[USRP-users] X300 configuration with SSD setting

Jack Yang ccjack at uw.edu
Thu Sep 25 11:15:10 EDT 2014


Hello, Marcus

Many thanks for your mail. I have some questions regarding the sampling
rate and data stream speed.

1. When data stream is setting in complex float 32, the raw data rate
1.6GB/s will be over single 10Gigabit Ethernet cable ability, isn't it?
One thing confuses me is the ADC resolutions is 14 bits ( ~ 2Byte, I and Q
channel for totally 4Byte). Hence, why we can have complex float 32 for
each sample( I and Q for totally 8Byte)?,   is it from auto gain control
assistance for making widely range?

2. Currently, I am using only one 10Gigabit cable in x300. Do you mean that
in dual channel receiver, I need to set up two 10Gigabit cable ? I saw some
information indicating that the two 10 Gigabit cable interface setting is
not finishing yet? In addition, When I am running uhd_fft at sampling 200MS
in single cable, I didn't see any overflow or dropping warning message. Why
this speed don't break the limitation of single 10Gigabit cable?  (I am
using INTEL 10Gigabit Ethernet card)


Again, really thanks for your answering and time

All Best,
Jack






On Thu, Sep 25, 2014 at 6:58 AM, Marcus Müller <marcus.mueller at ettus.com>
wrote:

> Hi Jack,
> In afraid this is something not inherently related to usrp usage, so this
> might not be the best place to ask. Usually, Ubuntu has community forums
> and a wiki that contain a lot of information, and also a rather active irc
> channel on freenode. Be sure to use a raid controller that really takes off
> as much load as possible from the cpu, which means that you'll want to have
> a hardware raid; configuration of that probably will include controller
> specific steps, so you'll need to google information on your specific
> device.
>
> As a side note: a raid of two fast ssds might sound impressive, but the
> raw data rate of a dual channel 100MS/s stream in complex int16 is 800MB/s
> (1.6GB/s for GNU radio's default complex float32), and you'll need to make
> sure your storage system is sufficiently oversized to not only offer a high
> average rate but guarantee this rate in a worst case scenario as well as
> being able to catch up if for some reason your os needs to suspend storage
> to do something else. Also, there is significant file system overhead, both
> with respect to storage speed and cpu load, so you'll definitely need a
> rather beefy computer to handle all this.
>
> Greetings,
> Marcus
>
> On September 24, 2014 11:30:10 AM EDT, Jack Yang via USRP-users <
> usrp-users at lists.ettus.com> wrote:
>
>> Hi,
>>
>> I have one X300 USRP and would like to do the dual receiver development
>> (coherent receiver for signal processing). I would like to record a data
>> for baseband bandwidth arounnd 66.66Mhz or 100Mhz. Therefore, I plan to use
>> two Samsung 850 Pro SSD to storage the data stream under 66.66Mhz or 100Mhz
>> sampling rate for two receiver by using File Sink block in
>> gnuradio-companing. My computer is using ubuntu 14.04.
>>
>> My question is how to set up SSD for this scenario? I guess I need to use
>> RAID 0 to set up this two SSD, but not for sure how to do it. Can anyone
>> give me some direction for this?
>>
>> Many thanks for that.
>>
>> All Best,
>> Jack
>>
>>
>>
>>  ------------------------------
>>
>> USRP-users mailing list
>> USRP-users at lists.ettus.com
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
> --
> Sent from my Android device with K-9 Mail. Please excuse my brevity.
>



-- 
Chou-Chang Yang

Graduate Research Assistant
Network Security Lab
Electrical Engineering
University of Washington
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