[time-nuts] GPS USB dongle for time server

[jim s]

This is probably the thousandth time this was asked, but I googled and 
didn't get a direct answer.

I want to do a crude (as in to the second or so) time server inhouse to 
add into a group of high accuracy servers.  This is so that I can go off 
grid and still get updates.

I see that there is a way to get a feed called PPS or with PPS via 
RS232.  The discussions of using USB instead are concerned with having 
too much jitter.

since USB by its nature won't have an accurate exact dedicated line to 
let the GPS toggle to do a time hack to the software, I can see why 
RS232 is preferable with the hardware signal lines they have.

If I just go with the NEMA stream as it gets to me via an USB HID Com 
port, I assume that there will be some jitter baring a way to send in 
the physical time hack.

Any pointers to reading or comment on this would be appreciated.  I am 
probably asking the query before I should, as far as research, and 
appreciate any replies.

Jim