Re: [Discuss-gnuradio] Max Output Power from the LFTX

[Marcus D. Leech]

>> 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 <address@hidden> 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" <address@hidden>
To: "address@hidden" <address@hidden>
Subject: [Discuss-gnuradio] Max Output Power from the LFTX
        daughterboard
Message-ID:
        <CACdmG=zCHATiwrtv=wBVLwG0_

5GQr0y=address@hidden>
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" <address@hidden>
To: address@hidden
Subject: Re: [Discuss-gnuradio] Max Output Power from the LFTX
        daughterboard
Message-ID: <address@hidden>
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

 

-- 
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org