Hi,
Previously I have posted the thread about the power issues of UBX 160 daughterboard, I have been trying new driver 3.11 and different version of UBX 160 and SBX v3. And I found that in TDD mode Tx power is different for different version of daughterboard. It seems that for SBX V3 and UBX160 V1, maximum Tx power is quite strong while TX and RX sharing one anteena in TDD mode. However, if I swap to UBX160 V2 to run with same code and setting, it shows dramatically Tx power drop of about 30dB weaker than with UBX160 V1. According to manual of SPDT switch SKY13350-385LF, the isolation is about 22dB at 3.5GHz , which means that if we use maximum Tx and Rx gain we could burn mixer with power leaked through SPDT switch in TDD mode(20-22+31=29dbm>15dbm)? It seems that in V2 this is avoided by constraining Tx power to very low level in TDD mode. However, in our project we really need to have full Tx power in TDD mode, is there anyway to apply full transmit power on UBX160V2 in TDD mode? Thank you very much! Liang Hi, Thanks for the reply! For the moment, if I upgrade to latest version of UHD, my programe does not work properly(lots of LLLLLL). Therefore I could not tell if it helps or not. The "L" indicator indicates *late* samples--you are setting a send time on your bursts and by the time the burst arrives at the USRP, that time has already passed. Make sure that you are properly synchronized in time with the USRP in scheduling bursts. ==================================================================================================== Yes, the TDD system is little complicated and it would be nice to figure out if new driver works before I adapt it to new driver. I will try to test new driver power output. One burst is about half millisecond. I thought it is long enough, is it? 500usec should be long enough, yes. There'll be a few usec of transition time at the beginning. ==================================================================================================== Do you have any clue about the reason for this very strange power issue? It seems that switch to port "RX2" change some setting and influence the power output. Could you list some source file of uhd driver which might influence the power output? Thank you very much! Sincerely, Liang Zhou ________________________________ 发件人: USRP-users <usrp-users-boun...@lists.ettus.com><mailto:usrp-users-boun...@lists.ettus.com> 代表 Marcus D. Leech via USRP-users <usrp-users@lists.ettus.com><mailto:usrp-users@lists.ettus.com> 发送时间: 2017年12月11日 8:13 收件人: usrp-users@lists.ettus.com<mailto:usrp-users@lists.ettus.com> 主题: Re: [USRP-users] Weak power with X310 and ubx160 with TDD system. On 12/09/2017 08:27 AM, 周 亮 via USRP-users wrote: Hi, I build a TDD system with X310 and ubx160 v2, which uses TX/RX for both TX and RX. However I found the TX output power is extremely weak. Then I tried to assign RX2 as receiver anteena and I get approximately 20dB stronger TX signal with almost same code. The main difference is: for two anteena case, in each subframe TX send one burst, while in one anteena case, TX just sends zeros instead of stoping transmission. The installed uhd version is 3.9.7. Does anybody know what could possibly be reason for this? And how could I achieve full power with single anteena TDD system? Thank you! Are you able to upgrade to a newer UHD version? Does that help? How long are your bursts? Is it possible that they're shorter than the switching time? _______________________________________________ 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
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