How to make sense of gps data sent to sigfox

[james.matthews]

Hi all,

I'm trying to send latitude and longitude from the Pytrack to sigfox. The code I am using to do this is this:

print(str(latitude), ":", str(longitude))
s.send(struct.pack('f',float(latitude)) + struct.pack('f',float(longitude)))

The print command gives me this:

51.753743 : -1.252524

but in Sigfox I see this:

d5034f42b552a0bf
ASCII: ..OB.R...

You can see this in the attached image

I've also tried this:

s.send(str(latitude), ':',str(longitude))

but it wasn't helpful. Can anyone help make this text something useful?

Eventually I'd like to be able to automatically view this on a map. Could anyone help with that? would AWS be helpful here?

Thanks

[Eric73]

@james-matthews struct.unpack work with "byte" objet. As we have to unpack a float this "byte" object must have a size of 4 bytes. [https://docs.python.org/2/library/struct.html]

This float , have been packed in a binary form
'''s.send(struct.pack('f',float(latitude)) + struct.pack('f',float(longitude)))'''
then sent to sigfox backend data and showed in hexadecimal
'''d5034f42b552a0bf'''
so, to have original value you just have to unpack it from hexadecimal to float
''' lat=b'\xd5\x03\x4f\x42' '''this is the way to create and assign hexadecimal value to a 'python byte object' with len=4

[james.matthews]

@eric73 said in How to make sense of gps data sent to sigfox:

struct.unpack('f',lat)

That's awesome, thanks!

However, I do not understand what you did. How (and why) did you know to write it like this:

lat=b'\xd5\x03\x4f\x42

Thanks,

[Eric73]

lat=b'\xd5\x03\x4f\x42
struct.unpack('f',lat)
(51.75374221801758,)

lon=b'\xb5\x52\xa0\xbf'
struct.unpack('f',lon)
(-1.2525240182876587,)

It's seem your sensor will to be near oxford isn't it ?

https://www.google.fr/maps/place/51°45'13.5"N+1°15'09.1"W/@51.7539049,-1.254124,17.42z/data=!4m5!3m4!1s0x0:0x0!8m2!3d51.7537422!4d-1.252524