RTLSDR/HDSDR buffer underruns

[machinegeek]

I have the RTLSDR installed and configured to RX with HDSDR. I am seeing signals and able to tune without problems; however, the audio is choppy regardless of the type of signal/mode I'm trying to monitor, and I see 1000+ buffer underruns on the EXTio tab. Sampling is set as high as 2.5.  Any ideas on how to correct?

[Miguel A. Vallejo]

Try sampling as low as 1 Msps or even 0.900001 Msps (the absolute minimum!).

Also play a bit with the readlen values:

RTL tuner=e4k readlen=65536
RTL tuner=e4k readlen=131072
RTL tuner=e4k readlen=262144
RTL tuner=e4k readlen=524288

Good luck!

[L A Smith]

Miguel: tried these settings/values and still choppy and unreadable. CPU usage is near 100%.

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[Steve Smith]

Can you provide some computer details (CPU type, memory, OS, etc.)? Just to confirm this is not a virtual machine?

On Sunday, May 20, 2012 2:29:25 PM UTC-7, machinegeek wrote:

Miguel: tried these settings/values and still choppy and unreadable. CPU usage is near 100%.

On May 20, 2012, at 4:41 PM, "Miguel A. Vallejo" <ea4...@gmail.com> wrote:

machinegeek wrote:

>>> I have the RTLSDR installed and configured to RX with
>>> HDSDR. I am seeing signals and able to tune without
>>> problems; however, the audio is choppy regardless of
>>> the type of signal/mode I'm trying to monitor, and I
>>> see 1000+ buffer underruns on the EXTio tab. Sampling
>>> is set as high as 2.5.  Any ideas on how to correct?

Try sampling as low as 1 Msps or even 0.900001 Msps (the absolute minimum!).

Also play a bit with the readlen values:

RTL tuner=e4k readlen=65536
RTL tuner=e4k readlen=131072
RTL tuner=e4k readlen=262144
RTL tuner=e4k readlen=524288

Good luck!

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[Adam Nielsen]

> Miguel: tried these settings/values and still choppy and unreadable. CPU usage
> is near 100%.

I think you answered your own question there! If there's not enough CPU power
available to do the decoding, it will sound choppy.

Cheers,
Adam.

[Youssef]

Just for fun, can you try SDR# (sdrsharp) on that machine? I just wonder how it will perform.

Youssef

[geo_stef]

i have the same problem here,

i use winxp sp3 in virtual machine but i gave 4 cores to vm

cpu is amd 1100t 6 core the host os is debian 64bit

[James Hall]

Turn up your readlen value. I've had goodish luck with 32768.

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[Paulino Kenji Sato]

Hi,

This is a alsa issue.
Underruns and overflow is very common on SDR (RT) applications
running on Linux box.
I suggest do test 4Front OSS, http://www.opensound.com/ , if you have
patience to modify all audio sub system. I don`t have patience to do.


Paulino

[GEORGE STEFANIDIS]

i dont think is alsa because i use hdsdr in windows machine, tomorrow
i am going to try using an external usb sound card

2012/5/29, Paulino Kenji Sato <pks...@gmail.com>:

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George Stefanidis

[Miguel A. Vallejo]

Try really large readlen values. Try also buflvl=0:

RTL tuner=e4k readlen=131072 buflvl=0

RTL tuner=e4k readlen=262144 buflvl=0

RTL tuner=e4k readlen=524288 buflvl=0

RTL tuner=e4k readlen=1048576 buflvl=0