Wang: Sounds good! Thanks! Did you try it?
Jean: many many thanks for sharing all the scripts! Your paper has caught my attention. I will print it and read it.
Marcus: I was not expecting to "see" the signal because I already knew it was under noise floor. My conclusion of "signal absence" was after my GPS receiver was not able to decode it when I replayed it with an USRP. However, due to my little knowledge of GPS, it did not occur to me any other way of searching, so I thank you for your suggestion. I nearly killed my pc with a naive approach. :P I need a wiser one.
Sylvain: interesting. I will try that too. Thanks!