Re: [Discuss-gnuradio] Could transmitter and receiver alternately work in time on the same USRP1 with LFTX/RX?

On Tue, 2011-02-08 at 13:29 -0500, Yan Nie wrote:
> Dear all,
>
> I'm developing a radar transmitter and receiver on USRP1 and LFTX/RX. The transmitter and receiver are working fine separately on two USRP1 with TX and RX daughter board plugged in. I'm trying to make the transmitter and receiver alternately work in time on the same USRP1. For instance, transmitting signal for 0.52ms then disabling TX and enabling RX simultaneously for signal reception for 1ms. Then this process will repeat over and over again.
>
> Is it possible to get the TX and RX wok on the same USRP1 motherboard with both RX and TX? The reason why I'm asking this question is that it seems impossible to call usrp_source or usrp_sink block every millisecond to enable TX or RX, since usrp_source loads FPGA image only with TX path enabled and usrp_sink does only with RX path enabled, if my reading of the source code usrp_standard.cc services me right. In addition, loading the whole FPGA image takes longer time than 1ms, which will cause USRP overrun problem if shifting TX to RX or RX to TX every millisecond as my experiments showed me. Therefore, I'm wondering if there is an approach to allow the TX and RX to alternately work in time on the same USRP1 board rather than calling usrp_source or usrp_sink to make this TX/RX altering. Simply, is there any mean to shift TX and RX back and forth every two milliseconds and repeat over and over again by loading FPGA image only once for the whole process.
>

You might consider just running TX and RX simultaneously instead of only
enabling RX after the TX pulse. This has the ancillary benefit of giving
you a precise time reference for the outgoing pulse, removing any
uncertainty in the delay time between turning off TX and turning on RX.

--n

> I will really appreciate if any suggestion on how to solve this problem.
>
> Wish you a great day!
>
> Thanks,
> Yan
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