Re: [Discuss-gnuradio] Just wondering why?

On 10/30/2017 04:04 PM, Adrian Hodgson wrote:
> Quite new to this so perhaps a dumb question.
>
> I have the following flowchart Narrow_band_QT.grc and screenshot attached,
> just something I have been playing with.

Note, you should set the RF again to 0 when receiving. There's frontend
on the hackrf and you run risk of smoking the receiving RF amplifier if
there's a strong RF transmission nearby.

Also, the RF gain is either 0 or 1 - on or off.

See the hackrf tutorials greatscottgadgets.com website.

>
> There are a few variables I use one is band_width. Now the strange thing is
> if I start with a default of 100KHz band width when running I can scroll down
> to 10 KHz bandwidth and then go back up again, but if I start with the default
> set to 10 KHz bandwidth it will not scroll up to 100KHz.
> It is more noticeable when looking at the bandwidth tab which is directly
> after the rational resampler. one can see the pass-band chance width as i
> change the bandwidth.

The bandwidth is equal the sampling rate - in your case - 2M.

Look at with hackrf WBFM tutorial greatscottgadgets.com website.

The channel width of the NBFM is roughly 12-16 kHz - or even 20 kHz
depending on which part of the RF spectrum your working.

The Power Squelch may not work on the hackrf - I tried it awhile back
and I couldn't get it to work. But things have changed since then so
your mileage may vary.

The only parameter you may be able to change reliably using a runtime
slider on the hackrf may be the center and offset frequencies - provided
the offset frequency is within the center frequency +- sampling rate/2.

I did play with sliders on the frequency and sampling rate but I had
trouble - and since I didn't need it - I didn't pursue it. That was a
couple of years ago so thing may have changed. And if I recall correctly
it was changing the runtime sampling rate which gave me trouble.

You should post your hackrf questions on the

hackrf-dev@greatscottgadgets.com

>
> I am using it with hackrf one, to which I will have several questions about
> but will leave that to a later post.
> I am lucky in that I have things like a spectrum analyzer and radio test set
> to work things through with. I am slowly working through the tutorials and a
> book called Practical Signal processing, perhaps my age but finding it hard
> going especially when it comes to Python, cmake, and some of the mathematics!
>
> Anyway if anyone can let me know why I get the results I do I would appreciate
> it.
> OS is SUSE Leap 42.3, GNU radio is 3.7.11, just in case that makes a
> difference.
> Cheers
> Adrian
>
>
>
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