[hpsdr] openHPSDR at the forefront of SDR development

[Helmut Oeller]

Hi,


I read a topical notification of the USB Promoter Group (HP, Intel, MS,
Renesas Elec, TI 
) that USB 3.1 will be already available end of 2014. This
smart (cheap) interface could be one option for a fast 10 Gbit/s connection
of future broadband DDC/DUC hardware and versatile computer architectures. I
think it's certainly worth to watch further progress and market.

73, Helmut, DC6NY
 


-----Ursprüngliche Nachricht-----
Von: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von John
Laur
Gesendet: Dienstag, 26. August 2014 22:27
An: HPSDR list
Betreff: Re: [hpsdr] openHPSDR at the forefront of SDR development

***** High Performance Software Defined Radio Discussion List *****

All,

Thank you for the good discussion. My intention was not to focus too much on
the Jetson discussion actually; I do know that if the code runs on Jetson I
can happily build a small linux machine that will also run it, so nobody is
"locking" anyone into any particular thing.
I just think the Jetson is a low mark to aim for. If it can do a realtime
30mHz FFT, so can basically any current GPU. Even low power cards like the
GeForce 750 Ti will run circles around it, while drawing 60W and costing
less. I think anyone who has ever compiled up the fosphor plugin on GNU
Radio has probably lamented not having that view available all the time. So
I wont beat on Jetson any more.

I just thought while we were on the subject of architectures it would be a
good time to cut to the chase on the bandwidth problem. While I will agree
with Hermann that SDR hardware (and the HDL features of
HPSDR) seem to be changing as fast or faster than SDR software in recent
months, I also think it ought to be the other way around. On the big list of
SDR's from Wikipedia
http://en.wikipedia.org/wiki/List_of_software-defined_radios I note only 2
devices use PCIe. I think the hardware is changing largely because of all
the ways that developers are choosing to deal with the problems of interface
constraints; hardware that can filter this amount of data at this datarate
is neither easy nor cheap to engineer.
There is no need to go to this length if you can just move all the data in
the first place. But if the GPU architecture is the way forward, it's just
silly to put an intermediate interface that requires a lot of HDL work in
the way. For a direct sampling design the most future proof design possible
is to make sure the hardware is at minimum capable of sending the raw
ADC/DAC/Clock data in and out at full datarate to an attached device.

IMO the reason working with the SoCKit hardware and Scotty's boards is
probably so nice is because the interface from the FPGA to the software is
basically transparent. (This is half speculation as I have a SoCKit that I
have used quite a bit but have not yet put funds together for a board set
from Scotty) There is no ethernet PHY and framing and protocol to get at the
DDC data; the CPU just opens a device and starts reading. If That eliminates
a lot of complexity. But you could easily plug his board set into a
different dev kit like this
http://www.altera.com/products/devkits/altera/kit-cyclone-v-gt.html
and with some (admitted) effort you could make yourself a prototype PCIe
HPSDR card right now that could do DMA transfers of ADC samples right into
GPU memory with the same sort of ease. This is the beauty of a high speed
interconnect standard. In this case it is HSMC, useful only within a certain
scope, but it makes the point I think.

A comment for Marc: From what I have seen Mini-PCIe is generally only ever
offered with a x1 interface with the exception of MXM, so it makes more
sense to adapt a PCIe card to the mini-PCIe form factor than vice versa;
that way the card can be designed as a 4x or such.
(It can always be allowed to fall back to 1x)

Anyway to sum it all up neatly, a single integrated board like Hermes with a
Cyclone V SoC part on board that can be used standalone or plugged in and
used as a PCIe card would be pretty attractive HPSDR platform, I gotta say.

73, John KF5SAB
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