Ray, Although Flex's decision is now in the past and there is not much point to discuss this, I have to disagree with this statement. > & USB 2.0 was simply not fast enough to handle the data transfer rates
I count only 5 streams of I/Q data and not all of them need to be (and they are actually not) concurrent on the line or with the same sampling rate. Even though with your assumption of 6 full blown streams concurrently we have 6 (streams) x 2 (I+Q) x 192000 (samples/sec) x 24 (bits) = 55 296 000 so its something in the range of 55 MBps and as we know, USB 2.0 is rated theoretically at 480Mbps with most of the market systems to be able to achieve ~300MBps Obviously the USB 2.0 data transfer rates are more than enough, so the decision has to be taken for other reasons. Also regarding the concurrent 'streams' issue, the USB by definition can handle 16 incoming and 16 outgoing pipes (or endpoints). I do not knkow how the 'only two' came on the table previously. My best bet on the firewire decision is that at the time it was a complete solution with a decent development environment that could make Flex programmers life easier. I mean the firewire cpu chip in the new designs F5K/F3K. Also it was an overkill, but more redundancy in power is better when in commercial applications. On the other hand I might be wrong, but that was my 2c. 73, Christos SV1EIA On Mon, Jan 11, 2010 at 10:25 PM, K9DUR <[email protected]> wrote: > Peter, > > The software is full duplex, plus it uses both I & Q signals for both TX & > RX. Therefore the communications link has to simultaneously handle 4 > real-time, high-speed streams (threads) of digitized audio plus digital > control signals. The is for the FLEX-3000 or the FLEX-5000 without RX2 > installed. The FLEX-5000 with RX2 requires 6 audio streams plus control. > > To the others who got into this discussion more recently: > > At the time that the FLEX-5000 was being designed, USB 3.0 was not a reality > & USB 2.0 was simply not fast enough to handle the data transfer rates > required. At the time, 1394 was the best option. > > Is USB 3.0 fast enough to handle the required data rate? I don't know. But > to switch now to USB 3.0 or to TCP/IP (Ethernet) would require major > redesign of the hardware. Existing radios would not be able to be easily > retrofitted to use the new technology. Plus a major software effort would > be required to support the new communications method. Could it be done? Of > course. Is it reasonable to do so? I think not. > > 73, Ray, K9DUR > http://k9dur.info > > > > > > _______________________________________________ > Flexedge mailing list > [email protected] > http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz > This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used > for posting topics related to SDR software development and experimentalist > who are using alpha and beta versions of the software. > _______________________________________________ Flexedge mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexedge_flex-radio.biz This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for posting topics related to SDR software development and experimentalist who are using alpha and beta versions of the software.
