Thread: GPS data using positioning module in Python s60

1. GPS data using positioning module in Python s60

Hi,

I am interested in using the positioning module with the internal GPS sensor of N95 8GB. I found the very helpful code example here: http://wiki.forum.nokia.com/index.ph..._read_GPS_data
However I have some question in relation to the use of GPS data from the positioning module.

1 - What's the unit of GPS speed obtained from the positioning module. I suppose it is meters/sec but I am not sure.

2 - What are the units of the GPS Longitude and Lattitude obtained in this code? I suppose they are in degrees but confimation would be very very helpful.

3 - What is the highest update rate we can obtain from the GPS unit? In the example code 0.2 sec is used to print the GPS data. Does the measurement actually come at 5 Hz?

4 - At the end of the example code, e32.ao_sleep(1) is used after every loop. Can we actaully use smaller sleep time at this step? Would choosing a shorter sleep time (let's say 0.01 sec) cause any problems for obtaining the GPS data?

I would be very glad if anyone can help me with these questions.

Selim

2. Re: GPS data using positioning module in Python s60

Hi,

Originally Posted by selimsolmaz
1 - What's the unit of GPS speed obtained from the positioning module. I suppose it is meters/sec but I am not sure.
I think it is either km/h or m/s, I'm not really sure which.

Originally Posted by selimsolmaz
2 - What are the units of the GPS Longitude and Lattitude obtained in this code? I suppose they are in degrees but confimation would be very very helpful.
They are indeed in degrees format using WGS84 datum. Positive numbers designate the northeast hemisphere (east of Greenwich, North of equator).

Originally Posted by selimsolmaz
3 - What is the highest update rate we can obtain from the GPS unit? In the example code 0.2 sec is used to print the GPS data. Does the measurement actually come at 5 Hz?
The spec allows you to set updates in microseconds. I have tested this practically up to 0.2 seconds, which seems to work, but leave little processing power to the rest of the system. Also I'm not sure if I really got up to 5Hz updates. Now I generally use 0.5, which works fine for me.

Originally Posted by selimsolmaz
4 - At the end of the example code, e32.ao_sleep(1) is used after every loop. Can we actaully use smaller sleep time at this step? Would choosing a shorter sleep time (let's say 0.01 sec) cause any problems for obtaining the GPS data?
Setting to 0.2 would work fine, setting to 0.01 may hog your cpu, your mileage may vary. I generally use 0.5, which means that I can still decently show a clock wich updates at least once per second.
Why would you want to use such a short sleep time?

Regards,
Mark.

3. Re: GPS data using positioning module in Python s60

Originally Posted by hurenkam
Hi,

I think it is either km/h or m/s, I'm not really sure which.

They are indeed in degrees format using WGS84 datum. Positive numbers designate the northeast hemisphere (east of Greenwich, North of equator).

The spec allows you to set updates in microseconds. I have tested this practically up to 0.2 seconds, which seems to work, but leave little processing power to the rest of the system. Also I'm not sure if I really got up to 5Hz updates. Now I generally use 0.5, which works fine for me.

Setting to 0.2 would work fine, setting to 0.01 may hog your cpu, your mileage may vary. I generally use 0.5, which means that I can still decently show a clock wich updates at least once per second.
Why would you want to use such a short sleep time?

Regards,
Mark.
Hi Mark,