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From: | Nowlan, Sean |
Subject: | Re: [Discuss-gnuradio] Transmitting bursts with GRC by inserting SOB and EOB |
Date: | Tue, 21 Oct 2014 18:18:42 +0000 |
>> ################################################## >> # Variables >> ################################################## >> self.tx_gain = tx_gain = 15 >> self.samp_rate = samp_rate = 200000 >> self.f_center = f_center = 1.47e9 >> self.device = device = "type=usrp2" >> >> ################################################## >> # Blocks >> ################################################## >> self.usrp_sink = uhd.usrp_sink( >> device_addr=device, >> stream_args=uhd.stream_args( >> cpu_format="fc32", >> length_tag_name="packet_len", >> channels=range(1), >> ), >> ) >> self.usrp_sink.set_samp_rate(samp_rate) >> self.usrp_sink.set_center_freq(f_center, 0) >> self.usrp_sink.set_gain(tx_gain, 0) >> self.usrp_sink.set_antenna("TX/RX", 0) >> self.blocks_vector_source_x_0 = >> blocks.vector_source_c((1,)*5, False, 1, []) >> self.blocks_stream_to_tagged_stream_0 = >> blocks.stream_to_tagged_stream(gr.sizeof_gr_complex, 1, 5,
>> "packet_len") >> >> ################################################## >> # Connections >> ################################################## >> self.connect((self.blocks_vector_source_x_0, 0),
>> (self.blocks_stream_to_tagged_stream_0, 0)) >> self.connect((self.blocks_stream_to_tagged_stream_0, 0),
>> (self.usrp_sink, 0)) > It's not working either... I can still observe the carrier at the receiver. >> - You'll know if your USRP hasn't acknowledged tx_eob if you see 'U's
>> between bursts. > I am getting exactly one "U". Both for the code in my previous post as
> well as for the above one. It really seems like the USRP is not
> recognizing the stream tags. > There are a few things to consider with this flowgraph (as posted): 1)
Your vector source is set to /not/ repeat. After your flowgraph terminates, is that when you observe the LO still running? 2)
You’re essentially sending a very short rectangular pulse modulated onto a carrier, which in the frequency domain would look like a sinc function
centered at the carrier. Is this what you want, or are you just experimenting with the burst interface? 3)
Is there a reason your burst pulses need to contain so few samples? Could you provide some information about what you’re trying to do in your end application? Sean From: discuss-gnuradio-bounces+address@hidden
[mailto:discuss-gnuradio-bounces+address@hidden On Behalf Of
Marcus Müller Sean, Frederik is observing has to do with the very short burst he is sending, something like 5 samples. I suspect this requires 1 call each to work and tag_work per 5 sample burst, which seems like an awful lot of context switching and overhead. > > -----Original Message----- > From: Marcus Müller [mailto:address@hidden]
> Sent: Tuesday, October 21, 2014 1:24 PM > To: Nowlan, Sean;
address@hidden; Martin Braun > Subject: Re: [Discuss-gnuradio] Transmitting bursts with GRC by inserting SOB and EOB > Hi Sean, > > _______________________________________________ > Discuss-gnuradio mailing list |
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