Re: GRC max sample rate

[Kyeong Su Shin]

Hello Koyel:

I used a generic Intel i5 PC, with a Mellanox 10Gbps NIC. I do not remember the 
exact model numbers, but I am pretty sure that the cpu was a relatively older 
generation on (DDR3-era).

I just created a tmpfs and used uhd_rx_cfile.py (a sample application included 
in gr-uhd) to collect the data. I do not remember further details.

Regards,
Kyeong Su Shin

보낸 사람: Koyel Das (Vehere) 
보낸 날짜: 2020년 7월 26일 일요일 오후 3:10
받는 사람: Kyeong Su Shin ; GNURadio Discussion List 

제목: Re: GRC max sample rate

Hi Kyeong,

Since you have received at 200 MSPS data from usrp, I am asking this to you. 
What were your system parameters to receive at 200 MSPS like clock speed of 
processor, did you have DDR4 ram with ssd? And 10 gbps nic card? What clock 
speed of processor is needed? And what other things are needed?

I am asking this to compare with the parameters told to me by one of my 
friends. Since you have handled this data rate yourself you will be able to 
tell exactly.

So please help.

Regards,
Koyel

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From: Kyeong Su Shin 
Sent: Friday, July 24, 2020 3:32:33 PM
To: Koyel Das (Vehere) ; GNURadio Discussion List 

Subject: Re: GRC max sample rate

Hello Koyel:

I did one channel with 200 MSPS before, so probably yes (assuming that you are 
not doing any other processing).

Consider using sc16. Also, you can try using libuhd directly.

Regards,
Kyeong Su Shin

보낸 사람: Koyel Das (Vehere)  대신 Discuss-gnuradio 

보낸 날짜: 2020년 7월 24일 금요일 오후 5:59
받는 사람: GNURadio Discussion List 
제목: GRC max sample rate

Can GRC handle writing data from two channels of USRP at 100 MSPS each to a 
file in a RAM disk ? I am using 10G server and PCIe cable.

Get Outlook for iOS

Re: GRC max sample rate

[Koyel Das (Vehere)]

Hi Kyeong,

Okay thanks for the information.

Regards,
Koyel

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From: Kyeong Su Shin 
Sent: Sunday, July 26, 2020 2:12:47 PM
To: Koyel Das (Vehere) ; GNURadio Discussion List 

Subject: Re: GRC max sample rate

Hello Koyel:

I used a generic Intel i5 PC, with a Mellanox 10Gbps NIC. I do not remember the 
exact model numbers, but I am pretty sure that the cpu was a relatively older 
generation on (DDR3-era).

I just created a tmpfs and used uhd_rx_cfile.py (a sample application included 
in gr-uhd) to collect the data. I do not remember further details.

Regards,
Kyeong Su Shin

보낸 사람: Koyel Das (Vehere) 
보낸 날짜: 2020년 7월 26일 일요일 오후 3:10
받는 사람: Kyeong Su Shin ; GNURadio Discussion List 

제목: Re: GRC max sample rate

Hi Kyeong,

Since you have received at 200 MSPS data from usrp, I am asking this to you. 
What were your system parameters to receive at 200 MSPS like clock speed of 
processor, did you have DDR4 ram with ssd? And 10 gbps nic card? What clock 
speed of processor is needed? And what other things are needed?

I am asking this to compare with the parameters told to me by one of my 
friends. Since you have handled this data rate yourself you will be able to 
tell exactly.

So please help.

Regards,
Koyel

Get Outlook for iOS

From: Kyeong Su Shin 
Sent: Friday, July 24, 2020 3:32:33 PM
To: Koyel Das (Vehere) ; GNURadio Discussion List 

Subject: Re: GRC max sample rate

Hello Koyel:

I did one channel with 200 MSPS before, so probably yes (assuming that you are 
not doing any other processing).

Consider using sc16. Also, you can try using libuhd directly.

Regards,
Kyeong Su Shin

보낸 사람: Koyel Das (Vehere)  대신 Discuss-gnuradio 

보낸 날짜: 2020년 7월 24일 금요일 오후 5:59
받는 사람: GNURadio Discussion List 
제목: GRC max sample rate

Can GRC handle writing data from two channels of USRP at 100 MSPS each to a 
file in a RAM disk ? I am using 10G server and PCIe cable.

