Re: [Discuss-gnuradio] Large Sample Spikes after Each Packet in tx_bursts Example

[Jason Tran]

Hi All,

"If you are seeing transients at the beginning of a burst, thats probably

the half band filters. They are implemented in block ram and dont clear
between bursts."

I'm actually sending one burst of a very long length so I can emulate an always-on signal (i.e. I'm not letting tx_bursts actually send an EOB packet). However, I still get the large samples with suppressed samples around.  The number of samples between every large sample (363) is directly equal to the samples per buffer size. i.e. the size of buffs used when invoking tx_stream->send(buffs, samps_to_send, md, timeout);

Regards,

Jason

---

From: Josh Blum <address@hidden>
To: address@hidden
Sent: Thursday, June 14, 2012 7:57 PM
Subject: Re: [Discuss-gnuradio] Large Sample Spikes after Each Packet in tx_bursts Example

> You can see the magnitude hovers over 30 which is good (noise hovers
> around 5). But, as you can see, there are two spikes with suppressed
> samples around it. These are exactly spaced 363 samples apart (this
> changes as I change the samples per buffer at the transmitter). Does
> anyone have an idea where this is coming from? I'm running out of
> ideas of where to look to figure out the problem. Any ideas of what I
> can do to remove it (even manually)?
>
> Regards, Jason T.
>

If you are seeing transients at the beginning of a burst, thats probably
the half band filters. They are implemented in block ram and dont clear
between bursts.

On the other hand, if they are at the end, it might actually be that
mini EOB packet. Its supposed to be a zero length packet but its
actually sending a single sample (value zero). If this is the case, you
might try setting EOB on the last packet actually with sample data.

-josh

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