# UHD Error: recv packet demuxer unexpected sid

**URL:** <https://www.ruby-forum.com/t/uhd-error-recv-packet-demuxer-unexpected-sid/234011>\
**Category:** GNU Radio\
**Created:** [January 30, 2015, 12:47pm UTC](https://www.ruby-forum.com/t/uhd-error-recv-packet-demuxer-unexpected-sid/234011 "2015-01-30T12:47:53Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![addis\_a](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/c4cdca/32.png) [@addis\_a](https://www.ruby-forum.com/u/addis_a)\
**Post date:** [January 30, 2015, 12:47pm UTC](https://www.ruby-forum.com/t/uhd-error-recv-packet-demuxer-unexpected-sid/234011/1 "2015-01-30T12:47:53Z")

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Sometimes I run my python program I continuously get this error:  
…  
UHD Error:  
recv packet demuxer unexpected sid 0x3fff9  
UHD Error:  
recv packet demuxer unexpected sid 0x4fff9  
UHD Error:  
recv packet demuxer unexpected sid 0xfffe0003  
UHD Error:  
recv packet demuxer unexpected sid 0xfffb0000  
UHD Error:  
recv packet demuxer unexpected sid 0x3  
UHD Error:  
recv packet demuxer unexpected sid 0x3fffc  
…

Does anybody know where this error could come from?

My python program just writes some samples in a file, reconfigure the  
central frequency and write again in a file with different name. Here is  
the related code:

```
   for num in range(1,24): #to iterate between 1 to 24
        tb.samp_rate = samp_rate = 2000000
        tb.fft_points = fft_points = 1024
        tb.frame_rate = frame_rate = int (samp_rate/fft_points/1000)
        center_freq = 914e6 + (num*2000000) # Center freq 

```

modification  
tb.set\_center\_freq(center\_freq)  
tb.disconnect((tb.logpwrfft\_x\_0, 0), (tb.blocks\_file\_sink\_0,  
0))  
tb.blocks\_file\_sink\_0 =  
blocks.file\_sink(gr.sizeof\_float\*fft\_points, ‘/home//FILE\_SINK/’+  
‘914\_+\_’

- str(num+num), False)  
tb.connect((tb.logpwrfft\_x\_0, 0), (tb.blocks\_file\_sink\_0, 0))  
tb.start()  
while(tb.blocks\_file\_sink\_0.nitems\_read(0) \<3): #3 arrays  
of  
1024  
pass  
tb.stop()  
tb.wait()

---

<div class="post-metadata">

**Author:** ![jorgegetafe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/eada6e/32.png) [@jorgegetafe](https://www.ruby-forum.com/u/jorgegetafe)\
**Post date:** [February 1, 2015, 1:27pm UTC](https://www.ruby-forum.com/t/uhd-error-recv-packet-demuxer-unexpected-sid/234011/2 "2015-02-01T13:27:16Z")

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Hi Jorge,  
if I’m not mistaken, this is still your B200, so this might be funky  
stuff happening on USB3.  
Important here is that you use the latest UHD; which version do you run  
(first line of output of uhd\_find\_devices)?

Best regards,  
Marcus

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<div class="post-metadata">

**Author:** ![jorgegetafe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/eada6e/32.png) [@jorgegetafe](https://www.ruby-forum.com/u/jorgegetafe)\
**Post date:** [February 2, 2015, 8:22am UTC](https://www.ruby-forum.com/t/uhd-error-recv-packet-demuxer-unexpected-sid/234011/3 "2015-02-02T08:22:42Z")

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Hi Marcus,

Many thanks for your answer.  
I got 3.8 version.

“linux; GNU C++ version 4.7.2; Boost\_104900;  
UHD\_003.008.001-42-g8c87a524”

Then is it USB driver related?  
Is it right the way I reconfigure my flowgrahp in order to change my  
center  
frequency ?  
Thank you for your help.

Ragards,  
Jorge.

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<div class="post-metadata">

**Author:** ![jorgegetafe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/eada6e/32.png) [@jorgegetafe](https://www.ruby-forum.com/u/jorgegetafe)\
**Post date:** [February 2, 2015, 4:02pm UTC](https://www.ruby-forum.com/t/uhd-error-recv-packet-demuxer-unexpected-sid/234011/4 "2015-02-02T16:02:31Z")

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Hi Jorge,

On 02/02/2015 08:21 AM, Jorge G. wrote:

> Hi Marcus,
> 
> Many thanks for your answer.  
> I got 3.8 version.  
> “linux; GNU C++ version 4.7.2; Boost\_104900; UHD\_003.008.001-42-g8c87a524”  
> 3.8.1 is quite recent; there’s only the 3.8.2 Release Candidate that you  
> could update to, so this is good.
> 
> Then is it USB driver related?  
> Possibly, but it often is.  
> Is it right the way I reconfigure my flowgrahp in order to change my  
> center frequency ?  
> I don’t think that has anything to do with the problem at hand.

Still: which sampling rate are you using? Can you try with a lower one?

Greetings,  
Marcus

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<div class="post-metadata">

**Author:** ![jorgegetafe](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/eada6e/32.png) [@jorgegetafe](https://www.ruby-forum.com/u/jorgegetafe)\
**Post date:** [February 4, 2015, 4:33pm UTC](https://www.ruby-forum.com/t/uhd-error-recv-packet-demuxer-unexpected-sid/234011/5 "2015-02-04T16:33:15Z")

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Hello Marcus,

I am using 10MS/s. The use of 5MS/s or 2MS/s  
does not make any difference though.

If I just make a FFT of 20MS/s everything goes smoothly. I get errors  
only  
when reconfiguring the center frequency back and forth so I am  
suspicious  
that the sample rate is not the problem.

However I need those different center frequencies since I need to scan a  
large BW. What is the best approach to do that?

Many thanks for you support.