[time-nuts] GPS-SDR-SIM

[jimlux]

On 3/30/19 10:42 AM, Tim Lister wrote:
> On Sat, Mar 30, 2019 at 9:01 AM jimlux <jimlux at earthlink.net> wrote:
>>
>> On 3/27/19 11:49 AM, coderman via time-nuts wrote:
>>
>> Compiled the software, but...
>>
>>> he user specifies the GPS satellite constellation through a GPS broadcast ephemeris file. The daily GPS broadcast ephemeris file (brdc) is a merge of the individual site navigation files into one. The archive for the daily file is:
>>>
>>> ftp://cddis.gsfc.nasa.gov/gnss/data/daily/
>>
>> There's a ton of files under that.. broken down by year/day of year/ and
>> then some subdirectories with dozens of files, that appear to be RINEX
>> (the names are things like
>>
>> ftp://cddis.gsfc.nasa.gov/gnss/data/daily/2019/088/19f/USN700USA_R_20190880000_01D_CN.rnx.gz
>>
>> A casual browse did not find the brdc.
>>
> 
> Yes the CDDIS holdings are not easy to find things in... The
> organization from the data/daily/ is 4 digit year (e.g. '2019'), 3
> digit day of the year. Then it's 2 digit truncated year, followed by
> 'n' (for 'n'avigation) e.g. '19n'. The brdc file is in there, and as
> you say, is in RINEX format. The individual observations made by the
> GNSS receiving sites live in the '19o' directories with a 4 letter
> site code name.



Aha, I think I found it..

ftp://cddis.gsfc.nasa.gov/gnss/data/daily/2019/088/19n/
(for DOY 88)

There's a file called bdrc0880.19n.Z which unzips to bdrc0880.19n

it is buried in amongst all the station files.

And I assume that's what gets put in with the -e switch..



It starts:
"""
      2              NAVIGATION DATA                         RINEX 
VERSION / TYPE
CCRINEXN V1.6.0 UX  CDDIS               30-MAR-19 12:31     PGM / RUN BY 
/ DATE
IGS BROADCAST EPHEMERIS FILE                                COMMENT 

     0.1118D-07  0.7451D-08 -0.5960D-07 -0.5960D-07          ION ALPHA 

     0.9011D+05  0.1638D+05 -0.1966D+06 -0.6554D+05          ION BETA 

     0.745058059692D-08 0.159872115546D-13    61440     2047 DELTA-UTC: 
A0,A1,T,W
     18                                                      LEAP 
SECONDS
                                                             END OF 
HEADER
"""