RSP1 and 14 bit resolution

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DaveB
Posts: 142
Joined: Sun Feb 01, 2015 6:04 pm

RSP1 and 14 bit resolution

Post by DaveB » Wed Nov 22, 2017 11:51 am

If I have read things correctly the RSP1A and RSP1 use the same Mirics chip and SDRPlay have "unlocked" a feature in to provide 14 bit ADC in sample rates of 6 MHz and below.

Does that mean that the latest API and ExtIO will allow the RSP1 to run at 14 bits ADC at less than 6 MHz sample rate?


Thanks

David

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Tech_Support
Posts: 499
Joined: Mon Jun 01, 2015 7:00 pm

Re: RSP1 and 14 bit resolution

Post by Tech_Support » Wed Nov 22, 2017 2:57 pm

Hello David,
We asked the question and the answer that we have received is that unfortunately, there is no way to increase the ADC resolution on the RSP1 and RSP2. Even had it been possible, you would have been unlikely to see any benefits anyway due to limitations in the design of the RF front end. The major improvements in the performance of the RSP1A come from the redesign of the RF front end.

Sincerely

SDRplay Tech_Support

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CaptainNemo
Posts: 146
Joined: Mon Jan 05, 2015 1:22 pm
Location: Genoa - Italy

Re: RSP1 and 14 bit resolution

Post by CaptainNemo » Thu Nov 23, 2017 11:03 am

So, dear tech support, you are saying, in other words, that there is no use in tweaking the "new" decimation parameter
that I see in the last (4.1) extIo dll for RSP1?

By the way, that parameter refer to some "software" decimation processing outside RSP1
or to a feature inside MSi2500 or so?

I know decimation (along with other tech. like dithering...) is one (maybe the only) technique to improve n. of bit
(virtually) when you have sampling capability in excess... (this is the case e.g. when you want to listen to
let say a 2.8k bw of an ham USB voice qso and you have let say 8M sampling rate...). A "good design" target is to
balance between SR needs and resolution needs...

I feel it is time to unveil with a technical paper all those concepts,
making a parallelism with terms widely used in DSP literature and the SDRplay implementation...
Today, having a scientific/technical scholar/professional background in addition to the huge amount of
info from internet, It happen to me (maybe to others) to be disappointed, to be confused when I try a parallelism on
how it is implemented in RSP1 (and the sw around it)...

gio
proud customer of RSP1

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Tech_Support
Posts: 499
Joined: Mon Jun 01, 2015 7:00 pm

Re: RSP1 and 14 bit resolution

Post by Tech_Support » Thu Nov 23, 2017 11:16 am

Hello Gio,
You can always use software decimation on the host PC. Theoretically, a decimation factor of 4 gives 1 additional bit of resolution at the expense of reducing the bandwidth by a factor of 4. Decimation will certainly help you resolve weak signals in the SP1 display, but that is really a visual effect associated with there being more frequency resolution in the FFT. We don't feel that it will significantly improve the reception performance of your RSP1.

In the previous post on this subject, we were referring to the native resolution of the ADCs on the RSP1 which cannot be increased.

Sincerely

SDRplay Tech_Support

Reason: No reason

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