Synchronising CSI readings from 2 receivers.

[Sourya Saha]

Hi.
I am working on an application which utilises the gr-ieee802-11 module. I
need to collect readings from 2 receivers. However, I want them
synchronised. What would be the best way to do that in GNURadio?

Re: Synchronising CSI readings from 2 receivers.

[Marcus Müller]

Hi,
can you elaborate what you mean with "synchronized"? A CSI estimate can only happen when 
the necessary pilots have been observed, and that will, due to finite speed of light, 
necessarily happen at different times at different receivers.


Best,
Marcus

On 08.08.24 18:19, Sourya Saha wrote:

Hi.
I am working on an application which utilises the gr-ieee802-11 module. I need to collect 
readings from 2 receivers. However, I want them synchronised. What would be the best way 
to do that in GNURadio?

Re: Synchronising CSI readings from 2 receivers.

[Marcus Müller]

Hi Sourya,

that is a different thing than you asked about originally :)

But in this case, this is "just" a matter of phase synchronizing different USRPs. See 
http://kb.ettus.com (and the Application notes there) on how, and for which specific USRP 
types, that can be achieved. All the things described there translate to GNU Radio.


Best,
Marcus

On 08.08.24 18:47, Sourya Saha wrote:

Hi Marcus,
By synchronized, I mean synchronization in phase and clock. I am not worrying about the 
CSI estimate because I can get that through the gr-ieee802-11 module itself. I am worried 
about phase and clock synchronizing 2 different USRPs in GNURadio. I do know that an 
octoclock can be used. But is there any other way to do it without any external hardware?


On Thu, Aug 8, 2024 at 12:44 PM Marcus Müller > wrote:


Hi,
can you elaborate what you mean with "synchronized"? A CSI estimate can 
only happen when
the necessary pilots have been observed, and that will, due to finite speed 
of light,
necessarily happen at different times at different receivers.

Best,
Marcus

On 08.08.24 18:19, Sourya Saha wrote:
 > Hi.
 > I am working on an application which utilises the gr-ieee802-11 module. 
I need to
collect
 > readings from 2 receivers. However, I want them synchronised. What would 
be the
best way
 > to do that in GNURadio?

Re: Synchronising CSI readings from 2 receivers.

[Sourya Saha]

Thanks, I'll check it out.

On Thu, 8 Aug 2024, 1:09 pm Marcus Müller,  wrote:

> Hi Sourya,
>
> that is a different thing than you asked about originally :)
>
> But in this case, this is "just" a matter of phase synchronizing different
> USRPs. See
> http://kb.ettus.com (and the Application notes there) on how, and for
> which specific USRP
> types, that can be achieved. All the things described there translate to
> GNU Radio.
>
> Best,
> Marcus
>
> On 08.08.24 18:47, Sourya Saha wrote:
> > Hi Marcus,
> > By synchronized, I mean synchronization in phase and clock. I am not
> worrying about the
> > CSI estimate because I can get that through the gr-ieee802-11 module
> itself. I am worried
> > about phase and clock synchronizing 2 different USRPs in GNURadio. I do
> know that an
> > octoclock can be used. But is there any other way to do it without any
> external hardware?
> >
> > On Thu, Aug 8, 2024 at 12:44 PM Marcus Müller  > > wrote:
> >
> > Hi,
> > can you elaborate what you mean with "synchronized"? A CSI estimate
> can only happen when
> > the necessary pilots have been observed, and that will, due to
> finite speed of light,
> > necessarily happen at different times at different receivers.
> >
> > Best,
> > Marcus
> >
> > On 08.08.24 18:19, Sourya Saha wrote:
> >  > Hi.
> >  > I am working on an application which utilises the gr-ieee802-11
> module. I need to
> > collect
> >  > readings from 2 receivers. However, I want them synchronised.
> What would be the
> > best way
> >  > to do that in GNURadio?
> >
>

Ettus N200 Connecting to Device

[Q W]

Hi there,
We are considering using a USRP N200 for a project,and want to figure out some 
technical details before placing the order. We planto use N200 to control our 
own device based on the analog RF signal sent fromthe device.
The general structure is to have the device’s outputconnected to the Rx port of 
N200. The output signal is processed in N200 and leads to the control (digital) 
signalswhich are fed back to tune the device. We plan to use SPI/GPIO ports for 
thefeedback channel. My question is if such SPI/GPIO ports are available on 
N200?Please note that our device is not a daughter board, so I am not sure if 
theSPI/GPIO shown on the data sheet of N200 can be used for the control 
purpose. 
If SPI/GPIO is not available for such control, is there any other connection 
interface for the control signal sent from N200? Our own device can be 
relatively flexible, so any connection scheme can be considered.  
Kind regards,

Tom

Re: Ettus N200 Connecting to Device

[Marcus D. Leech]

On 08/08/2024 20:18, Q W wrote:

Hi there,

We are considering using a USRP N200 for a project, and want to figure 
out some technical details before placing the order. We plan to use 
N200 to control our own device based on the analog RF signal sent from 
the device.


The general structure is to have the device’s output connected to the 
Rx port of N200. The outputsignal is processed in N200 and leads to 
the control (digital) signals which are fed back to tune the device. 
We plan to use SPI/GPIO ports for the feedback channel. My question is 
if such SPI/GPIO ports are available on N200? Please note that our 
device is not a daughter board, so I am not sure if the SPI/GPIO shown 
on the data sheet of N200 can be used for the control purpose.


