Understanding Pulsed signal Demodulation and decimation in GNU Radio
Hello everyone My name is Isaac. I'm dealing with a curious behaviour that I can't understand... I'm generating my pulsed signal by multiplying a vector source and a signal source. Then I'm multiplying this pulsed signal with a continuous signal source at the same frequency, passing then for a low pass filter and seeing it in a time sink block. The result should be a set of rectangles with the same amplitude and period. The curious thing here is that the amplitude varies in time (from 0 to max amplitude and vice versa). Any idea why the amplitude varies in time? I attach the flowgraph just in case. Any idea or help will be appreciated. Thanks Isaac t. PruebDemodImag.grc Description: Binary data PruebDemodImag.grc Description: Binary data
Problems in my Python OOT specifications using input and output vectors
Hello GNURadio Community,
I wrote a Python OOT block that takes a vector input and outputs a vector
of the same size.
In the grc, my OOT block is preceeded by a stream to vector and followed by
a vector to stream (I specify the vector number items in both blocks as
well as the yml for my Python OOT). My problem lies in the input/output
specification that I am unable to figure out.
First I specified the input/output profile as:
in_sig = [np.float32*vectlen],
out_sig = [np.float32*vectlen])
The OOT compiled, but when I ran the grc, it showed that the * breaks the
code.
Next I tried:
in_sig = [(np.float32, vectlen)],
out_sig = [(np.float32, vectlen)])
The grc plot for the output came up, but did not work. So I put in some
print statements in the work() function after the following lines:
in0 = input_items[0]
out = output_items[0]
print("length of input data: {}".format(len(in0))
for i in range (0, vectlen):
print(" Iteration i = {}".format(i))
out[i] = in0[i]
The printed results in the grc were:
length of input data: 4 definitely an indication of error
For the Iterations it printed i = 0,1,2,3,4 and broke with an Error stating
index 4 is out of bound for axis 0.
Obviously, my input/output profile specification must be the problem.
I will appreciate any help or suggestions.
Thank you!
George
B200 minis time and frequency synchronization
Hello everyone, I have multiple B200 minis and would like to know if I could synchronize them using the external frequency reference and 1 PPS signal. I know that there's only one reference input port on each B200 mini which can either take an external 10 MHz reference or 1 PPS signal to share same time across multiple units. Any guidance would be much appreciated. Best regards, Ankit
Re: B200 minis time and frequency synchronization
On 2022-07-20 15:33, Ankit Jain wrote: Hello everyone, I have multiple B200 minis and would like to know if I could synchronize them using the external frequency reference and 1 PPS signal. I know that there's only one reference input port on each B200 mini which can either take an external 10 MHz reference or 1 PPS signal to share same time across multiple units. Any guidance would be much appreciated. Best regards, Ankit Strict phase synchronization with B200 "mini" is not possible. But the "combined" input can be used to both provide a 1PPS input and steer the internal clock using a DPLL implementation inside the FPGA. I recall that you just set the "time" source to external, and leave the REF clock as "internal", and the DPLL will steer the internal clock using the 1PPS input. If you provide a 10MHz clock on the 1PPS input, it is simply divided down internally into a 1PPS reference, and the steering logic is the same.
Re: Understanding Pulsed signal Demodulation and decimation in GNU Radio
Hi Isaac - it sounds like there's a beat frequency - probably between the pulsed signal and the second freqency. I'm assuming you didn't see the problem in the pulsed signal signals. -- Cinaed The definition of the beat freuency is the absolute difference between two frequencie. On 7/20/22 10:03, isaac mario tupac davila wrote: Hello everyone My name is Isaac. I'm dealing with a curious behaviour that I can't understand... I'm generating my pulsed signal by multiplying a vector source and a signal source. Then I'm multiplying this pulsed signal with a continuous signal source at the same frequency, passing then for a low pass filter and seeing it in a time sink block. The result should be a set of rectangles with the same amplitude and period. The curious thing here is that the amplitude varies in time (from 0 to max amplitude and vice versa). Any idea why the amplitude varies in time? I attach the flowgraph just in case. Any idea or help will be appreciated. Thanks Isaac t.
