Christian Gagneraud cgagneraud at techworks.ie
Sun Jun 7 18:23:14 CEST 2009

Christian Gagneraud wrote:
> Hi all,
> I'm using cellhunter since few month, with which i have gathered some 
> data (1646 cells so far here in Ireland) and uploaded to their server.
> I would like to give a try with OpenBmap, is there a way to convert 
> data from CH to OBM and upload them to OBM server?
> I know that OBM log more details than CH but i guess that CH's data 
> are still usable by OBM.
> Generally speaking, what people think about these two project? And of 
> course the 2 billion euros/dollars question: Which one is the best?
> Does the 2 projects collaborate, if not are there any plan to do so?

I did a comparison of what's get logged/store by CH, OBM and OCI 

Cell data:
                 OBM     CH      OCI
time            x       x       x
provider                x
mmc             x       x       x
mnc             x       x       x
lac             x       x       x
id              x       x       x
signal (1)      x       x
arfcn                   x
type (2)        x (3)
ta              x (3)
c1              x (4)
c2              x (4)
serving         x       x

GPS data:
                 OBM     CH      OCI
time            x
lat             x       x       x
long            x       x       x
alt             x       x
heading         x
speed           x
hdop            x
vdop            x
pdop            x

Meta data:
                 OBM     CH      OCI
hwmanuf         x
hwid            x       x
hwver           x
swid            x       x (5)
swver           x       x (5)
login/pass/key  x       x       x

(1) OBM: signal strength in dBM and rxlevel in % (?), CH: signal 
strength according to GSM specs
(2) Network type: GSM, UMTS, HSDPA, ...
(3) OBM: only with serving cells
(4) OBM: only with non-serving cells
(5) Via HTTP agent when uploading

So finally, OCI logs basic information, CH a bit more, and OBM a lot 

Here is the compatibility matrix between the loggers and the servers 

             OCI    CH    OBM	
L G  OCI     x
O E  CH      x     x
G R  OBM     x            x

Both CH and OBM loggers can be used to populate OCI database.
For CH logger to be compatible with OBM database, there's lot of data 
that need to be added to the CH logger.
For OBM logger to be compatible with CH database, there's very few 
data that need to be added to the OBM logger:
- provider: the network operator, as reported by fso.GSM.Network.g 
getStatus() or Status() signal
- arfcn: current channel number, as reported by 
And only one data is expressed in a different unit:
- signal strength: OBM use dBm and CH use a scale as per %EM AT command

So finally, it would be ideal to enhance slightly the OBM logger, this 
way it will be universal in regards to the 3 databases. And this will 
give the user the complete freedom to upload his data to whatever 
database he wants (for example i would like to upload data to CH 
server for the fun and still contribute to OBM because i'm convinced 
of the higher quality of their data).

Some personal remarks (a bit OT):
- I was really surprised to see that CH logger use AT commands 
directly (via fso.GSM.Debug), whereas OBM logger use plainly the FSO 
- It's a pity that CH use signal strength in GSM scale, FSO use 
percent and OBM dBm. There's lot of wasted CPU (and battery) around...


PS: I don't pretend that this analysis is accurate nor mistake-free, 
so please correct me if i'm wrong somewhere.

> Chris.
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