[evlatests] Phase vs. Frequency

[Barry Clark]

The on-the sky phase jumps are not 180d, but about 135d.  Are the line
lengths in the module mismatched enough to accout for this?  Seems
a little improbable.  (I would believe they give rise to 10d, maybe
even 20d, but not 45d.)  Do the discriminators really jump a measured
90d?  Or can it be 70d?

Vivek Dhawan wrote:
> Ken and I had a discussion with Rob Long and Jim Jackson yesterday
> afternoon. The L302 from bench tests show small phase jumps at some
> places (currently blamed on analog components) and 180d jumps at
> polarity changes of the 2 DDS's (due to the phase discriminator).
> 
> The tests so far, as Barry summarized, were near one of the polarity
> change frequencies, which are the L302 (modulo 128) set to 0, 32, 65,
> 96 MHz. Yesterday afternoon another test was done with AC, BD tuned
> +5MHz, -5MHz away from 32 MHz, steps up to 340KHz. No jumps are seen.
> ea05, 25, 26 are doing funny things, but let's ignore that for now.
> 
> Two more tests are planned, with frequencies centered at the other
> polarity changes.
> 
> 
> On Mon, March 28, 2011 4:54 pm, Barry Clark wrote:
> | We've been doing some stuff that probably deserves wider
> | circulation.
> |
> | First attachment - Vivek's description of the tests run.
> |
> | Second attachment - Ken notices that jumps occur at fixed
> |     L302 frequencies
> |
> | Third attachment - I expand on what Ken said, and organize it
> |     a little prettier.
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