[ntp:questions] precision server

[nikolay at rootshells.eu]

Hello folks,
how to check,understand and compare how accurate/precise is this old ntp 
server.Output info is this:

root at sv1:/var/log# ntptime
ntp_gettime() returns code 0 (OK)
   time da4100d5.1b210be8  Wed, Jan 13 2016 18:59:01.105, (.105973695),
   maximum error 3000 us, estimated error 0 us
ntp_adjtime() returns code 0 (OK)
   modes 0x0 (),
   offset 1.291 us, frequency 45.645 ppm, interval 1 s,
   maximum error 3000 us, estimated error 0 us,
   status 0x2001 (PLL,NANO),
   time constant 4, precision 0.001 us, tolerance 500 ppm,

root at sv1:/var/log# ntpq -crv
associd=0 status=0418 leap_none, sync_uhf_radio, 1 event, no_sys_peer,
version="ntpd 4.2.8p5 at 1.3265 Tue Jan 12 16:13:38 UTC 2016 (1)",
processor="x86_64", system="Linux/2.6.32-18-pve", leap=00, stratum=1,
precision=-21, rootdelay=0.000, rootdisp=1.180, refid=GPSs,
reftime=da4100d1.4f5520bb  Wed, Jan 13 2016 18:58:57.309,
clock=da4100de.1ff106f3  Wed, Jan 13 2016 18:59:10.124, peer=18055, 
tc=4,
mintc=3, offset=0.001375, frequency=45.645, sys_jitter=0.000477,
clk_jitter=0.000, clk_wander=0.000, tai=36, leapsec=201507010000,

root at sv1:/var/log# ntpq -p
      remote           refid      st t when poll reach   delay   offset  
jitter
==============================================================================
*SHM(0)          .GPSs.           0 l    6   16  377    0.000   -0.001   
0.000

Regards,
Nikolay Stoyanov