[LinuxPPS] PPS probelm

[Simchaev Arthur-BAS071]

Hi .
Could you please help me with the following problem ?
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 .
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 )
Our configuration is following :
Ntp configuration (ntpd 4.2.6p5) :
server 127.127.1.0 #lo server
fudge 127.127.1.0 stratum 7

restrict 127.127.1.0 noquery nomodify notrap
server 127.127.20.0 minpoll 4 maxpoll 4 iburst #NMEA Server
server 127.127.22.0 prefer
fudge 127.127.22.0 flag3 1 refid PPS

ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*LOCAL(0)        .LOCL.           7 l    5   64  377    0.000    0.000   0.031
xGPS_NMEA(0)     .GPS.            0 l    4   16  377    0.000  -63.203   5.256
xPPS(0)          .PPS.            0 l    3   64  377    0.000  -347.47   7.428
root at am335x-evm:/dev# ntpdc
ntpdc> kerninfo
pll offset:           0 s
pll frequency:        0.000 ppm
maximum error:        0.013456 s
estimated error:      1e-05 s
status:               2007  pll ppsfreq ppstime nano
pll time constant:    6
precision:            1e-09 s
frequency tolerance:  500 ppm


root at am335x-evm:/dev# ntptime
ntp_gettime() returns code 0 (OK)
  time d6dd71e6.aaf4cf0c  Wed, Mar 26 2014 15:33:58.667, (.667798707),
  maximum error 23956 us, estimated error 10 us, TAI offset 0
ntp_adjtime() returns code 0 (OK)
  modes 0x0 (),
  offset 0.000 us, frequency 0.000 ppm, interval 1 s,
  maximum error 23956 us, estimated error 10 us,
  status 0x2007 (PLL,PPSFREQ,PPSTIME,NANO),
  time constant 6, precision 0.001 us, tolerance 500 ppm,

Regards
Arthur
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