What Is A Telemetry Receiver ?

[bob miller]

not being too technical , what is a telemetry receiver ?....thanks....bob

 

[JimZaremski]

a two way receiver/transmitter system. The Rx can send back data like engine temp, RPM, etc. to the Tx which will show it on its display.

 

[bob miller]

can a telemetry system send back top speed info ?

 

[Bob Morton]

Yes. If there is a GPS in the system. There are lots of radios that come with Telemetry. I use Eagle Tree system.

Nails

 

[Blackout]

Hi Bob,

I just bought the Eagle Tree data recorder and GPS expander to measure top speeds on the whole race course. I did not get the Telemetry option yet so I will have to download the info to my computer to see the speeds. The Eagle Tree telemetry is a good bit more expensive than just the data recorder.

I was told by my LHS that no current radios come with GPS speeds as an option. It sounds like I may have been told wrong?...

See you in Elmira, we can talk.

 

[Don Ferrette]

Hi Bob,

I just bought the Eagle Tree data recorder and GPS expander to measure top speeds on the whole race course. I did not get the Telemetry option yet so I will have to download the info to my computer to see the speeds. The Eagle Tree telemetry is a good bit more expensive than just the data recorder.

I was told by my LHS that no current radios come with GPS speeds as an option. It sounds like I may have been told wrong?...

See you in Elmira, we can talk.

GPS speeds and r/c boats are a mixed bag. When used in straight line testing they are fairly accurate but going around in ovals not so much. There are no commercially available GPS units out there that have a refresh rate fast enough to read properly going around our race courses. Sure they're accurate in your car (many argue the accuracy using the well it works in my car bit) but then again you're not turning a 35 foot radius at 60 or 70mph. If you want to use for straight line testing speeds you blast one way, SLOW WAY DOWN, turn around easily then hit it again in a straight line. As far as telemetry in the actual radio goes (there are ones that transmit to laptops) I'd rather not see that option at all, we have a hard enough time getting people to pay attention without the added distraction of trying to look at a transmitter for data. I can hear it now - "sorry man, didn't mean to run over you, I was just trying look at the telemetry on my radio". Stick with the Eagle Tree like Bob uses and download your info after you run.

 

[Blackout]

Hi Bob,

I just bought the Eagle Tree data recorder and GPS expander to measure top speeds on the whole race course. I did not get the Telemetry option yet so I will have to download the info to my computer to see the speeds. The Eagle Tree telemetry is a good bit more expensive than just the data recorder.

I was told by my LHS that no current radios come with GPS speeds as an option. It sounds like I may have been told wrong?...

See you in Elmira, we can talk.

GPS speeds and r/c boats are a mixed bag. When used in straight line testing they are fairly accurate but going around in ovals not so much. There are no commercially available GPS units out there that have a refresh rate fast enough to read properly going around our race courses. Sure they're accurate in your car (many argue the accuracy using the well it works in my car bit) but then again you're not turning a 35 foot radius at 60 or 70mph. If you want to use for straight line testing speeds you blast one way, SLOW WAY DOWN, turn around easily then hit it again in a straight line. As far as telemetry in the actual radio goes (there are ones that transmit to laptops) I'd rather not see that option at all, we have a hard enough time getting people to pay attention without the added distraction of trying to look at a transmitter for data. I can hear it now - "sorry man, didn't mean to run over you, I was just trying look at the telemetry on my radio". Stick with the Eagle Tree like Bob uses and download your info after you run.

Interesting. I haven't used mine yet, just got it. I would imagine radar gun measurements would be off as well since you are making an arc when the trigger is pulled. Do GPS speeds show false highs or false lows in the corners. I would imagine the refresh rate of Eagle Tree is way better than my Garmin hand held? When plotting the Eagle Tree on Google Earth, does the course traveled show a smooth curve or many short straights? That may give an idea of how accurate the Eagle Tree GPS corners speeds are. Either way, it's all relative, and should be consistent, so you will know which props are faster in the corners, but that speed may not be 100% correct.

 

[lohring]

We've done a lot of testing with several GPS units. Most of this was in a straight line but often with very fast acellerations. The oldest Eagle Tree GPS units lagged and read several mph below the peak radar speed at around 100 mph on SAW riggers. The newest units seem much better. We also tested Garmin and Eagle Tree GPS units as well as a dedicated GPS speedometers on the electric SAW hydro and compared their readings with the average speeds throught the traps. I've also looked at radar versus GPS at the exit of turns. The results seem to be very similar. Below are a couple of examples. The trap speeds were very similar to the GPS speeds.

