|Subject:||Re: [Discuss-gnuradio] how to deal with "underride"|
|Date:||Thu, 13 Dec 2012 21:35:48 +0000|
I think I make some progress. I think the problem are mainly associated with "blob" used in simple_trx. I wonder except John Malsbury, who write simple_trx in pre-cog, if there is anyone who can fix the problem. The problem is to make simple_trx work with other modulation in two host computers, like bpsk, QAM.
I compared radio block in simple_trx and benchmark_tx and benchmark_rx. Radio_hier of simple_trx can be seen in https://github.com/buoyboy/pre-cog/wiki/A-Simple-Packet-Radio-Example.
I find in the receive path, they are same, except in simple_trx, gr_msg_queue() is set to gr_msg_queue(4) and in benchmark, it is default.
The detail of receive path is
demodulator, and correlator are modules in gr-digital.
But in transmitter path, there is a big difference.
From the codes of framer and burst_gate, I do not really understand how they works. But
But after I change the transmitter path of simple_trx,(remove framer and burst_gate) it can receive some data from radio, but the data type is not righ, so the recieve host print its address "86" and data receive and "not a blob --simple MAC".
But if I keep them, then modulator fails for DBPSK, but it works for GMSK. It is really strange after changing the modulation, then simple_trx fails to work.
There is some link describe pmt_blob. But I am not sure the advantage of using blob and where blob is defined.
ECE Department, Virginia Tech
Office: Durham Hall 365
Date: Thu, 13 Dec 2012 11:16:01 -0500
Subject: Re: [Discuss-gnuradio] how to deal with "underride"
On Wed, Dec 12, 2012 at 6:20 PM, zhengxiangwei <address@hidden> wrote:
Neither of those figures really shows anything. The bandwidth is way too high. But the fact that the scope is telling you that the signal is clipping might be an indication that you're feeding way too much power into the transmitter.
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