A Clarification

GNU Radio
1

Hi,

I would appreciate if the following are clarified regarding USRP,

1.Is it necessary to have two daughter boards in USRP1 to receive data
at
two different frequencies?
2.If one daughterboard is used,can it receive the data individually and
separately at different frequencies?

Thanks!!

2

It depends.

If those frequencies are separated by less than the analog bandwidth of
a single daughtercard, then you can use the dual-DDC feature to
pick both of those frequencies out of the larger bandwidth.
Otherwise, you must use another card. Each daughtercard has only a
single
analog downconverter, and there’s only a single dual-channel ADC to
sample the output of the card.

–
Marcus L.
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

3

Hope i am not asking a silly question…

Where can i find the "Dual -DDC"feature.Is it confined to a particular
version.Since i don’t find it .

Thanks!

4

Hope i am not asking a silly question…

Where can i find the "Dual -DDC"feature.Is it confined to a particular
version.Since i don’t find it .

Thanks!

For USRP1 and N2XX, you get it by default, and UHD figures out what to
do (for the most part) based on your configuration.

For B100, you need the _2rx FPGA image.

See the attached dual_channel_wbx.grc example attached.

Note that the subdev spec shows the same subdev for both channels: A:0
A:0 in this case

And you have to use some of the magic in uhd.tune_request() to enable
manual setting of the RF frequency, which we simply calculate as the
midpoint between the two desired frequencies, and then we let the
DDCs sort things out from there.