[LinuxPPS] NTPD and the ATOM patch

[Alberto Cabellos]

Dear all,

This is Albert Cabellos from Technical University of Catalonia
(http://www.upc.edu). I have an Accutime 2000 GPS starter kit and I would
like to connect the PPS signal to a linux box. I am using Ubuntu Daper in a
Dell Laptop. 
I have compiled your kernel 2.6.20 and all the userland utilities. 

They are working correctly:

root at UPC:~/user# ./ppstest 
found PPS source #0 "serial0" on "/dev/ttyS0"
ok, found 1 source(s), now start fetching data...
source 0 - assert 1178212818.999670834, sequence: 1743 - clear  0.000000000,
sequence: 0
source 0 - assert 1178212819.999670820, sequence: 1744 - clear  0.000000000,
sequence: 0

I have compiled ntp-4.2.2p4 patched with the ATOM patch. My configuration:

(...)
server 127.127.22.0        # ATOM(PPS)
fudge 127.127.22.0 flag2 1
(...)

However, I don't know if NTP is effectively reading the PPS signal:

root at UPC:/home/upc/ntp/ntp-4.2.2p4# ntpq -pin
     remote           refid      st t when poll reach   delay   offset
jitter
============================================================================
==
*192.168.0.2     .GPS.            1 u   12   64  377    0.461    0.428
1.349
+192.168.0.3     .GPS.            1 u   61   64  377    0.445    0.398
0.033
 127.127.22.0    .PPS.            0 l    -   64    0    0.000    0.000
0.002

root at UPC:/home/upc/ntp/ntp-4.2.2p4# ntptime
ntp_gettime() returns code 0 (OK)
  time c9e498db.1eaac000  Thu, May  3 2007 19:22:35.119, (.119793),
  maximum error 34724 us, estimated error 24 us
ntp_adjtime() returns code 0 (OK)
  modes 0x0 (),
  offset 395.000 us, frequency 0.224 ppm, interval 1 s,
  maximum error 34724 us, estimated error 24 us,
  status 0x1 (PLL),
  time constant 6, precision 1.000 us, tolerance 512 ppm,
root at UPC:/home/upc/ntp/ntp-4.2.2p4#

When I run ppstest I see capture messages at the kernel:

[20326.569562] pps_core: capture assert seq #1753 for source 0

But I do not see them when I just run ntpd

[20086.954052] pps_core: PPS_FETCH: source 0
[20086.954056] pps_core: start sending reply to ID 27690...
[20086.954061] pps_core: ... reply sent (180)
[20087.952575] pps_core: New message from PID 27690 (flags 0)

Is my NTPD reading the PPS signal?

Thank you in advance,

Best Regards,

Albert