nanog mailing list archives
Re: anyone running GPS clocks in Southeastern Georgia?
From: Cutler James R <james.cutler () consultant com>
Date: Fri, 21 Jan 2011 16:52:32 -0500
On Jan 21, 2011, at 4:23 PM, Michael Holstein wrote:
I'd be curious to see what effects (if any) those who use GPS-disciplined NTP references in Southeastern Georgia see from this experiment.Aren't CDMA BTS clocked off GPS? NTP isn't going to be the only "ripple". Regards, Michael Holstein Cleveland State University
Possibly relevant section from Agilent Designing and Testing 3GPP W-CDMA Base Transceiver Stations (Including Femtocells) Application Note 1355 1.15 Asynchronous cell site acquisition One of the W-CDMA design goals was to remove the requirement for GPS synchronization. Without dependence on GPS, the system could potentially be deployed in locations where GPS is not readily available, such as in a basement of a building or in temporary locations. W-CDMA accomplishes this asynchronous cell site operation through the use of several techniques. First, the scrambling codes in W-CDMA are Gold codes, so precise cell site time synchronization is not required. There are, however, 512 unique Gold codes allocated for cell site separation that the UE must search through. To facilitate this task, the SSC in the S-SCH channel is used to instruct the UE to search through a given set of 64 Gold codes. Each set represents a group of eight scrambling codes (64 x 8 = 512). The UE then tries each of the eight codes within each code group, in an attempt to decode the BCH. The ability to recover the BCH information (system frame number) completes the synchronization process. James R. Cutler james.cutler () consultant com
Current thread:
- Re: anyone running GPS clocks in Southeastern Georgia?, (continued)
- Re: anyone running GPS clocks in Southeastern Georgia? Matthew Kaufman (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Gary E. Miller (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Owen DeLong (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Brandon Ross (Jan 22)
- Re: anyone running GPS clocks in Southeastern Georgia? Gary E. Miller (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Michael Holstein (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Gary Buhrmaster (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Cutler James R (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Robert E. Seastrom (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Owen DeLong (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Jay Ashworth (Jan 23)
- Re: anyone running GPS clocks in Southeastern Georgia? Cutler James R (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Robert E. Seastrom (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? James Brown (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Anton Kapela (Jan 23)
- Re: anyone running GPS clocks in Southeastern Georgia? Joel Jaeggli (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Robert E. Seastrom (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Peter Lothberg (Jan 22)
- Re: anyone running GPS clocks in Southeastern Georgia? Gary Buhrmaster (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Matthew Kaufman (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Lamar Owen (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Pete Carah (Jan 21)
- Re: anyone running GPS clocks in Southeastern Georgia? Cameron Byrne (Jan 23)