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=======  Multi Element Water Content Meter System (WCM) =======

====== Problems and Solutions ======

===== Problem (Spring 2025) =====
==== Introduction ====
During previous field campaigns in which the WCM model 3000 was used it had been noticed that the initial value during no water content present was a non zero value. This is still noticed in the WCM 3000 where on initial start up the probe indicated that there is water content present. This issue was normally resolved with post processing of the data from past campaigns where the non zero data would be adjusted down to zero and then further studied after that correction was applied. 

==== Cause ====
In the fml.300 table that is present on the m300 computer and is used by the WCM data collection software it was noticed that the code that is supposed to correct for this non zero value wasn't included in the table. There was however correction code in there but it appeared to be from the older WCM model in which it had a compensation term that would remove this non zero value and instead keep the probe at a zero value until water content is present. 

==== Solution ====
In the manual for the WCM 3000 probe there is a section in which a couple different ways are discussed as to how to get the probe to go to a zero value during the non presence of water. The way that was used in our correction of this issue was as follows; Psensedry = K1 * (Tsense - Tambient)*(Pambient * TAS)^k2. Where Psensedry is the value that is subtracted from Psensetotal which gives us Psensewet, K1 is a constant that is used which can be changed based upon testing of the probe, Tsense is the temperature of the sensor, Tambient is the ambient temperature, Pambient is the ambient pressure, TAS is the true airspeed, and K2 is another constant that can again be found by testing of the probe. This together does appear to work in the laboratory setting but still should be tested in the field as the higher airspeed values might cause the need for changing the constants K1 and K2 as needed. 

===== Problem (Spring 2025) =====
==== Introduction ====
During the use of the WCM it was noticed that when compared to other instruments such as the Cloud Droplet Probe, RICE probe, and the hot wire boom probe there is a decay present after the water content should have gone to zero over the probe head. This is now something that is being lab tested to better understand what is going on with the probe and to try and correct this invalid data that is being collected. Below are references to where the data is located for this particular lab run. 

  * Reference: /nas/und/NorthEast/2025/Lab/CH423/GroundData/20250416_165626/PostProcessing
  * Reference: /nas/und/NorthEast/2025/Lab/CH423/GroundData/20250416_165626/Camera_Data

Below is a side by side comparison of what was recorded during this test by both the probe head and the video which in the video shows when water droplets are present and when they aren't. The graph is also marked as to roughly where the video is showing data at and where the corresponding area is on the graph. 

==== Video Comparison ====

{{:atmos:instruments:wcm:16_59_59_water_on.jpg?400|}} {{:atmos:instruments:wcm:wcm_water_off_graph_m-300_16_59_59.jpeg?400|}}

{{:atmos:instruments:wcm:17_00_00_water_off.jpg?400|}} {{:atmos:instruments:wcm:wcm_water_off_graph_m-300_17_00_00.png?400|}}

{{:atmos:instruments:wcm:17_00_01_water_off.jpg?400|}} {{:atmos:instruments:wcm:wcm_water_off_graph_m-300_17_00_01.png?400|}}

{{:atmos:instruments:wcm:17_00_02_water_off.jpg?400|}} {{:atmos:instruments:wcm:wcm_water_off_graph_m-300_17_00_02.png?400|}}

==== NOTICE ====
One thing to note with the data displayed in the graphs is that the zero baseline is at 2.2 instead of being at zero. This is another noticeable issue with the M-300 and the way it records data. I will refer to this baseline as 'zero' in the rest of the analysis. 

==== Analysis ====

The delay between when the WCM displays a 'zero' value and when the probe should be at 'zero' is around about a five or so second delay which can be observed by the graphs. Which after applying a 66.7% data validity factor to the delayed seconds this comes out to being about a 3.34 second delay where data is being displayed that shouldn't be. This is of course just one case but, during this particular data set I did a few other runs where I would run a minuet without water and then a minuet with water. Below are the other runs that I did which all show this similar decay that occurs right after the water is cut off from flowing over the probe head. 

