On 18/02/2025 18:45, Brendan Horsfield wrote:
Yes, I assumed that was the case. However, it is not clear from the
X300 documentation how sharp those filters are. Can you tell me how
wide the transition band is at the lower sample rates?
To give you some context, I would like to use an X300 (or X310) with a
UBX-160 daughterboard to digitise the entire 2.4 GHz Wi-Fi band, which
is 83.5 MHz wide. Ideally I would like to use a sample rate of 100
Msps to minimise the data rate between the USRP and the host PC.
However, before I do this I need to be certain that the usable
bandwidth at this sample rate will be greater than 83.5 MHz. Is this
information documented somewhere?
It somewhat depends on the decimation. If the decimation has a factor
of two or 4, the edge roll-off is fairly sharp. Otherwise,
there's a half-band filter in-place that causes a less-desirable
pass-band.
But I don't know, precisely, what the transition band is in the "nicer"
filter shapes.
If you have an X310+UBX-160, you can always just use a noise source, and
measure it yourself to see if it's appropriate for
your application.
On Tue, 18 Feb 2025 at 23:11, Marcus D Leech <patchvonbr...@gmail.com>
wrote:
There will always be some edge roll off. Decimation includes
filtering and those filters cannot be infinitely steep.
Sent from my iPhone
> On Feb 18, 2025, at 2:12 AM, Brendan Horsfield
<brendan.horsfi...@vectalabs.com> wrote:
>
>
> Hi All,
>
> I have a question about the usable bandwidth of the X300 USRP /
UBX-160 daughterboard combo at sampling rates below 200 Msps:
>
> As I understand it, the UBX-160 receiver has an analog
(hardware) filter before the ADC that limits the usable bandwidth
to 160 MHz, while the ADC runs at 200 Msps. Therefore the usable
bandwidth is around 80% of the sample rate.
>
> My question is: What is the usable bandwidth at lower sampling
rates? Does the 80% factor always apply?
>
> For example, if I set the decimation factor to 4, so that my
sampling rate is 50 Msps, does this mean that the usable bandwidth
will be 40 MHz?
>
> Thanks & Regards,
> Brendan.
>
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