Get Outlook for iOS

GSoC 2020: New BlogPost for Week 9

[Alekh]

Hello everyone,

I have updated the new blogpost for this week on my blog 
. Here is the link for the blogpost: 
https://grdpd.wordpress.com/2020/07/26/week-9-addition-of-dpd-lms-algorithm-block/


Major Week Highlights are:

* Addition of /LMS_postdistorter /block having two methods: Newton based 
and EMA/.

/

/* //Addition of /LMS_test_two_tone_setup /flowgraph./

/* //Added the /LMS_coeff. estimator /prototype codes in 
the/Prototype_Codes.//



Upcoming Week Tasks are:

 * Working on synchronisation in passing of message /‘taps’/ to
   eliminate the strange behaviour.
 * Proper testing of the LMS based algorithm to eliminate bugs.
 * Working on analysing other performance characteristic parameters.

Regards,

Alekh Gupta,

NIT Hamirpur

Re: GRC max sample rate

[Koyel Das (Vehere)]

Hi Marcus,

Good that you replied my email. Since you work on Radio Astronomy as I heard 
from Neel, I want to ask you something. By using USRP I saw that without any 
special configuration the phases of any two channels of USRP 2955 are phase 
coherent and the phase difference value is constant for a stationary source in 
one run of the application. However, for phase aligned operation that is 
instrumental phase difference between two channels to be zero we need LO 
sharing and time commands. So suppose I don’t phase align the system and find 
delay- rate spectrum then what impact the instrumental phase offset between two 
channels will have on the delays of sources in the DR spectrum. Will the offset 
add an additional delay to every source by a fixed amount or this will have 
some random effects on the delays of the sources in DR spectrum. You may be 
knowing but still, in delay-rate, rate stands for Doppler shift.

Regards,
Koyel

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From: Discuss-gnuradio  
on behalf of Marcus D. Leech 
Sent: Monday, July 27, 2020 12:18:01 AM
To: discuss-gnuradio@gnu.org 
Subject: Re: GRC max sample rate

On 07/26/2020 02:10 AM, Koyel Das (Vehere) wrote:
Hi Kyeong,

Since you have received at 200 MSPS data from usrp, I am asking this to you. 
What were your system parameters to receive at 200 MSPS like clock speed of 
processor, did you have DDR4 ram with ssd? And 10 gbps nic card? What clock 
speed of processor is needed? And what other things are needed?

I am asking this to compare with the parameters told to me by one of my 
friends. Since you have handled this data rate yourself you will be able to 
tell exactly.

So please help.

Regards,
Koyel


Let us for a moment pretend that we aren't talking about SDRs and USRPs and DSP.

Let us cast the problem more generally as "I need my computer to do 200 million 
'things' every second--can my computer do this?".

The answer to that question is categorically NOT simple and well characterized. 
 It really isn't.

The analysis breaks down along a number of different dimensions, including:

  o What are the 'things' you want to do at 200e6 'things per second'--how many 
CPU instructions does 'thing' decompose into, on average?
  o What is your CPU architecture?  Can it even handle that many 
instructions/second?
  o Is your CPU heavily or lightly pipelined?
  o Is it RISC or CISC?
  o Is there meaningful branch prediction and cache pre-fill?
  o Are there more than one CPUs in a given system
  o Does the CPU architecture have internal parallelism--multiple execution 
units for common operations like basic arithmetic
  o Are there multiple instruction-decode units in a single CPU?
  o Are floating-math units shared among CPUs on the chip, or are there 
dedicated FPUs?   Is there inherent parallelism in the FPU?
  o Are there vector execution units available, and does the software take 
advantage of them
  o What is the memory architecture? How fast is it?
  o What is the cache size--are there separate I and D caches?  How is 
cache managed?
  o What is the basic clock-rate of the CPU, and how does that decompose 
into memory bandwidth and instruction-fetch and other sub-cycles?
   o What is the I/O architecture, and how fast are the relevant buses--are 
there multiple buses?
   o Do I have enough RAM so that there's never any pressure on it so that 
large working-set sizes can be maintained?

   o What of the application?   What is the average code-path length for each 
'thing' that needs to be done?
   o Are there opportunities for parallelism in the application?  Have they 
been taken advantage of?
   o Does the operating system schedule CPU-bound jobs appropriately?  Can this 
be tweaked?

