Am 10. August 2021 22:44:44 MESZ schrieb Kristoff <firstname.lastname@example.org>:
Thanks, i'll try both options and compair them.
I remember from my books on DSP it is possible to combine multiple
consecutive FIT filters into one, so I did a little bit of more research
I found (*) that -as convolution as associative- this implies this:
(( f * h1) * h2) = f * (h1 * h2)
So I guess I just use firdes.root_raised_cosine to calculate the RRC and
then "numpy.convolute()" it with itself, I should get the RC.
Feel free to correct me if I am wrong. :-)
On 10.08.21 21:01, Fabian Schwartau wrote:
You can just put an additional RRC in front of it or you can calculate
the tabs by folding die tabs of the RRC with themself. There is
probably a numpy function to do that. Have not tested any of that, but
both ways should do the trick.
Am 10. August 2021 20:44:05 MESZ schrieb Kristoff <email@example.com>:
I am playing around with PSK demodulation, now doing a small project
trying to decode the slow-speed PSK data on the 198 KHz carrier of BBC
The specs are here:
According the document (page 2 of the document, page 8 of the PDF), the
system uses a shaping-filter of cos(pi * f * Td / 4).
(with Td = 50)
If I am correct, this is in fact a raised-cosine filter with beta = 1.
So the document seems to specify a raised-cosine filter, both on the
transmit and receive side; so not a ROOT raised-cosine as is used in
most PSK systems.
How do I create the filter-taps for the Polyphase clock sync block for a
I found a function firdes.root_raised_cosine, but no firdes.raised_cosine?
Is there a way to easily convert the taps of a RRC filter to those of a
RC filter? (RC = RRC^2, so square the value of all taps?)
Any other ideas?
- put an additional RRC low-pass filter in front of the Polyphase
- use firdes.pm_remez() ?
Thanks in advance,