RTL-SDR: Decoding P25 Phase I QPSK with DSD and SDR#

In this video, I'm using an RTL2832U based TV Tuner dongle with the RTL-SDR open source communications blockset to get an SDR view of the Dauphin County Public Safety P25 digital radio communications system. Since this system is trunked, I have to do a lot of frequency hopping to go to the right channels. Hopefully in the future, the OP25 project will implement an operational trunking receiver for RTL-SDR so that the software can automatically hop to the right frequencies. In this video, I'm using SDR# to demodulate the raw I/Q data from the dongle. To decode properly, I've found that using Narrowband FM with a filter of about 12.5KHz is sufficient. Since the demodulated audio is still a raw digital P25 baseband signal, I need to feed the signal into a decoder. To do this, I pipe the demodulated baseband digital signal from SDR# into a Virtual Audio Cable. The audio from SDR# is passed to the DSD P25 decoder through this VAC. The DSD does the final bit of work by doing the final demodulation of the baseband signal and modulates the digital audio into an analog audio signal. I'm hopeful that trunking support will come shortly so that free open source software and a cheap $30 RF front end can do the same thing as a $300 digital trunking scanner handheld. EDIT: There's a band aid method out there to enable P25 trunking. Here's a link to a video demo of Unitracker and SDR Sharp http://www.youtube.com/watch?v=J3vaA1GKD1U&feature=related EDIT 2: Here's a link to DSD: http://goo.gl/PncNSm