iListener
=========

Full Hopping Channels, Uplink and Downlink GSM receiver base on Airprobe


The project was started in 2011, and till the end of the project iListener can capture the whole hopping channels.
(i.e. all the traffic between multi-handsets and BTS together)

And uplink data from handset too.

The output is an XML is the same from gammu by a  Nokia 3310 which can be read by Wireshark.


Our project has been closed last year, and now we decide to open the source as it might be useful for someone.



There are two parts: server and gsm-receiver


gsm-receiver is just the gsm-receiver from Airprobe. 
We modified some codes so it can receive and decode the signals in other channels beside the (FCCH), 
that's the uplink or hopping traffic. Instead of adjusting the ARFCN on the USRP, we use multi-USRP together 
in order to capture all the traffic.

Then, it sends to server to rebuild the GSM frames.


In the case of multichannels hopping are deployed in the base station, 
many instands of gsm-receiver are turned on at the same time to recieve the signals.

The theory is, USRP/1 has two channels, we use RX-A to listen the FCCH, 
the other channels/Uplink channel are in sync with FCCH, we assigns RX-B to listen this channel.


Theoretically, futher synchronization can be deployed over many USRP/1 with DBSRX,
so the hopping channels can be ripidly rised. 



Also, we've tested "wideband" using one USRP channel, to "cut" the channels Xlating filter in GNURadio. 
We could successfully decode SMS in 2 hopping channels by wideband using USRP/1. 
But in pratical, hardware with more bandwidth(e.g. BladeRF) are necesssary.



For this project, we've produced some USRP/1, DBSRX, RFX boards using Ettus's open PCB file ourselves. 
Now, there are still around 4 or 5 USRP, 20+DBSRX, 10+RFX remains, 
we'd like to sell for some fund for a new project. If someone need them, please email us.


Nick Chan (Guangxi Normal University)  nick(dot)chitchan(AT)gmail.com
Wirelessddcat (Guangxi Normal University)  wirelessddcat(AT)gmail.com
Project Leader: Howard Wong ffp(dot)howard(AT)gmail.com

Special Thanks to Prof. Qin Shao Hua (Guangxi Normal University)