==== Decay Graphs ====

{{:atmos:instruments:wcm:wcm_graph_17_02_00_m-300.png?400|}} {{:atmos:instruments:wcm:wcm_graph_17_04_00_m-300.png?400|}}

{{:atmos:instruments:wcm:wcm_graph_17_06_00_m-300.png?400|}} {{:atmos:instruments:wcm:wcm_graph_17_08_00_m-300.png?400|}}

Top left - 17_02_00 Graph, Top right - 17_04_00 Graph, Bottom left - 17_06_00 Graph, Bottom right - 17_08_00 Graph 

Each graph is marked at roughly where the video indicated no more water being present over the probe head. 

The way that I determined the delay interval was by determining that each tick on the graph is roughly one second of data and then counting the ticks it took to get to a baseline value. The way I determined this baseline was by observing where the data mostly stabilized at so this is mostly subjective in terms of determining this value. But I mostly settled on a value of at or below 2.2 on the x-axis. The corresponding values that I then found for each graph are as follows; 6 seconds for 17_02_00, 6 seconds for 17_04_00, 5 seconds for 17_06_00, and 7 seconds for 17_08_00. This then came out to be an average of 6 seconds of data present during this decay. Then after applying the 66.7% validity to this average I found that there is about 4.00 seconds of incorrect data during these runs. 

==== Suggested Solutions ====
After contacting SEA they suggested that a possible reason for this issue is the PID controller that is in the WCM may not be set to correct settings thus resulting in a decay in the graph after water content becomes non present. It was also shared that there are a couple different settings that they tested when calibrating the WCM 3000 where they gave us what the default values should be along with a mid aggressive and aggressive setting for the PID board. 

=== Implementation ===
These values were all tried and each one preformed in a manner that wasn't necessarily similar to what SEA had gotten for results after using these values. The output was more so aggressive when set to an aggressive setting as it should be but there were still noticeable decays in the graph even with these more aggressive values. 

From here values were changed based upon the way that PID controllers should be calibrated where you first start with the Proportional term and get it to an appropriate value that causes the instrument to operate stable and then you adjust the Integral and Derivative terms as needed to get the output from the instrument to be as stable and responsive as possible. After changing these values many times there was still the same decay issue present in the recorded graphs. 

==== Solution One to Decay ====  
Checking the fml.300 table within the m300 computer it was noticed that the data this is being recorded is being averaged which seemed like it could be causing an issue with our recorded data and thus was removed to see the effect. After removing this averaging function there was a noticeable improvement in the data collected where now instead of these long 5 to 7 second data delays there was now only about a 2 to 3 second delay present with the data (This delay can now be fixed by tuning the PID controller).

==== Solution Two to Decay (Tentative) ====
Now that the long decay was removed from the graphs by removing the averaging function in the fml.300 table the PID controller should now have a more noticeable impact on the data collected. **Another thing to note which was found during the initial PID tuning was that the derivative term will also contribute to a decay since the derivative term is acting as a dampener to stop the probe from immediately going to zero after water content is stopped.** So now taking that into account when tuning the PID board it is known that the derivative term should be set fairly low so as to stop the probe from over dampening itself during data collection. The values that were found that allowed the probe to work fairly well are as follows; **(TWC terms Kp- 2000 Ki- 90 Kd- 20) (LWC terms Kp- 9500 Ki- 95 Kd- 20)**. These values were only tested during no airflow to try and calibrate the probe to be as stead as possible. This was done as a control just to factor out the unpredictability of the airflow that would normally be present over the probe and to make the tuning of the probe more easier. 

