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An Accessible Project 25 Receiver Using Low-Cost Software Defined Radio

Koch, Mick V.

Abstract Details

2016, Master of Science (MS), Ohio University, Electrical Engineering & Computer Science (Engineering and Technology).
Project 25 (P25) radio, now used by at least 33% of public safety agencies in the US, is accessible to only specialized, digital receivers. These receivers, though, are expensive consumer products – starting at $400. As public safety communications remain legal to receive in unencrypted digital form, the current migration to digital radio has simply made these communications less accessible to the public. What’s missing from the current ecosystem is a sub-$100 P25 receiver with usability similar to a traditional device – automatic, hands-free operation in a portable package – that makes these communications accessible again with a more affordable price. The result of this research is a device meeting these requirements, made from a $20 RTL-SDR software defined radio, a Raspberry Pi, and a software P25 receiver pipeline. This implementation was evaluated as follows: baseband symbol decoding and frame synchronization accuracies were measured over 4 million random symbols in the presence of varying levels of noise and distortion, and overall performance was compared to a commercial P25 receiver by measuring voice frame muting errors. This evaluation found the baseband symbol decoder had over 89% accuracy down to a 3:1 SNR, and the frame synchronizer had fewer than 0.0001% false positive and false negative errors at 0.001:1 SNR. Compared to the commercial receiver, the de-signed receiver recovered over 95% of voice frames without muting errors. These findings show that recent advances in low-cost software defined radio allow the device to satisfy the above requirements with suitable real-world performance.
Shawn Ostermann (Advisor)
136 p.

Recommended Citations

Citations

  • Koch, M. V. (2016). An Accessible Project 25 Receiver Using Low-Cost Software Defined Radio [Master's thesis, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1464007525

    APA Style (7th edition)

  • Koch, Mick. An Accessible Project 25 Receiver Using Low-Cost Software Defined Radio. 2016. Ohio University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1464007525.

    MLA Style (8th edition)

  • Koch, Mick. "An Accessible Project 25 Receiver Using Low-Cost Software Defined Radio." Master's thesis, Ohio University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1464007525

    Chicago Manual of Style (17th edition)