DIY Solar Scintillation Seeing Monitor with FC support

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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by RTJoe »

Hello,

plugin version v0.92 is released now.

This version now "officially" supports the SSM from AiryLab in FireCapture. Thanks to user rxdeath for testing:
SSSMonScr_AiryLab.jpg
SSSMonScr_AiryLab.jpg (152.42 KiB) Viewed 14359 times
One main addition is the new chart window with graphical plot of the seeing values. This windows is a FireCapture window, it's no longer necessary to use additional software to display a chart.
SSSMonScr_ChartEN.jpg
SSSMonScr_ChartEN.jpg (89.34 KiB) Viewed 14359 times
The plugin writes the average seeing value during a recording run into the FireCapture log file and optionally can write an additional log file with the seeing value for each captured frame. The format of this log file is CSV, it can be easily processed or imported e.g. into Excel.

A new firmware is also available, providing calculation of an alternative seeing value based on more (and longer) scintillation measures.

Plugin and Firmware are available for download here: http://www.joachim-stehle.de/sssm_eng.html. Please use the latest release version 2.5 of FireCaputue.

Joachim


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Perfect job Joachim!

I will test it out a soon as I get some decent sunshine. The SSSM monitor with the Nano now seems to function as expected while testing during a short period of sunshine. (But then trees got in the way ...)

Kind regards,
Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Hi,

so first real outside testing today.
This is what I got in the SSSM
Measure1.jpg
Measure1.jpg (174.31 KiB) Viewed 14293 times
I had the impression seeing was worse than what the device was reporting. Only could get this poor result. (but of course Quark runs at f/24.5 and that seemed to be to much today)
PP2016-11-25-1019_5-PDB-Ha__SSSM_1.8.jpg
PP2016-11-25-1019_5-PDB-Ha__SSSM_1.8.jpg (24.26 KiB) Viewed 14293 times
little bit later seeing got worse (also through the camera)
This data was collected using the larger number of samples
Measure4.jpg
Measure4.jpg (152.96 KiB) Viewed 14293 times
The plugin works as expected, starting at the right moment, pausing when needed. Now need to figure out what settings work best.

Kind regards,

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Any particular updates from anyone who has completed a monitor?

I'm interested in building one just for fun to monitor seeing while I'm at my scope.

I have no experience with boards, circuits, etc, though. May be beyond what I can do without someone helping or a video or something.

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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Hello Marty,

not that difficult to make (i have no experience in electronics either), but you need to be able to do a little bit of soldering on a strip- or veroboard.
What I found the most difficult thing was to mounting the sensor.
Difficult parts to find were the original sensor, so replaced in by the BPW34. That one is tiny and difficult to solder, but beeing cheep, I ordered 4 so i had some spare parts. Also the NP capacitor can be hard to find.

Seems I have thrown away my veroboard design (was just a sketch on paper). Will "clean" my desk a bit, maybe I can find it back.

As for the device, it works very well and is a great help reducing the captures to usefull and much smaller files than before.

Regards,

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Hi Paul,

Thanks. I suppose I'd have to start by finding out how to even interpret the schematic on the original PDF to know what any of it means. I actually found all the bits, the boards, the sensor and the amp, so I can get the parts quite inexpensively (though I have no idea what any of the wires, resistors, capacitors, or anything of that stuff is). More just a matter of knowing what I'm doing putting them together and how to load the software and how to have it output to a laptop and produce data to interpret.

I bought two of the sensors (VTP4085H), two of the LMC6484 amps, and an Arduino uno R3 board.

From here, I just need to know if I need to get a solder setup, or if I can get some kind of wires that allow me to use them without soldering so I can see if it works without it being permanent and ruining stuff. Jumper wires? I'm looking at small bread boards and wire kits that are commonly listed with the arduino boards. But I'm not sure of any of it.

I figure one to learn on, one to do right (maybe), once I get everything I need and figure this stuff out. And if it works out, maybe I'll build a few since I can get the parts so easily and inexpensively.