This is a fairly-standard "capacity planning" exercise that is, at a high 
level, unrelated to USRPs or SDRs or DSP.

Being robustly successful with SDR requires knowledge and experience in a 
number of disciplines including:

  RF and analog design
  Sometimes FPGA development and design
  Digital signal processing
  Computer system design and capacity planning
  Software development methodologies
  Non-trivial algorithm comprehension and development

If you, as an individual, or in aggregate as a development team, are missing 
too many of these, robust success will be a much longer time
  coming.  That's just an inherent property of doing SDR development, and 
deploying SDR-based systems.

Re: GRC max sample rate

[Marcus D. Leech]

On 07/26/2020 02:10 AM, Koyel Das (Vehere) wrote:

Hi Kyeong,

Since you have received at 200 MSPS data from usrp, I am asking this 
to you. What were your system parameters to receive at 200 MSPS like 
clock speed of processor, did you have DDR4 ram with ssd? And 10 gbps 
nic card? What clock speed of processor is needed? And what other 
things are needed?


I am asking this to compare with the parameters told to me by one of 
my friends. Since you have handled this data rate yourself you will be 
able to tell exactly.


So please help.

Regards,
Koyel


Let us for a moment pretend that we aren't talking about SDRs and USRPs 
and DSP.


Let us cast the problem more generally as "I need my computer to do 200 
million 'things' every second--can my computer do this?".


The answer to that question is categorically NOT simple and well 
characterized.  It really isn't.


The analysis breaks down along a number of different dimensions, including:

  o What are the 'things' you want to do at 200e6 'things per 
second'--how many CPU instructions does 'thing' decompose into, on average?
  o What is your CPU architecture?  Can it even handle that many 
instructions/second?

  o Is your CPU heavily or lightly pipelined?
  o Is it RISC or CISC?
  o Is there meaningful branch prediction and cache pre-fill?
  o Are there more than one CPUs in a given system
  o Does the CPU architecture have internal parallelism--multiple 
execution units for common operations like basic arithmetic

  o Are there multiple instruction-decode units in a single CPU?
  o Are floating-math units shared among CPUs on the chip, or are 
there dedicated FPUs?   Is there inherent parallelism in the FPU?
  o Are there vector execution units available, and does the 
software take advantage of them

  o What is the memory architecture? How fast is it?
  o What is the cache size--are there separate I and D caches? How 
is cache managed?
  o What is the basic clock-rate of the CPU, and how does that 
decompose into memory bandwidth and instruction-fetch and other sub-cycles?
   o What is the I/O architecture, and how fast are the relevant 
buses--are there multiple buses?
   o Do I have enough RAM so that there's never any pressure on it so 
that large working-set sizes can be maintained?


   o What of the application?   What is the average code-path length 
for each 'thing' that needs to be done?
   o Are there opportunities for parallelism in the application? Have 
they been taken advantage of?
   o Does the operating system schedule CPU-bound jobs appropriately?  
Can this be tweaked?


This is a fairly-standard "capacity planning" exercise that is, at a 
high level, unrelated to USRPs or SDRs or DSP.


Being robustly successful with SDR requires knowledge and experience in 
a number of disciplines including:


  RF and analog design
  Sometimes FPGA development and design
  Digital signal processing
  Computer system design and capacity planning
  Software development methodologies
  Non-trivial algorithm comprehension and development

If you, as an individual, or in aggregate as a development team, are 
missing too many of these, robust success will be a much longer time
  coming.  That's just an inherent property of doing SDR development, 
and deploying SDR-based systems.

Re: GRC max sample rate

[Marcus D. Leech]

On 07/26/2020 03:15 PM, Koyel Das (Vehere) wrote:

Hi Marcus,

Good that you replied my email. Since you work on Radio Astronomy as I 
heard from Neel, I want to ask you something. By using USRP I saw that 
without any special configuration the phases of any two channels of 
USRP 2955 are phase coherent and the phase difference value is 
constant for a stationary source in one run of the application. 
However, for phase aligned operation that is instrumental phase 
difference between two channels to be zero we need LO sharing and time 
commands. So suppose I don’t phase align the system and find delay- 
rate spectrum then what impact the instrumental phase offset between 
two channels will have on the delays of sources in the DR spectrum. 
Will the offset add an additional delay to every source by a fixed 
amount or this will have some random effects on the delays of the 
sources in DR spectrum. You may be knowing but still, in delay-rate, 
rate stands for Doppler shift.


