Re: [Discuss-gnuradio] Scaling down IFFT values
No, I did not mean that. Ok, this might be a problem: "Scaling", for me, means "multiplying with a scalar value". My suggestion therefore was that you just insert a multiplier before the IFFT. Maybe we're talking about a different "scaling"? Greetings, Marcus On 10/22/2014 06:46 AM, zealdeal wrote: Did you mean something like: self.connect(self._pkt_input, 0), self.scale, (self.preambles,0)) ? That's not working as it's giving itemsize mismatch error! -- View this message in context: http://gnuradio.4.n7.nabble.com/Scaling-down-IFFT-values-tp50833p50967.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Scaling down IFFT values
Also I tried manually scaling down the output array in fft_vcc_fftw:work function. That has no effect no IFFT output! -- View this message in context: http://gnuradio.4.n7.nabble.com/Scaling-down-IFFT-values-tp50833p50968.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Scaling down IFFT values
Did you mean something like: self.connect(self._pkt_input, 0), self.scale, (self.preambles,0)) ? That's not working as it's giving itemsize mismatch error! -- View this message in context: http://gnuradio.4.n7.nabble.com/Scaling-down-IFFT-values-tp50833p50967.html Sent from the GnuRadio mailing list archive at Nabble.com. ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Scaling down IFFT values
You should probably look at the new OFDM codes. If you see the ofdm_tx.grc example, I think there's already a scaler in there. M On 10/16/2014 01:35 PM, zealdeal wrote: > Hi All, > > I need to scale down the OFDM transmission signal in time domain, after IFFT > is done, so that, all the values are within the range -1 to 1. But, I cant > simply add one more "scaling" block after cp_adder in > > self.connect(self.preambles, self.ifft, self.cp_adder, self.scale, self) > (file: ofdm,py) > > as it will scale down the preamble also, leading to non-recognition of > packet at receiver end. > > Any pointer on where should I make the change? > > > > -- > View this message in context: > http://gnuradio.4.n7.nabble.com/Scaling-down-IFFT-values-tp50833.html > Sent from the GnuRadio mailing list archive at Nabble.com. > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
Re: [Discuss-gnuradio] Scaling down IFFT values
Hi you! >Any pointer on where should I make the change? Yes. Do it before preambling! The inverse dft is a linear operation; it doesn't really matter whether you scale before or after. Note though that the IFFT as we use it adds a sqrt(length_of_fft) factor, so account for that by dividing your scaling factor by it. Greetings, Marcus On 16.10.2014 13:35, zealdeal wrote: > Hi All, > > I need to scale down the OFDM transmission signal in time domain, after IFFT > is done, so that, all the values are within the range -1 to 1. But, I cant > simply add one more "scaling" block after cp_adder in > > self.connect(self.preambles, self.ifft, self.cp_adder, self.scale, self) > (file: ofdm,py) > > as it will scale down the preamble also, leading to non-recognition of > packet at receiver end. > > Any pointer on where should I make the change? > > > > -- > View this message in context: > http://gnuradio.4.n7.nabble.com/Scaling-down-IFFT-values-tp50833.html > Sent from the GnuRadio mailing list archive at Nabble.com. > > ___ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio ___ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
