<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div><span>Hello Larry,</span></div><div><span>I'm intrigued by what you mean by 'bit closer to analog performance' sounds like a backward step to me!?? As it is, you are very unlikely to suffer intermodulation issues or phase noise issues as Mercury / Hermes is way ahead of practically any analog receivers unless you run a really larger antenna system or like in an exceptionally high signal area. <br></span></div><div><span>The IMD performance at full scale for Mercury / Hermes should be around 25-30dBm, which is excellent, but typical HF band noise should push any IMD into the noise due to the dither effect in the ADC.</span></div><div><span>You will find it difficult to find an ADC better than the LTC2207, ADI and TI etc devices can't touch
them.<br></span></div><div><span>Andrew</span></div><div><span>G4XZL</span></div><div><br></div> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div dir="ltr"> <font face="Arial" size="2"> <hr size="1"> <b><span style="font-weight:bold;">From:</span></b> Phil Harman <phil@pharman.org><br> <b><span style="font-weight: bold;">To:</span></b> Larry Gadallah <lgadallah@gmail.com>; Andrew <irbsurfing@yahoo.co.uk> <br><b><span style="font-weight: bold;">Cc:</span></b> hpsdr@lists.openhpsdr.org <br> <b><span style="font-weight: bold;">Sent:</span></b> Friday, 27 July 2012, 6:51<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [hpsdr] ADC Question<br> </font> </div> <br><div id="yiv324689247">
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<div>Hi Larry,</div>
<div> </div>
<div>I confirm that the LTC2209 is a drop-in replacement for the 2208 and runs
fine at a higher clock frequency since I have one installed on a Mercury
board.</div>
<div> </div>
<div>The NF of the LTC2208 is about 30 dB (as long as you don’t follow the
data sheet and resistively terminate the input) so is usable up to about 17 m
without a preamp when connected to an efficient antenna. </div>
<div> </div>
<div>73 Phil....VK6APH </div>
<div> </div>
<div> </div>
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<div style="BACKGROUND:#f5f5f5;">
<div style=""><b>From:</b> <a rel="nofollow" title="lgadallah@gmail.com" ymailto="mailto:lgadallah@gmail.com" target="_blank" href="mailto:lgadallah@gmail.com">Larry Gadallah</a> </div>
<div><b>Sent:</b> Friday, July 27, 2012 11:36 AM</div>
<div><b>To:</b> <a rel="nofollow" title="irbsurfing@yahoo.co.uk" ymailto="mailto:irbsurfing@yahoo.co.uk" target="_blank" href="mailto:irbsurfing@yahoo.co.uk">Andrew</a> </div>
<div><b>Cc:</b> <a rel="nofollow" title="hpsdr@lists.openhpsdr.org" ymailto="mailto:hpsdr@lists.openhpsdr.org" target="_blank" href="mailto:hpsdr@lists.openhpsdr.org">hpsdr@lists.openhpsdr.org</a> </div>
<div><b>Subject:</b> Re: [hpsdr] ADC Question</div></div></div>
<div> </div></div>
<div style="FONT-STYLE:normal;DISPLAY:inline;FONT-FAMILY:'Calibri';COLOR:#000000;FONT-SIZE:small;FONT-WEIGHT:normal;TEXT-DECORATION:none;">*****
High Performance Software Defined Radio Discussion List *****<br><br>
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Hi Andrew:<br><br>
<div class="yiv324689247gmail_quote">On 26 July 2012 13:46, Andrew <span dir="ltr"><<a rel="nofollow" ymailto="mailto:irbsurfing@yahoo.co.uk" target="_blank" href="mailto:irbsurfing@yahoo.co.uk">irbsurfing@yahoo.co.uk</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex;" class="yiv324689247gmail_quote">
<div class="yiv324689247HOEnZb">
<div class="yiv324689247h5">***** High Performance Software Defined Radio Discussion List
*****<br><br></div></div>
<div> </div>
<div>
<div style="FONT-FAMILY:times new roman, new york, times, serif;FONT-SIZE:12pt;">
<div>Hi Larry,</div>
<div>Unfortunately the LTC2207 and LTC2208 are not pin compatible, the former
is 48 pin QFN and the latter a 64 pin due to the use of LVDS for the output
data lines.</div></div></div></blockquote>
<div> </div>
<div>Hmmm, I must have confused it with the LTC2209. Regardless, the point is
that it would be interesting to experiment with an HF-only arrangement where an
ADC with the absolute best ENOB and SFDR was used in an attempt to get a bit
closer to analog Rx performance without needing a preamp. From my casual
research it doesn't look like anyone (TI, LTC, ADC) has anything much more than
2-3 dB better than the LTC2208, so it seems that this might be a
process/technology limitation.</div>
<div> </div>
<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex;" class="yiv324689247gmail_quote">
<div>
<div style="FONT-FAMILY:times new roman, new york, times, serif;FONT-SIZE:12pt;">
<div>I had already thought about doing this! Trying to make it fit would be
very interesting and not recommended without a specially designed pcb carrier
- that just might work.....mmm.<br></div></div></div></blockquote>
<div> </div>
<div>I keep thinking that if we limit ourselves to a maximum Rx frequency of 30
MHz or so, it should be possible to build a nice little Rx with 100-Base-T
Ethernet (maybe even PCI). It probably wouldn't be much cheaper than Mercury
given the costs of the ADC and FPGA, but it would be getting close to having a
"blade" receiver architecture :-).</div>
<div> </div>
<blockquote style="BORDER-LEFT:#ccc 1px solid;MARGIN:0px 0px 0px 0.8ex;PADDING-LEFT:1ex;" class="yiv324689247gmail_quote">
<div>
<div style="FONT-FAMILY:times new roman, new york, times, serif;FONT-SIZE:12pt;">
<div></div>
<div>73's,</div>
<div>Andrew</div></div></div></blockquote></div><br>Cheers,<br>-- <br>Larry
Gadallah,
VE6VQ/W7
lgadallah AT gmail DOT com<br>PGP Sig: B5F9 C4A8 8517 82AC 16B6 02B6 0645
69F0 1F29 A512<br>
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