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)? 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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