Fwd: QTGui Number Sink, Demodulation Problems

GNU Radio
1

The purpose of my current experiments is to create a 16QAM transmitter
and
receiver, with UDP sources/sinks, and using bladeRFx40’s to
transmit/receive.

I’m using Number sinks to check values at various points of my
flowgraph.
If I use a constant source value of 1, a float input type to a Number
sink
displays a “1”, but a byte input type displays a “0”. This is
problematic
because I’m trying to troubleshoot the QAM demodulator which has an
output
type of byte.

I’ve got Number sinks throughout the flowgraph. The source, modulator,
and
polyphase clock all output correct values for samples/symbols of “1111”
but
the demodulator is giving outputs of “0”.

Are these bugs, or am I doing something wrong?
Also, I tried replacing the QAM mod/demod blocks with 8PSK blocks and
still
have the save problem.

Thanks in advance for any assistance.

2

On Mon, Oct 13, 2014 at 4:30 PM, Jason N. [email protected]
wrote:

I’ve got Number sinks throughout the flowgraph. The source, modulator, and
polyphase clock all output correct values for samples/symbols of “1111” but
the demodulator is giving outputs of “0”.

Are these bugs, or am I doing something wrong?
Also, I tried replacing the QAM mod/demod blocks with 8PSK blocks and
still have the save problem.

Thanks in advance for any assistance.

Yeah, this was a bug. Looks like a very stupid mistake on my part.

I’ve pushed a fix that mostly works, but we can’t really fix it without
breaking the api. It should work fine now for char, short, and float
inputs. There’s a note in the block’s documentation about this.

Tom

3

Tom,

Thanks for the quick bug fix Re: the number sinks. In the interim I’ve
been
troubleshooting by dumping output to a binary file and discovered other
mistakes on my part. But once again I’m at an impasse. I captured some
data
which I view in the terminal using xxd -b filename.

The interesting thing is that the first portion of the file is all 1’s
“1111 1111 1111”, which is the correct output that I’m looking for.
However, it transitions to outputting “0101 0101 0101” and stays with
that
output apparently indefinitely. Could this in some way be caused by the
Polyphase Clock Sync?

Thanks,
-Jason