tag:blogger.com,1999:blog-4559002410879446409.post2187678858841865334..comments2024-03-28T16:12:40.861+01:00Comments on Electrospaces.net: President Reagan using a STU-II telephoneP/Khttp://www.blogger.com/profile/12681178058475882593noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-4559002410879446409.post-38177061381083490662014-04-08T20:13:52.917+02:002014-04-08T20:13:52.917+02:00Thank you very much for these interesting addition...Thank you very much for these interesting additions!P/Khttps://www.blogger.com/profile/12681178058475882593noreply@blogger.comtag:blogger.com,1999:blog-4559002410879446409.post-37148901443255451802014-04-08T04:44:10.514+02:002014-04-08T04:44:10.514+02:00I meant to say that the military applied digital e...I meant to say that the military applied digital encryption to digitized voice.<br /><br />The STU-II was designed before there were one-chip signal processors (that contained one-step multipliers). John Mick (of AMD) and I designed the first one-chip 16x16 multiplier (the Am2516). The STU-III was smaller because it was designed after one-chip signal processors became available.JChttps://www.blogger.com/profile/12753309808254573131noreply@blogger.comtag:blogger.com,1999:blog-4559002410879446409.post-78372592084756695102014-04-08T03:56:13.618+02:002014-04-08T03:56:13.618+02:00Your description of the wall-mounted component of ...Your description of the wall-mounted component of the STU-II is somewhat inaccurate. It was more than an crypto unit, but also included voice codec and modem functions.<br /><br />I was the chief designer of the Quintrel processor that implemented in software the codec and modem and 1/3 of the crypto. (The crypto consists of two encryptors and one decryptor.)<br /><br />Historically, scrambling of analog voice was attempted, but could not be as secure as digital encryption. For years, the military applied digital encryption, but at 64,000 bits/sec. That was too high a rate for the civilian phone network.<br /><br />The development of algorithms for encoding voice signals at rates such as 2400 bits/sec made it possible to achieve secure voice connections on the civilian phone network.JChttps://www.blogger.com/profile/12753309808254573131noreply@blogger.com