[USRP-users] Basic TX - Can DAC keep a voltage level ?
matt at ettus.com
Mon Nov 15 00:05:59 EST 2010
The attenuation is a function of frequency. If you send a sine wave, it
is only one frequency, so it is just attenuated. A square wave is
composed of many frequencies, each attenuated a different amount, thus
The BasicRX and BasicTX are not designed to be used below 1 MHz. I've
said this several times.
On 11/13/2010 01:10 AM, Jorge Miguel wrote:
> Now I wonder how it is possible that I can send a perfect sine wave at
> frequencies of KHz (20KHz, 50KHz, 100KHz) to my oscilloscope from the
> basic TX. Shouldn´t it be filtered by the transformers?
> On 12 November 2010 17:34, Matt Ettus <matt at ettus.com
> <mailto:matt at ettus.com>> wrote:
> On 11/12/2010 06:13 AM, Jorge Miguel wrote:
> I am trying to tx different signals with USRP2-basic Tx and
> I can transmit a perfect sine wave.
> I can transmit a perfect pulsed carrier
> However, when trying to input the modulating pulse of the pulsed
> I see on my scope spikes corresponding to the moment in which
> the pulse
> should go up and down (negative and positive respectively) but I
> see a pulse shape. The duration of the pulse (time between
> spikes) and
> frequency as exactly the ones I set on my software.
> My thought is that the it can be possible that the DAC cannot drive
> enough current to my 50okms oscilloscope.
> Am I right? If not, what can be the reason?
> The DAC has absolutely no problem holding a DC level. You are using
> the BasicTX which has a transformer. The transformer blocks DC. If
> you want to output signals below 1 MHz you should use the LFTX
> instead, which does not have a transformer.
> This goes for the RX side as well. Anything under 1 MHz should use
> the LFRX instead of the BasicRX.
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