Recent Posts

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1
General Discussion / Re: Enclosure for SQM
« Last post by kyba on October 18, 2017, 10:33:32 am »
Hello Beclyn, Anthony, and all,

Thomas Posch used a setup to reduce the influence of moonlight: https://arxiv.org/pdf/1304.7716

Something like that might work, but I would caution that you be careful, because depending on how you did it, you could potentially see light from the streetlamps reflected by the collimator surface.

However, it should be emphasized that the results will be different, that is darker, than what you would get with an SQM at the same location (assuming you could turn off the nearby lamps). Depending on what you are trying to do, that might be ok or problematic.

I would strongly recommend against tilting the SQM unless you can very accurately re-position the SQM after taking it down for cleaning/etc., and that you record the tilt angle in the metadata.

Best,

Chris
2
General Discussion / Re: Enclosure for SQM
« Last post by admin on October 18, 2017, 09:57:30 am »
The L (lensed) model meters have a field of view shown in the plot below on the right side (SQM-L):



You should ensure that your shield does not interfere with the light coming in to the meter from the sky above.

While the Full Width Half Maximum (FWHM) is ~20, the unit is still sensitive to light at +/-30 or 60 (as can be seen at the bottom of the right hand plot).

You can also set the meter (and housing) on an angle to point to a part of the sky that is free from artificial light and obstructions.
3
General Discussion / Enclosure for SQM
« Last post by Beclyn on October 18, 2017, 01:04:31 am »
I am preparing to install SQM-LU-DL and want to keep in shielded from surrounding street lights.  If I can place the device with weather housing in a larger container to block light from entering from the sides, there will be more location options for placement.  Would this interfere with meter readings?
4
Connected meters (SQM-LE/LU/LR/DL) / Windows local hub for multi Ethernet (LE) devices
« Last post by admin on October 05, 2017, 11:30:37 pm »
If you need to connect more than one SQM-LE to the local Ethernet port on a Windows computer:
  • Connect an Ethernet hub to the local Ethernet port on the computer.
  • Connect the SQM-LE devices to the hub.
  • Use the Lantronix Device Installer (LDI) to enable the local port (Tools-> Options -> Local Area Connection). Press Search to see if devices show up.
  • Record the IP addresses that were identified.
  • Start up the Unihedron Device Manager (UDM) and enter one of the IP addresses into the Ethernet tab.
  • Press the Version or reading button to make the connection.
  • Repeat the last two steps for the second SQM-LE.

Note:
  • The SQM-LE devices can have the IP address fixed with the LDI.
  • UDM can be started from the command line with the IP address defined.

5
Connected meters (SQM-LE/LU/LR/DL) / Windows task scheduler: start/stop recording
« Last post by admin on August 14, 2017, 10:22:55 pm »
In Windows, you can use the Task Scheduler to start and stop recording.

First make sure that UDM can read your meter and can log data using the Log Continuous feature.
Also, use UDM to determine the MAC address of the meter (on the main page).
Then, close UDM.

Enter the start/stop times into the Windows Task Scheduler. Start the task scheduler as follows:
  • Click the Windows "Start" button
  • Start typing Schedule Tasks
  • select the Schedule Tasks or Task Scheduler program.

Other ways to get to the Task Scheduler are shown here:
https://www.isunshare.com/windows-10/4-ways-to-open-task-scheduler-on-windows-10.html
  • Press "Create basic task" on the right side in the Actions window.
  • Name: Start UDM
  • Next
  • Daily
  • Enter the desired start time
  • Select Start a program
  • Click on browse to find the program which is usually located at C:\Users\User\AppData\Local\Programs\Unihedron\udm.exe
  • Enter additional parameter: -SEM,x -LCMS,y -LCR
     where x is the MAC address of the SQM-LE to be monitored, for example: 00204AAF20A2
     where y is the number of seconds between recordings, for example: 10
  • Next, Finish

Tasks may not show up in the Task Scheduler library immediately, you may have to close the Task scheduler and re start it.

