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Hi Alphonso,
I implemented a transmitter for the DRM(30) standard in GNU Radio and
published it on github (GitHub - kit-cel/gr-drm: DRM transmitter using GNU Radio).
To (partly) answer your questions:
- DRM only accepts specific audio sample rates, make sure to read the
standard documents carefully. - Mixing is usually done by the USRP. You as the user only deal with
the complex baseband centered around DC. 12 kHz would also be a VERY low
carrier frequency, short-wave radio usually uses frequencies between 3
and 30 MHz.
–Felix
On 03.06.2015 12:57, [email protected] wrote:
everything works fine but there is a problem with the spectrum of this
should i use a resampler block because there is a problem with
nyquist? how can i handle this problem?
2) the same problem goes with the output. if i mix up the ofdm signal
to a carrier frequency (for example 12khz) how can i handle this?
there is also a problem with nyquist.
thanks in advance!
alphonso
–
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)
Felix W., M. Sc.
Research Associate
Kaiserstra??e 12
Building 05.01
76131 Karlsruhe
Phone: +49 721 608-46276
Fax: +49 721 608-46071
E-Mail: [email protected]
www.cel.kit.edu
KIT – University of the State of Baden-W??rttemberg and
National Laboratory of the Helmholtz Association
Hi,
please remember to always reply to the list.
If you mix your baseband signal in a way that no part of your spectrum
includes negative frequencies BEFORE doing the complex-to-real
conversion, this should work. At least from a signal processing
perspective. I never used my soundcard as a transmitter, so I can’t
really help you with that.
–Felix
On 03.06.2015 15:02, [email protected] wrote:
were problems with licensing and changed or removed functions in
2) i don’t have an USRP. i want to use a sound card to get my signal
Hi Alphonso,
low carrier frequency, short-wave radio usually uses frequencies
standard. so my first try was to implement the transmitter with
with the parameters above and the wish of a bandwidth of 10khz (to
this? there is also a problem with nyquist.
Kaiserstra??e 12
National Laboratory of the Helmholtz Association
–
Karlsruhe Institute of Technology (KIT)
Communications Engineering Lab (CEL)
Felix W., M. Sc.
Research Associate
Kaiserstra??e 12
Building 05.01
76131 Karlsruhe
Phone: +49 721 608-46276
Fax: +49 721 608-46071
E-Mail: [email protected]
www.cel.kit.edu
KIT – University of the State of Baden-W??rttemberg and
National Laboratory of the Helmholtz Association
I’d also like to point out that you should use an oscilloscope to verify
that a sine with a 17 kHz frequency has the same peak-to-peak voltage as
one with the same digital amplitude at 7 kHz – sound cards do have nice
DACs (bitdepth-wise), but the analog filtering that you must do after
DAC’ing tends to be implemented in a one-stage passive way (at least for
the cheap consumer-grade sound cards I’ve encountered), which will not
make your spectrum pretty.
However, you said there’s an existing Matlab implementation – was the
“Soundcard channel” measured with respect to frequency selectivity?
Best regards,
Marcus