Hi All, Thank you for your valuable comments. Another problem I faced is that when I used selector block of Gnuradio to switch between two different flow of data, it disconnected the ethernet and did not connected again unless I restart the application. I think this behavior is due to lock()/unlock() commands used in Selector block. Because of this problem I am unable to transfer data from one application to the other using TCP module of Gnuradio. Any suggestion would be appreciable
Regards: Muhammad Munir On Sat, Aug 26, 2017 at 5:12 PM, Marcus Müller via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi Kyeong, hi Cladio, dear Muhammad > > so, let me confirm a few things: > > 1. yes, a USRP can only be "owned" by one host at a time. > > 2. yes, a USRP N2xx has one complex ADC and one complex DAC. It usually > makes no sense to "split" these. They're really just one channel of complex > signal. Exceptions do exist (Basic and LF daughterboards), but in that > case, I'd still wonder what application this would be useful for. > > 3. UDP is not offering any link-layer security, indeed. But: The N2xx > isn't meant to be used over "the internet", but on direct links, where one > doesn't even have to expect reordering of packets, leave alone packet loss. > So yes, UDP is used, and the USRP never drops a packet (or at least, in my > years working with USRPs, I've never seen that happen). If a packet is > dropped, it's by a switch, or by your computer, because they aren't able to > keep up with the load, or they are buggy (yes, there's buggy ethernet > hardware). > > 4. No different software solution will inherently solve this. The "U" is > not because a packet got lost, but because your computer was *too slow* at > sending samples to the USRP. You must make your sending flowgraph faster, > or you must use a more capable PC, or maybe both. > > Then: > > Yes, with the N200, there is a chance to control the USRP with UHD running > on one computer, and streaming samples to another computer [1] and stream > them from another computer (simply send vita49 packets with a fake sender > IP address to the right port on the N200). Again, I highly doubt this > solves Munir's real problem, but I don't *know* that problem so far. I only > know what he thinks the solution is (which I doubt it is). > > So, Muhammad, please do feel encouraged to tell us in detail what your > application does, and where it spends the most of its time; then I'm > optimistic we'll be able to help you better! > > Best regards, > > Marcus > [1] http://files.ettus.com/manual/page_usrp2.html#usrp2_altstream > > On 25.08.2017 12:59, Kyeong Su Shin via USRP-users wrote: > > To whom it may concern: > > First, I am not an expert of USRP, so I could be wrong. > > A few thoughts: > > 1. A USRP N200 does have two DACs / ADCs, but they are typically used for > the I-Q sampling, so whether you can get two RX channels from a USRP N200 > depends on the installed daughterboards. (Well, you can theoretically split > the I channel and the Q channel, but I don't really see much benefit.) > > 2.I did not try manually decoding packets from the USRPs, so I could be > wrong, but maybe you can LAN tap your USRP using a dumb hub if the passive > listening is sufficient. (However, you probably have to write your own GNU > Radio sources). > > 3. Yes, TCP and UDP are theoretically unreliable, but you really shouldn't > lose too much packets when the connection is reliable and you are staying > under the capability of your network hardare. In fact, USRP N200 *uses* > UDP to communicate with your PC at approx. 800Mbps rate (for 25MS/s I-Q > sampling), and it rarely drops a packet (I saw a few packet drops, but when > and only when I used old NICs, switches, or cables). > > Regards, > Kyeong Su Shin > > On Fri, Aug 25, 2017 at 1:14 AM, Claudio Cicconetti via USRP-users < > usrp-users@lists.ettus.com> wrote: > >> Dear Munir, >> Your experiment confirms my theory: you cannot drive a single USRP from >> two applications. >> >> You need a custom application. I am no expert on Gnuradio, but I very >> much doubt you can achieve your objective with it. You should try >> writing a C/C++ application (or python with the new API if performance >> is not a major concern). >> >> Claudio >> >> On 08/25/2017 09:44 AM, Muhammad Munir wrote: >> > Dear Claudio, >> > Thanks for the reply. >> > I connected a single USRP with two PCs and tried to access USRP using >> two >> > different host PCs. When a USRP is engaged with one host, the other can >> not >> > get access to USRP. It means, we can access USRP by a single host at a >> > time. >> > The problem with the solution you suggested is that Gnuradio support for >> > communication between two applications is only through TCP or UDP which >> is >> > not reliable. I connected the application as given in figure. It gives >> USRP >> > underflow or overflow error. (UUUUUUUUUUUUUU or DDDDDDDDDDDD). >> > >> > Regards: >> > Munir >> > >> > >> > On Fri, Aug 25, 2017 at 12:16 PM, Claudio Cicconetti < >> > cciccone...@mbigroup.it> wrote: >> > >> >> Dear Muhammad, >> >> 1. Yes, it is possible to connect an N200 to a switch, then you can use >> >> any PC connected to that as the host for the USRP device. Just make >> sure >> >> the switch is GbE (1000 Mb/s), not Fast Ethernet (10/100 Mb/s). Note >> >> that this approach has been discouraged by Ettus in the past for a >> >> number of reasons, but it works in practice. >> >> >> >> 2. No, it is not possible for multiple applications to use the same >> USRP >> >> device, regardless of whether they reside in the same host or in >> >> different hosts in a LAN. >> >> >> >> If you really need to access the same USRP (any series) from two >> >> applications, then you have to use a "broker": a single application >> >> drives the USRP, then it dispatches/receives data via network or any >> >> other mechanism (shared memory, whatever) to/from other applications, >> >> possibly on different hosts. This solution is 100% in your hands: AFAIK >> >> there are not examples from Ettus on this. >> >> >> >> Note: the N200 has a single ADC/DAC, therefore I am assuming you have >> in >> >> mind some kind of TDD operation. >> >> >> >> Ciao, >> >> Claudio >> >> >> >> On 08/25/2017 07:41 AM, Muhammad Munir via USRP-users wrote: >> >>> Hi, >> >>> The USRP N200 has two channels. I want data of each channel to two >> >>> different computers (PCs). There is only one Ethernet connection is >> >>> available with USRP. My questions are >> >>> 1. Is it possible to connect a single USRP with two different PCs >> >> connected >> >>> on a same network through Ethernet switch? >> >>> 2. Is it possible to stream two channels of USRP to two different PCs? >> >>> Please Let me know the solution? >> >>> >> >>> Thanks in advance >> >>> Muhammad Munir >> >>> >> >>> >> >>> >> >>> _______________________________________________ >> >>> USRP-users mailing list >> >>> USRP-users@lists.ettus.com >> >>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> >>> >> >> >> >> >> > >> >> >> _______________________________________________ >> USRP-users mailing list >> USRP-users@lists.ettus.com >> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >> > > > > _______________________________________________ > USRP-users mailing > listUSRP-users@lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > > > > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com > >
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