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

Fri Feb 16 17:01:55 EST 2007

As a signal level data point, I've connected an HP3400 wideband true RMS 
voltmeter to my log periodic antenna (M2 7 MHz & 10-30 MHz) at 100 ft 
above ground level here in Northern Virginia (near Washington DC). The 
total integrated voltage into 50 ohms (I use a 50 ohm thru termination 
at the  voltmeter input) works out to a power level around -20 dBm. The 
strongest broadcast signal I see is WWCR which clocks in around -40 dBm 
normally, with -35 dBm being the maximum level I can recall seeing, as 
measured on an Advantest R3463 spectrum analyzer or my older HP8558B SA.

When my nearby neighbor W3YY lights off his high power station, his 
signal is well over 0 dBm, expected as the straight line distance is not 
more  than 1500 feet.

Jack K8ZOA

Gary Geissinger wrote:
> Mark,
>
> Here is my take on this.  I'd love to hear other opinions.
>
> The problem is that if the input bandpass is "wide open", then the top
> of the dynamic range is adjusted to peak amplitude of the composite of
> the signals in the passband.
>
> For example, say that a US shortwave signal is at 60 dB over S-9 on 49
> meters and you are trying to hear a 1/2 microvolt CW signal on 40
> meters.  The AGC will adjust the gain so that the strong signal is not
> clipped. This will push the CW signal down into the noise floor.  
>
> This is the problem with the DC-light wide open receiver concept in
> general.  As you can see, a signal at 6 MHz can take out a signal at 7
> MHz; just think what AM broadcast signals and other strong local sources
> would do if you chose to digitize 10 KHz - 30 MHz all at once.
>
> You only get 6 dB of dynamic range improvement for each bit in the A/D
> converter.  To make a fully functional wide open HF receiver you would
> need a 66 MHz or faster A/D with a lot more than 14 or 16 bits.
>
> Gary WA0SPM
>   
>
> -----Original Message-----
> From: premium-rx-bounces at mailman.qth.net
> [mailto:premium-rx-bounces at mailman.qth.net] On Behalf Of Mark Donaldson
> Sent: Friday, February 16, 2007 2:09 PM
> To: Premium-Rx at mailman.qth.net
> Subject: Re: [Premium-Rx] The new R&S EM510 Direct-Sampling HF Receiver
>
> I don't know if I'm missing something here but wouldn't adding a stage
> or two of AGC after the RF amp eliminate all the dynamic range issues?
>
> Mark Donaldson WA1QHQ
>
>
> --- sig346 at netscape.net wrote:
>
>   
>> -----Original Message-----
>> From: sig346 at netscape.net
>> To: premium-rx at mailman.qth.net
>> Sent: Thu, 15 Feb 2007 10:32 PM
>> Subject: Re: [Premium-Rx] The new R&S EM510 Direct-Sampling HF 
>> Receiver
>>
>>
>>
>>
>>
>>  -----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
>>
>>
>>
>>  -----Original Message-----
>>  From: farson at shaw.ca
>>  To: Premium-Rx at mailman.qth.net
>>  Sent: Thu, 15 Feb 2007 2:31 AM
>>  Subject: [Premium-Rx] The new R&S EM510 Direct-Sampling HF Receiver
>>
>>   Rohde & Schwarz have announced their new EM510 direct-sampling HF
>>
>>
>> intercept/surveillance receiver:
>>
>>
>>
>>
>>
>> http://tinyurl.com/2lan7h  (EM510 brochure in PDF format, in German)
>>
>>
>>
>>
>>
>> Cheers for now, 73,
>>
>>
>> Adam VA7OJ/AB4OJ
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>   --------
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>>     
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>>     
>
>
>
>  
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