"I am not trying to attenuate anything in the signal
But effectively you are. And theoretically you have to in order to prevent aliasing in you 1/40 decimation stage.
"
Kári Davíðsson's Discussions
Drift Issues - Aliasing
Started this discussion. Last reply by Henrik Larsson Sep 10, 2011. 35 Replies 1 Like
This is a followup to the aliasing discussion in http://diydrones.com/forum/topics/arducopter-drift-issuesHere is a short…Continue
Release management
Started this discussion. Last reply by Kári Davíðsson May 31, 2011. 1 Reply 0 Likes
I have been following the release of Arducopter 2.0.x.There are few things I have noticed that I think should be fixed for better tracking of bugs and better release management.1) Libraries in svn…Continue
Tags: management., release, management, Code
Code Proposal - Fix For Arming Motors bug
Started this discussion. Last reply by Jose Jimenez Dec 26, 2010. 24 Replies 0 Likes
This is for ArduCopterNG_b2.Fixes motor arming where motors will rotate continously after having calibrated the minimum throttle throught the CLI.I post the complete files (in a zip file) that I…Continue
Code patches
Started this discussion. Last reply by Kári Davíðsson Dec 19, 2010. 2 Replies 0 Likes
It is possible to upload photos and videos of flying and not so flying Cop..... Things. Wouldn't it be of much interrest and uttermost convenience to be able to upload normal text files with code…Continue
Kári Davíðsson's Page
Latest Activity
Kári Davíðsson commented on William Premerlani's blog post Measuring Tilt Dynamics of Multicopters"O.k. so basically you are using 200 tap mean filter for the decimation.
That filter gives you approx -45dB attenuation in the stop band. You can actually do much better with 200 taps filter, easily reaching -80dB attenuation in the…"
Kári Davíðsson commented on William Premerlani's blog post Measuring Tilt Dynamics of Multicopters"Aliasing is hard (almost impossible) to deal with (except by raising the sampling rate).
Do you have any details on the decimation filters you are using?
I guess you are measuring the closed loop response, i.e. with the PID controller active?
"
Kári Davíðsson replied to Gerard's discussion ESC Getting hot? Ideas?"I noticed that the ESC driving the APM gets hotter in my setup.
Now I run the APM on a separate powersupply."
Henrik Larsson replied to Kári Davíðsson's discussion Drift Issues - Aliasing"Just to update: if a single channel is wanted - 250kHz sampling is possible from the Atmega side in interfacing with the ADS7844.
If 6 channels - 41.7kHz. If nothing else is to happen. I've tested 1.5kHz sampling. Removes all…"
DeveloperOlivier ADLER replied to Kári Davíðsson's discussion Drift Issues - Aliasing
"
I changed my forum name so that it's easier for users and team people to make connections.
Sure it's feasible, perhaps not with a 5-10$ chip (if we need to embed 3 or 4 AVR core or other controller or a Floating point…"
Henrik Larsson replied to Kári Davíðsson's discussion Drift Issues - Aliasing"Ah, thanks JMD45 for the insight! Yes, it seems one must look into how big a chip we'd need and the licencing on the IP's and such to keep it reasonably open source and low cost.
Actually, there has already been folks…"
DeveloperOlivier ADLER replied to Kári Davíðsson's discussion Drift Issues - Aliasing
"
I didn't touch to FPGAs since 7 years.
7 years ago, i did a product study for a project and i found that the easier products was Altera ones. At this time, Quartus II was very friendly. It had a goog GUI with a graphic design engine and…"
Henrik Larsson replied to Kári Davíðsson's discussion Drift Issues - Aliasing"Well, you may be absolutely right that we could have a small group of people doing the very low stuff such as implementing (or at least finding and testing) the core CPU/DSP and then when an interface has been laid upon that it should make able for…"
DeveloperOlivier ADLER replied to Kári Davíðsson's discussion Drift Issues - Aliasing
"
I'm not sure that the FPGA would be a great handicap for opening. After all, as soon as you embedd one or more controlers inside it, you get normal C++ programming, like we can have for the ppm encoder or the main actual AVR.
The…"
Henrik Larsson replied to Kári Davíðsson's discussion Drift Issues - Aliasing"Yeah, well this is certainly a double edges sword full of counter considerations! On the one hand, you have the possible performance and flexibility which comes with great change, on the other hand you have the comfortability and usability with very…"
DeveloperOlivier ADLER replied to Kári Davíðsson's discussion Drift Issues - Aliasing
"
I second this for ARM power.
But you have only one processor. Realtime tasks are not easy to do on a single chip.
For example, actually Roberto has a big problem on the STM32 : there is no 9 bits hardware mode for the serial…"
Henrik Larsson replied to Kári Davíðsson's discussion Drift Issues - Aliasing"I really agree on the FPGA ideas! Much more flexibility and foremost: the optimal performance! Choosing the right FPGA and operating frequencies could enable us to use the full 200kHz capability of the ADS7844 (the ADC unit of the Oilpan). Which…"
Heino R. Pull replied to Kári Davíðsson's discussion Drift Issues - Aliasing"I've been playing with Xilinx FPGAs such as the Spartan 3E and had some similar thoughts. ISE Webpack is also free along with the Picoblaze softcore. There are numerous cores available on http://opencores.org such as an AVR processor…"
DeveloperOlivier ADLER replied to Kári Davíðsson's discussion Drift Issues - Aliasing
"
I didn't used FPGA since about 7 years, but at this time it was from 5$ each for smallest ones by 1000 parts quantity, to about 100 $ for mid sized ones.
Big multi millions gates FPGAs can cost $$$, more than 1000 or 2000$. They…"
Kári Davíðsson replied to Kári Davíðsson's discussion Drift Issues - Aliasing"True.. I was just thinking of a solution that will benefit all that allready have the apm and the oilpan.
The coprocessor board would mount inbetween the apm and oilpan. Making a three PCB sandwich and stealing the SPI port that goes to the ADC on…"
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