레이다 관련 소스
https://github.com/zefir-kurtisi/USRP-Radar-Relay
Radio Transport Protocols
http://files.ettus.com/manual/page_rtp.html
GnuRadio
http://jmson.tistory.com/6
http://jhha85.tistory.com/2
https://ko.wikipedia.org/wiki/GNU_%EB%9D%BC%EB%94%94%EC%98%A4
http://sourceforge.net/projects/libusb-win32/
The customized USRP-1
Our FPGA build and host-side code has the following features:
USB packets
There are 256 16-bit words in each USB packet. The upper 4 bits (or eventually upper 2 bits, for the 14-bit USRP model) are used to hold up to 1024 (or up to 512 for the 14-bit USRP model) bits of metadata - see below.
반드시 확인해봐야할 USR Packet 데이타 헤더
gnuradio/usrp/host/include/usrp_bbprx.h
- the metadata use up 448 of the 1024 metadata bits, leaving room for additional metadata such as inclinometer readings or weather station data
- no attempt has been made to optimize the size of counters (we don't really need 32-bits to count heading pulses!), but this can be done to make more room for other metadata
- the apparently overlapping meanings of these fields allow us enough information to very precisely estimate the azimuth angle for each digitized pulse
- so far, I haven't incorporated Dave's "window" scheme for determining whether the azimuth has returned to heading based on the heading line, or whether the ACP count should be used
- the USB packet serial numbers allow us to detect various buffer overruns, and to throw away data from incomplete pulses
- only the first USB packet for each pulse contains the radar metdata; these metadata (except for the USB serial no) are zero in the subsequent packets for a given pulse. This lets us determine which packets are the first packet of a pulse by checking whether the clock_ticks field is non-zero.
- we keep track of the true radar PRF independently of how we are digitizing, by counting trigger pulses. For example, even if the listen period is longer than the inter-pulse interval, so that we are dropping pulses, we can detect this by looking at the n_trigs field. It is guaranteed not to miss valid pulses because this counter is updated independently of any video digitizing or USB data transfers
http://www.trondeau.com/grcon15-agenda
