Decimating FIR Filter Taps and gr.firdes.complex_band_pass incompatibility - Marcus SARA SID SDR

GNU Radio
1

In the April/May 2010 SARA Journal, Marcus L. had an article entitled
“Building an SDR SID Receiver in an Afternoon” which was highly
information and inspirational. While my sound card only goes to 48 KHz
sampling, I decided to try his implementation and in terms of entry into
GRC, things have gone well except for the taps and their variables and a
non-cooperative import box.

While the screenshot in the article shows variables of ID: c1…4_taps
and value of gr.firdes.complex_b… the text hints are band_pass and the
variable blocks do accept this though it is displayed as value:
<functio… 0x8801ae4> , however, the Decimating FIR Filters complain
about:

Problem 1

Param - Taps(taps):
Expression “[<function complex_band_pass at 0x8801ae4>]” is invalid
for
type complex vector.

no matter which “type” I specify for the filter.

Problem 2

import :notchfilt

Param - Import(import):
Bad import syntax: “notchfilt”.

have tried notchfilter etc. but without success. Not sure if this is
related to Problem 1?

   Kind Regards,

                John
2

variable blocks do accept this though it is displayed as value:

related to Problem 1?
[email protected]
Discuss-gnuradio Info Page

John, let me send you the latest TAR image of my SID receiver work–it
has progressed quite a bit beyond that article, and Gnu Radio
has also changed since I wrote that article.

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

3

Thanks very much Marcus. I eventually figured out that in the variable
block, I needed to include:

gr.firdes.complex_band_pass (gain,sampling_freq,low_cutoff_freq,

high_cutoff_freq, transition_width, window = WIN_HAMMING,beta = 6.76)

and when I plugged in some variables based on the b/w and centre
frequency, the Decimating FIR filter block went good!

Of course, no idea if my guesses are real-world.

Look forward to getting the latest and greatest.

       Slainte,



                 John