[Discuss-gnuradio] Howto tune RF frequency in blocks?
Hi, I wonder if it is possible to tune the RF frequency in blocks written in c++. In python, statements as the follow are used to tune the frequency of RF board. r = u.tune(0, subdev, freq) I want to adjust the receiver's RF according that of the transmitter automatically with some frequency offset estimation methods before doing communication. I guess it's better to do the adjustment in DSP blocks. Thanks! ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Question about carrier syncronization fordemodulating QPSK/BPSK signal.
Thanks for your working. I wonder if 1.28Msymbol/s (2.56Mbps for qpsk) is possible to be archieved through costas loop. I'm worry about the 32Mbyte/s of USB 2.0 interface may not be enough. I've read the code from http://aphex.media.mit.edu/wiki/tiki-index.php?page=BPSK (using costas loop) and found that 8 samples are used to build a sinusoid wave at the baseband level. Consindering complex sampling (4 bytes for one samle), the maximum symbol rate is only 1M. If filter with over sampling is employed, the data rate may be much lower. Right now, I'm thinking about using pilot seqence for doing carrier sync and symbol sync together. I hope it works, but more experiments are needed. 2006/6/2, Matt Ettus <[EMAIL PROTECTED]>: Eric Blossom wrote:>On Thu, Jun 01, 2006 at 08:54:28AM -0400, Tom Rondeau wrote:>> >> Set the>>alpha value somewhere around 0.005 - 0.05 to get started (and play with it>>from there). The beta value should be about an order of magnitude smaller>>(it's been set to 0.25*alpha^2; I'm not sure where that comes from, though).>>The next two arguments are the max and min frequency deviation in terms of>>scaled frequency, so 0.05 and -0.05 work well. The final value of the >>reference phase can just be set to 0. This block's been around for a bit of>>time and used in BPSK.>>beta = alpha^2/4 gives a critically damped loop.>> >From here, you'll need to worry about symbol synchronization. We build a>>complex modified Mueller and Muller clock recovery circuit for this called>>gr_clock_recovery_mm_cc (this file existed already, but we modified it >>some). Set mu=0.05, omega is approximately the samples per baud,>>gain_mu=0.05, gain_omega=0.25*mu^2, and omega_rel_limit=0.5. These values>>will get you started. Same way of setting beta here.Matt___Discuss-gnuradio mailing listDiscuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Question about carrier syncronization for demodulating QPSK/BPSK signal.
Hi, all The problem is HOWTO do carrier syncronization. I am using two USRP with FLEX 2400, one for Tx, the other for Rx. The RF of both Tx and Rx are tuned to 2.45GHz. I generate and transmit a QPSK signal. At the receiver, an obvious frequency deviation can be observed from the fft sink. And of course, nothing can be demodulated. (using simple correlator to deframing, no seqno outputs). So I adjust Tx RF a little bit, and I realy get some seqno from simple_correlator, but they are uncontinuous and snatchy, which means the manual freq adjustment is not so accuracy. I think the linear bidimention mouduation such as BPSK/QPSK/16QAM requires much more accurate syncronization of carrier than FSK does. There are already some discusses on the archive about BPSK demod, but I still have no idea about that. http://aphex.media.mit.edu/wiki/tiki-index.php?page=BPSK I read the code and find that the author wrote a costas loop which require sinusoid input. This scheme will produce higher speed baseband signal, which cost much USB bandwidth. I wonder if only pure IQ complex at the speed of QPSK symbol rate can do carrier sync and demodulation. Thanks! The following are the key src code of my QPSK mod/demod. qpsk_tx.py:src = "" (gr.sizeof_char, filename, options.repeat)framer = gr.simple_framer (payload_size)bytes_to_syms = gr.bytes_to_syms ()qpsk_mod = gr.float_to_complex()interp = gr.interp_fir_filter_ccf (8, interp_taps)...# usrp initself.connect (src, framer, bytes_to_syms, qpsk_mod, interp, gain, u) qpsk_rx.py:filter = gr.fir_filter_ccf (1, rx_taps) c2f = gr.complex_to_float()corr = gr.simple_correlator (payload_size)filesink = gr.file_sink (gr.sizeof_char, options.filename)self.connect (u, filter, c2f, corr, filesink) ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Questions about using sound card for data tranfer.
