<HTML><HEAD></HEAD>
<BODY dir=ltr>
<DIV dir=ltr>
<DIV style="FONT-FAMILY: 'Arial'; COLOR: #000000; FONT-SIZE: 10pt">
<DIV>
<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT
size=2 face=Arial>Hi Andrew,</FONT></DIV></DIV>
<DIV>
<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT
size=2 face=Arial></FONT> </DIV></DIV>
<DIV>
<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT
size=2 face=Arial>In answer to your questions:</FONT></DIV></DIV>
<DIV
style="FONT-STYLE: normal; DISPLAY: inline; FONT-FAMILY: 'Calibri'; COLOR: #000000; FONT-SIZE: small; FONT-WEIGHT: normal; TEXT-DECORATION: none"><FONT
size=2 face=Arial></FONT>
<DIV><BR>What triggers the overload warning, is it the actual ADC overflow
output or triggered by the input level exceeding a certain <SPAN
id=yiv657549159misspell-6 class=yiv657549159mark>dBFS</SPAN> level determined in
software (if so, what is it -1<SPAN id=yiv657549159misspell-7
class=yiv657549159mark>dBFS</SPAN> or 0<SPAN id=yiv657549159misspell-8
class=yiv657549159mark>dBFS</SPAN> etc??)</DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>There is a pin on the LTC2208 that gets set when
the ADC overloads. It’s this pin state the gets sent to the PC via the C&C
data bits in the USB protocol. Not sure exactly when this gets triggered
but I would expect at +/- full scale. </FONT></DIV>
<DIV><BR>Incidentally, I notice that there is about as far as I can estimate a
-7dB (maybe its 6dB, can't tell) difference between ADC input level (<SPAN
id=yiv657549159misspell-9 class=yiv657549159mark>dBFS</SPAN>) and the level
indicated on the <SPAN id=yiv657549159misspell-10
class=yiv657549159mark>Powersdr</SPAN> s meter set to read ADC level.</DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Have you calibrated PowerSDR with a known signal
level at the antenna socket?</FONT></DIV><FONT size=2 face=Arial></FONT>
<DIV><BR>Is there any way to observe the actual ADC <SPAN
id=yiv657549159misspell-11 class=yiv657549159mark>wideband</SPAN> level in <SPAN
id=yiv657549159misspell-12 class=yiv657549159mark>dBFS</SPAN>??</DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>KISS Konsole will display either the actual I and Q
data being sent to the PC (after filtering and decimation) or an FFT of a 16k
block of contiguous samples taken directly out of the ADC – i.e. the
wideband 0-55 MHz bandscope display. At least with my Hermes and Mercury
boards the displayed level is within 0.5dB of a signal from my HP8640B signal
generator. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>73 Phil...VK6APH
</FONT></DIV></DIV></DIV></DIV></BODY></HTML>