title: NTPD Pseudo Servers
body: <p>Good evening!</p>
  
  <p>I'm configuring NTP on an embedded Linux system connected with an U-Blox GPS receiver. I've used NTPD and GPSD.</p>
  
  <p>I would like to know what's the technical difference between:</p>
  
  <ul>
  <li>PPS Signal provided by the GPSD shared memory SHM, (Pseudo IP Address 127.127.28.1);</li>
  <li>PPS Signal "Stand Alone", but always connected in some way I would like to understand, with GPS (Pseudo IP Address 127.127.22.0)</li>
  </ul>
  
  <p>It is critical for me to understand because I really need an high level synchronization and I would like the right information from the receiver.
  Searching all over the web I've found only confused answers to my doubt...</p>
  
  <p>Thanks in advance! </p>
  
  <p>FL</p>