The code is hard to read in the formatting that came through. But some comments: - start_of_burst is not actually required, that's true. It's a remnant from the past. - You don't send a zero after EOB, rather, you need to attach the EOB to something. In your example, you could also attach EOB to the last loop iteration's send() call.
--M On Thu, Oct 24, 2024 at 10:47 AM <yibinden...@outlook.com> wrote: > Hi, I am new to usrp. In a test I want to send a constant bit for a while > using my B210 at a sampling rate of 1M. One way is to call send_wave() in > python api. The received signal is shown in fig.1, which is relatively good. > > As an alternative, I wrote a send function on my own based on send_wave(), > and invoke it in a loop. The code is as follows. However there are spikes > in the received signal with a periodic of length of samples, which is shown > in fig.2. > > def my_send( > > waveform_proto, > > start_time=None, > > streamer=None, > > metadata=None, > > ): > > buffer_samps = streamer.get_max_num_samps() > > proto_len = waveform_proto.shape[-1] > > send_samps = 0 > > if len(waveform_proto.shape) == 1: > > waveform_proto = waveform_proto.reshape(1, waveform_proto.size) > > # Now stream > > print(usrp_tx.get_time_now().get_real_secs()) > > if metadata is None: > > metadata = uhd.types.TXMetadata() > > if start_time is not None: > > metadata.time_spec = start_time > > metadata.has_time_spec = True > > while send_samps < proto_len: > > real_samps = min(proto_len - send_samps, buffer_samps) > > samples = streamer.send(waveform_proto[:, > send_samps:send_samps+real_samps], metadata) > > send_samps += samples > > # Send EOB to terminate Tx > > metadata.end_of_burst = True > > # streamer.send(np.zeros((1, 1), dtype=np.complex64), metadata) > > return send_samps > > tx_signals = np.ones([500, 1]).reshape(num_channels, -1) > > md_tx = uhd.types.TXMetadata() > > while True: > > md_tx.start_of_burst = True > > send_samples = my_send(tx_signal, streamer=tx_streamer, metadata=md_tx) > > When I looked into the send_wave() I found these lines: > > # Send EOB to terminate Tx > metadata.end_of_burst = True > streamer.send(np.zeros((1, 1), dtype=np.complex64), metadata) > > Moreover, it seems there are no mentions of start_of_burst. If I delete > these lines, spikes are removed but the received signal looks very strange, > which is shown in fig.3. > > These facts made me confused at the functions of start_of_burst and > end_of_burst. Moreover, why should the streamer send a zero after > end_of_burst? > _______________________________________________ > USRP-users mailing list -- usrp-users@lists.ettus.com > To unsubscribe send an email to usrp-users-le...@lists.ettus.com >
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