RTLSDR also allows us to view GSM traffic using a tool called kal
or kalibrate-rtl
. This tool can scan for GSM base stations in a frequency band. In this recipe, we will learn about using kalibrate and then confirm the channel in gqrx
.
Following are the steps to use kalibrate:
- Most of the countries use the GSM900 band. In the USA, it's 850. We will use the following command to scan for GSM base stations:
kal -s GSM900 -g 40
The following screenshot shows the output of the preceding command:
- In a few minutes, it will show us a list of base stations:
- We note the frequency; in our case, we will use
947.6 MHz
along with the offset.
- Now we open GQRX and enter it in the
Receiver Options
window:
- We can see in the waterfall that the device is able to catch signals perfectly.
- Now we will look at this data at the packet level. We will use a tool known as
gr-gsm
. - It can be installed using apt install
gr-gsm
:
- Once it is done, if we type
grgsm_
and press the Tab...