The SETI Institute's Allen Telescope Array (ATA) is a radio interferometer composed of forty-two dishes, each 6.1m in diameter. Its main science goal is to perform searches for technosignatures, which appear as narrowband signals 'drifting' in frequency. My project seeks to further the ATA's capability of performing technosignature searches through the implementation of a GNU Radio data processing pipeline. The pipeline streams radio telescope data from the ATA through a USRP source, then 'channelises' the data using a polyphase filterbank followed by a Fast Fourier Transform. The resulting high-spectral resolution product is lastly analysed with an adapted version of turboSETI software to identify potential technosignatures. As a free open-source software for developing signal-processing routines already in use by a large community of amateur radio astronomers, GNU Radio is well-suited to expanding the scope of the project beyond the ATA. This will make the search for extraterrestrial intelligence more accessible to smaller radio observatories and citizen scientists.