Too bad there's not a simple video tutorial out there to show one of these being built with instruction!

Very best,
Marty
Last edited by MalVeauX on Fri Jun 02, 2017 7:38 pm, edited 1 time in total.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Marty,

give me a few days and I will reconstruct the board layout I made for a strip-board. (not that difficult)

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Thanks Paul, appreciate it.

BTW, I edited in some more information prior to this post:

"

I bought two of the sensors (VTP4085H), two of the LMC6484 amps, and an Arduino uno R3 board.

From here, I just need to know if I need to get a solder setup, or if I can get some kind of wires that allow me to use them without soldering so I can see if it works without it being permanent and ruining stuff. Jumper wires? I'm looking at small bread boards and wire kits that are commonly listed with the arduino boards. But I'm not sure of any of it.

"

Example: not sure if I can use this (to avoid soldering at first to at least learn with):

https://www.amazon.com/dp/B004RXKWDQ/re ... UTF8&psc=1

Very best,


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Need to check. In theory you could place the components on a breadbord and then connect with wires to the Arduino, but of course theory an practice do not always go hand in hand.

Very best

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Hrm,

So just going back and reviewing some material:

Looks like from the program, basically the IR sensor is measuring light intensity and its becoming converted to a voltage value that is monitored. Basically the intensity of the light change over time is being correlated to seeing quality. Does that sound correct?

I've watched some YouTube tutorials on the Arduino boards, basic circuitry, etc. Looked at the software to load the sketches onto the Arduino too. Seems easy enough for the most part. Looks like I can use solderless jumper wires to practice on a breadboard to make sure the circuit works before moving to a permanent build, so that's good.

So now I really just need to learn to read the schematic on the original PDF so that I understand what the symbols mean and how to follow the circuit design because when I compare the schematic in the PDF to the image of the breadboard, I'm not able to follow it very far before losing where the circuit is going. For example in the PDF I read about 5 instances of a resistor (values 220, 47k, 10k, 10k, and 20meg) and I see them on the board, but I guess I'm getting lost on where it translates to the mirror side of the board and back.

So really I don't think I'm able to read the schematic yet.

Looks like the microprocessor is referenced 4 times (U1 through U4) and that there are two capacitors (non polarized) in the schematic? One that's 3.3 micro-ferads and one that is 20 pico-ferads, right?

Also, I probably need to figure out how to connect the photodiode to a cable, like the shielded RCA, so that I can mount that on the scope and run the cable to the board near the computer. That will take soldering I'm sure, so I will have to get into that a bit too. But I don't mind testing it without a cable at first just to ensure its working and to get the voltage correct at that stage (to 1V). I think I'll get a variable resistor to attenuate it to 1V, even though it says 220 ohm resistance, but says to change it to get to 1V).

Very best,


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Marty,

will send you a private message.

Rgrds,

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Hey all,

So I'm trying to make sure I get the right components per the original PDF, just want to make sure I'm reading it correctly and found the correct items if anyone familiar wouldn't mind confirming:

10k Resistor x 2: http://www.mouser.com/ProductDetail/KOA ... YulfaVM%3d

20 Meg Resistor x 1: http://www.mouser.com/ProductDetail/Ohm ... lJaLh0I%3d

47k REsistor x 1: http://www.mouser.com/ProductDetail/KOA ... wvink34%3d

Capacitor 3.3 micro Ferad non-polar x 1: http://www.mouser.com/ProductDetail/Vis ... %252b7o%3d

Capacitor 20 pico Ferard x 1: http://www.mouser.com/ProductDetail/Vis ... W9kYh4o%3d

Very best,


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

The 3.3 mF capacitor should be of type NP. Could not see that from the spec. Looks like a standard one. (there seems to be a way to use normal capacitators, if you use 2, but then the value will be different, and that is far beyond my knowledge)

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Turns out all most all of that above is the wrong stuff. I didn't know the difference between carbon film, metal, etc, none of this is in the schematic so I have no idea what the differences really are, there's so much as it is.

