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Today's Topics:
1. basic question about usrp (Ahmed Alsawi)
2. Re: UHD buffer and libusb buffer, socket buffer and mmapped
ring buffer relations. (Nguyen Truong)
3. Re: SBX RF board simultaneous mode with USRP HardwareSupport
for MATLAB (Stan Gamla)
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Message: 1
Date: Sat, 14 Jul 2012 21:08:55 +0300
From: Ahmed Alsawi <[email protected]>
To: [email protected]
Subject: [USRP-users] basic question about usrp
Message-ID:
<ca+9pi22zbd9srbr3vsf2rezvc4e7quengupnhohttbwzsd9...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi All,
I want to know the function of decimation in receiver. i understand that
interpolation in transmission is to increase sample rate to 128 MS/s for
DAC.
is my understanding is right ? what decimation does ?
also, is there a way to search the mailing list archive ?
thanks for help.
-Ahmed
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Message: 2
Date: Sun, 15 Jul 2012 17:22:27 +0900
From: Nguyen Truong <[email protected]>
To: [email protected]
Subject: Re: [USRP-users] UHD buffer and libusb buffer, socket buffer
and mmapped ring buffer relations.
Message-ID:
<CAOpSyJSxkFDkBg1aynCdzNvd3UTg3U+dphic+SL9sWxHs+TH=g...@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"
Thank Josh,
I would like to ask you some questions.
Since USRP has three kinds of buffer: buffer at host (several MB); buffer
at FPGA (4kB for TX and 4kB for RX in USRP1 case) and buffer at the bus
controller (USB Fx2 is 2kB for Tx and 2kB for RX in USRP1 case)
- Buffer at host, as I know, is called UHD buffer that we can manage by the
*recv_buff_size and send_buff_size parameters *. Is it correct?
- How about buffer at FPGA and buffer at bus controller (Ethernet, GPMC) in
USRP2 and USRP E100? Are they the same with USRP1? Could we change these
buffers?
Let's take USB controller buffer as an example. For Tx side, the USB packet
is 512byte. The TX USB controller buffer is 2kB. Does that mean the
controller will send 4 USB packets at once to the FPGA when the buffer is
full?
- Could you explain more about the memory-mapped ring buffer in USRP E100
case?
Yes. Therefore, if you want to increase the samples per packet, you will
> need to increase the buffer size. Typically this is done to reduce
> header overhead.
>
> If you want to decrease samples per packet. Typically to reduce latency
> at low samples rates. TX control is already there, you just send smaller
> packets. For RX, set the spp parameter, documented here:
>
Did you mean the buffer at host?
Thank you!
On Mon, Jul 9, 2012 at 2:32 PM, Josh Blum <[email protected]> wrote:
>
>
> On 07/08/2012 12:57 PM, Nguyen Truong wrote:
> > Dears all,
> >
> > I would like to ask about the relations between UHD buffer and USB buffer
> > (USRP1 and USRP B100), Ethernet buffer (on USRP2 and USRP N series) and
> > memory-map ring buffers (USRP E series).
> >
>
> I think you will find helpful information here:
> http://files.ettus.com/uhd_docs/manual/html/transport.html
>
> > And another question is: does number of samples per packet play any role
> in
> > these buffers?
> >
>
> Yes. Therefore, if you want to increase the samples per packet, you will
> need to increase the buffer size. Typically this is done to reduce
> header overhead.
>
> If you want to decrease samples per packet. Typically to reduce latency
> at low samples rates. TX control is already there, you just send smaller
> packets. For RX, set the spp parameter, documented here:
>
>
> http://files.ettus.com/uhd_docs/doxygen/html/structuhd_1_1stream__args__t.html#a4463f2eec2cc7ee70f84baacbb26e1ef
>
> -josh
>
> _______________________________________________
> USRP-users mailing list
> [email protected]
> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
>
>
>
>
>
>
>
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Message: 3
Date: Sun, 15 Jul 2012 12:13:59 +0200
From: Stan Gamla <[email protected]>
To: "'Marc Erickson'" <[email protected]>,
<[email protected]>
Subject: Re: [USRP-users] SBX RF board simultaneous mode with USRP
HardwareSupport for MATLAB
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
Hi Marc,
Thanks for the kind offer to provide support.
