Forum: GNU Radio Playback

98cda97ac889e9a4f20309c4f39125fa?d=identicon&s=25 Paul B. Huter (Guest)
on 2013-12-26 23:32
(Received via mailing list)
Is there a way to slow the playback of a data file through an FFT Sink?
If
I recorded at 50M and I set my FFT rate to 25M, would that result in
playback twice as long?

Thanks.
C539637020fd56193dd6daec746c4a84?d=identicon&s=25 Tom Rondeau (Guest)
on 2013-12-30 15:52
(Received via mailing list)
On Thu, Dec 26, 2013 at 5:31 PM, Paul B. Huter <paul.b.huter@gmail.com>
wrote:
> Is there a way to slow the playback of a data file through an FFT Sink? If I
> recorded at 50M and I set my FFT rate to 25M, would that result in playback
> twice as long?
>
> Thanks.


No, the sample rate of the FFT sink is just for display purposes: it
sets the range of the x-axis and nothing more.

If you want to slow down your display, assuming there is no hardware
in the loop, you can use a throttle block with a fairly low rate.

Tom
98cda97ac889e9a4f20309c4f39125fa?d=identicon&s=25 Paul B. Huter (Guest)
on 2013-12-30 15:53
(Received via mailing list)
Sounds good, thanks.

Paul B. Huter
98cda97ac889e9a4f20309c4f39125fa?d=identicon&s=25 Paul B. Huter (Guest)
on 2013-12-30 22:54
(Received via mailing list)
Tom:

What would you recommend if my data was recorded at 50M for about 15
seconds and I would like to double to playback time with a throttle. If
I
set the throttle to 25M, would that do the trick, or is it more
complicated
than that? I'm waiting for a new shipment of RAM, and once I have that I
will be able to play around with things, but I just thought I would
query
the group to get a good starting point.

Thanks.
62e152f885746ecd6f9d2e470722bed1?d=identicon&s=25 Dan CaJacob (Guest)
on 2013-12-31 00:45
(Received via mailing list)
I often "speed up" the playback of large recordings by adjusting the
throttle only.  In the throttle block, I just multiple the recorded
sample
rate by a factor (say 10) to get increased playback speed.  Don't change
any other blocks' parameters - just the throttle.

Very Respectfully,

Dan CaJacob
7d89a70df32c0ae27c1235016f9e5441?d=identicon&s=25 "Marcus Müller" <marcus@hostalia.de> (Guest)
on 2014-01-01 15:01
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Hi Paul,
yes, that would basically make a 1s recording (50e6 Samples) play in 2s.
Be aware however that 25Msam/s is still a lot to process, so the
throttled samples might still stress out your CPU ;)

Have nice new year,
Marcus

On 26.12.2013 23:31, Paul B. Huter wrote:
> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>
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98cda97ac889e9a4f20309c4f39125fa?d=identicon&s=25 Paul B. Huter (Guest)
on 2014-01-02 02:44
(Received via mailing list)
Thanks, Marcus. The limiting factor for the flows I have seems to be RAM
more than anything, and I will be back at 8GB tomorrow, hopefully, and
things should be good.

Thanks, and Happy New Year.

Paul B. Huter
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