[Premium-Rx] The new R&S EM510 Direct-Sampling HF Receiver

[Karl-Arne Markström]

A very interesting discussion of how direct-sampling receivers behave under real-life conditions can be found at
http://www.sm5bsz.com/digdynam/practical.htm

It i.a. discusses the use of "dithering" as one means of increasing the dynamic range. 
Dithering was also successfully used in early DSP receivers such as the HF-2050.


73/

Karl-Arne
SM0AOM


----- Original Message ----- 
From: "Adam Farson" <farson at shaw.ca>
To: "Premium-Rx" <Premium-Rx at mailman.qth.net>
Sent: Saturday, February 17, 2007 7:49 AM
Subject: RE: [Premium-Rx] The new R&S EM510 Direct-Sampling HF Receiver


> Hi Pieter,
> 
> You are right - I missed a step in the reasoning. I was considering the
> noise power in a bandwidth of 1/2 the sampling rate, and not taking DDC
> process gain into account.  
> 
> Thanks for the link to that excellent ADI article. It is a very concise
> explanation of ADC S/N performance.
> 
> Cheers for now, 73,
> Adam VA7OJ/AB4OJ
> 
> 
> -----Original Message-----
> From: Pieter Ibelings [mailto:sietetrescincoprimo at hotmail.com] 
> Sent: 16 February 2007 10:33
> To: farson at shaw.ca
> Cc: premium-rx at mailman.qth.net
> Subject: RE: [Premium-Rx] The new R&S EM510 Direct-Sampling HF Receiver
> 
> This is the biggest misconception on ADCs. When your ADC is 16 bits, the
> 96dB number means that if you insert a signal at full scale (0dBfs), the
> integrated noise over half the sample rate will be 96 dB down. In other
> words, if you inject a signal of say 10dBm (assuming full scale is 10dBm)
> and you are sampling at 100 MHz, then the noise will be broadband in nature
> and will be -86dBm (96dB down) spread over the band of 0-50 MHz. If you set
> the display to have a 1Hz resolution bandwidth, you will see the noise floor
> at -86dBm-10*log(50MHz) = -163 dBm. This is equivalent to a noise figure of
> the ADC of 11 dB. In this setup, I would be able to insert a carrier and see
> it from about -163 dBm all the way to 10dBm on the display. So dynamic range
> is not equal to S/N of an ADC which is calculated from the Effective Number
> of bits (ENOB) multiplied by 6.02dB +1.76dB. The signal to noise numbers
> above assumes that all of the noice is random in nature and caused by
> quantization noise in the ADC.
> 
> Pieter, N4IP
> 
> Here is a link to an explanation:
> http://www.analog.com/en/content/0,2886,760%255F%255F88014,00.html
> 
> 
> 
> 
> Scanned for viruses by Blue Coat
> http://www.WinProxy.com/
> _______________________________________________
> Premium-Rx Mailing List
> To Post: premium-rx at mailman.qth.net
> For Info: http://mailman.qth.net/mailman/listinfo/premium-rx
> Visit the Website: http://kahuna.sdsu.edu/~mechtron/PremRxPage/
> Help: http://mailman.qth.net/mmmain.htm
> 
> 
> 
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.441 / Virus Database: 268.18.1/690 - Release Date: 2007-02-16 14:25
> 
> 


-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.5.441 / Virus Database: 268.18.1/690 - Release Date: 2007-02-16 14:25