13 Oct
2012
13 Oct
'12
5:30 p.m.
Hi John,
On Sat, Oct 13, 2012 at 11:11 PM, John Orlando <john(a)epiqsolutions.com> wrote:
On Sat, Oct 13, 2012 at 3:47 PM, Alexander Chemeris
<alexander.chemeris(a)gmail.com> wrote:
The datasheet is not very clear on this topic. I'm referring to the
following line at the Table 1:
Baseband Bandwidth 14MHz
Originally I read this line as "digital I/Q bus has limitation of
14Msps" and this is what confuses me.
Hi Srdjan,
We're looking into re-purposing UmTRX for LTE and there a few things which
we need to understand better.
1. Is it possible to support 15MHz and 20MHz LTE channel bandwidths? To
achieve this we at least need to sample at 23.04Msps and 30.72Msps
respectively. LMS6002D datasheet specifies the maximum I/Q samplerate of
14Msps, which is not enough. But at the same time, datasheet claims that ADC
and DAC are specified up to 50Msps. How does this fits together?
Alexander,
Can you provide a reference to where the datasheet calls out a max I/Q
sample rate of 14 Msps? The analog low pass filters support a max
bandwidth of 14 MHz (which leads to 28 MHz RF bandwidth assuming
zero-IF operation)...is this what you're referencing? We run the A/D
converters in the LMS6002d at sample rates greater than 14 Msps all
the time, including 30.72 Msps.
Just to be sure - do you mean you feed RX_CLK and TX_CLK of LMS6002D
with 61.44MHz clock? It's divided by 2 internally, so if you feed them
with 30.72MHz clock you actually get only 15.36Msps out of LMS6002D.
--
Regards,
Alexander Chemeris.
CEO, Fairwaves LLC / ООО УмРадио
http://fairwaves.ru