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Re: [Discuss-gnuradio] Question of tx_ampl range: [0, 1) or [0, 2^15/2)
Re: [Discuss-gnuradio] Question of tx_ampl range: [0, 1) or [0, 2^15/2) ?
Mon, 08 Nov 2010 01:07:21 -0800
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In transmit_path.py ( ..-> packet_transmitter -> Multiply Const -> USRP
Sink), I see that the range of Multiply Const is [0, 1).
However, in one of the GRC example usrp_tx_dpsk.grc (Random Source -> DPSK2
Mod -> Multiply Const -> USRP Sink), Multiply_Const = tx_ampl*p2p/2 , where
p2p = 2^15.
There is a multiply_const(2**15) in the transmit_path example. See
The gr-usrp sink always takes samples between +/-2**15. See the docs in
the USRP sink block in GRC.
Does anyone know why the Multiply_Const is set to tx_ampl*p2p/2 and what
does p2p refer to?
It means peak to peak and the purpose is to scale the signal to the
expected range of the usrp sink block. I believe that p2p should
actually be 2**16 in this case, but it works.