==== Solution Two Continued... ====
Continuing on with the second solution the PID values were now tuned with airflow present over the probe which did result in different values from the zero airflow calibration. The values that were found are as follows **(TWC terms Kp - 1500 Ki - 25 Kd - 200) (LWC terms Kp - 2000 Ki - 25 Kd - 150)**. These values overall did improve the response time in the WCM 3000 but something to still note is that these are not perfect. There is still a 1-2 second delay present in the data which seems to be just a limitation of the probe itself and not necessarily something that can be fixed. **(These values have yet to be tested on an aircraft at higher airspeeds meaning that these are still subject to change since these values were only derived at lower airspeeds, further updates may be needed to these values)**

===== Problem (Winter 2024) =====
During the setup of the WCM, we were having issues with the power not being supplied to the WCM Power Box which prompted the WCM software to say that ser17 can't open. 

==== Cause ====
The power connection of the leads from the WCM Power box to the D/C Power supply was not making a good connection with the prongs themselves on the D/C Power supply. 

==== Solution ====
The leads coming from the WCM power box where squeezed together to help in making better contact with the prongs on the D/C Power supply. 

==== Directions for Setting up the WCM-3000 in the Lab ====

1. Connect the Spade Terminals to the Binding Posts on the DC power distribution panel installed below the table. The cable attached to each spade terminal is labeled with a description, and a +/-. Ensure that the negative spade terminals are attached to the negative (black) binding posts, and that the positive spade terminals are attached to the positive (red) binding posts.
 
2. Check to make sure that the spade terminals are connected to the SEA box via the cable labeled "WCM-HWB Power Cable"

3.Plug in and turn on the Laboratory DC power supply under the table. There is a series of outlets under the table that you should use to do this. 

4. Use a multimeter to check the voltage on the test points. These will be two binding posts which do not sport connected spade terminals. The voltage should be 28 volts, adjust the Laboratory DC power supply gently and as needed to achieve this goal. 

5. Once you have confirmed you have the correct voltage, click the red switch on the DC power distribution panel. This will send power to your attached spade terminals, so ensure that you are safe and ready to perform this step.
 
6. Turn on the computer that is installed on the rack using the black power switch and wait for it to boot up. This can be a time consuming stage, that does not mean you did anything wrong. If you are worried about finding the correct switch, it is beneath a printed label which reads "36 pounds". The weight label is not important for this specific process, but it can help you navigate the machinery! 

7. On the m300 box that is on the rack, you will need to flip two metal switches, one for system power and one for element power. Both will be needed to engage the WCM-3000, otherwise it will not work. A good way to troubleshoot this process is to assess the amplitude on the Laboratory DC power supply, and ensure that power is being drawn.

8. When you see /home/operator%, type: ph and hit enter

9. When the system is on, right click and select the option that says: Shell...

10. In the terminal window that pops up, type: m300. Many pop-ups will populate the screen, those pertaining to the WCM-3000 can also help you troubleshoot the process. 

====Insights from WCM-3000 Lab Work====

Hello! Summer Coleman started experimenting with the WCM 3000 on 7/6/2026

The following documentation will take you through the experimentation process and contain key details on the lab set up, how to operate the hardware and software necessary, and any other crucial descriptions gleaned during that time. The current date is 8/31/26, I will try to update this page frequently as I continue to experiment. 

===7/6===

Open a terminal window when working with the camera 

In order to collect imagery with the OSCRE Blackfly camera from Aaron Kennedy, type: python3 summer.py 

To view the approximate feedback from the camera, type: spinview 
- The camera is called the Blackfly on the menu, so select it by double clicking 
- Sometimes, to "look through the camera's eyes" you have to select the "Stretch to Fit" option from the dropdown menu 

The camera also has a password that it may ask you to enter, that password is: snowcam24!

The lamp that the camera operates with can get hot when it has been running for a while, it can also heat up metal surfaces that it is shining upon, particularly if they are dark in color. 

