[hpsdr] Introducing Angelia

[Joe Martin K5SO]

Hi Jacques, 

As Abhi is likely in bed at the moment I'll respond to your inquiry.  

The biggest difference between multiple Mercury and Agelia (pronounced ain-jell-LEE-uh) platforms is that the ADCs in Angelia are truely coherent, whereas the ADCs in multiple Mercury platforms are "almost" coherent.  In practice, this means that Angelia will perform critical phasing activities better than does a multiple Mercury platform, especially over extended periods of operation.  

For example, I was never quite able to adequately solve a couple of disturbing issues related to maintaining a fixed and stable phase relationship between the ADCs on multiple Mercury boards over long periods of time or between multiple Mercury boards at initial startup.  At initial power up of the Atlas bus the Mercury boards presently do not come up with fixed and repeatable phase relationships of their output IQ streams and there is a tendency of the Mercury boards to develop a seemingly random phase shift on one or more of the Mercury boards sporadically as they operate.  These two issues do not exist with Angelia…indeed, solving these two critical issues was a principal driving force for proceeding with Angelia's development!  Angelia solves these problems.  

This does not mean that it is impossible to resolve the startup-phase and random-phase-jump issues with multiple Mercury boards but I'm thinking that a solution would likely turn out to be considerably "less clean" than using the straightforward approach to the issue that is implemented in Angelia.  

For the time being, the PC programs that run with multiple Mercury platforms also run similarly on Angelia,  with the caveat that at present only two coherent receivers are implemented in Angelia firmware (…note that up to 7 incoherent/independent receivers may be used with a single ADC in Angelia, however).  The present two-coherent-receiver limit for Angelia will soon be expanded to three (or possibly to four) coherent receivers for Angelia when the Angelia daughterboard development is completed.  It has been a design objective of the Angelia project to make Angelia backward compatible with the current HPSDR PC software programs.  So far that objective seems to have been met, including operation of multiple independent receivers and operation of up to two coherent receivers.  

It is expected that firmware/software developed for Angelia will continue to adhere to the USB protocol that is established for the OpenHPSDR project; so, in that respect, software that runs on OpenHPSDR hardware will also run on Angelia and vice versa, up to the phasing limitations imposed by the particular set of hardware you are using, of course.  If your hardware doesn't contain multiple coherent receivers then the phasing functionality of a "phasing" PC program will not be present but the program will likely function perfectly well otherwise.  

I hope that answers your questions adequately.  If not, please ask again.  Also, Abhi may wish to add his comments.  He, or anyone else for that matter, is welcome to correct me if I have misspoken or have poorly explained something. 

73,  Joe K5SO

On Aug 4, 2012, at 1:07 PM, <f6bki at orange.fr> wrote:

> ***** High Performance Software Defined Radio Discussion List *****
> 
> ABhi, What is going to be the difference between the multiple Mercury  platform and Angelina as far diversity and beam forming is concerned ? are the software developed for one can be used for the other ? is the issue of phase at start up you have describe on Mercury  solved ?
> Thank you
> 73
> Jacques F6BKI
>  
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