Paparazzi, the RTF Autopilot? - Page 11 - RC Groups
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Jun 25, 2008, 09:12 PM
Registered User
I tried the GPS comparison again with google earth this morning with an unobstructed view of the sky and the data was off when referred to google earth
read from ublox: lon: 77.557871, lat13.030098
coordinates from google earth: lon: 77.332827, lat13.014822
any suggestions or thoughts on this.....
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Jun 25, 2008, 10:14 PM
Registered User
4 satellites is hardly a fix. The receiver will give you a 3D, but in my experience its never very good. Also, its possible that Paparazzi and google earth use different spherical models, but we use google earth imagery and it couldnt explain 24 km. I would guess its because you only had 4 sats and you are in india.

Jun 25, 2008, 10:53 PM
bmw330i's Avatar
...another good reason to get the LEA-5H in the air. They are so much more sensitive. Anton any more suggestions? If you could extract the config from yours I could load it into mine and help me determine what's going on. Someone on IRC today was having issues with know in u-center just save the GPS config to a file...I'll do the reverse and be able to pre-program the Tiny2.11 I sell with the proper win for everyone.
Jun 25, 2008, 10:57 PM
Registered User
This morning I had 8 sats and had a 3D fix, but still was off in comparison to google earth...could it be that something is wrong with the congifg file as I am using a LEa4H module and the config file is for a Lea 4P...could not find a config file on the wilki for LEA4h. The only difference I thought was the LEA4h was much more sensitive than the lea4p
Last edited by Prashanth; Jun 26, 2008 at 09:12 AM.
Jun 26, 2008, 09:17 AM
Registered User
later I reinstalled google earth and tried again, this time it worked fine, dont really know what changed the ublox is quite accurate with the cordinates matching the location of my house in google earth... next on to the IR sensors...
Jun 26, 2008, 01:11 PM
Registered User
I am in the middle of a post office strike and still i haven't got the stuff from mouser.
The receiver is ready, the plane is ready and flew already but the connectors and modems are still not here.
Jun 26, 2008, 05:51 PM
bmw330i's Avatar
Strike, that suxs, sorry to hear. I just have to set my CG and do a test flight myself. No big open areas near my house (at least not that's public land) so I will try this weekend.
Jun 26, 2008, 11:05 PM
bmw330i's Avatar

LEA-5H setting....

Hey all,

Someone on IRC the other day was having issues with their LEA-5H tiny 2.11. I didn't have this handy but now I do so I'm going to post it. This is the line in the aircraft file that is supposed to allow the LEA-5H to work.
ap.srcs += gps_ubx.c gps.c latlong.c
It also makes the greed LED blink when a 3D fix is found.

This line is down in the <makefile> section at the bottom of the file.

I have used it without success buy hey, worth a try if you have an LEA-5H based Tiny2.11 so let us know if it works for you. Remember, as with all changes here you'll have to re-compile the aircraft and upload it to the Tiny.

Last edited by bmw330i; Jul 01, 2008 at 04:23 PM.
Jun 27, 2008, 02:10 AM
Registered User
has anyone made a simple light weight antenna for the 900 Mhz 9xtend modem....
a simple dipole or a ground plane antenna at 900 Mhz should be about 7.9 cm in length of each element...on the wiki there are some pictures of copper foil antenna for 900 mhz but no details of how one goes about making one. RC cam has a goof proof antenna that can be made for 900 Mhz good for the ground station but difficult to mount on a plane

any working solutions for 900Mhz antenna

I would like to use the 9xtend but with a light weight antenna...
Jun 29, 2008, 10:53 PM
Registered User
Originally Posted by Prashanth

I would like to use the 9xtend but with a light weight antenna...

question for you...

I have been working with the 9xtend with the development kit. However, I'm looking to trim down the profile even more by dropping the development kit and strapping the modem directly onto my laptop cover. The problem that I'm running into is I can't get computer the recognize the modem via the USB connection without the development kit. Have you had any success? Is so, are you using the power from the USB for pins 2 and 7 or are you utlizing an external power source?
Jun 29, 2008, 11:03 PM
Registered User
in order to do this you need to use an FTDI cable. This will take the serial data from the xtend and convert it to USB. The Xtend does not do standard USB comms. I believe most FTDI cables pass the 5V rail through so you could power the modem off it. Be careful though, must laptops have a half amp limit, and at 1W Im not sure what that thing will pull.

Jun 30, 2008, 11:37 AM
Registered User
Dear graves
I still dont have an ant for the 9xtend so havent powered it on, hope to get is soon, I think it will draw abt 800ma of current at default setting with 1w power output, if you plan to power it from the USB power you need to set the power output to less than 500mw.
Jul 01, 2008, 11:56 AM
bmw330i's Avatar

Update: Arf

Well, I just wanted to write a quick update for those following this thread.

Current status hasn't changed. I need to find someplace to fly in manual then when I get the IR sensors working I'll try auto1 and mechanical trimming.

I think the Single IR sensor is the issue. If I unplug it the GCS attitude display (artificial horizon) seems to work. With it plugged it does not. I will try without. I'm not sure how many people even use it.

That's about it. I did take it outside and power everything up including the GCS and all but the attitude sensing seems to be working perfectly.

Oh, I guess I do have one more thing. I have to assign switch G to the autopilot mode switch in the radio config file per Anton (thank you Anton again).

Jul 01, 2008, 01:29 PM
Registered User
Im guessing you are trying the Z sensor stuff indoors? The reason it doesnt work is quite simple. Simplified, the math is something like roll angle = roll_ir_sensors/z_sensor.

if you have the z_sensor plugged in, its probably reading the temperature difference between your floor and your ceiling(about 0 degrees). so you have a divide by 0 case. making roll angle measure 90+ degrees. When you unplug it the ADC remains active, but reads a random voltage, unsually like 1.6ish. so the attitude display will kind of work. The Scale wont be right, but it should show direction. I hope that helps. As far as who uses it. Everyone! in fact Im not sure the code would even work anymore without it.

Jul 01, 2008, 09:16 PM
Registered User
BMW and AJ
I read in the wiki somewhere that with the IR sensors one has to do the cupboard test (put the autopilot with sensors in a strofoam box etc) and get the neutrals....
after doing this calibration for the ir sensors would it still behave like how bmw is describing?