In order to continue this thread within the community, I would like to
respond by repeating my previous request:
Could you please comment and perhaps provide an illustration of how to
configure the N210/SBX using both MATLAB and Simulink so that a signal is
transmitted from the RF1 port and received by the RF2. As a suggestion,
slider controls could be used in Simulink to independently adjust the RF
settings of both the transmitter and receiver to include at least gain and
center frequency. A spectrum of the received signal should be displayed.
With many thanks,
Stan
_____
From: Marc Erickson [mailto:[email protected]]
Sent: 05 July 2012 19:19
To: Stan Gamla; [email protected]
Subject: RE: [USRP-users] SBX RF board simultaneous mode with USRP
HardwareSupport for MATLAB
Hi Stan,
Sorry for the confusion about our support. We have stated some limitations
of our support in the product release notes which are available in the
download package. Type 'help sdru' and follow the 'Help and Examples' link.
Then click on the link under 'Release Notes'. The relevant limitation is
stated as follows:
"Communications with USRPT only supports half-duplex applications. MATLAB
and Simulink applications must be receive-only or transmit-only. Full-duplex
is not supported."
Our package has separate Rx and Tx blocks (for Simulink) and separate Rx and
Tx System objects (for MATLAB) with their own configuration parameters. We
allow binding the Rx and Tx to the same board in order to support some
duplex operations. Full duplex operation might be possible when adhering to
some modeling constraints.
Please feel free to contact us directly to discuss any use-cases and
specific applications you might be interested in pursuing and we'd be happy
to work with you.
Regards,
Marc
From: [email protected]
[mailto:[email protected]] On Behalf Of Stan Gamla
Sent: Friday, June 29, 2012 7:03 AM
To: [email protected]
Subject: [USRP-users] SBX RF board simultaneous mode with USRP Hardware
Support for MATLAB
As far as I understand, the Ettus SBX RF board comprises a full-duplex
transceiver with separate receive and transmit chains, each having its own
local oscillator.
https://www.ettus.com/product#tabs-3 states that:
"The SBX is a wide bandwidth transceiver that provides up to 100 mW of
output power, and a typical noise figure of 5 dB. The local oscillators for
the receive and transmit chains operate independently, which allows
dual-band operation. The SBX is MIMO capable, and provides 40 MHz of
bandwidth. The SBX is ideal for applications requiring access to a variety
of bands in the 400 MHz-4400 MHz range. Example application areas include
WiFi, WiMax, S-band transceivers and 2.4 GHz ISM band transceivers."
Further, according to their website "The MathWorks USRPR Hardware Support
from [sic] MATLAB and Simulink is compatible with UHDT-based Ettus radios".
http://www.mathworks.com/discovery/sdr/usrp.html viz:
"MATLAB and Simulink support for USRPR devices has been tested on N210 and
USRP2R devices with WBX, SBX, XCVR2450, TVRX, TVRX2, LFRX, LFTX, DBSRX, and
DBSRX2 daughterboards. Support may also extend to other UHDT-based radios
and daughterboards from National InstrumentsR."
Are both of these statements correct, I wonder?
If The MathWorks is tuned in to this channel, could you please comment and
perhaps provide an illustration of how to configure the N210/SBX using both
MATLAB and Simulink so that a signal is transmitted from the RF1 port and
received by the RF2. As a suggestion, slider controls could be used in
Simulink to independently adjust the RF settings of both the transmitter and
receiver to include at least gain and center frequency. A spectrum of the
received signal should be displayed.
On the other hand, if I have misunderstood what is meant by the word
"supported" could either Ettus or The MathWorks comment please.
Thanks,
Stan
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