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

[Clemens Paul]

Hi AW,

>The RS Datasheet reveals potentially weakness of all Direct Sampling
>HF Receivers: their limited
> dynamic range.

I believe it's not wrong to take the typical data.
Then you have a noise figure of 22dB and an IP3 of +35dBm.
Or 12dB NF and IP3 +25dBm (normal mode).
A WJ8712B has 14dB NF and an IP3 of +25dBm
(IIRC are Cubics not better.)
Would you call this/these rx(s) to have a "limited dynamic range" in your sense?

If you calculate the DR3 for the EM510 from the data above you arrive at about 100dB DR3
for 2,4kHz BW or ~105dB for 500Hz BW
That's like a EK070 and only about 6,6dB worse than a EK895.
Ok, the E1800 is 10dB better...
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