If anyone is familiar with the stuff and can link the items per the original PDF, that would be really helpful.

+++++++++++

Looks like I need 1/4watt, 5% carbon film. I'd have never known! Hah.
I guess the size of the capacitors and all that eluded me as well.
Also, no idea how to know if the potentiometer for the variable resistance would have the ranges needed to achieve something around 220ohm, or whatever it turns out to be to achieve the 1V at the photodiode.

++++++++++++++

Let's see if I can get any of this right:

10k Resistor x 2:
http://www.mouser.com/ProductDetail/KOA ... %2f2Y24%3d

20Meg Resistor x 1:
http://www.mouser.com/ProductDetail/KOA ... XXOMQTs%3d

47k Resistor x 1:
http://www.mouser.com/ProductDetail/Yag ... CvOsHqQ%3d

Is this an appropriate 3.3 uF non-polar capacitor?
https://www.parts-express.com/33uf-100v ... mpaign=pla

Is this an appropriate 20 pF capacitor?
http://www.mouser.com/ProductDetail/Vis ... hgodkEcL8A

No idea how to even select an appropriate variable resistance, or potentiometer. Or if I follow the original schematic, a 220ohm is used, so should be possible to just do that again. But if I extend the sensor off the board with a cable, will that change anything?

Very best,


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

As variable resistor use one for 2K (that will give all the range from 0 to 2K). When testing you adjust it until you get an input value between 0.6 to 0.9 when the cell is in full sunlight. (even 1K value could be ok)

The capacitor looks ok.

Rgrds,

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Thanks,

Way more complicated even just finding parts that are appropriate than anything it seems!

Very best,


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

So, I have most of the parts now.

I have:

VTP4085H sensors
LMC6484 I/O OP Amp
Arduino Uno R3 Controller
Breadboard & Jumper Wires

I haven't picked up any resistors, capacitors, etc, yet because I can't seem to find exactly what is needed due to my inexperience and lack of education in this kind of stuff. I at least know the type of basic resistors I need, but I'm not confident with the capacitors, and I'm really not sure of the variable resistor pot to make sure its the right kind and range of values. And then, I still am not confident on how to set it up on the board, but I can at least play with it a little with the jumper wires. I have multiples of everything above in case I torch it.

I've linked some resistors, capacitors and a variable resistor pot above; if someone can help me confirm what I can/cannot use. I'm trying to follow the original PDF design as closely as possible. If I can make it work, I will then look into extending the sensor off the board and onto an audio cable or something to get it onto the telescope. But that's later, if I can get this to work.

?

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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by RTJoe »

Hello,

I guess the parts you have selected should work, but here is some information about the parts I have used:

This is the 3.3 uF non-polar capacitor I have used:
http://www2.mouser.com/ProductDetail/WI ... DLXjc8zLm2

Please check the value of your 20 pF capacitor; when I click on your link there is a 68 pF capacitor displayed.

The resistors don't seem to be critical, but I have spend some cents more and used metal film types with 1% tolerance only.

I would recommend (and have used) a trimming potentiometer of 250 or 500 ohm instead of the fixed value 220 Ohm resistor. This allows easy adjusting of the input value.

Of course it's a good idea to start building on a breadboard with jumper wires. If everything works, you might start soldering.

Best regards,
Joachim


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Hi Joachim,

Thanks for the info.

That capacitor you linked, how is it designated to be non-polar?

Thanks!

Very best,


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by RTJoe »

Hi Marty,

the capacitor I have linked is a film capacitor, these capacitors are nonpolarized by nature. The capacitor you have linked is an electrolytic nonpolarized (bi-polar) capacitor, that means actually two polarized capacitors in series. I guess both capacitors should work, but I'm no expert about the details.

