[Halld-tracking-hw] Tracking minutes posted

[Gerard Visser]

hi Dave,
	I think it might be better to provide a more generic and all-encompassing 
redundancy in the data, such as by inserting a CRC word every N hits or at end 
of block or something like that. Just a fixed pattern on a few bits is a pretty 
minimalist sort of redundancy, e.g. would not detect if an even number of 
longwords was dropped, for instance.
	I also suspect that more bits might be good for quality/status of the hit, 
although I don't have a specific proposal. At the moment I see it is proposed 
(1c) to have 13 bits for "pedestal"&quality (these are all quality bits IMHO). 
This may eventually prove not to be enough, then the 5 slot bits could be added 
into this purpose.
	Regardless of the slot bits, I think you are certainly right to put some 
redundancy in the data that can be used for integrity check, so IMHO you should 
add some CRC words explicitly for that purpose.
	Sincerely,

		Gerard

p.s. Minor point: If you do keep slot field, how about putting it to the left of 
channel field, so that the whole thing can be interpreted as a 12 bit 
superchannel number? Of course the bit arrangement doesn't matter except to 
improve human readability of the code and data.


On 7/23/2013 1:14 AM, David Lawrence wrote:
>
> Hi Gerard,
>
>     That's correct, "slot" is the slot in the VME crate. You're right, it
> could be sacrificed from the hit record if needed. Right now, it appears
> in the both the block header and hit record and is currently used by the
> parsing software to provide a small integrity check on the data. If
> there is something else more worthy of those bits, we can consider
> dropping it from the hit record.
>
> Regards,
> -Dave
>
> On 7/23/13 12:47 AM, Gerard Visser wrote:
>> hi Naomi, Dave,
>> 	What is 'slot' by the way? (5/62 hit payload bits used for this.) I guess it is
>> the ADC module number? But why put this in the hit record? It can just as well
>> be in the block or event header from the module, it will be constant for all hit
>> records from the module...
>>
>> 	- Gerard
>>
>>
>> On 7/22/2013 7:58 PM, Naomi Jarvis wrote:
>>> Minutes are online at https://halldweb1.jlab.org/wiki/index.php/July_17,_2013_Tracking_CDC/FDC
>>>
>>> Also I think I forgot to email the same for the previous meeting, sorry, those are at https://halldweb1.jlab.org/wiki/index.php/July_3,_2013_Tracking_CDC/FDC
>>>
>>> Best regards,
>>>
>>> Naomi.
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