Q15X25 is a 15 tone packet mode with a Kiss/AX25 interface, and from its performance, should long ago have replaced conventional packet for HF use! Q15X25 is now available for Motorola EVM, LINUX PC and Windows PC sound card operation.
Q15X25 is a DSP intensive mode that operates the like a TNC and modem, to provide an ARQ mode designed for AX.25 and TCP/IP on HF with speed and reliability much greater than traditional HF ARQ modems (such as 300 baud packet). It uses 15 QPSK modulated carriers separated by 125 Hertz, each modulated at 83.333 baud. Q15X25 uses FEC (Forward Error Correction), and like MT63, uses time and the frequency interleaving in order to avoid most error sources. The raw transmission data rate is typically 2500 bps.
The source of the EVM software is on the TAPR site.
Hot news - MIXW Version 2.07 will include Q15X25, in a well organized implementation which allows single station connects, very easy setup, excellent performance, and much easier tuning than other versions (it has a good waterfall display). At present there are no higher layers, but dedicated applications are being considered (bulletin boards, gateways, message handling systems?) as separate products. Numerous stations are currently testing the MIXW version. It has not yet been released. Keep an eye on the MIXW Web Site for an announcement.
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