Best regards,
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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Thanks, that helps!

Very best,


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by MalVeauX »

Any chance there's a 20pF capacitor on there? I just looked under film and could only find a 22pF. Just trying to follow the PDF at the beginning of this thread, if that helps.

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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

All right, I'm joining the SSM club! Parts have been ordered - I'll use BPW34 diode too, and an LM224AN op-amp; parameters similar to LMC6484, we'll see how it goes...

I wanted to understand what's what, so I've tried to recall the electronics course (wasn't my favourite one) from studies, and also read the original article on solar scintillation by Dr. Seykora. Eq. (5) therein (page 391) gives the angular diameter of the average “seeing cell”:

ω = θI / <I>)

where θ is Sun’s angular diameter, ΔI the RMS of irradiation intensity changes (our second ADC input), <I> is average intensity (our first ADC input).

The 4.46 coefficient in output formula is due to the fact that we want to express ω in arc seconds, and the circuit magnifies ΔI by a factor of 20M/47k ≅ 425.5 (which we have to cancel out in our final calculation), while we can take the Sun to be ~1900 arc sec in diameter, so:

ω [arc sec] = 1900/425.5 * (ΔI / <I>) ≅ 4.46 * (ΔI / <I>)

As for the 10 000 samples taken for each returned seeing value, it seems it's due to Arduino's ADC read-out rate:
It takes about 100 microseconds (0.0001 s) to read an analog input, so the maximum reading rate is about 10,000 times a second.
i.e. we sample the RMS and the average over a period of 1 second.

The photodiode also checks out; according to specs, it produces 50 µA photocurrent at 1 mW/cm² irradiance. In full Sun (assuming 1000 W/m² = 100 mW/cm² irradiance), and converted to voltage and amplified 220x (due to the 220-ohm resistor) by the first op-amp, it should be about 1.1 V. Of course it's good to have a variable resistor to fine-tune it.

I'm wondering about filtering; Seykora's article mentions using filters which gave 220 nm FWHM at 510 nm. If the SSM is used during an Hα imaging session, shouldn't we e.g. slap a red filter on the diode to give more meaningful seeing values? Would there be any noticeable difference anyway?


P.S. Marty, I'm taking my chances with a 22 pF too.
Last edited by GreatAttractor on Sat Jun 24, 2017 10:13 pm, edited 1 time in total.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Hmm ... my answer from this morning seems to have vanished.
Interesting remark GreatAttractor. Now I remember the filters in the original document. I did a small test with a red Wratten 25 filter (that was all I had on hand). What I expected the input value dropped by approximately 0.2 but calculated seeing values did not change very much. (Difficult to compare in a short test, not reallt scientific, under varying sky conditions, more work needed.

Some remarks on the builds
A 22 pF capacitor will work (using it as well)
I am using the cheap Arduino Nano's but find these fairly unreliable. Also the mini USB connector is not very sturdy. With the SSSM i get sometimes hangups (could als be due to the one wire LCD display I am using, that sometimes hangs on startup as well). But I also made a focus controller with the same nano model and it works very well excexpt that it sometimes reset and all stored values are set to default. (Very annoying if you count on these positions to make sure the focuser does not go outside it boundary. The very strong stepper motor could the ruin the gearbox or the rack-and-pinion assist rail) So I decided to do some rebuilding and test it with an UNO which looks much better and has better usb connectors.

Regards,

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

I've just realized it's perhaps better not to use filters; if all/most of us use just a naked diode, it'll make sense to compare seeing values among all SSM users (not depending on people using exactly the same filters etc.).

Also, if I'm not mistaken, the U2 op-amp together with the 47k resistor and the 3.3 µF capacitor form an active high-pass filter with cut-off frequency of 1/(2π · 47k · 3.3µ) ≅ 1 Hz, so I suppose that's why the average (<I>) is obtained by summing over 1 s. The faster-changing portion of the intensity signal goes to the RMS calculation.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

GreatAttractor wrote: Sat Jun 17, 2017 3:35 am and an LM224AN op-amp; parameters similar to LMC6484
...not really, after a closer look (which also explains the price difference, I guess). Fortunately I found a supplier and got a few LMC6484AIN op-amps.

