Yes, it is 1 Mohm, and my probe is set to 1X.
Khalid
On Tue, Jan 6, 2015 at 3:33 PM, Nick Foster <bistrom...@gmail.com> wrote:
> Is the input impedance of your scope 1Mohm or 50 ohms? You sure you have
> the voltage multiplier (1x/10x) set correctly?
>
> On Tue, Jan 6, 2015 at 11:01 AM, khalid.el-darymli <
> khalid.el-dary...@mun.ca> wrote:
>
>> >> 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...
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>>>> 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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