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

[Pieter Ibelings]

Paul,

The 34dB DR3 of the SDR-14 sounds absurd, because it is. The ARRL had no 
clue what they were doing. When they measured the IP3 they extrapolated a 
very small spur at low levels and assumed it was a 3rd order product. They 
did not even notice that as they increased the level of the two carriers, 
the spur that they though was a 3rd order product would not change. That is 
why they came up with an absurd IP3 number of -15dBm to +29dBm. The ADC used 
in the SDR-14 (AD6644) has pretty good performance. If you insert two tones 
at -2dBm, the third order products are still lower than -95dBc.
The EM510 is a much more complex radio than the SDR-14, but it is also 30-40 
times the cost. If you tried the SDR-14, you would see that the performance 
is a lot better than you think. I have been using one for about 3 years, 
almost every day.

Best Regards,

Pieter, N4IP






>The SDR-14 has a DR3 of *34*dB for 500HZ BW (ARRL) which sounds absurd 
>(like the whole comparison) compared to 105dB.
>The EM510 can process realtime I/Q data with a BW of 10MHz, the SDR14 
>max.150kHz.
>The ADC of the SDR14 overloads at -23dBm,the EM510's IP3 is tested with 
>2x-7dBm.
>The EM510 is fully LAN controllable.
>It's also interesting to have a look at the filter specs (there are none 
>with the SDR-14).
>There seems indeed  to be a bit more than the price and the R&S logo on the 
>case
>(as someone said here on the list), which makes the difference between a 
>SDR14 and a EM510.
>The preamp of the EM510 delivers an output of +16dBm into the ADC with a 
>SFDR of >96dB.
>It was not easy even for the R&S engineers to design such a preamp.
>So there's a LOT more than buying an off the shelf  16bit ADC to design a 
>digital radio with
>those specs.
>And therefore I think the whole package inside the case IS exciting.
>
>73
>Clemens
>DL4RAJ
>
>
>
>
>
>---Original Message-----
>From: sig346 at netscape.net
>To: farson at shaw.ca; Premium-Rx at mailman.qth.net
>Sent: Thu, 15 Feb 2007 10:01 PM
>Subject: Re: [Premium-Rx] The new R&S EM510 Direct-Sampling HF Receiver
>
>    The RS Datasheet reveals potentially weakness of all Direct Sampling
>HF Receivers: their limited
>  dynamic range. To hide this RS tries stretching both German and
>English languages . As a result,
>  a new wording has been invented: LOW DISTORTION MODE. In this mode,
>which actually is nothing
>  more than an attenuator at the input, the receiver has IP3 of 30dBm,
>BUT NOISE FIGURE OF 26dB!.
>
>  I will send email to Rhode und Schwarz suggesting one more mode:
>ULTRALOW DISTORTION,
>  to obtain 50 dBm of IP3, but that would require 30dB attenuation,
>bringing noise froor to
>  45 dB. It would be, nevertheless, sufficient to listening to Deutsche
>Welle in the World Bavarian Capital of Munich.
>
>  Rockwell Collins describing their similar direct sampling receiver
>CX7800 simply "forgets" include some data
>  regarding dynamic range. That makes their life simpler: no need to
>hide an army of technical linguists.....
>
>  On a serious note, I tried CX7800. It is a respectable receiver, but
>far from being "Premium", not much
>  better than SDR14. So, you, gentlemen - owner of WJ, TCI, CUBIC,
>Telefunken, etc - remain cool -
>your receivers are still "Premium" without stretching imagination.
>
>Regards,
>AW
>
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