The MSDS is here:
https://simplegreen.com/data-sheets/
They claim that it is non reactive and chemically stable.
It is for water tolerant surfaces and should be rinsed.
Probably due to the citric acid.
Glenn
On 5/27/2018 11:52 AM, Oleg Skydan wrote:
Hi!
From: "Magnus Danielson" <mag...@rubidium.dyndns.org>
You build two sums C and D, one is the phase-samples and the other is
phase-samples scaled with their index n in the block. From this you
can
then using the formulas I provided calculate the least-square phase
and
frequency, and using the least square frequency measures you can do
PDEV. The up-front processing is thus cheap, and there is meathods to
combine measurement blocks into longer measurement blocks, thus
decimation, using relatively simple linear processing on the block
sums
C and D, with their respective lengths. The end result is that you can
very cheaply decimate data in HW/FW and then extend the properties to
arbitrary long observation intervals using cheap software
processing and
create unbiased least square measurements this way. Once the linear
algebra of least square processing has vanished in a puff of logic, it
is fairly simple processing with very little memory requirements at
hand. For multi-tau, you can reach O(N log N) type of processing
rather
than O(N^2), which is pretty cool.
I had some free time today to study the document you suggested and do
some experiments in matlab - it was very useful reading and
experiments,
thanks!
Thanks for the kind words!
It looks like the proposed method of decimation can be
efficiently realized on the current HW.
I had some free time yesterday and today, so I decided to test the new
algorithms on the real hardware (the HW is still an old "ugly
construction" one, but I hope I will have some time to make normal HW
- I have already got almost all components I need).
I had to modify the original decimation scheme you propose in the
paper, so it better fits my HW, also the calculation precision and
speed should be higher now. The nice side effect - I do not need to
care about phase unwrapping anymore. I can prepare a short description
of the modifications and post it here, if it is interesting.
It works like a charm!
The new algorithm (base on C and D sums calculation and decimation)
uses much less memory (less than 256KB for any gaiting time/sampling
speed, the old one (direct LR calculation) was very memory hungry - it
used 4xSampling_Rate bytes/s - 20MB per second of the gate time for
5MSPS). Now I can fit all data into the internal memory and have a
single chip digital part of the frequency counter, well, almost single
chip ;) The timestamping speed has increased and is limited now by the
bus/bus matrix switch/DMA unit at a bit more then 24MSPS with
continuous real time data processing. It looks like it is the limit
for the used chip (I expected a bit higher numbers). The calculation
speed is also much higher now (approx 23ns per one timestamp, so up to
43MSPS can be processed in realtime). I plan to stay at 20MSPS rate or
10MSPS with the double time resolution (1.25ns). It will leave a
plenty of CPU time for the UI/communication/GPS/statistics stuff.
I will probably throw out the power hungry and expensive SDRAM chip or
use much smaller one :).
I have some plans to experiment with doubling the one shoot resolution
down to 1.25ns. I see no much benefits from it, but it can be made
with just a piece of coax and a couple of resistors, so it is
interesting to try :).
All the best!
Oleg UR3IQO
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Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4...@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"
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