= OsmocomBB EMI Firmware =

[[Image(emi-firmware:emi_main.jpg)]]

Introduction

OsmocomBB EMI is a tool to generate interferences. It can be used to test how GSM radiation affects other equipment, e.g. amplifiers, radios and wireless devices. It is capable of transmittng in all GSM bands (1800, 1900, 850, 900), uplink and downlink. Because it only transmits, no filter rework is required. There are several test patterns, from SDCCH on a single time slot to PDCH on 5 time lots.

Branch

Check out jolly/emi branch of osmocombb GIT. It contains the EMI app and Sylvain's TRX hack to transmit multiple bursts per frame.

Settings

Use left function key (left key below display) to toogle between DCS1800 and PCS1900 band. This is only required for ARFCN rage from 512 to 810.

Use right function key to toggle between uplink (interference of a mobile station) and downlink (interference of a base station).

To change ARFCN, enter digits and acknowledge with right function key. Press or hold right and left cursor buttons to adjust current selected ARFCN.

Press the menu button to select a test pattern (scroll up and down) and acknowledge with the right function key.

Operation

'''Note: This device transmits on frequencies that require a license in most countries. Only use this device, if you have a license for the selected ARFCN or if you use it inside a Faraday cage'''

Press the green button (off-hook) to start transmitter. The transmit power is shown.

Turn off transmitter by pressing green button again or by pressing red button (on-hook).

To increase or decrease TX power, press or hold up and down cursor buttons.

==== RACH Burst ====

In case of test pattern "RACH", transmit power is shown, but nothing is transmitted. To transmit a single Access Burst, press the green button (off-hook). Whenever the green button is pressed again, an Access Burst is transmitted.

Simulation

When transmitter is on, the transmitted bursts can be made audible on the phone's buzzer. To increase volume, press or hold # key. To decrease, press or hold * key.

Restrictions * GSM 850 and 900 will not allow to go down lower than 4 dBm, even if displayed so. * Transmission of two or more timeslots will always be 30 dBm (1 Watts)