Re: Advice on PC Based Logic Analyzer

On Apr 15, 2:01 pm, Jean-Yves <no-pub-for-jypoc...@xxxxxxx> wrote:
In article
<9591c2c7-93e1-4bbf-bd75-35bcfcfad...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,





 logicgeek <logic.analy...@xxxxxxxxxxx> wrote:
8 channels is too low for a logic analyzer
16 is a minimum
34 is far enought

you must count $500 for a complete logic port with some grabbers...!

I never heard of this annie-usb before...
but saw a lot of people around here happy with their logicport

so...make your choice !

--
Jean-Yves.- Hide quoted text -

- Show quoted text -

What I like about the Annie-USB is that it comes complete with SMD
grabber clips that optionally would cost some extra money.
If you have the time go towww.janatek.com/annie-usbmain.htm. It
retails just below $500..My only concern thou is that it sports only 8-
channels. However they have a nice little article on their website
about evaluating logic analyzers and I must say that I agree with this
article in that I will rather buy 8 'good channels' with sufficient
buffer depth than 32 channels and anyway not be able to use them all.

The faq article is at:http://www.janatek.com/faqbuying logic analyzer.html#6

I've talked to some people and most of them said that I should opt for
sufficient buffer depth. What is the feedback of those happy okes
using logicport?

the logicport has a compression algorythm so that he can record days of
datas. it only records when the data changes.

That is true. It only records when data changes, But when your data
never changes why do you need a logic analyzer, and when your data
actually changes even at a moderatly freqency your little buffer would
fill up in no time.
Come on, if data compression was the epiphany solution, why would any
developing company at all offer you a deep sampling buffer.
Data compression is much cheaper to develop and manufactured. Quote
article in Evaluation Engineering.
"Lossless signal compression is included in this product because
its basic memory depth is 2,048 S/channel. To conserve memory, the
LA1034 only records data
transitions. Lossless data compression relies on redundancy
within the data, which can be encoded to reduce storage requirements.
The amount of compression
possible depends on the nature of the data. For example, the
LA1034 data*** quotes a 233:1 maximum compression ratio or a factor
of greater than eight
billion. This degree of compression is possible for a signal
starting with a single logic 1 followed by eight billion zeros. If
your signals typically consist of a few fast
pulses with lots of dead time, compression can be very useful.
However, for very active signals with a large number of transitions,
the effective compression ratio
will be small.
The reason Logicport offers data compression rather than a larger
sampling buffer is that they only use the little onboard memory
available in the single FPGA in their instrument. (Quote article in
Evaluation Engineering)
"The LA1034's logic and memory are entirely contained within a
single FPGA," commented Harrison Young III, company CEO. "This keeps
the speed up and the
cost down compared with products having external memory
interfaces. The LA1034's efficient lossless compression algorithm
allows its buffer depth to be greatly
extended with no loss in signal integrity."

Makes sense to me. Larger buffer makes even more sense




the annie usb record also when the data dont change which is a waste of
buffer...
and definitely 8 channels is not enought

the logicport with 34 grabbers (and channels)  is around $500

the sufficient buffer depth is to compare with old logic analyzers that
had only some ko of memory and that are unusable today.
the logicport has enought.

.

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