So far I've assembled and tested the "first stage" (sampling only the averaged light intensity), seems to work fine (I'm using Arduino Micro):
stage1.JPG
stage1.JPG (237.49 KiB) Viewed 12886 times
Indeed, I had to put the cell phone's LED-flashlight very close to the photodiode to see some smallish increase in the sampled value. I should have some breaks in the clouds tomorrow for proper testing.

The diode is really tiny, here it is with a pendrive and a chunky 3.3 µF film capacitor:
dc.JPG
dc.JPG (174.43 KiB) Viewed 12886 times
Beside the current (1-second) seeing value and the 10- or 30-second average, I'm also going to display an "average of the best percentage", which I think is more meaningful for us imagers. For example, with my current setup I usually shoot a 15-second video and then stack 30% best frames. The expected image quality should correspond with the average of seeing values of the best 5 seconds out of 15 s.

Another change is using the timer interrupt to calculate the average (and update display/send data to PC) over exactly 1-second intervals ‒ and not by polling the ADC until 10 000 samples are collected. As you can see in the first photo, there were just 7754 read-outs in the last second.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by IanL »

Inspired by this thread, I built an SSSM a few months back with good results. I've written a detailed build guide here:

http://www.blackwaterskies.co.uk/2017/0 ... itor-sssm/

- Full strip-board layout diagram included for the less electronically inclined.
- Step-by-step build and test instructions.
- Refactored the SSSM sketch to make it more readable and modular (to support different display types for example).
- Plenty of use of #define and #ifdef blocks so that only required code is included for the functions enabled, minimising sketch size.
(https://github.com/IanLauwerys/SSM/blob ... Sketch.ino)
- Optional OLED display with graph functionality (you can pick up suitable modules from eBay for a few pounds/dollars).

Hope this is useful to someone and thanks to Joachim for bringing this to the masses and the great FireCapture plugin.

The OLED display didn't come out well in this photo, but it does work in practice!

Image

Image

Image
Last edited by IanL on Sat Jun 24, 2017 12:11 pm, edited 1 time in total.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Ian,

this is a fantastic guide you provided. Also the Arduino code looks very good. (Think I will test it out as soon weather permits)

Regards,

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

Thank you, Ian. As I've already finished my sketch today, I guess we'll have yet another on Github ;)

UPDATE:

I managed to test today during a short break in the clouds. It was a hot day, I put the rig in front of an open window and got consistently 10-12", which seems too high. Maybe temperature difference from the outside was bigger than I thought... Will try again tomorrow (though it's going to be partly cloudy again).

Sunday Update:

There were still some super-thin uneven clouds today and the SSM always clocked more than 10". I hope it's just the clouds, not some problem with the circuit. I hope it won't be the traditional two cloudy weeks after getting a new toy until I can test properly.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by RTJoe »

GreatAttractor wrote: Sat Jun 17, 2017 3:35 am
I'm wondering about filtering; Seykora's article mentions using filters which gave 220 nm FWHM at 510 nm. If the SSM is used during an Hα imaging session, shouldn't we e.g. slap a red filter on the diode to give more meaningful seeing values? Would there be any noticeable difference anyway?
Some months ago I have asked exactly this question to Mr. Seykora, here is his reply:

"Schott filters with a 220 nm passband centered at 510nm. Nothing is to be gained by using the filters. These filters used in the original Scintillation Seeing Monitor paper were used to relate seeing measured with Scintillations and Angle of arrival fluctuations. Scintillations are very independent of wavelength in the Vis. and near IR wavelengths, angle of arrival fluctuations are dependent on wavelength."

