[Discuss-gnuradio] Star-10 Transceiver article in QEX

[Robert McGwier]

Dear QEX Editor:

Cornell Drentea, designer of Dentron amplifiers, and one of the many who 
claim to have invented DDS referenced PLL's (he has as good a case as 
any) has shown a beautiful example of serious professional engineering 
in his Star-10 article and he is to be congratulated on a brilliant 
design and beautiful craftsmanship in building it.  It is a very clever 
and beautifully done traditional design.

This notwithstanding, I have to say that I am particularly disappointed 
that the editors of QEX allowed the tone of the article to go unchecked. 
I have comments on the "commentary" and the pseudoscience in the article.

As the ARRL Software Defined Working Group Chairman,  I found much of 
his commentary both insulting and just plain wrong both personally and 
in my position as a member of this working group.  Let me go through my 
objections in detail. Drentea refers to several projects as "so called 
software defined radio" projects.  The so called software defined radio 
projects to which he refers are now in use in the Department of Defense, 
 Department of Justice, Department of Transportation,  and many radio 
astronomy sites and many laboratories in many countries.  Virginia Tech, 
the premiere university in the United States for Mobile and Wireless 
communications engineering education has one of the strongest, if not 
the strongest, software defined radio program in the country and it is 
but one.  This and many other universities use GnuRadio, DttSP, and more 
which are the objects of Drentea's scorn.  The SOFTWARE defines them as 
software defined radios and they meet every definition of a software 
defined radio in the recent FCC rules on SDR and cognitive radio in 
their application to the SDR-1000, Flex 5000, Softrock, Universal 
Software Radio Peripheral, HPSDR, uwSDR, and more.

In a clear reference to Flex Radio's SDR-1000,  Flex 5000A, Softrock, 
Norcal 2030 and other radios based upon the Quadrature Sampling Detector 
or Tayloe detector (balanced or unbalanced), Drentea denies that the 
measurements made by the ARRL labs in the review of the SDR-1000 and the 
reviews made of the Flex 5000A by Rob Sherwood (published recently in 
Passport to HF and soon on his web site) constitute credible authorities 
on the characterization of radios.  Having never seen any of Drentea's 
measurements of his own radio, I cannot attest to the credibility of his 
measurements but I do have a comment.  As a person who works 
professionally to do software radio for the U.S. government, I do not 
know of a lab that can measure 150 dB of IMD dynamic range.  The 
required purity of the oscillators alone involved in both the Star-10 
and the test equipment is beyond imagining.  The PRODUCT of their noises 
must be so low as to require something like temperatures that are 
physically impossible to get and have the oscillators continue to 
function!  The editorial board of QEX should not allow such ridiculous 
claims to go into print.

Finally, let me state as emphatically as possible.  Neither the QSD or 
the Tayloe mixers are direct conversion receivers of the type Drentea 
refers to in his article.  He simply does not understand what they are. 
 Having analyzed the QSD in the SDR-1000 with the mathematics of 
Laplace Transforms to find both its transitory and steady state 
response, I can assure you, he simply does not know what he is talking 
about and has made a fool of himself.

To say that I am disappointed is to really understate the situation. I 
am livid beyond almost all repair.

Bob
N4HY

--
AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL,
TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair
“An optimist may see a light where there is none, but why
must the pessimist always run to blow it out?” Descartes