If SPI/GPIO is not available for such control, is there any other 
connection interface for the control signal sent from N200? Our own 
device can be relatively flexible, so any connection scheme can be 
considered.


Kind regards,

Tom


USRP-specific questions should probably be posted on the usrp-users 
mailing list, rather than here.


However.  In the N200/N210 devices, the GPIO was exposed on the 
daughtercards.  SPI was really only used internally,

  between the motherboard and whatever daughter card(s) were installed.

The GPIO wasn't really designed for high-speed "stuff", which is what 
you'd need to "bit bang" an SPI interface out of

 the GPIO pins on whatever daughtercard you're using.

Re: Ettus N200 Connecting to Device

[Q W]

 Hi Marcus,
Thanks very much for your comments. I am sorry for sending my enquiry to the 
wrong mail-list. I agree with you that usrp users mailing list would be a 
better place to seek for help.
I am new to SDRs and this mail list system, and really appreciate your 
feedback. I come from the theoretical study of wireless communications, and 
this is my first practical project. Would you please be more specific on SPI 
and GPIO on N200? I reckon there won't be heavy traffic on the SPI/GPIO 
connection for control signals, so not sure if high data rate is necessary. 
Also can you please advise if there is any other interface on N200/N210 which I 
can use for the control purpose?
Kind regards,Tom 
On Friday, 9 August 2024 at 10:28:00 am AEST, Marcus D. Leech 
 wrote:  
 
  On 08/08/2024 20:18, Q W wrote:
  
 
 Hi there,   
We are considering using a USRP N200 for a project, and want to figure out some 
technical details before placing the order. We plan to use N200 to control our 
own device based on the analog RF signal sent from the device.
 The general structure is to have the device’s output connected to the Rx port 
of N200. The output signal is processed in N200 and leads to the control 
(digital) signals which are fed back to tune the device. We plan to use 
SPI/GPIO ports for the feedback channel. My question is if such SPI/GPIO ports 
are available on N200? Please note that our device is not a daughter board, so 
I am not sure if the SPI/GPIO shown on the data sheet of N200 can be used for 
the control purpose.  
  If SPI/GPIO is not available for such control, is there any other connection 
interface for the control signal sent from N200? Our own device can be 
relatively flexible, so any connection scheme can be considered.   
Kind regards,
 
Tom
  
   USRP-specific questions should probably be posted on the usrp-users mailing 
list, rather than here.
 
 However.  In the N200/N210 devices, the GPIO was exposed on the daughtercards. 
 SPI was really only used internally,
   between the motherboard and whatever daughter card(s) were installed.
 
 The GPIO wasn't really designed for high-speed "stuff", which is what you'd 
need to "bit bang" an SPI interface out of
  the GPIO pins on whatever daughtercard you're using.
 
 
   

Re: Ettus N200 Connecting to Device

[Marcus D. Leech]

On 08/08/2024 20:48, Q W wrote:

Hi Marcus,

Thanks very much for your comments. I am sorry for sending my enquiry 
to the wrong mail-list. I agree with you that usrp users mailing list 
would be a better place to seek for help.


I am new to SDRs and this mail list system, and really appreciate your 
feedback. I come from the theoretical study of wireless 
communications, and this is my first practical project. Would you 
please be more specific on SPI and GPIO on N200? I reckon there won't 
be heavy traffic on the SPI/GPIO connection for control signals, so 
not sure if high data rate is necessary. Also can you please advise if 
there is any other interface on N200/N210 which I can use for the 
control purpose?


Kind regards,
Tom
The SPI interface from the motherboard is really intended for 
communication with the internal workings of the daughtercards

  it connects to.

The GPIO is normally controlled by a host-based API, but one could write 
custom FPGA code to make GPIO do things in a more
  "clocked" fashion. One could even, I suppose, bring the SPI signals 
out of the box, but that isn't a supported thing, and

  both host-side and FPGA code would likely be required to make that work.

The N200 isn't really intended to operate without *SOME* kind of 
daughtercard(s) installed.  The motherboard itself

  doesn't really "do" RF by itself.




On Friday, 9 August 2024 at 10:28:00 am AEST, Marcus D. Leech 
 wrote:



On 08/08/2024 20:18, Q W wrote:
Hi there,

We are considering using a USRP N200 for a project, and want to figure 
out some technical details before placing the order. We plan to use 
N200 to control our own device based on the analog RF signal sent from 
the device.


The general structure is to have the device’s output connected to the 
Rx port of N200. The outputsignal is processed in N200 and leads to 
the control (digital) signals which are fed back to tune the device. 
We plan to use SPI/GPIO ports for the feedback channel. My question is 
if such SPI/GPIO ports are available on N200? Please note that our 
device is not a daughter board, so I am not sure if the SPI/GPIO shown 
on the data sheet of N200 can be used for the control purpose.


If SPI/GPIO is not available for such control, is there any other 
connection interface for the control signal sent from N200? Our own 
device can be relatively flexible, so any connection scheme can be 
considered.


Kind regards,

Tom


USRP-specific questions should probably be posted on the usrp-users 
mailing list, rather than here.


However.  In the N200/N210 devices, the GPIO was exposed on the 
daughtercards.  SPI was really only used internally,

  between the motherboard and whatever daughter card(s) were installed.

The GPIO wasn't really designed for high-speed "stuff", which is what 
you'd need to "bit bang" an SPI interface out of

 the GPIO pins on whatever daughtercard you're using.