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 <mailto: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 <mailto: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 <mailto:USRP-users@lists.ettus.com> > >>> > http://lists.ettus.com/mailman/listinfo/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 <mailto:USRP-users@lists.ettus.com> > http://lists.ettus.com/mailman/listinfo/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
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