to dip lower than they were with a medium-charged battery.

Andy
Thanks!! Can you add additional RPM and Voltage sensors (such as for 2-4 motors or for multiple batteries)? If so, do you use additional Y's on the Voltage/RPM port?
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Old May 02, 2012, 08:16 AM
AndyKunz's Avatar
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No, only single sensors are supported. If you use a PowerBox you can see multiple voltages as well as capacities. If you've got a big twin, you're likely to be using a PowerBox.

Andy
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Old May 02, 2012, 08:21 AM
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Originally Posted by AndyKunz View Post
No, only single sensors are supported. If you use a PowerBox you can see multiple voltages as well as capacities. If you've got a big twin, you're likely to be using a PowerBox.

Andy
Thanks!! I have a friend who has a big Twin. So he would not be able to read the RPM of both engines? I just wanted to understand the limits of the Telemetry system.
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Old May 02, 2012, 08:41 AM
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Just 1 RPM.

Andy
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Old May 02, 2012, 08:48 AM
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Originally Posted by AndyKunz View Post
Just 1 RPM.

Andy
OK!! Thanks!!
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Old May 06, 2012, 07:45 AM
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Portugal, Setubal District, Setubal
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Originally Posted by VasMan View Post
Although Spektrum telemetry has been covered in various threads, I'd like to start a new thread that's dedicated to Spektrum telemetry options. At this time my interest in particular is in the following areas:

  • Will the RPM port on a SR3300T take serial data input? I use a DX3S/SR3300T combo for flying kites and being able to get live altitude information would be very useful.
Feel free to add information related to Spektrum's telemetry (air or surface).

Vas
Hi ppl, im develloping a system to read speed from Gps parsing the $GPRCM data, and convert to pulses to plug to rpm port of the Spektrum rx or SPM1325.

I have a working c code, using the same type of Psoc Cypress chips that Spektrum use.

I use roll out in 0.10 setting, that give the most lower precision unit , is 109 meters per hertz.
Bit i have a problem, canīt find the right formula to find periods to generate the Hertz, take a look at the table, measurements are made with a pulse generator connected to the rpm port.

1hz = 0.109Kmh = 109mtrs = 32754 pulses used to gen 1hz
2hz = 0.219kmh = 219mtrs = 16377 pulses used to gen 2hz
3hz = 0,329kmh = 329mtrs = 10918 pulses used to gen 3hz
4hz = 0,439kmh = 439mtrs = 8188.5 pulses used to gen 4hz
5hz = 0,548kmh = 548mtrs = 6550.8 pulses used to gen 5hz
6hz = 0,658kmh = 658mtrs = 5459 pulses used to gen 6hz
7hz = 0.768kmh = 768mtrs = 4679.1 < >7hz
8hz = 0,878kmh = 878mtrs = 4094.2 < >8hz
9hz = 0.988kmh = 988mtrs = 3639.3 < >9hz
10hz = 1.097kmh = 1097mtrs = 3275.4 < >10hz
.................................................
100hz = 10.86kmh = 10860mtrs = 327.54 < >100hz
1000hz= 108.6kmh=108600mtrs = 32.754 < >1000hz

Conclusion, i know the speed in Kh, or meters/h, and need calculate pulses to generate the rpm, is a proportional inverse value, but many time thinking and canīt find the constant k or formula, is not linear, i think.
Someone help please?
Thks. regards.
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Old May 07, 2012, 01:27 PM
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Is there any information (other than the pictures from the Nurenberg toy show) on the Spektrum dual energy sensor and the high current sensors? Does the dual energy sensor provide the necessary isolation to prevent a ground loop when the RX and the main power system are isolated from each other so you can still monitor main power system voltage? What do these sensors actually do?

Thanks,
Peter+
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Old May 07, 2012, 03:33 PM
AndyKunz's Avatar
Illinois
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The Dual Energy has a common ground. It's intended for use with our PowerSafe receivers, which are also common ground. They aren't for monitoring foamie batteries.

