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Why Because no one else seems to be able to crack the PA State Police PASTARNet/OpenSky radio system...
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Tags radio communications, Pennsylvania, OpenSky, TDMA 4-slot, USRP, GNU Radio, PASTARNet

In November, 2011, all Pennsylvania statewide agencies, most notably the Pennsylvania State Police, switched their routine day to day radio communications to an UNENCRYPTED 800 Mhz TDMA 4-slot digital radio system utilizing Harris Communications' OpenSky protocol. The system is known as PASTARNet.

Parameters for this system can be found at:

This new system effectively prevents anyone, including the media and local public safety agencies, from monitoring radio comms by State Police units. If you live anywhere in Pennsylvania, you are within radio range of at least one of these system towers. Listen for the digital buzz on frequencies 852.7875 MHz, 853.625 MHz, 853.8625 MHz and 853.925 MHz using your regular FM radio scanner receiver.

The big scanner manufacturers do not plan to market any receivers for this system, presumably due to intellectual property licensing issues. If we hack this protocol for our own educational purposes and not for commercial sale or distribution, we should be OK.

I believe that these digital transmissions can be turned into intelligible speech via one of two approaches: either by modding the C code for the Digital Speech Decoder (dsd) Linux software package (available at ) to decode TDMA 4-slot (it already does 2-slot), OR trying hacking at the signals using an Ettus Inc. USRP software defined radio and the open source GNURadio package.

If interested, you can contact me at project33 [at]