Then, make another task to stop UDM at a specific time as follows:
  • Press "Create basic task" on the right side in the Actions window.
  • Name: Stopt UDM
  • Next
  • Daily
  • Enter the desired stop time
  • Select Start a program
  • Type the following ointo the program area: taskkill
  • Enter additional parameters: /IM udm.exe /F
  • Next, Finish

The logged files are stored in your log directory, usually located at: C:\ProgramData\Unihedron\logs

The above was tested with Windows 10 and UDM ver.105.
6
Connected meters (SQM-LE/LU/LR/DL) / Re: GPS integration
« Last post by admin on August 03, 2017, 07:04:51 pm »
To get the Comm Port for Windows 10 and the GlobalSat BU-353 GPS:
  • Click the Start button
  • Click the Settings button
  • Click Devices
  • Click Connected devices
  • The GPS should show up there as "Prolific USB-to-Serial Comm Port (COMx)"
  • Note which Comm port is listed, mine happens to be COM5

Start up UDM, then:
  • Make sure you meter is selected
  • Select Log Continuous
  • Select GPS tab
  • Enter the Comm Port into the Port: field, in my case I just typed in COM5
  • Click the Enable Check box, and then you should see some green indicators.
  • If the Validity indicator shows "Warning", then you may have to wait while the GPS collects enough information from the satellites. This happens faster if you are outdoors.
  • If your location appears in the Latitude and Longitude fields, then everything is ready to start logging.


To get the Comm Port for a Mac and the GlobalSat BU-353 GPS:
  • Follow the instructions provided on the CD provided with the GPS
  • Connect the GPS
  • Open a text terminal
  • cd /dev
  • ls -altr  to look for the most recently created file that looks like tty.usbserialx
  • The newly connected GPS is located at file /dev/tty.usbserialx
  • In UDM->Log-continuous->Port:, type in that filename. For me it was: /dev/tty.usbserial5
  • Click the Enable check box, and then you should see some green indicators.
  • If the Validity indicator shows "Warning", then you may have to wait while the GPS collects enough information from the satellites. This happens faster if you are outdoors.
  • If your location appears in the Latitude and Longitude fields, then everything is ready to start logging.


7
SQM-LU-DL (Datalogging light meter) / Re: Firmware updates
« Last post by admin on April 26, 2017, 02:38:44 pm »
New firmware released, see top post for details.

Some features of the new firmware are not supported on the old version of UDM, so make sure to update UDM as well. The latest version can be found here: http://unihedron.com/projects/darksky/cd/

Specific problems may include no apparent readings gathered under battery power. Using the latest firmware version allows retrieval of those gathered readings.
8
Problem:Microsoft Edge cannot find UDM software on the CD. Error "Can't reach this page".
Cause:Microsoft Edge has protections in place to hide file lists on remote drives.
Solution:Use the File Manager to navigate the CD to the Windows directory then install from there. Or, get the latest Windows version of UDM from the Unihedron website:
unihedron.com/projects/darksky/cd/Windows/
9
SQM-LU-DL (Datalogging light meter) / Real Time Clock enhancement
« Last post by admin on April 15, 2017, 11:10:49 am »
One of the drawbacks of using a real time clock (RTC) in electronics is that temperature variations will make it gain or lose time over long periods of time. The real time clock (timekeeper) inside out our original data-logger used a standard watch chip that had an accuracy of +/- 20 ppm. Generally this is not such a big problem, but for multiple data-loggers in different temperature conditions, the clocks will drift apart and other techniques are required to synchronize the readings.

We introduced an "Extremely accurate" RTC into the data-logger product line last year (around 2016-03-24) with an accuracy of +/- 3.5ppm from -40C to +85C.

The new RTC is identified on the back of the meter with the model number suffix "-R1" as:
  SQM-U-DL-R1
This model number can also be found using our UDM software.
10
General Discussion / Re: Reports
« Last post by admin on April 04, 2017, 11:40:02 pm »
Here is an interesting report about a telescope mounted SQM-LE and the trials and tribulations of a long term study of sky brightness:
Quantifying and Monitoring Darkness over the RAO (Rothney Astrophysical Observatory)
by Phil Langill and Benjamin George
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