Andy
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Old May 07, 2012, 07:34 PM
Team JetiUSA
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I'm not after monitoring foamie batteries, I'm after monitoring my 10S and 12S (two different planes) main system batteries (whose ESC obviously has no BEC) in addition to monitoring my PowerSafe receiver batteries... Since there is NO common ground between the main system battery and the rx battery, I can't use the standard voltage sensor on the main system battery as that would create a ground loop and let the magic smoke out...

Peter+
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Old May 07, 2012, 08:05 PM
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I'm not after monitoring foamie batteries, I'm after monitoring my 10S and 12S (two different planes) main system batteries (whose ESC obviously has no BEC) in addition to monitoring my PowerSafe receiver batteries... Since there is NO common ground between the main system battery and the rx battery, I can't use the standard voltage sensor on the main system battery as that would create a ground loop and let the magic smoke out...

Peter+
I am not sure I follow you. I have electric aircraft running 12S motor batteries and a separate 2cell LiFe Rx battery. I am using an AR8000, so it is not a Power Safe Rx. I receive Rx voltage Telemetry and Motor battery voltage Telemetry (with the sensor connected to the Motor battery leads on my ESC).

Is that what you are referring to?
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Old May 07, 2012, 08:07 PM
AndyKunz's Avatar
Illinois
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Dual Energy is only for 15A in a 2S or 3S configuration (I forget which). It will tell you how much juice each pack has used for running your receiver and servos.

Andy
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Old May 07, 2012, 08:35 PM
Team JetiUSA
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Quote:
Originally Posted by Buschbarber View Post
I am not sure I follow you. I have electric aircraft running 12S motor batteries and a separate 2cell LiFe Rx battery. I am using an AR8000, so it is not a Power Safe Rx. I receive Rx voltage Telemetry and Motor battery voltage Telemetry (with the sensor connected to the Motor battery leads on my ESC).

Is that what you are referring to?
Yes. So you've managed to avoid a ground loop causing magic smoke (good) because your LiFe and your main system batteries ground potential are very close to each other. HOWEVER, what you've done is broken the electrical isolation between your system battery and your receiver (the ESC throttle connection on HV ESCs is optically isolated from the main FETs) which means you are much more vulnerable to electrical noise in your receiver. The FET switching frequency of an ESC can be pretty high as its doing pulses on the three motor wires * the number of poles in your motor * the number of times/sec it needs to switch from on to off on each wind to deliver the voltage + current needed for the throttle setting you've selected (typically millions) couple million * 28 poles (Hacker Q80 or Q60 in my case) * 3 is getting up into the range where the noise could cause trouble...

Andy, am I off base here? Does Spektrum support a system wired as Buschbarber describes?

Peter+
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Old May 07, 2012, 08:52 PM
AndyKunz's Avatar
Illinois
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I don't know what our official answer is.

You aren't switching FETs in the gHz range.

The E-Flite 80A ESC drives a Habu 32 pretty well on 6S. It has a switching BEC in it.

I know guys are flying their BVM e-Bandits with those power levels successfully.

In short, I would try it, on the bench first for sure. I only use the red lead on my flight pack sense, though, even on low-power stuff. I can live with the small inaccuracy.

Andy
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Old May 07, 2012, 08:53 PM
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Originally Posted by pvogel View Post
Yes. So you've managed to avoid a ground loop causing magic smoke (good) because your LiFe and your main system batteries ground potential are very close to each other. HOWEVER, what you've done is broken the electrical isolation between your system battery and your receiver (the ESC throttle connection on HV ESCs is optically isolated from the main FETs) which means you are much more vulnerable to electrical noise in your receiver. The FET switching frequency of an ESC can be pretty high as its doing pulses on the three motor wires * the number of poles in your motor * the number of times/sec it needs to switch from on to off on each wind to deliver the voltage + current needed for the throttle setting you've selected (typically millions) couple million * 28 poles (Hacker Q80 or Q60 in my case) * 3 is getting up into the range where the noise could cause trouble...

Andy, am I off base here? Does Spektrum support a system wired as Buschbarber describes?

Peter+
I checked this out before I set it up and it seems to be working as advertised. No hint of any Interference. I am only seeing 20 Fades on one antenna via the Flight Log telemetry.
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