OP25j

Welcome to OP25

OP25 is a project to bring together folks that are interested in implementing APCO P25 using a software-defined radio. Our goal is to build a software-defined P25 analyzer that is available under the GNU Public License (GPL).

APCO P25 is the digital communications standard used by many police and emergency services throughout the world. Most notably the US, Canada and Australia deploy systems based on P25. Compared to existing analogue systems P25 offers improved spectrum use, coverage and flexibility. Provision is made to ensure the confidentiality of traffic, to allow the use of trunking and the provision of data in addition to voice services.

Although hardware scanners such as the Uniden BCD996T offer APCO P25 functionality a software radio offers reduced costs and improved flexibility. For example, software radios can receive many channels at once, handle both voice and data (including the trunking control channel), decrypt encrypted traffic when the key is known and log traffic to disk for later analysis. With the right software a software radio is, therefore, a powerful analysis tool for debugging and monitoring of P25 networks.

From here we have a number of tasks that immediately suggest themselves. In increasing order of difficulty (and inverse of necessity) these are:

• Understand P25, the physical layer and the messages being passed over the air.
• Implement a demodulator which takes a P25 signal and produces a message stream.
• Extend the !WireShark sniffer to allow sniffing of P25 messages.
• Analyzing the various security issues and demonstrating the insecurity of P25 systems.
• Implement an IMBE/AMBE decoder to recover voice traffic.
• Provide a practical logging service for P25 operators.
• Locate and track the locations of P25 mobile stations.
• Implement a P25 gateway so that future IP-based emergency systems can inter-operate with P25.

As all Wiki pages, this page is editable so these ideas are not fixed in stone. Developers can simply click on the "Edit this page" link at the bottom of the page (although it is worth familiarizing oneself with Wiki formatting beforehand). For now its only developers who can do this because of the inevitable !WikiSpam problem.

Starting Points * [HardwarePage] -- The recommended hardware for this project. * [SoftwarePage] -- An overview of the project software. * [DemodulatorPage] -- A GNURadio program that turns a P25 signal into a message stream. * [WireSharkPage] -- Patches to !WireShark that allow for the sniffing of P25 traffic. * [SecurityIssuesPage] -- A summary of the security issues of P25. * [SpecificationsPage] -- The APCO P25 specifications. * [QandAs] -- Frequently asked questions and answers.

For a complete list of local wiki pages, see TitleIndex.

Request for Help
If any visitor has access to the current P25 standards and would consider donating their copies to our university's research group please contact us. Without the specifications we are unable to make progress on many of the exciting tasks we've laid out above. Please email "specs[delete-and-replace-with-an-atsign]sedition.org.au".