There is a description in config.h from MultiWii 2.3 about GPS baud:
// avoid using 115200 baud because with 16MHz arduino the 115200 baudrate have more than 2% speed error (57600 have 0.8% error)
All the resource form Google or MWC forum just tell me to set GPS baud to 115200. Should I ignore the message above?
I have tried to connect my GPS module with baud 57600(By I2C board), but it seemed to become worse.
So, my question is: which GPS Baud is more accurate when i use MultiWii 2.3?
ps:
My FC board is Crius Multiwii SE v2.5.
GPS module is Ublox 6M.
I2C board to connect GPS module with FC board.
Which GPS Baud is more accurate?
Re: Which GPS Baud is more accurate?
beebu wrote:So, my question is: which GPS Baud is more accurate when i use MultiWii 2.3?
The lower the baud rate the lower the error rate.
Of course, you have to select a minimum baud rate in order to have the bandwidth for transferring all data 5 times per second.
This minimum baud rate amounts to 19200 bd for a UBLOX gps device due to i2c-gps-nav documentation.
A good compromise is 38400 bd - more than 57600 bd are neither way necessary nor accurate and therefore not recommended.
Re: Which GPS Baud is more accurate?
Thank you so much, QuadBow!
I tried 38400 bd， and it works fine and be more accurate depends on the ALT the Speed data.
I have another question.
Below is the configuration of my GPS 6M:
Measurement period: 100 ms
Navigation Frequency: 10 Hz
If i change it to:
Measurement period: 200 ms
Navigation Frequency: 5 Hz
Will it improve the performance of ALT Hold?
Or ALT Hold performance is mostly depend on the Barometer accuracy but not GPS data?
I tried 38400 bd， and it works fine and be more accurate depends on the ALT the Speed data.
I have another question.
Below is the configuration of my GPS 6M:
Measurement period: 100 ms
Navigation Frequency: 10 Hz
If i change it to:
Measurement period: 200 ms
Navigation Frequency: 5 Hz
Will it improve the performance of ALT Hold?
Or ALT Hold performance is mostly depend on the Barometer accuracy but not GPS data?
Re: Which GPS Baud is more accurate?
Gps is not used in alt hold
Re: Which GPS Baud is more accurate?
Hi beebu,
The question is valid what better is, 5Hz or 10Hz. I heard the argument that the excellent filtering algorithm is applied only to 5Hz due to performance reasons.
At 10Hz this filter would be switched off and therefore, 5Hz would be better as to teh accuracy.
But, that is just a rumor I have heard, I don't have any personal experience or measurements.
ALT HOLD depends in deed only on the barometer.
Maybe you are thinking of POS HOLD? That depends on the GPS device. But, in case you have both - baro and GPS - the GPS is used for horizontal accuracy, the baro for vertical accuracy. Since the GPS's vertical accuracy is rather poor, it is better to combine both, which can be done by combining POS HOLD and RETURN HOME with BARO in the matrix.
The question is valid what better is, 5Hz or 10Hz. I heard the argument that the excellent filtering algorithm is applied only to 5Hz due to performance reasons.
At 10Hz this filter would be switched off and therefore, 5Hz would be better as to teh accuracy.
But, that is just a rumor I have heard, I don't have any personal experience or measurements.
ALT HOLD depends in deed only on the barometer.
Maybe you are thinking of POS HOLD? That depends on the GPS device. But, in case you have both - baro and GPS - the GPS is used for horizontal accuracy, the baro for vertical accuracy. Since the GPS's vertical accuracy is rather poor, it is better to combine both, which can be done by combining POS HOLD and RETURN HOME with BARO in the matrix.
Re: Which GPS Baud is more accurate?
Hi Quadbow,
Thanks for your advice, It helps me so much.
If i want to make ALT Hold be more accurate, i should focus on the ALT PID tuning.
I have tried to enlarge D of ALT and decrease P, because of the poor Barometer BMP085.
(D depends on Acc Z, P depends on Barometer)
Then my quadcopter hold altitude more easily. But compared with APM FC quadcopter, my multiwii quadcopter is not good enough.
Maybe i have to upgrade to ATmega2560 or MS5611 barometer.
Anyway, Quadbow,
Thanks for your help. i owe you a beer!! Prosit !
Thanks for your advice, It helps me so much.
If i want to make ALT Hold be more accurate, i should focus on the ALT PID tuning.
I have tried to enlarge D of ALT and decrease P, because of the poor Barometer BMP085.
(D depends on Acc Z, P depends on Barometer)
Then my quadcopter hold altitude more easily. But compared with APM FC quadcopter, my multiwii quadcopter is not good enough.
Maybe i have to upgrade to ATmega2560 or MS5611 barometer.
Anyway, Quadbow,
Thanks for your help. i owe you a beer!! Prosit !
Re: Which GPS Baud is more accurate?
Hi guys , I am monting one quad whith crius se 2.5 whith skecth 2.1 , my question is setting gps baudrate in FC like 38400 i have to change any settings in i2c our in gps my gps is crius neo6 cirocomm , wait news guys .
Sorry for the pour english but i am from portugal
Best Regards all users and i hope sugestions .
Sorry for the pour english but i am from portugal
Best Regards all users and i hope sugestions .
Re: Which GPS Baud is more accurate?
Iter wrote:Hi guys , I am monting one quad whith crius se 2.5 whith skecth 2.1 , my question is setting gps baudrate in FC like 38400 i have to change any settings in i2c our in gps my gps is crius neo6 cirocomm , wait news guys .
Sorry for the pour english but i am from portugal
Best Regards all users and i hope sugestions .
Hi,
I am also from Portugal, welcome!
Any reason to use MW 2.1? I think 2.3 still supports the i2c for GPS interfacing but unfortunately I don't have experience with this configuration. I think the GPS should be configured with 115200 and 5Hz position update but check this links:http://www.multiwii.com/forum/viewtopic.php?f=6&t=3346
http://www.rcgroups.com/forums/showthread.php?t=1724694
I hope it helps.
Regards,
Luis Sismeiro