What's the detailed GPS protol used to generated GPS bin file?

Question

I encountered a problem recently.
) When we used actual GPS signals instead of simulated signals generated from the PXI-5671, the receiver functioned normally.
2) When we streamed bin file to generate signals repeatedly using the PXI-5671, the receiver could receive correctly for the first time, while at the rest of it the receiver couldn't receive the signals nor display how many satellites there were and what the signal strengths were.
The R&D engineers of the receiver in German want to know the detailed GPS protocol used to generated GPS bin file. They want to find the differences between the receiver and NI GPS generator.
Could you give me the detailed GPS protocol? thanks!

Answer 1

Hello,
In the ni GPS bin file ther header is is stored as following.
Of the first 8 bytes the first two bytes are version of GPS toolkit it was use to save the data, the next 4 bytes will be IQ rate, the next 4 bytes will be peak power in dBm and then rest 488 bytes will be just buffer data or 0 padding. Here is the screenshot of that. The actual data is stored as I16 format as I and Q data block. Hence the actual offset from the starting of the file is 512 bytes. 
Hope this helps. For reference you can look at the  niGPS Streaming From File.vi located in C:\Program Files\National Instruments\LabVIEW 2009\examples\RF Toolkits\GPS\Programming
Thanks
NI-khil 
Message Edited by NIyer on 05-14-2010 12:40 PM