<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Phil, <div><br></div><div>That is wonderful news!! In fact, if the "phase word" approach works for multiple Mercury boards too then this may be the breakthrough approach I was seeking and could make using perhaps up to five Mercury boards for DF and beam steering feasible with the Atlas bus. </div><div><br></div><div>I'll definitely check it out! Great observation! Thanks!!</div><div><br></div><div>73, Joe K5SO</div><div><br><div><div>On Aug 5, 2012, at 1:08 AM, Phil Harman wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite">
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<div>Hi Joe,</div>
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<div>There may be a solution to this issue. I’ve been writing the code to
turn Hermes into a Vector Network Analyser. IN which case I need to guarantee
the phase relationship between the Tx and Rx is totally consistent and
repeatable across numerous power cycles. Since the Tx and Rx FPGA
code run off the same clock on the Hermes board then that is half the
problem solved.</div>
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<div>What I found is if I feed the same frequency to the individual
frequency-to-phase converter code for the Tx and Rx CORDICs then every
time I change frequency the phase relationship varies in a totally uncontrolled
manner. However, if I calculate the phase word from the frequency and feed
the phase word to *both* CORDICs then the phase relationship is rock
steady under all conditions that I’ve tested so far. </div>
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<div>In which case if we run all the Mercury boards off the same 122.88 MHZ
clock and feed the phase word, calculated in say Metis, over the Atlas bus
rather than the frequency then we may find an improvement.</div>
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<div>73 Phil....VK6APH </div>
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