Questions about gps time reception

For details about how to accept the GPS time-Linux general technology-Linux technology and application information, see the following. The problem is that in linux (version is ubuntu10), the ntp server can synchronize the Network Time, but cannot synchronize the gps time. Add the following in make meunconfig:
Kernel timer client (Testing client, use for debug)
PPS line discipline
{MB} 8250/16550 and compatible serial support
New kernel compilation takes effect


My ntp. conf settings are as follows:
Server 127.127.20.1 mode 8 prefer # nmea gpzda format
Fudge 127.127.20.1 time2 0.090 # NMEA offset
Server 127.127.22.0 minpoll 4 maxpoll 4 # pps atom driver
Fudge 127.127.22.0 flag3 1 flag2 1
Driftfile/etc/ntp. drift

No GPS data is received. I don't know why?
Can receive the normal pulse 1pps.

My attachments are being uploaded.


Who knows how to help? Thank you very much. Thank you. Thank you ........