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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by Spectral Joe »

With regard to high, thin clouds, these indicate high altitude wind shear that would cause poor seeing. Sounds like you are getting the right number. As for the filters, this combination would give a photopic response in combination with the photodiode spectral sensitivity. This type of detector / filter combination is commonly used in light measurement. As Joachim says, not needed in this application. I've built a slightly different version of this device, since I'm an old timer I prefer watching a needle move on a meter movement so I used digital pins 5 and 6 (on an Uno) for analog (PWM) outputs that represent seeing and level. A switch selects which one is displayed.

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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

Good news - it turned out I forgot to connect 2.5 V reference voltage to pin 5 of the op-amp, so the analog input 2 was returning some garbage values. After fixing this I'm getting the expected seeing levels (0.8"-2.5" at the moment, during breaks in passing high clouds).

I've started assembling the final "box" version.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

The box is almost finished; the circuit board didn't turn out much tidier than the test version...:
ft2.jpg
ft2.jpg (140.12 KiB) Viewed 12509 times
The sensor assembly is made out of sawed-off RCA connector:
cz1.jpg
cz1.jpg (77.04 KiB) Viewed 12509 times
cz2.jpg
cz2.jpg (60.35 KiB) Viewed 12509 times
Field test:
ft1.jpg
ft1.jpg (100.36 KiB) Viewed 12509 times
It's attached with a 1 meter long shielded RCA cable, to be mounted on the telescope. I'll make a second, directly pluggable sensor on a right-angle RCA plug for operation in the field (I'd like to take some readings from my favourite mountain in good weather, and maybe from a lake too; probably save them in the Arduino's EEPROM for later retrieval).

I've uploaded my Arduino code to: https://github.com/GreatAttractor/ssm
It uses timer interrupt (via TimerThree library) to sample over predetermined duration, and includes comments for the 4.46 "magic number".


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Looks Good Filip.
Which Arduino are you using? I don't get your code compiled on the Nano. (It does for the ATMega) Some problem in the Timer file definitions.
Also tested Ian's code, but since use I2C versions of the LCD and OLED display had to do a few modifications in the display settings.
Works fine on the Mega, but displaying 2 graphs on the Nano is just too much and becomes unstable (not enough memory?) If I comment out one of the 2 graphs it works on the Nano as well. (Could see the Micro has slighly more memory, so that could help?)

Regards,
Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by IanL »

Paul,

Yes the code is pretty tight on memory. Another option worth trying might be to reduce the number of points stored and displayed for the graphs as they use a fair amount of memory.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

Paul,

I have Arduino Micro. If TimerThree causes problems, one can comment out the whole timer thing and just use a fixed number of samples as in the original.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

The box is a hack job, but at least it's not in pieces anymore ;) The input-regulating variable resistor is accessible via the central hole. The knob is for LCD backlighting (the good thing about black-on-green LCD is that it's also perfectly legible in full sunlight with backlight off).
bo2.jpg
bo2.jpg (146.88 KiB) Viewed 12355 times
bo1.jpg
bo1.jpg (106.91 KiB) Viewed 12355 times
bo3.jpg
bo3.jpg (71.2 KiB) Viewed 12355 times
I've also put together (github repository) a simple client (text-mode) to display and store SSM data in CSV format for later analysis, e.g. in LibreOffice Calc. Some data from today's golden evening (timestamps are in UTC, add 2 hours for my local time):
ssm_log.png
ssm_log.png (299.61 KiB) Viewed 12355 times
Not bad, considering that the Sun was at barely 17° down to 8° altitude.

