Re: [Discuss-gnuradio] Multiplexing modulators

[John Ackermann N8UR]

Thanks, all, for the replies.

For my simple test case, I'm trying just two modulators with a frequency 
translating FIR following each, one set to 0 Hz and the other to +25kHz.

I set the NBFM modulator quadrature outputs to 128ksps, then add them 
together and feed to the USRP at 256ksps.  (At this point, I'm not 
worrying about gain setting; I know I need to address that but wanted to 
get the basic flow correct first.)

When I run the program I get this error:

UHD Warning:
    The hardware does not support the requested TX sample rate:
    Target sample rate: 0.256000 MSps
    Actual sample rate: 0.255102 MSps

Since I'm summing two 128ksps streams, I thought I'd get a 256ksps 
stream at the output of the adder.  Where are these 898 samples per 
second disappearing?  And how do I correct that?  (The single channel 
version of the program, with the NBFM quadrature rate set directly to 
256ksps, worked fine.)

Thanks,

John
----
Marcus D. Leech said the following on 06/21/2011 12:33 PM:
> On 21/06/2011 12:05 PM, Alexandru Csete wrote
> > Sorry, I meant multiply with a complex sine or cosine wave of
> > frequency f, where f is the offset.
> >
> > Marcus suggested using filters, which will also work but it's a bit
> > overkill for a simple translation, isn't it?
> >
> > Alex
> Yes, it's overkill, but I thought it might be the simplest "form" to get
> working first.
>
>
>
>
>
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