Re: [Discuss-gnuradio] Multiplexing modulators

[Alexandru Csete]

On Tue, Jun 21, 2011 at 4:08 PM, Alexandru Csete <address@hidden> wrote:

On Tue, Jun 21, 2011 at 3:28 PM, John Ackermann N8UR <address@hidden> wrote:

In GRC I would like to combine the outputs of several NBFM modulator blocks to drive a USRP sink.  The idea is to output several discrete channels within the USRP transmit bandwidth, e.g., three signal channels at -30 kHz, 0 kHz, and +30 kHz offset from the USRP tune frequency.

I'd appreciate suggestions on how best to accomplish this.

I think there is an example to do exactly this in Python but you can also do it in GRC:
(1) multiply the output of each modulator with a complex number corresponding to the offset from center
(2) add all channels together

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