Small bumps/disturbances will compromise the image quality 

The focus of the camera is adjusted by the wheel behind the front of the camera, you will probably feel it if you tool around with it enough. Dr. Kennedy's advice to me was: "turn the knob until you see all the sparkles". As you work with the tool you'll see what I mean. The metal gets all shimmery when it's in focus 

===7/17===

The current camera configuration collects data for five seconds 

The M300 (described in the notes above, follow those to set it up. This is the computer that collects data for the M300 and a wide variety of other probes during flight)often exhibits a time lag from UTC time. To note this offset, visit time.gov on another device. Then, in the M300 terminal window, type: date 

Do this several times until you are aware of the offset as precisely as possible and write that offset down

You will have to do this for the camera computer as well, the process is the same 

I used to drain the mister before operating by unscrewing the nozzle. However, I've found in recent times that I haven't required that step. You need to do this sometimes if there are deposits or build up in the line, which can happen if you have left it undisturbed for an extended period. 

MAKE SURE YOU TURN THE WATER SUPPLY OFF when you are done working with the set up for the day 

The mister pump box shakes which can ruin the camera image. It must be placed on a different surface from the camera to work properly. 

Don't get Aaron's light wet. This hasn't happened yet but he did tell me this when we conferred about the camera. 

The heated sensing elements get up to 140 celsius, that is their set point temp.

Keep the fan on every time you turn the probe on, it will overheat!! I suspect is has a sensor in it which will de-activate the probe when it gets too hot. When this happens, it will give you a weird, kinda square-wave signal. I've only ever seen it happen on the LWC element and I don't know if that's exactly what causes it. But. That's my operating hypothesis. 

You need a USB drive to get the data off the M300. Buy one if you don't have one. 
- If you have it, plug it into the port on the actual M300 
- type: flash 
- It will show you that the directory associated with the drive is /dos/c
-Typing flash again will unmount the drive 
-There will be more about this in a later entry 

Keep good energy up, lab work is supposed to be fun!! 

===7/20=== 

The electronics above the probe head need to be shielded from incoming mist. Right now that's being done with a plastic bag. We 3D printed a part but I think it's too bulky. 

It helps to verify that the mister is functional before you start. This was an issue for a while but I haven't had any trouble with it in recent times. Right now, to get the mister to supply mist, you have to plug it in. To turn it off you have to unplug it. Dave and I are thinking about workshopping this. 

The fans pull A LOT of power, make sure they are not both on the same outlet set. It's ideal that they are the only thing pulling from any given outlet set. 

You can visualize data from the M300 on "Strip1a". You can access that by clicking around on the tab strip on the bottom of the M300 screen. I've found this very helpful in terms of basic functionality checks, and I would definitely recommend keeping an eye on it. 

To change TAS: 
- Click F1 on the keyboard 
-Click the fancy f tab 
- Enter: 38012 in the NUMBER section, not the formula section 

You should be able to confirm that TAS has been changed because you will see that change on the NASA TAS and the M300 variables windows. Those both come up right when you type M300 in the terminal, so I think you will know what I mean haha. 

Right now the Pitot tube is measuring about 3.3 m/s. More on the Pitot tube set up and airspeed situation later 

Try to think of Lab Work as a series of small victories. If you work at it long enough, every day you will learn one new, important thing. 

===7/31===

One of your first orders of business should be verifying a visual on Aaron's camera using the process outlined above. Also, I'll probably say this later, but make sure you TAKE SOME ACTUAL PICTURES WITH PYTHON3 SUMMER.PY, there is processing that happens that changes the way the image looks and you could end up with total garbage on something that looked great on first glance. 

If the Pitot tube isn't working right away, check that all plugs are secure. It can be a little finicky

When you click the little house/shop window icon it will give you a WCM window to access: BUT if you have two of these open at the same time it will refuse to collect data for you. I'm still kinda getting to the bottom of this. 

