Venus modules

And AGPS should be directly available but it will take some time to decode (anyone want to help? hint hint).

The Eph.dat can be obtained from (.netrc):


login skytraq

password skytraq

macdef init




cd ephemeris

get Eph.dat

Or the equivalent ftp:// url


Note ftp://skytraq:skytraq@ shows the directory with other files.

To the GPS, each ephemeris record is 86 bytes (see data sheet), and this file has many sets of 86 byte records. The early fields have satellite number and some kind of time or place value, and the groups are in sequence of satellite number for a given time/place. You will get nearby time values somewhere if you save the ephemeris for the satellites using the utility.

Other files there are for individual satellites at various times, or Eph_4.dat which seems to be a “ready to upload to the chip” file.

“od -tx1 -w86” shows the pattern on a widescreen.

So to convert a cold start (taking 5 minutes with limited signal, or 1-2 minutes even open sky) to a warm/hot start, it might just be uploading the right set of records or copying Eph_4.dat out the serial port to the GPS.

I will probably try to experiment, but others might also want to try.