On 10/06/2017 07:45 AM, Marcus Müller wrote:
Hi Robin,
Yeah, I didn't mean to imply the Pluto was "worse" than others. It's
really that as you, and I thought that was really great about your
talk, showed that SDRs aren't "totally harmless toys". Indeed, I
hadn't even noticed so far the different band-specific paths of the
B2x0 were gone on the B200mini!
And yes, who am I to tell you that, but that's the price you pay for
frequency-agile SDR: Either you spend a lot of money on dedicated
filtering per band (E310, TwinRX), or you get the cheap flexibility at
the expense of selectivity. That might be the reason why an R&S
spectrum analyzer might be a tad more expensive then the average COTS
SDR device that we're considering below.
But the fact that you need your own filters, in the end, is – in my
experience – something that people building systems are very willing
to accept, because you can use one and the same SDR device that you
got to know intimately in products which you optimize for the bands
that you'll actually use in that incarnation of your system by adding
(relatively cheap) filters for exactly what you care about. That's why
it makes sense for the B200mini to lack these filters – the form
factor means it lends itself to systems integration. And that's also
why it makes sense for the Pluto to not have filters – aside from the
(extremely nice) price tag, hell, it's an experimentation platform, so
the flexibility is more important than the raw signal quality.
So, yeah, my wording was misleading there – thank you for the response!
Don't see why you need filters. Analog components with 220dB of
dynamic range ahead of 27-bit ADCs, and no filters required :)
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