Update – histogram of seeing values:
histogram.png
histogram.png (18.39 KiB) Viewed 12347 times
I'm already thinking of rebuilding into nicer and smaller version 2; already ordered one of those nice small OLED displays like Ian's, I'll probably have a PCB made too.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Hi,

first version of the Linux version of a real-time Solar Scintillation Monitor. (on Ubuntu 16.04) Still a long way to go ... Error handling and decent graphs (need to learn more about qcustomplot libraries, but first results are promising. It should work with different versions of the Arduino code (Original, RTJoe, Ian and GreatAttractor) Since there was no sunshine for real testing, I also build in a simulator device generating (erratic) random seeing levels and fixed 0.95 input value. (Thanks GreatAttractor for the coding example :D )
Code is not in a "publishing" state yet, but hope to do that very soon ..

here is a screenshot
Screenshot.png
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Regards,

Paul


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

As was to be expected, I haven't had imaging opportunities since finishing version 1 of my SSM :evil:

In the meantime, I bought a 1.3" mono OLED display and learned to use it; also, version 2 of the board is almost built, and new Arduino code is ready. Not that having a seeing graph is particularly useful, but it was fun to implement:
oled.jpg
oled.jpg (38.22 KiB) Viewed 11830 times
The thicker black line is the central running average (30 s). Using Polish style decimal separator for the screenshot, but it can be redefined to period. As I'm not attempting to keep a copy of frame buffer in SRAM (that would be 128x64 bits = 1 KiB), there's still plenty of memory left:

Code: Select all

AVR Memory Usage
----------------
Device: atmega32u4

Program:   13824 bytes (42.2% Full)
(.text + .data + .bootloader)

Data:        702 bytes (27.4% Full)
(.data + .bss + .noinit)
I think the code is cleanly split into components, so feel free to have a look/reuse: https://github.com/GreatAttractor/ssm/tree/dev/v2/src


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

Finally! Two nice cloudless days, and I could at last verify the values reported by SSM. After attaching the sensor so it would follow the Sun:
moco1.jpg
moco1.jpg (187.9 KiB) Viewed 11576 times
moco2.jpg
moco2.jpg (216.09 KiB) Viewed 11576 times
moco3.jpg
moco3.jpg (99.53 KiB) Viewed 11576 times
i started data collection, and captured a 50-second video at 20 fps. It would seem the SSM works correctly, because on a joint graph of the seeing and the (exported from Stackistry) frame quality, I got:
seeing_vs_quality.png
seeing_vs_quality.png (193 KiB) Viewed 11576 times
Frame quality on the right-hand vertical axis (0 = best, 1 = worst). Correlation seems to be quite good.

Quality estimation

Stackistry uses a simple method of determining the quality of an image A; it's the sum of absolute differences of pixel values between A and a blurred version of A:

q = Σ |AAblur|

In other words, the total brightness of the “high frequency component”. If A is already blurred, then the differences, and therefore q, will be small. If A contains a lot of sharp details, they will remain after subtracting the blurred version, and the sum will be higher.

This quality measure is not affected by simple geometric distortion (“rubber membrane”) of images, which might explain imperfect correlation at some moments.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by PDB »

Hi Rainer,

if it will run on the UNO depends on which Arduino code you have downloaded. There are several versions now and some are not compatible with all Arduinos. (Size of data and program for the graphics display, use of timer routines). The most simple version without display, should run on every Arduino.

Mine is running on an cheap Nano, but tested on and UNO and a Mega. If you use a display, then it depends which one you choose. I have been creating some code for a graphical version and small memory footprint but haven't published it yet.

Regards,
Paul

Sorry: can't answer your first question (too little real electronics knowledge)


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by rsfoto »

PDB wrote: Mon Dec 11, 2017 9:41 pm Hi Rainer,

if it will run on the UNO depends on which Arduino code you have downloaded. There are several versions now and some are not compatible with all Arduinos. (Size of data and program for the graphics display, use of timer routines). The most simple version without display, should run on every Arduino.

Mine is running on an cheap Nano, but tested on and UNO and a Mega. If you use a display, then it depends which one you choose. I have been creating some code for a graphical version and small memory footprint but haven't published it yet.

