discuss-gnuradio
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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


From: Marcus D. Leech
Subject: Re: [Discuss-gnuradio] Max Output Power from the LFTX
Date: Fri, 16 Jan 2015 14:11:36 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0

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 <address@hidden> 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 <address@hidden> 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 <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


 

_______________________________________________
Discuss-gnuradio mailing list
address@hidden
https://lists.gnu.org/mailman/listinfo/discuss-gnuradio







reply via email to

[Prev in Thread] Current Thread [Next in Thread]