<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="Generator" content="Microsoft Word 12 (filtered medium)">
<style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri","sans-serif";
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.25in 1.0in 1.25in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang="EN-US" link="blue" vlink="purple">
<div class="WordSection1">
<p class="MsoNormal">Hi .<o:p></o:p></p>
<p class="MsoNormal">Could you please help me with the following problem ?<o:p></o:p></p>
<p class="MsoNormal">Our board supports PPS & NTP . I connect & define the Garmin GPS(GPS16x-HVS) as the NMEA reference clock . Unfortunately when I add the atom reference clock to ntp in order to receive pps , after sometime NMEA & ATOM(pps) clocks marked
as falsetick servers . I see that it can related to the jitter and can be fixed by setserial low_latency . But out UART doesn’t support this flag .
<o:p></o:p></p>
<p class="MsoNormal">Therefore could you please explain how I can fix servers falsetick problem witout use setserial . Maybe the problem related to number of the servers (I use only only 2 stratum 0 servers which take the data from the same GPS device )
<o:p></o:p></p>
<p class="MsoNormal">Our configuration is following :<o:p></o:p></p>
<p class="MsoNormal">Ntp configuration (ntpd 4.2.6p5) :<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">server 127.127.1.0 #lo server<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">fudge 127.127.1.0 stratum 7<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">restrict 127.127.1.0 noquery nomodify notrap<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">server 127.127.20.0 minpoll 4 maxpoll 4 iburst #NMEA Server <o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">server 127.127.22.0 prefer <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">fudge 127.127.22.0 flag3 1 refid PPS<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal">ntpq -p<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> remote refid st t when poll reach delay offset jitter<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">==============================================================================<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">*LOCAL(0) .LOCL. 7 l 5 64 377 0.000 0.000 0.031<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">xGPS_NMEA(0) .GPS. 0 l 4 16 377 0.000 -63.203 5.256<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">xPPS(0) .PPS. 0 l 3 64 377 0.000 -347.47 7.428<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">root@am335x-evm:/dev# ntpdc<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">ntpdc> kerninfo<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">pll offset: 0 s<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">pll frequency: 0.000 ppm<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">maximum error: 0.013456 s<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">estimated error: 1e-05 s<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">status: 2007 pll ppsfreq ppstime nano<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">pll time constant: 6<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">precision: 1e-09 s<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">frequency tolerance: 500 ppm <o:p>
</o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal">root@am335x-evm:/dev# ntptime<o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">ntp_gettime() returns code 0 (OK)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> time d6dd71e6.aaf4cf0c Wed, Mar 26 2014 15:33:58.667, (.667798707),<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> maximum error 23956 us, estimated error 10 us, TAI offset 0<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">ntp_adjtime() returns code 0 (OK)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> modes 0x0 (),<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> offset 0.000 us, frequency 0.000 ppm, interval 1 s,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> maximum error 23956 us, estimated error 10 us,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> status 0x2007 (PLL,PPSFREQ,PPSTIME,NANO),<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"> time constant 6, precision 0.001 us, tolerance 500 ppm,<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards<o:p></o:p></p>
<p class="MsoNormal">Arthur<o:p></o:p></p>
</div>
</body>
</html>