On 01/16/2015 02:54 PM, khalid.el-darymli wrote:
I see. If you would like to diagnose the problem, we can ship you the malfunctioned daughterboard?

Thanks,
Khalid

Thanks. I personally wouldn't have time/equipment to really diagnose it. So it would be up to Ettus R&D as to whether they want it back to see
  what the failure mode is.

I've been doing Ettus support for 6 years, and LF_TX are not generally items that show up with RMA requests very often.




On Fri, Jan 16, 2015 at 4:17 PM, Marcus D. Leech <mle...@ripnet.com <mailto: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 <mailto: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 <mailto: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
            <mailto: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 <mailto: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
                    <mailto:khalid.el-dary...@mun.ca>>
                    To: "Discuss-gnuradio@gnu.org
                    <mailto:Discuss-gnuradio@gnu.org>"
                    <discuss-gnuradio@gnu.org
                    <mailto:discuss-gnuradio@gnu.org>>
                    Subject: [Discuss-gnuradio] Max Output Power
                    from the LFTX
                    daughterboard
                    Message-ID:
                    <CACdmG=zCHATiwrtv=wBVLwG0_
                    5GQr0y=wksequrcajrtuv5...@mail.gmail.com
                    <mailto: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
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                    Message: 3
                    Date: Tue, 06 Jan 2015 08:48:08 -0500
                    From: "Marcus D. Leech" <mle...@ripnet.com
                    <mailto:mle...@ripnet.com>>
                    To: discuss-gnuradio@gnu.org
                    <mailto:discuss-gnuradio@gnu.org>
                    Subject: Re: [Discuss-gnuradio] Max Output
                    Power from the LFTX
                    daughterboard
                    Message-ID: <54abe798.5060...@ripnet.com
                    <mailto: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 Consortium
                    http://www.sbrac.org




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