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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The AX.25 and APRS protocol specifications say nothing<o:p></o:p></p><p class=MsoNormal> at all about modems.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The reason that we are using 1200 bps is because early <o:p></o:p></p><p class=MsoNormal>packet radio developers, in Canada, in the late 1970s, happened <o:p></o:p></p><p class=MsoNormal>to acquire a pile of old Bell 202 modems for 75 cents each.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The method that we use for 9600 bps was developed in<o:p></o:p></p><p class=MsoNormal>the late 1980s. It has been widely implemented but won't<o:p></o:p></p><p class=MsoNormal>work with the microphone and speaker connections because<o:p></o:p></p><p class=MsoNormal>the audio processing distorts the signal and limits the bandwidth.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>In the early 1990s, multiple TNC vendors produced products capable<o:p></o:p></p><p class=MsoNormal>of 2400 bps: MFJ-2400, AEA PK232-2400, Kantronics KPC-2400.<o:p></o:p></p><p class=MsoNormal>Maybe if other vendors had offered the same we would all be using<o:p></o:p></p><p class=MsoNormal>2400 bps today.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>With the shift from hardware modems to software modems,<o:p></o:p></p><p class=MsoNormal>the possibilities are endless. Upgrades are easy. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Two methods of Forward Error Correction are currently being used:<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>(1)<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>FX.25 which is completely interoperable with original AX.25.<o:p></o:p></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>(2)<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>IL2P which has less overhead but is not compatible.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Better alternatives are available today for those who want to use <o:p></o:p></p><p class=MsoNormal>them. The problem is trying to convince most of the installed base<o:p></o:p></p><p class=MsoNormal>to break free of a precedent set more than 40 years ago.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>73,<o:p></o:p></p><p class=MsoNormal>John WB2OSZ<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>