Lohring Miller



Older GPS lag Note difference in speed & rpm



Newer Eagle Tree GPS Note speed & rpm match

 

[Bob Morton]

Hi Craig,

I only use the Eagle Tree Gps as a tuning tool. I also use RPM and Temprature as data for tuning. Then I save the good

Results in my notes on the IPhone so I can use them as a bench mark. Plus it's fun to see the results of your work.

And you can put the GPS in the radio box just make sure the antenna is pointing to the sky. The Eagle Tree GPS is the most accurate

Measuring tool you can use. Beside a sensored times IMPBA course.

Craig, I bought an extra USB extension, I cut the wires so I could expose them thru the the radio box I then tinned the wires and put heat shrink tubing on them. Now I leave the extension plug in to the data logger so I can download the data to the PC with out opening the radio box. I only used it for SAW, but Google Earth will give you results around an oval race course.

Have a good day. (*¿*)

No more hacking and guessing.

Go Pens

 

[Ray Sametz]

"OLD SCHOOL" Legal oval course. GO RANGERS

 

[Blackout]

Hi Craig,

I only use the Eagle Tree Gps as a tuning tool. I also use RPM and Temprature as data for tuning. Then I save the good

Results in my notes on the IPhone so I can use them as a bench mark. Plus it's fun to see the results of your work.

And you can put the GPS in the radio box just make sure the antenna is pointing to the sky. The Eagle Tree GPS is the most accurate

Measuring tool you can use. Beside a sensored times IMPBA course.

Craig, I bought an extra USB extension, I cut the wires so I could expose them thru the the radio box I then tinned the wires and put heat shrink tubing on them. Now I leave the extension plug in to the data logger so I can download the data to the PC with out opening the radio box. I only used it for SAW, but Google Earth will give you results around an oval race course.

Have a good day. (*¿*)

No more hacking and guessing.

Go Pens

Good info! Thanks! I like the idea for quick USB down loading without opening the radio box.

 

[Bob Morton]

Yep great minds think alike. Õ¿Õ

 

[Tim Harris]

Agree with above on telemetry distraction risk. I have it on my futaba plane system. Unless your "eyes are young" changing focus to look at the transmitter then back to a model is risky. I do use the battery receiver voltage telemetry but have that coming up in large numbers on the screen so i don't wast time trying to focus. New things like the buzzing vibration on the transmitter when time is up i do find useful.

 

[JimZaremski]

the one part of a telemetry setup I could get behind is a temperature alarm, but with a boat you should be able to see you don't have water flow soon enough to shut her down.

 

[Jim Caldwell]

I agree the old ET GPS units at 5hz were slow, no such problem with the newer 10hz units.

Set for update at 4 times a second and the GPS data correlates very closely with the stop watch and if that isn't enough set it of 10 a seconds.

I haven't seen a thumb that can be as accurate as 4 time a second.

If you REALLY want to lower your lap times, load into Goggle Earth, as Bob suggested and you will see where you are losing all that lap time!!!

 

[Terry Keeley]

Here's a Google Earth plot of a recent SAW testing session:

 

[lohring]

I've used the Eagletree GPS latitude and longitude readings for an XY plot of the boat's course. It's embarrasing to see how curved your SAW run was or how poorly you really drove a race.

Lohring Miller

2006 record run course.bmp

 

[Hydro Junkie]

I recently bought a 4PLS and, after reading the manual and using it a couple times, find the only thing I really will use during a race is the receiver battery voltage. During prerace testing, the temp and RPM would be a nice feature but not during an actual heat

 

[Blackout]

Well, I tried the Eagle Tree data logger with GPS and it didn't seem to record speed. When I down loaded the sessions to the computer, there was a time frame recorded and a single latitude and longitude, but no sign of movement. Any ideas? I'll have to try again.

Thanks.

 

[Terry Keeley]

Well, I tried the Eagle Tree data logger with GPS and it didn't seem to record speed. When I down loaded the sessions to the computer, there was a time frame recorded and a single latitude and longitude, but no sign of movement. Any ideas? I'll have to try again.

Thanks.

Did the GPS update, ie: green light stop flashing on it?