Re: Re: ??: code tracking

Actually the position fix is not affected by this.  It simply appears
to be an additional clock bias.

Cliff
----- Original Message ----- 
From: "tebinuma" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Tuesday, May 25, 2004 5:57 AM
Subject: [OpenSource_GPS] Re: ??: code tracking


> Yes, you are right. However, the receiver can still
> give you accurate position solutions with 1/4 chip
> offset in time estimates. As far as it stationary
> or moving slowly, it doesn't really cause any problem.
> 
> Tak
> 
> --- [email protected] wrote:
> > 
> >     Thank you,Cliff,
> >               
> >              I'd like to continue the question:
> >               Since  The prompt arm looks like a
> > late arm thus the  loop will lock 1/4 chip early of
> > the "real" code phase
> >               then when we calculate transmit time
> > from code phase,we should subtract 1/4 chip from the
> > code phase we get from GP2021.
> >                Right?
> > 
> > 
> >    Zhu Di 
> > 
> > 
> > -----????-----
> > ???: Clifford Kelley [mailto:[email protected]]
> > ????: 2004?5?21? 12:40
> > ???: Di Zhu (Beijing); [email protected]
> > ??: Re: code tracking
> > 
> > 
> > Dear Zhu Di,
> > 
> > You will notice in chan_allocate() and in
> > cold_allocate()
> > this statement:
> > 
> >       ch_cntl(ch,prn_code[prnn]|0xa000);
> > 
> > 
> > 0xa000 sets the high order bits as    15  14  13  12
> >  11  10
> >                                                     
> >    1    0    1    0
> > 0    0
> > 
> > bit 15 sets it for GPS
> > bits 14 & 13 set the track select to late code
> > bit 12 sets the update mode
> > bit 11 sets the code to on
> > bit 10 sets the source as sign0 and mag0
> > 
> > So the difference between prompt and late, not
> > dithering.
> > 
> > 
> > I hope this helps,
> > 
> > Cliff
> > 
> > ----- Original Message ----- 
> > From: <[email protected]>
> > To: <[email protected]>; <[email protected]>
> > Sent: Thursday, May 20, 2004 9:00 PM
> > Subject: ??: code tracking
> > 
> > 
> > 
> >       Hi,Tek and Cliff:
> > 
> >            sorry,I still cann't understand why
> > that's a early-minuts-late
> > discriminator
> > 
> >            I understand it in this way :
> >            the tracking arm is set to dithering
> > mode, It will output
> > accumulated data as : 1/2 chip early correlation,1/2
> > chip late
> > correlation,1/2 chip early corrlation,.....and son
> > on
> >           the prompt arm will output accumulated
> > data: prompt
> > corrlation,prompt correlation,prompt
> > correlation....and so on.
> >          Then,we use "dreq=
> > trk_code_k*(prompt_mag-dith_mag)"
> >           we get
> > dfreq=trk_code_k*(rss(prompt,prompt,prompt...
> > )-rss(early
> > +late+early+late,... ) );
> >           so, I cann't see it's means
> > early-minus-late.
> > 
> >           pls give me a help!
> >           Thanks!
> > 
> >         Zhu Di
> > 
> > 
> 
> 
> 
> 
> 
> __________________________________
> Do you Yahoo!?
> Friends.  Fun.  Try the all-new Yahoo! Messenger.
> http://messenger.yahoo.com/ 
> 
> _______________________________________________
> opensource_gps mailing list
> [email protected]
> http://lists.psas.pdx.edu/cgi-bin/mailman/listinfo/opensource_gps
>