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Re: [Discuss-gnuradio] USRP packet parsing
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] USRP packet parsing |
Date: |
Wed, 21 Mar 2007 10:47:47 -0700 |
User-agent: |
Mutt/1.5.9i |
On Wed, Mar 21, 2007 at 12:52:30PM -0400, Brian Padalino wrote:
> On 3/21/07, Thibaud Hottelier <address@hidden> wrote:
> >How do the fpga know is data is interleaved or not ?
>
> I believe all samples sent down is interleaved over USB to 16-bit I
> followed by 16-bit Q samples.
See below for more about 1, 2, 4, 8 and 16-bit I/Q.
> These can be concatenated (since they are of the same sample time)
> to 1 32-bit number to store within a block ram within the FPGA.
Yes.
> Doing real-only transmissions could possibly be a status bit to say
> what the data format is?
I think that the format should be an attribute of the data channel.
Below is the current format register def. Assume we (eventually)
support 1, 2, 4, 8 and 16 bit components. The half-band bit (B)
probably ought to get moved to a different register.
/*!
* \brief Specify Rx data format.
*
* \param format format specifier
*
* Rx data format control register
*
* 3 2 1
* 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0
* +-----------------------------------------+-+-+---------+-------+
* | Reserved (Must be zero) |B|Q| WIDTH | SHIFT |
* +-----------------------------------------+-+-+---------+-------+
*
* SHIFT specifies arithmetic right shift [0, 15]
* WIDTH specifies bit-width of I & Q samples across the USB [1, 16] (not
all valid)
* Q if set deliver both I & Q, else just I
* B if set bypass half-band filter.
*
* Right now the acceptable values are:
*
* B Q WIDTH SHIFT
* 0 1 16 0
* 0 1 8 8
*
* More valid combos to come.
*
* Default value is 0x00000300 16-bits, 0 shift, deliver both I & Q.
*/
> >I am still worried about the number of fifo that will be used and their
> >size. The FPGA looks pretty full. Is there a way to have a memory
> >separated from the FPGA that I could access through a bus?
>
> We'll be removing one of the RX channels I believe, which frees up a
> multiplier and a whole boatload of memory. Moreover, the Cyclone has
> special hard memory blocks that are 4096 bits of dual-port memory.
> That gives us 128 locations for complex sample storage in a single
> block. If more blocks are used (which are available), you just double
> the number every time.
>
> It's a lot of FIFOs, but if they are necessary then you have to use
> them. It's a trade off that you should be aware of, but is also
> easily checked. Download Quartus II from altera.com and compile the
> design for the target FPGA. Disable the other RX channel and
> re-compile to see the change in resources.
>
> What do you think?
Sounds good to me.
> >Thibaud
>
> Brian
Eric
- Re: [Discuss-gnuradio] USRP packet parsing, (continued)
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/19
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/19
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/20
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/20
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/20
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/20
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/20
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/20
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/21
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/21
- Re: [Discuss-gnuradio] USRP packet parsing,
Eric Blossom <=
- Re: [Discuss-gnuradio] USRP packet parsing, Eric Blossom, 2007/03/21
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/21
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/21
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/22
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/22
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/22
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/22
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/22
- Re: [Discuss-gnuradio] USRP packet parsing, Brian Padalino, 2007/03/22
- Re: [Discuss-gnuradio] USRP packet parsing, Thibaud Hottelier, 2007/03/22