From: Thomas T. <tt...@vt...> - 2011-08-01 22:08:06
|
On Mon, Aug 1, 2011 at 11:42 AM, nghia phan <ngh...@gm...> wrote: > Hello > > Does anyone have a good description of the path taken (packetisation, size, > timing, additional control info) by a ready-to-transmit burst (full encoded > and interleaved BUT before being modulated into IQ waveform) from the gsm > core to transceiver module via UDP socket, to USRP via USB packet. Then > within USRP from Cypress to FPGA or AD9862? There isn't much documentation on the OpenBTS specific paths, but different parts of the USRP have been written about by a couple of people. For example, "The USRP under 1.5X Magnifying Lens!" by Firas Abbas Hamza. http://gnuradio.org/redmine/attachments/129/USRP_Documentation.pdf > In which module is the burst modulated into IQ? The GMSK modulator outputs I and Q. > In which module the intended transmission timestamp of a burst is checked > against actual time in order to decide whether the burst should be sent or > not? Or > At which stage is a burst confirmed for actual transmission? See Transceiver::pushRadioVector() for timing at the GSM burst level. Sample level timing is checked in the FPGA. Thomas |