Hi, bodys:) I'm trying to use the sound card to transferring bits and I find it may not be as easy as using USRP. My efforts are based on the fsk_tx.py and fsk_rx.py. The audio.sink & audio.source only I/O float type data, and not like USRP, we cannot set decimation ratio or interpolation ratio for sound card. So I set this two ratio to 1 and use complex_to_float & float_to_complex connecting the sound card with modulating & demodulating blocks. But I seriously doubt if it is right in this way, and not surprising, I get nothing at the rx. To ensure the validation of the configuration of fsk mod and demod, I write another script with framing, modulation, demodulation and deframing connected in a line without sound card. It works well and the received frame seq number can be correctly printed out. Besides, I can here the sound of transmitted signal from the sound card, and the line-in input is ok. Needing some hints about doing communication with sound card. My source codes are mailed. Hanwen audio_send.py Description: application/python audio_recv.py Description: application/python check_fsk.py Description: application/python ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Problem with making sound card as source
Thanks Breett:) I've solved this problem by turn on capture item in the mixer. And I guess that's why there are many people say that there linux cannot recording sound. Hanwen2006/5/10, Brett L Trotter <[EMAIL PROTECTED]>: I had a similar problem- turned out not to be the hardware.Run alsamixer and make sure to turn on capture on your line input (withspacebar) and turn up the volume all the way, then turn on capture oncapture and turn the volume up all the way again. You should then be getting audio and adjust the volume down to reduce clipping.2 1 wrote:> Hi, Matt :)>> I do set the line-in as the record source in the mixer. But I found that> the> audio recorder app of my FC4 can't record either. I'm doubt that the sound > drive of FC4 cannot support the card well. Besides, I tried on 3 different> machines and all of them failed. They all have a intel integrated sound> card. I'm using gr-audio-alsa.0.3.tar.gz.> > Have you ever met this problem before? And do you know how to make the> sound> card well supported under linux?>> Thanks a lot.>> Hanwen>> 2006/5/10, Matt Ettus < [EMAIL PROTECTED]>:>>>>>> Can you record sound in other applications? Have you set the audio>> mixer properly?>>>> Matt>> >>>> On Tue, 2006-05-09 at 20:34 +0800, 2 1 wrote:>> > Hi, all>> >>> > My USRP is on delievering, so I try to do someting with the sound>> > card. >> >>> > Unfortunately, the integrated AC97 sound card of my pc seem to not>> > work properly as source.>> > I connect a mp3 player with the line-in port of sound card with an >> > audio wire.>> > In a script, the sound card is set to source and connected to a file>> > sink, so the sampled raw audio is written to a file.>> > In another script, the raw audio file is set to the source and >> > replayed by the sound card as sink.>> > But, I hear nothing from my sound card.>> >>> > The dialtone.py can work making the sound properly, so the sound card>> > as sink is ok. >> >>> > Hanwen>> > ___>> > Discuss-gnuradio mailing list>> > Discuss-gnuradio@gnu.org >> > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio>> -->> Matt Ettus [EMAIL PROTECTED] >>>>>>> >> ___> Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___Discuss-gnuradio mailing listDiscuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Problem with making sound card as source
Hi, Matt :) I do set the line-in as the record source in the mixer. But I found that the audio recorder app of my FC4 can't record either. I'm doubt that the sound drive of FC4 cannot support the card well. Besides, I tried on 3 different machines and all of them failed. They all have a intel integrated sound card. I'm using gr-audio-alsa.0.3.tar.gz. Have you ever met this problem before? And do you know how to make the sound card well supported under linux? Thanks a lot. Hanwen 2006/5/10, Matt Ettus <[EMAIL PROTECTED]>: Can you record sound in other applications? Have you set the audiomixer properly?Matt On Tue, 2006-05-09 at 20:34 +0800, 2 1 wrote:> Hi, all>> My USRP is on delievering, so I try to do someting with the sound> card.>> Unfortunately, the integrated AC97 sound card of my pc seem to not > work properly as source.> I connect a mp3 player with the line-in port of sound card with an> audio wire.> In a script, the sound card is set to source and connected to a file> sink, so the sampled raw audio is written to a file. > In another script, the raw audio file is set to the source and> replayed by the sound card as sink.> But, I hear nothing from my sound card.>> The dialtone.py can work making the sound properly, so the sound card > as sink is ok.>> Hanwen> ___> Discuss-gnuradio mailing list> Discuss-gnuradio@gnu.org > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio--Matt Ettus [EMAIL PROTECTED] ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
[Discuss-gnuradio] Problem with making sound card as source
Hi, all My USRP is on delievering, so I try to do someting with the sound card. Unfortunately, the integrated AC97 sound card of my pc seem to not work properly as source. I connect a mp3 player with the line-in port of sound card with an audio wire. In a script, the sound card is set to source and connected to a file sink, so the sampled raw audio is written to a file. In another script, the raw audio file is set to the source and replayed by the sound card as sink. But, I hear nothing from my sound card. The dialtone.py can work making the sound properly, so the sound card as sink is ok. Hanwen ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
