Re: [Discuss-gnuradio] OFDM modulator and pilots
Tom After reading gr_ofdm_insert_preamble.cc it looks like the pilots are sent periodically after every few payload symbols on all frequency bins. Is it like what I have shown attached ? If yes, then how may payload symbols are sent between two pilots ? Another related question is: Who sets the parameters for the work function in this block ? particularly noutput_samples. Srinivas WINLAB, Rutgers University, NJ On Thu, Aug 26, 2010 at 11:58 AM, Tom Rondeau trondeau1...@gmail.comwrote: On Tue, Aug 10, 2010 at 9:53 AM, Marcin Szelest marcin.szel...@gmail.com wrote: Hello, I'm trying to add pilots to an OFDM modulation, is it possible with OFDM_mod block? How I can boost energy of pilot in OFDM signal? Regards, Marcin http://szelest.org Yes, this is possible. There is a subcarrier mask concept in the modulator and demodulator block that you should be able to use. Right now, it specifies if a carrier is in use or not (e.g., data or nothing). There are some hooks in there to add pilot tones pretty easily to the modulator. Actually using them in the demodulator is where you'll have to focus most of your attention. Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- Srinivas attachment: PilotTones.jpg___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] OFDM modulator and pilots
On Fri, Aug 27, 2010 at 12:19:53PM -0400, Srinivas wrote: Another related question is: Who sets the parameters for the work function in this block ? particularly noutput_samples. Srinivas, The parameters passed to work are determined by the GR runtime system. Their values depend on a lot of things, including free space in the upstream and downstream buffers, the return values from forecast; various settings such as history and output_multiple. Eric ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] OFDM modulator and pilots
On Fri, Aug 27, 2010 at 12:19 PM, Srinivas srini...@winlab.rutgers.edu wrote: Tom After reading gr_ofdm_insert_preamble.cc it looks like the pilots are sent periodically after every few payload symbols on all frequency bins. Is it like what I have shown attached ? If yes, then how may payload symbols are sent between two pilots ? Another related question is: Who sets the parameters for the work function in this block ? particularly noutput_samples. Srinivas WINLAB, Rutgers University, NJ No, that's a slight mistake in terminology. What you are pointing out are the preamble symbols that are used to set the initial synchronization (phase, timing, and frequency). I thought you were asking about pilots, which are specific subcarriers sent along in a payload symbol that contain known data and are used for channel estimation (equalizer settings) throughout a packet transmission. In other words, the sync preambles are used to get the initial channel estimation and pilots can be used to track channels that change between preambles. If you were talking about preambles, you should be able to use insert_preambles, which takes a list of symbols so you can use as many as you'd like. If you want to use pilots, you have to work with the gr_ofdm_mapper_bcv and gr_ofdm_frame_acquisition to make use of the subcarrier map. Hope that clears it up. Tom On Thu, Aug 26, 2010 at 11:58 AM, Tom Rondeau trondeau1...@gmail.com wrote: On Tue, Aug 10, 2010 at 9:53 AM, Marcin Szelest marcin.szel...@gmail.com wrote: Hello, I'm trying to add pilots to an OFDM modulation, is it possible with OFDM_mod block? How I can boost energy of pilot in OFDM signal? Regards, Marcin http://szelest.org Yes, this is possible. There is a subcarrier mask concept in the modulator and demodulator block that you should be able to use. Right now, it specifies if a carrier is in use or not (e.g., data or nothing). There are some hooks in there to add pilot tones pretty easily to the modulator. Actually using them in the demodulator is where you'll have to focus most of your attention. Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio -- Srinivas ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] OFDM modulator and pilots
On Tue, Aug 10, 2010 at 9:53 AM, Marcin Szelest marcin.szel...@gmail.com wrote: Hello, I'm trying to add pilots to an OFDM modulation, is it possible with OFDM_mod block? How I can boost energy of pilot in OFDM signal? Regards, Marcin http://szelest.org Yes, this is possible. There is a subcarrier mask concept in the modulator and demodulator block that you should be able to use. Right now, it specifies if a carrier is in use or not (e.g., data or nothing). There are some hooks in there to add pilot tones pretty easily to the modulator. Actually using them in the demodulator is where you'll have to focus most of your attention. Tom ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] OFDM modulator and pilots
Hello, I'm trying to add pilots to an OFDM modulation, is it possible with OFDM_mod block? How I can boost energy of pilot in OFDM signal? Regards, Marcin http://szelest.org ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
