[hpsdr] VHF-millimeter up/down converters?

[Glenn Elmore]

Tom,
Thanks for writing. I've looked at the AD9361 and didn't think that 
approach was really appropriate. I suppose at the heart of the question 
is the architecture. At this point I'm rather presuming that for some 
sufficiently high frequency/short wavelength we simply have to face the 
fact that it is going to be an analog process.  12 bits seems quite a 
compromise and since it isn't it doesn't represent a wideband approach, 
I think I tend to rule it out.  This is why I was thinking of converting 
the SDR to a high side fixed IF and then filtering/converting with a 
clean, stepping LO.  This could be quite high performance, very fast (at 
least if a sufficiently good varactor oscillator were used, of which 
Hittite offers some possibilities) and also a reasonable price/cost 
point.  My personal interest is in having an all-band station with an 
SDR core that could also be useful as instrumentation - but as a 
secondary feature.

I do think that agreement about an architecture might be the hardest 
part since there can easily be different opinions, each justified on 
some grounds, about this. I previously presented an "all band" 
architecture and approach with transverter example at 10 GHz in an old 
Ham Radio Magazine (see my web page for a bad copy of that series of 
articles http://www.sonic.net/~n6gn) article but I don't think I'd want 
to do it that way again.

For someone considering this sort of thing, how does it work, do those 
interested go off on a private mailing or does some of the early work go 
on within this list?  I'm a total newbie here and have never worked on a 
distributed, Open Source hardware project before. Please redirect me if 
I'm being inappropriate.

Glenn n6gn


On 04/18/2015 06:14 PM, Tom McDermott wrote:
> Hi Glenn,
>
> I've not worked on this, but there are several ASICs that provide 
> bits-to-VHF/UHF and VHF/UHF-to-bits functions
> for Software Defiend Radios.The Analog Devices AD9361 is used on the 
> Ettus B200 series SDR modules, has frequency
> coverage of 70 MHz to 6 GHz. It has 12-bit I & Q ADC's and 12-bit I & 
> Q DACs. The Rev E datasheet can be downloaded
> from the AD webpage. It's in a 144-ball-grid array package.
>
> The LimeMicro LMS6002D is used on Nuand BladeRF 300 MHz to 3.8 GHz, 
> and also has 12-bit ADCs and DACs.
> Lime micro has a newer chip planned (LMS8001 but not yet released 
> according to their webpage) which is planned
> to  cover 100 KHz to 12 GHz. The Lime micro site doesn't have 
> information (that I can find) about the ADC / DAC sizes,
> nor can I find how to download those datasheets.
>
> Whether the synthesizers are sufficiently clean, or the DACs good 
> enough would depend on the application of course.
>
> -- Tom, N5EG
>
>
>
>
>
>
>
> On Sat, Apr 18, 2015 at 2:50 PM, Glenn Elmore <n6gn at sonic.net 
> <mailto:n6gn at sonic.net>> wrote:
>
>     ***** High Performance Software Defined Radio Discussion List *****
>
>     I'm a total newbie on this list. I hope this is an appropriate
>     posting.
>
>     I'm wondering who might have worked on, or be working on,
>     frequency extensions for OpenHPSDR.  Specifically, it seems to me
>     that an effort to extend the range of OpenHPSDR to include 50 MHz
>     - 6 GHz or higher must have been considered if not attempted or
>     accomplished by someone by this time. Who has done this or might
>     be interested in discussing it?
>
>     I'm asking because, although new to OpenHPSDR with an Angelia just
>     freshly boxed up and working, I already see the desirability of
>     having coverage of 144,220,432,900,1296 and 2304. It seems to me
>     that it would be a shame to limit this to a conventional banded
>     transverter approach and that doing a conversion to a higher fixed
>     IF followed by a down conversion to cover,say 50 MHz to 6 GHz with
>     a clean LO up/down converter is an obvious choice.  Allow this is
>     a "radio" project, continuous coverage would allow extension of
>     signal analyzer and vector network analysis throughout this range
>     and should be a pretty useful capability.
>
>     Is this already being done by someone?
>
>     Glenn Elmore
>     n6gn
>
>
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