Re: [Discuss-gnuradio] Understanding flow control

2010-01-18 Thread Tom Gross
On Sat, Jan 16, 2010 at 2:09 PM, Matt Ettus m...@ettus.com wrote: What daughterboards are you using?  If it is the BasicRX or LFRX and BasicTX or LFTX, the you are probably better off doing this all in the same USRP2.  It would take some relatively small modifications to the FPGA. We are

Re: [Discuss-gnuradio] Understanding flow control

2010-01-16 Thread Tom Gross
Hi Matt, I'll try hooking up my ttl line on Monday (I have done that but not with our current configuration, so far only when I was playing around with building custom firmware). Here's the official description of what we are doing (I hope this helps!): We have two USRP2s sharing common clocks

Re: [Discuss-gnuradio] Understanding flow control

2010-01-16 Thread Matt Ettus
On 01/16/2010 09:03 AM, Tom Gross wrote: Hi Matt, I'll try hooking up my ttl line on Monday (I have done that but not with our current configuration, so far only when I was playing around with building custom firmware). Here's the official description of what we are doing (I hope this helps!):

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Tom Gross
We've tried it with and without a switch - definitely better without the switch. Thinking about our setup the behavior actually makes sense to me, although I'm waiting to discuss it with my signal processing guru. two usrp2s, connected with a mimo cable. the slave is just getting its clock from

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Tom Gross
Thanks Eric, that's exactly what I thought. I think in our application it's probably better to drop data, or at least that's why things are more stable for us when RX is OFF. Or maybe we should just slow down a bit. Something to think about. On Fri, Jan 15, 2010 at 2:07 PM, Eric Blossom

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Matt Ettus
Incidentally my System Engineer/Project Lead points out that if the USRP2 is actually telling the host to stop sending (which certainly appears to be the case) then we are only able to get overall throughput with two USRP2s over two gig-e connections comparable to what we were getting with a

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Tom Gross
yes of course we have two separate gig-e cards. if the usrp2 is sending us pause commands then it seems evident the usrp2 is having trouble keeping up, not the computer. On Fri, Jan 15, 2010 at 6:04 PM, Matt Ettus m...@ettus.com wrote: Incidentally my System Engineer/Project Lead points out

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Tom Gross
Matt, What is the maximum data rate that the USRP2 transmitter can accept from the host without firing pause signals back to the host? -Tom On Fri, Jan 15, 2010 at 6:04 PM, Matt Ettus m...@ettus.com wrote: Incidentally my System Engineer/Project Lead points out that if the USRP2 is actually

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Johnathan Corgan
On Fri, Jan 15, 2010 at 15:08, Tom Gross tomgr...@gmail.com wrote: yes of course we have two separate gig-e cards.   if the usrp2 is sending us pause commands then it seems evident the usrp2 is having trouble keeping up, not the computer. The host software, when creating a data stream to be

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Matt Ettus
On 01/15/2010 03:14 PM, Tom Gross wrote: Matt, What is the maximum data rate that the USRP2 transmitter can accept from the host without firing pause signals back to the host? See my other message. The USRP2 will ALWAYS put out pause frames. In fact, when the data rate is low it will

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Matt Ettus
On 01/15/2010 03:08 PM, Tom Gross wrote: yes of course we have two separate gig-e cards. if the usrp2 is sending us pause commands then it seems evident the usrp2 is having trouble keeping up, not the computer. First off, the USRP2 will only send pause frames when you are transmitting, not

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Tom Gross
Thanks Matt, Eric and Jonathan (hope I didn't forget anyone. :-) ). We greatly appreciate the information and need to think about stuff on our end. I've been deliberately vague about our application (not that I could really explain it even if I felt authorized discuss it). The thing to

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Matt Ettus
On 01/15/2010 03:53 PM, Tom Gross wrote: Thanks Matt, Eric and Jonathan (hope I didn't forget anyone. :-) ). We greatly appreciate the information and need to think about stuff on our end. I've been deliberately vague about our application (not that I could really explain it even if I felt

Re: [Discuss-gnuradio] Understanding flow control

2010-01-15 Thread Jeff Brower
Tom- Thanks Matt, Eric and Jonathan (hope I didn't forget anyone. :-) ). We greatly appreciate the information and need to think about stuff on our end. I've been deliberately vague about our application (not that I could really explain it even if I felt authorized discuss it). The thing

[Discuss-gnuradio] Understanding flow control

2010-01-14 Thread Charles Irick
Hello, I'm trying to understand the flow control between the USRP2 and host machine. I assume that it needs to be worked out where the USRP2 will always have a constant stream of uninterrupted radio data when sending and receiving (unless a more complex radio is in place which allows the signal to

Re: [Discuss-gnuradio] Understanding flow control

2010-01-14 Thread Eric Blossom
On Thu, Jan 14, 2010 at 02:13:01PM -0500, Charles Irick wrote: Hello, I'm trying to understand the flow control between the USRP2 and host machine. I assume that it needs to be worked out where the USRP2 will always have a constant stream of uninterrupted radio data when sending and receiving

Re: [Discuss-gnuradio] Understanding flow control

2010-01-14 Thread Tom Gross
That's very interesting... just this morning we were playing with turning rx OFF with ethtool and convincing ourselves that it seemed to stabilize our system. If we turn off RX pause (ethtool -A eth0 rx off), does the USRP2 stop sending pause frames? We are running two USRP2s connected with a

Re: [Discuss-gnuradio] Understanding flow control

2010-01-14 Thread Tom Gross
Following up on my previous email, thinking about this some more: I'm guessing that we are sending the USRP2 more data than it can handle, it is sending pause packets back, which when RX is ON, the ethernet card recognizes and slows down its output (not knowing anything about gig-e control flow