<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<br>
Hi Naomi,<br>
<br>
Thanks for the feedback. I have some comments on your suggestions
below:<br>
<br>
<div class="moz-cite-prefix">On 7/15/13 4:27 PM, Naomi Jarvis wrote:<br>
</div>
<blockquote cite="mid:7261DD58-EED5-4D94-937B-BD0C0E4E8B14@cmu.edu"
type="cite">
<div><span class="Apple-style-span" style="border-collapse:
separate; color: rgb(0, 0, 0); font-family: Helvetica;
font-style: normal; font-variant: normal; font-weight: normal;
letter-spacing: normal; line-height: normal; orphans: 2;
text-align: -webkit-auto; text-indent: 0px; text-transform:
none; white-space: normal; widows: 2; word-spacing: 0px;
-webkit-border-horizontal-spacing: 0px;
-webkit-border-vertical-spacing: 0px;
-webkit-text-decorations-in-effect: none;
-webkit-text-size-adjust: auto; -webkit-text-stroke-width:
0px; font-size: medium; "><span class="Apple-style-span"
style="border-collapse: separate; color: rgb(0, 0, 0);
font-family: Helvetica; font-style: normal; font-variant:
normal; font-weight: normal; letter-spacing: normal;
line-height: normal; orphans: 2; text-indent: 0px;
text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-border-horizontal-spacing: 0px;
-webkit-border-vertical-spacing: 0px;
-webkit-text-decorations-in-effect: none;
-webkit-text-size-adjust: auto; -webkit-text-stroke-width:
0px; font-size: medium; ">
<div style="word-wrap: break-word; -webkit-nbsp-mode: space;
-webkit-line-break: after-white-space; "><span
class="Apple-style-span" style="border-collapse:
separate; color: rgb(0, 0, 0); font-family: Helvetica;
font-style: normal; font-variant: normal; font-weight:
normal; letter-spacing: normal; line-height: normal;
orphans: 2; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-border-horizontal-spacing: 0px;
-webkit-border-vertical-spacing: 0px;
-webkit-text-decorations-in-effect: none;
-webkit-text-size-adjust: auto;
-webkit-text-stroke-width: 0px; font-size: medium; ">
<div style="word-wrap: break-word; -webkit-nbsp-mode:
space; -webkit-line-break: after-white-space; ">Hello,</div>
<div style="word-wrap: break-word; -webkit-nbsp-mode:
space; -webkit-line-break: after-white-space; "><br>
I prefer option 1, the coupled words with pedestal, as
it packs more info into the same space.</div>
</span></div>
</span></span>
</div>
<div><br class="webkit-block-placeholder">
</div>
<div>First word</div>
<div><br>
</div>
<div>Do we need the 2bits for 'pulse'? From looking through the
spec it seems that this is to label up to 4 pulses for which
time data is to be sent. For the CDC this would always be 1,
just 1 pulse, so could we dispense with it?</div>
<div><br>
</div>
</blockquote>
I think there should be enough room in the 64 bits to keep the 2
bits for this. I would hate to give this up unless we really have
to. Since we'll be using these for the FDC cathodes which will have
a much higher rate, it could be very useful.<br>
<br>
<blockquote cite="mid:7261DD58-EED5-4D94-937B-BD0C0E4E8B14@cmu.edu"
type="cite">
<div>We would like to increase the bits available for time data
from 10 to 11 bits, as an integer # of ns, that gives us 0-2047
ns. This allows some headroom for slower drift times. </div>
<div><br class="webkit-block-placeholder">
</div>
</blockquote>
This seems reasonable to me. If we move the 3 bits for the Q.F. down
to the second word as you suggested, we can use one of those.<br>
<br>
<blockquote cite="mid:7261DD58-EED5-4D94-937B-BD0C0E4E8B14@cmu.edu"
type="cite">
<div><br>
</div>
<div>Second word</div>
<div><br>
</div>
<div>Pedestal. I would indeed like to include this but it is not
necessary to have full range 0-4095 available in integer steps.
We will set the pedestals to something low, ~55-60. How about
outputting pedestal/8 to cover the subrange pedestal=0-504 as
pedestal/8=0-63 in 6 bits. ? </div>
<div><br>
</div>
</blockquote>
I'm not sure if I fully understand your notation of pedestal/8, but
I think your main point is that we can just limit the range of the
pedestals to be within that defined by 6 bits. Either by adjusting
voltage offsets or applying an offset parameter to the FPGA. Just to
be clear though, the 6bits of pedestal would have the same
resolution as the integral right? (i.e. changing the pedestal by 1
is equivalent to changing the pulse integral by 1)<br>
<br>
<blockquote cite="mid:7261DD58-EED5-4D94-937B-BD0C0E4E8B14@cmu.edu"
type="cite">
<div>Integral. OK.</div>
</blockquote>
<br>
Actually, I'm thinking we could reduce this by a couple of bits.
With a 12bit ADC, storing 19 bits for the integral means we could
have up to 7bits=128 samples in saturation without overflowing. This
would correspond to a pulse that is over 1V high for more than 1
microsecond. That seems unlikely to provide anything useful (correct
me if I'm wrong here.) We could move 2 bits from this to the Q.F.
allowing use to keep 8 bits for the pedestal.<br>
<blockquote cite="mid:7261DD58-EED5-4D94-937B-BD0C0E4E8B14@cmu.edu"
type="cite">
<div><br>
</div>
<div>Integral quality factor.</div>
<div>I would like to include a count of the number of overflowed
samples contributing to the integral, this could count up to 63
samples (504ns) in the 6 bits freed up from the pedestal. <br>
</div>
</blockquote>
<br>
OK<br>
<br>
<br>
Here is a revised diagram which incorporates your suggestions and
then my modifications to those. Let me know what you think.<br>
<br>
<img src="cid:part1.01070705.05020205@jlab.org" alt=""><br>
Regards,<br>
-Dave<br>
<br>
</body>
</html>