I see. If you would like to diagnose the problem, we can ship you the malfunctioned daughterboard?
Thanks, Khalid On Fri, Jan 16, 2015 at 4:17 PM, Marcus D. Leech <mle...@ripnet.com> wrote: > On 01/16/2015 02:42 PM, khalid.el-darymli wrote: > > We were using only one Tx channel with the Subdev Spec in the USRP Sink is > set to A:AB > > Could the failure be due to that the other (idle) Tx channel is left > open circuit (i.e., not terminated by 50 ohms)? > > That seems quite unlikely. These aren't "precious princess" RF power > transistors, but reasonably-robust differential-to-unbalanced drivers. I'd > be very surprised if they couldn't handle an open-circuit condition. > > > > > > Khalid > > > On Fri, Jan 16, 2015 at 3:41 PM, Marcus D. Leech <mle...@ripnet.com> > wrote: > >> On 01/16/2015 02:08 PM, khalid.el-darymli wrote: >> >> Hi All, >> >> Just to update you in case somebody else comes across this problem. >> Following Mike's advice, we replaced the LFTX daughterboard with a new one. >> We're getting now 1 V p-p. This is around 4 dBm. >> >> Thanks very much for your help. >> >> Best regards, >> Khalid >> >> >> Interesting. The driver chip that's used, as a unity-gain >> differential-to-single-ended driver, is, according to the datasheets, >> pretty robust. So, it would >> be interesting to know exactly what the failure mode is. >> >> >> >> >> >> On Tue, Jan 6, 2015 at 2:38 PM, Michael Rahaim <mrah...@bu.edu> wrote: >> >>> Hi Khalid, >>> >>> I had a similar issue with an LFTX that I had been working with for >>> about two years. I actually had two boards running on separate USRP2's and >>> both were working fine for quite a while, but I recently noticed that one >>> had a drastically lower output range. I ended up replacing the LFTX and all >>> is working well now, so I'm assuming it was a hardware issue that came up >>> at some point. >>> >>> I didn't take the time to look for the problem, but I figured I'd >>> share this info since what you're seeing might be a hardware issue rather >>> than something you can resolve with settings. >>> >>> -Mike >>> >>> On Tue, Jan 6, 2015 at 12:59 PM, khalid.el-darymli < >>> khalid.el-dary...@mun.ca> wrote: >>> >>>> >>>> >> Output power is determined largely by baseband signal magnitude in >>>> that case. >>>> Yes, I understand. And I noticed that for baseband signal with an >>>> amplitude *> 1, * the pass-band signal gets clipped off. So I assume >>>> that an amplitude of 1 for the baseband signal should deliver the maximum >>>> output power (for the pass-band signal). >>>> >>>> My question was, what is the maximum power one can get for the >>>> pass-band signal output from LFTX? In your earlier reply, you said it is >>>> around +7dBm, am I getting this right? In my case, for a baseband amplitude >>>> of around 1, I am only getting *-28.13dBm*, much less than what you >>>> said, I am not sure,* why?* >>>> >>>> Thanks, >>>> Khalid >>>> >>>> >>>> On Tue, Jan 6, 2015 at 1:56 PM, Marcus D. Leech <mle...@ripnet.com> >>>> wrote: >>>> >>>>> Thanks Marcus for your reply. >>>>> >>>>> >> Probably somewhere in the neighborhood of +7dBm, maybe a little >>>>> more. >>>>> >>>>> >> The LF/BASIC series have *no* gain in either path, so you're just >>>>> looked >>>>> at buffered ADC ouput. >>>>> >>>>> So, ~ *+7dBm* is the max output power I supposed to get from the LFTX >>>>> daughterboard? How do I get that? >>>>> >>>>> Since I am only getting -28.13 dBm, does that mean I have some issue >>>>> with my LFTX daughterboard? >>>>> >>>>> >>>>> Khalid >>>>> >>>>> >>>>> Output power is determined largely by baseband signal magnitude in >>>>> that case. >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> Message: 2 >>>>> Date: Tue, 6 Jan 2015 10:13:45 -0330 >>>>> From: "khalid.el-darymli" <khalid.el-dary...