>> Trying setting a gain in your sink block of, let's say, 20dB, with a
magnitude of 0.9. What power output do you get? How are you measuring
power?
This gives me 23.2 mV (peak to peak). This is the reading I get from a
scope connected to a T. For the input ends of the T, one end is connected
to a 50-ohm terminator and the other end is connected to the output from
LFTX. This gives a power of: 30+10 log_10[{23.2e-03/[2*sqrt(2)]}^2/50]=
*-28.711* dBm.
>> What is your flow-graph actually doing? Have you tried both connectors
on the LFTX?
Simple, a signal source (Sine) block directly connected to a USRP Sink
block.
Yes, both connectors on the LFTX daughterboard give the same voltage
reading.
Thanks,
Khalid
On Tue, Jan 6, 2015 at 2:34 PM, Marcus D. Leech <mle...@ripnet.com> 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
>
> For a magnitude of ~1, you should see maximum amplitude signals coming
> out of it.
>
> You could try setting gain, but on any platforms with VGAs in the DAC,
> there's only about 6dB of gain range settable. Trying setting a gain in
> your
> sink block of, let's say, 20dB, with a magnitude of 0.9. What power
> output do you get? How are you measuring power? What is your flow-graph
> actually doing? Have you tried both connectors on the LFTX?
>
>
>
>
> 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
>>
>>
>
>
>
>
>
> --
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org
>
>
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