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--></style></head><body lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Thanks!</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Cosine of 10 degrees is 98.5% so that is very little error. That means only about 1 MPH difference at 60 MPH…</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Thanks</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d">Bob</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1f497d"> </span></p><div><div style="border:none;border-top:solid #e1e1e1 1.0pt;padding:3.0pt 0in 0in 0in"><p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Rusty Bryant <<a href="mailto:rustyb78@yahoo.com">rustyb78@yahoo.com</a>> <br><b>Sent:</b> Tuesday, June 9, 2020 11:15 AM<br><b>To:</b> aprssig <<a href="mailto:aprssig@lists.tapr.org">aprssig@lists.tapr.org</a>>; Robert Bruninga <<a href="mailto:bruninga@usna.edu">bruninga@usna.edu</a>><br><b>Cc:</b> <a href="mailto:wb4apr@aprs.org">wb4apr@aprs.org</a><br><b>Subject:</b> Re: [aprssig] APRS speed and Cosine Rule?</span></p></div></div><p class="MsoNormal"> </p><div><div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif">Bob,<br><br>If you want me to keep you safe I'll say YES, but the reality is, most radar units in police cars do not use a cosine rule.<br><br>Part of our training is that we should keep a 10 degree or less angle between our unit and the target. <br><br>But, any increase in angle will only benefit the suspect. If they are going 30 mph over the speed limit and our radar indicates that you are only going 20mph over the limit, then you just got away with the 10mpg delta.<br><br>Just remember this, when you double your speed, you quadruple the impact force if you crash. <br><br>Speed Kills!<br><br>Rusty<br>WB4BSD</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif"> </span></p></div></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif"> </span></p></div></div><div id="ydp2a87c1ecyahoo_quoted_2114946630"><div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">On Monday, June 8, 2020, 4:07:49 PM EDT, Robert Bruninga <<a href="mailto:bruninga@usna.edu">bruninga@usna.edu</a>> wrote: </span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"> </span></p></div><div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">APRS speed related?</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">Have cop radars implemented the Cosine rule? IE, it should be possible to</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">include a magnetic compass in a handheld radar gun and to initialize it in</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">the direction perpendicular to the road with just a button push...</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">Then the gun can display the actual speed using the cosine rule as the cop</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">sweeps to keep up with your car, (or statically when the cop is at an</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">angle to the line of approach) and not just the relative speed (which</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">approaches zero) as the car goes past the perpendicular point.</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">Curious as to whether I need to consider this when speeding past a</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">radar...</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">Bob, WB4APR</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"> </span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">_______________________________________________</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a">aprssig mailing list</span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"><a href="mailto:aprssig@lists.tapr.org" target="_blank">aprssig@lists.tapr.org</a></span></p></div><div><p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Helvetica",sans-serif;color:#26282a"><a href="http://lists.tapr.org/mailman/listinfo/aprssig_lists.tapr.org" target="_blank">http://lists.tapr.org/mailman/listinfo/aprssig_lists.tapr.org</a></span></p></div></div></div></div></div></body></html>