At this time my goals were:
1. Get both heated sensing elements to approximately agree on what they are reporting
2. Gain muscle memory on collecting camera data 

In our current set up, it's hard to see the height of the peak since this is A LOT more water than you would measure in a real cloud. Pulling the data off and processing it is the only way to be sure, more on that later 

When you first power up the probe, there will be a little jump that looks like an LWC measurement. This does not mean that something wrong or that it is mis-measuring. This has happened every time I've booted the probe up and my colleague Bryce Rickbeil said it was okay. He also has experience with the probe and is another good contact for questions. 

===8/20===

NOTICED RUST AND DEPOSITS ON THE PROBE HEAD ELEMENTS - contacted Dave immediately 
-If something weird like this happens just talk to Dave right away, it's what he's there for 
-This was a bigger problem for the TWC element, makes sense, that scoop shape holds water a lot better than the LWC element 

I have never been able to update the M300 time despite always following the protocol in the manual and Dave's protocol. Other student researchers have reported this as a problem, including those who flew with it in the air. Lately, I have just been noting the offset and accounting for it when I do my analysis, which has not been so bad. I'm not unhappy with the results, maybe I will include those later. 

Key insight: "Someone will be able to help, just maybe not in this moment, and that is okay", try to forge on and use what you do know/can figure out to produce a result. That's not a bad thing, it's how the work is done. 

I suspect that changing the time on Aaron's computer will be easier since it's newer, but I have not done that 

Verify that the two elements seem to be reporting similarly, doing an initial test run is never a bad idea and it will give you confidence moving forward as well.

Note the PID setting before you start working. This is less of an issue in this preliminary stage but it will definitely be important later as we get into that part of the research. 

Trials from this day were 10s water on and 30s water off. 
-Yes you have to plug in and unplug the mister 
-I also need another person to operate the camera when I do this. Lately, I have just been telling them to run python3 summer.py when they see me unplug the mister. Honestly the results from this weren't that bad, more on that later 

Yep, this was the day that I took pictures and they were just a dark box. The camera processing requires the image to be REALLY INTENSELY LIT. An image that looks way too white/illuminated on spinview is actually exactly what you want.
-Quote: "I'm not too shocked by this, Aaron almost always had the light right on it!...the image processing does in fact need dead-on light"

As I said before, take at least one set of pictures to make sure it works. 

If camera images are bad, delete them. We don't want to clutter up Aaron's camera with poor quality images that we won't even use 
-I did keep the ones from when Aaron was setting it up to use as a reference. Not a bad idea. 

Also, bumping the light during image collection will result in bad image collection. So, you will need to configure your set up such that this will NOT HAPPEN. 

===8/21===

Dave did give us some rusting protocol that you should use every time you're done collecting data with this set up
1. Clean both heated sensing element AFTER THEY COOL DOWN with isopropyl alcohol. You might need a senior lab member like Shawn to open up the flammable chemicals. Even I can't get in there, and I'm a grad student! 
2. Dry the probe elements with compressed air. I often have to towel it off a little with a paper towel/rag. We do not want ANY WATER sitting on it for hours and making it all gross.

This isn't a problem when we fly it because the plane is going so fast, it's pretty rare it would just be sitting in water for an extended period. This is a lab-specific flaw.

Data collection with flash drive steps:
1. flash 
2. cd /dos/c
3. ls (shows you what you have in there already)
4. cd ..
5. ls
6. cd ..
7. ls 
8. cd ..
9. ls 
10. cd 2025 
11. ls 
12. cd impacts 
13. ls 
14. cd .. 
15. ls 
16. cd m300data 
17. ls 
18. SEE THE FILE you took 
19. cp <your file name> /dos/c
20. Remove flash drive and type flash, confirm that you see the word "unmounted" on that output 

Yes, a lot of these instructions are directory navigation, but I wanted to be as thorough as possible if terminal window directory navigation is foreign to you. 

An example of an M300 file name: 2026_08_21_16_21_42.sea 

It was at this point that I started thinking water delivery should be controlled by a switch, we will see how that unfolds. I was getting pretty quick with my unplugging and plugging though!