@mun.ca> >>>>> To: "Discuss-gnuradio@gnu.org" <discuss-gnuradio@gnu.org> >>>>> Subject: [Discuss-gnuradio] Max Output Power from the LFTX >>>>> daughterboard >>>>> Message-ID: >>>>> <CACdmG=zCHATiwrtv=wBVLwG0_ >>>>> 5GQr0y=wksequrcajrtuv5...@mail.gmail.com> >>>>> Content-Type: text/plain; charset="utf-8" >>>>> >>>>> Hi, >>>>> >>>>> What is the maximum output power from the LFTX daughterboard when used >>>>> with >>>>> the USRP N200? >>>>> >>>>> According to this datasheet [1], the N200 with the WBX daughterbaord >>>>> provide an output power of 15 dBm. However, when using the LFTX >>>>> daughterboard, I am getting a much less output power. >>>>> [1] >>>>> http://www.ettus.com/content/files/07495_Ettus_N200-210_DS_Flyer_HR.pdf >>>>> >>>>> In GNU Radio with the USRP N200, we use a sinusoid with a frequency of >>>>> 150 >>>>> kHz and an amplitude of 0.98, fed into the LFTX daughterboard for a >>>>> center >>>>> frequency of 5 MHz. When the output of LFTX is plugged into a scope >>>>> terminated with a 50-ohm terminator, the scope reads 24.8 mV >>>>> (peak-to-peak). This is around -28.13 dBm. >>>>> >>>>> Is this the max power one can get out of the LFTX daughterboard? >>>>> >>>>> >>>>> Thanks. >>>>> >>>>> Best regards, >>>>> Khalid >>>>> -------------- next part -------------- >>>>> An HTML attachment was scrubbed... >>>>> URL: < >>>>> http://lists.gnu.org/archive/html/discuss-gnuradio/attachments/20150106/37846ff4/attachment.html >>>>> > >>>>> >>>>> ------------------------------ >>>>> >>>>> Message: 3 >>>>> Date: Tue, 06 Jan 2015 08:48:08 -0500 >>>>> From: "Marcus D. Leech" <mle...@ripnet.com> >>>>> To: discuss-gnuradio@gnu.org >>>>> Subject: Re: [Discuss-gnuradio] Max Output Power from the LFTX >>>>> daughterboard >>>>> Message-ID: <54abe798.5060...@ripnet.com> >>>>> Content-Type: text/plain; charset=UTF-8; format=flowed >>>>> >>>>> On 01/06/2015 08:43 AM, khalid.el-darymli wrote: >>>>> > Hi, >>>>> > >>>>> > What is the maximum output power from the LFTX daughterboard when >>>>> used >>>>> > with the USRP N200? >>>>> > >>>>> > According to this datasheet [1], the N200 with the WBX daughterbaord >>>>> > provide an output power of 15 dBm. However, when using the LFTX >>>>> > daughterboard, I am getting a much less output power. >>>>> > [1] >>>>> > >>>>> http://www.ettus.com/content/files/07495_Ettus_N200-210_DS_Flyer_HR.pdf >>>>> > >>>>> > In GNU Radio with the USRP N200, we use a sinusoid with a frequency >>>>> of >>>>> > 150 kHz and an amplitude of 0.98, fed into the LFTX daughterboard for >>>>> > a center frequency of 5 MHz. When the output of LFTX is plugged into >>>>> a >>>>> > scope terminated with a 50-ohm terminator, the scope reads 24.8 mV >>>>> > (peak-to-peak). This is around -28.13 dBm. >>>>> > >>>>> > Is this the max power one can get out of the LFTX daughterboard? >>>>> > >>>>> > >>>>> > Thanks. >>>>> > >>>>> > Best regards, >>>>> > Khalid >>>>> Probably somewhere in the neighborhood of +7dBm, maybe a little more. >>>>> >>>>> The LF/BASIC series have *no* gain in either path, so you're just >>>>> looked >>>>> at buffered ADC ouput. >>>>> >>>>> >>>>> >>>>> -- >>>>> Marcus Leech >>>>> Principal Investigator >>>>> Shirleys Bay Radio Astronomy Consortium >>>>> http://www.sbrac.org >>>>> >>>>> >>>>> >>>>> -- >>>>> Marcus Leech >>>>> Principal Investigator >>>>> Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org >>>>> >>>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> Discuss-gnuradio mailing list >>>> Discuss-gnuradio@gnu.org >>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio >>>> >>>> >>> >> >> >> >> > > > - > > >
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