[USRP-users] LFTX Pk-Pk voltage

Nemanja Savic vlasinac at gmail.com
Thu Apr 30 04:46:50 EDT 2015


Hi all,

well, the problem is as usual, time, so the fastest solution was to cjange
feedback resistor and to boost gain, which I did.
@Marcus Mueller: Thank you for your suggestion. I would probably end up
with some schmitt trigger, but since I use only square wave signal, maybe
it would only be a transistor. I would also make DC coupling without C1 and
C2.

Best,
Nemanja

On Wed, Apr 29, 2015 at 5:34 PM, Marcus Müller <usrp-users at lists.ettus.com>
wrote:

>  In addition to what the other Marcus said, if you really want to make an
> TTL impulse out of the signal, I'd try something like hooking up a
> comparator between the center and either a reference voltage (zener diode
> or just a voltage divider); the LM339 isn't really an investment by itself,
> and I'm pretty optimistic that TI might give you a sample for free, but
> basically any comparator should work (note that I wouldn't trust this one
> over >1MHz). All these values are absolutely "Um, I just came up with this,
> because that's what I'd have in my cabinet" (OK, R1 matches the source
> impedance, so you might want to stick with it, but then again... this
> doesn't really matter). Add a feedback resistor between Pin 1 and 3 if you
> want hysteresis; it depends a bit on your signal and the comparator you use
> which resistance you'd want for that. I'd start with 5 times R3. Notice
> that without any feedback, you might see this thing go into oscillation if
> you just let its inputs float (or just supply a DC voltage). So maybe I
> should have added that to the schematic below. Oh well.
> [image: schematic]
>
>
> Best regards,
> Marcus
>
>
> On 04/29/2015 03:51 PM, Nemanja Savic via USRP-users wrote:
>
>  Hello and thank you Marcus (and other guys),
>
>  I should have taken a look on schematic. My idea was to drive external
> trigger of HAMEG programmable synthesizer, which accepts TTL level and it
> looks like I will have to change that feedback resistors.
>
>  Best
>
> On Tue, Apr 28, 2015 at 7:15 PM, <mleech at ripnet.com> wrote:
>
>>  In  my reply earlier, I said "ADC", when in fact I meant "DAC".  The
>> DAC still has a reference level, set by the DAC hardware--thanks to Ian for
>> politely and discretely pointing this out :)
>>
>>
>>
>> Which means that output levels will vary somewhat among different USRP
>> "host" devices.
>>
>>
>>
>>
>>
>>
>> On 2015-04-28 06:27, Nemanja Savic via USRP-users wrote:
>>
>>   Hi all guys,
>>
>>  I wonder whether possible to drive LFTX output to more than 1V Pk-Pk,
>> which is at the moment maximum that I can get.
>>
>>  Thanx,
>>
>> --
>> Nemanja Savić
>>
>>   _______________________________________________
>> USRP-users mailing listUSRP-users at lists.ettus.comhttp://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>
>
> --
> Nemanja Savić
>
>
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-- 
Nemanja Savić
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