Regards,
Koyel

Thinking about it for 30 seconds, I don't think it would have any impact 
on perceived doppler shift--it's a one-time phase diference only.  So 
distance
  estimates would be affected, but not doppler or doppler derivative, I 
think.


In radio astronomy interferometry, if the phases aren't aligned, then 
the "phase center" of the array isn't where you think it is, and that can
  lead to sky-position estimates being a bit wrong.  If your science 
goals don't include high-quality position estimates, then as long as the
  two sides "march together" (that is, are long-term phase-coherent, 
without necessarily having a zero phase offset), then you can still

  do science.

Re: GRC max sample rate

[Koyel Das (Vehere)]

Hi Marcus,

Many thanks for your reply. I saw in simulation adding a DC offset in the phase 
difference between two channels has no impact in the Delay- Rate spectrum. It 
is giving the same spectrum without this offset. The delays (td1-td2) are same 
in the delay spectrum with and without offset. Possibly a DC offset is not 
counted for while generating the DR spectrum by 2D FFT. Need to think what’s 
going on.

Regards,
Koyel

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From: Marcus D. Leech 
Sent: Monday, July 27, 2020 1:19:51 AM
To: Koyel Das (Vehere) ; discuss-gnuradio@gnu.org 

Subject: Re: GRC max sample rate

On 07/26/2020 03:15 PM, Koyel Das (Vehere) wrote:
Hi Marcus,

Good that you replied my email. Since you work on Radio Astronomy as I heard 
from Neel, I want to ask you something. By using USRP I saw that without any 
special configuration the phases of any two channels of USRP 2955 are phase 
coherent and the phase difference value is constant for a stationary source in 
one run of the application. However, for phase aligned operation that is 
instrumental phase difference between two channels to be zero we need LO 
sharing and time commands. So suppose I don’t phase align the system and find 
delay- rate spectrum then what impact the instrumental phase offset between two 
channels will have on the delays of sources in the DR spectrum. Will the offset 
add an additional delay to every source by a fixed amount or this will have 
some random effects on the delays of the sources in DR spectrum. You may be 
knowing but still, in delay-rate, rate stands for Doppler shift.

Regards,
Koyel

Thinking about it for 30 seconds, I don't think it would have any impact on 
perceived doppler shift--it's a one-time phase diference only.  So distance
  estimates would be affected, but not doppler or doppler derivative, I think.

In radio astronomy interferometry, if the phases aren't aligned, then the 
"phase center" of the array isn't where you think it is, and that can
  lead to sky-position estimates being a bit wrong.  If your science goals 
don't include high-quality position estimates, then as long as the
  two sides "march together" (that is, are long-term phase-coherent, without 
necessarily having a zero phase offset), then you can still
  do science.

Re: GRC max sample rate

[Koyel Das (Vehere)]

Hi Kyeong,

Since you have received at 200 MSPS data from usrp, I am asking this to you. 
What were your system parameters to receive at 200 MSPS like clock speed of 
processor, did you have DDR4 ram with ssd? And 10 gbps nic card? What clock 
speed of processor is needed? And what other things are needed?

I am asking this to compare with the parameters told to me by one of my 
friends. Since you have handled this data rate yourself you will be able to 
tell exactly.

So please help.

Regards,
Koyel

Get Outlook for iOS

From: Kyeong Su Shin 
Sent: Friday, July 24, 2020 3:32:33 PM
To: Koyel Das (Vehere) ; GNURadio Discussion List 

Subject: Re: GRC max sample rate

Hello Koyel:

I did one channel with 200 MSPS before, so probably yes (assuming that you are 
not doing any other processing).

Consider using sc16. Also, you can try using libuhd directly.

Regards,
Kyeong Su Shin

보낸 사람: Koyel Das (Vehere)  대신 Discuss-gnuradio 

보낸 날짜: 2020년 7월 24일 금요일 오후 5:59
받는 사람: GNURadio Discussion List 
제목: GRC max sample rate

Can GRC handle writing data from two channels of USRP at 100 MSPS each to a 
file in a RAM disk ? I am using 10G server and PCIe cable.

Get Outlook for iOS