Forum: GNU Radio Padding for USRP

A82aa1d4b86ddc98aac2e6203440468d?d=identicon&s=25 Manu T S (Guest)
on 2013-02-27 03:08
(Received via mailing list)
In gnuradio/digital/packet_utils, the packets are padded to make it a
multiple of 512 bytes to be sent across the USB(As per the comment
there).

USRP2 and N210 uses ethernet connection. Is it important to have padding
for USRP in for these devices? If so is it the same number? ( 512 bytes
to
be sent across ethernet )

Thank you in advance.
D7c45fe2b9d1bc4156cebeb19a3a2b63?d=identicon&s=25 Josh Blum (Guest)
on 2013-02-27 03:13
(Received via mailing list)
On 02/26/2013 08:03 PM, Manu T S wrote:
> In gnuradio/digital/packet_utils, the packets are padded to make it a
> multiple of 512 bytes to be sent across the USB(As per the comment there).
>
> USRP2 and N210 uses ethernet connection. Is it important to have padding
> for USRP in for these devices? If so is it the same number? ( 512 bytes to
> be sent across ethernet )
>

You should not need any padding. All of the devices (except usrp1) send
samples encapsulated in a packet format so the boundaries of the samples
are known by the device.

I dont think you need the padding for USRP1 either, since UHD will flush
out the buffer to a 512 byte multiple if it sees the EOB specified.

-josh
C539637020fd56193dd6daec746c4a84?d=identicon&s=25 Tom Rondeau (Guest)
on 2013-02-27 16:11
(Received via mailing list)
On Tue, Feb 26, 2013 at 9:12 PM, Josh Blum <josh@ettus.com> wrote:
>
> You should not need any padding. All of the devices (except usrp1) send
> samples encapsulated in a packet format so the boundaries of the samples
> are known by the device.
>
> I dont think you need the padding for USRP1 either, since UHD will flush
> out the buffer to a 512 byte multiple if it sees the EOB specified.
>
> -josh

Yeah, that requirement comes from back in the libusrp days where it
was just a pipe that we provided samples to and had to make sure the
boundaries were met ourselves before sending along. With the UHD
interface, you can safely ignore it.

Tom
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