Regards,
Paul

Sorry: can't answer your first question (too little real electronics knowledge)

Hi Paul,

Thanks for the answer. Ordered also some LMC6484.

Will start with the original sketch in the paper of E.J.Seykora and then work upwards.

I just read a lot about all this and I see that we need 2 values and not just one wn the input is different as they camoe from 2 different pins of the LMC6484.

So I will set up the board as in the original paper.

BTW I found an interesting software package for displaying values on a PC. Easy to implement together with the Arduinos. It is called MegunoLink

regards Rainer
Last edited by rsfoto on Fri Dec 15, 2017 3:44 pm, edited 1 time in total.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by rsfoto »

Hi,

I am waiting to get the Photo diodes and the OP amps to start with the building.

What did draw a bit my attention is the follwong in the paper of Dr. Seykora
Care should be taken that the cable is grounded only at the circuit board and not at the detector.
A coax cable has only 2 lines for data transmission, the inner core and the outer mesh ...

So if I do not connect the outer mesh to the cathode of the BPW34 then I will get no signal :-)
CB-COAX-Cable.jpg
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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

It seems clear to me: "not grounded at detector" = "don't try to attach the outer mesh at the detector to an external ground".


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by rsfoto »

GreatAttractor wrote: Thu Dec 14, 2017 8:59 pm It seems clear to me: "not grounded at detector" = "don't try to attach the outer mesh at the detector to an external ground".
Hi,

Thanks for that. Now if I understood correctly that menas that if I have a metal case for the detector then I should not ground it to that metal case ?

Again thanks :bow2

BTW. I got my BPW34 today and made some mesurements having connected it to an OpAmp. WOW this little buggers are really sensitive :bow

I think I can use them for my ongoing project of the Solar guider I am building.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

Now if I understood correctly that menas that if I have a metal case for the detector then I should not ground it to that metal case ?
Right, that's my understanding too.
I think I can use them for my ongoing project of the Solar guider I am building.
That's cool! Also keep an eye on the Planetary Imager – automatic tracking (self-guiding) is in the works.


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ImPPG — stack post-processing and animation alignment
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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by rsfoto »

GreatAttractor wrote: Fri Dec 15, 2017 3:26 pm
Now if I understood correctly that menas that if I have a metal case for the detector then I should not ground it to that metal case ?
Right, that's my understanding too.
I think I can use them for my ongoing project of the Solar guider I am building.
That's cool! Also keep an eye on the Planetary Imager – automatic tracking (self-guiding) is in the works.
Hi,

Thanks. Will take a look at the Planetary Imager Software.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by rsfoto »

Hi,

In regard to the Scintillation Monitor ...

Has anyone tried to diminish the angle of entrance ? So far I think everybody is using the full angle of the sensor is active.

Would it mean that using it recessed some values would heve to be changed ?

Looks like my LMC6484 will arrive today.


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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by GreatAttractor »

As long as you don't use any optics in front of the naked diode, I think recessing won't make a difference. The Sun is thousands of times brighter than any other light source you'll encounter on a typical day, so no "background light shielding" should be needed.


My software:
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ImPPG — stack post-processing and animation alignment
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SW Mak-Cass 127, ATM Hα scopes (90 mm, 200 mm), Lunt LS50THa, ATM SSM, ATM Newt 300/1500 mm, PGR Chameleon 3 mono (ICX445)
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Re: DIY Solar Scintillation Seeing Monitor with FC support

Post by rsfoto »

GreatAttractor wrote: Fri Dec 15, 2017 8:51 pm As long as you don't use any optics in front of the naked diode, I think recessing won't make a difference. The Sun is thousands of times brighter than any other light source you'll encounter on a typical day, so no "background light shielding" should be needed.
Hi,

Thanks for the input. Well the circuit is ready on the bread board and now I have to see how I do get the sensor into the sun. I guess I will prepare a long cable from my desk to the window :D

Also making up my mind how to eventually integrate this BPW34 photo diode into my solar guider project.


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