Recent Posts

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61
General Discussion / Re: Naked Eye Limiting Magnitude
« Last post by admin on November 27, 2014, 12:38:59 pm »
I have a simple python script running for the SQM-LR.  Still need to generate a nightly graph.

How is the Naked Eye Limiting Magnitude calculated?  I did not see it coming back from the instrument.

cheers, Dan Klinglesmith

Hi Dan,

NELM calculation can be found here:
  http://unihedron.com/projects/darksky/NELM2BCalc.html

NELM=7.93-5*log(10^(4.316-(Bmpsas/5))+1)


Or using this chart which also depicts the not so precise conversion to NELM because of differences in human vision:




Cheers,
Anthony
62
General Discussion / Naked Eye Limiting Magnitude
« Last post by dklinglesmith on November 27, 2014, 04:08:16 am »
I have a simple python script running for the SQM-LR.  Still need to generate a nightly graph.

How is the Naked Eye Limiting Magnitude calculated?  I did not see it coming back from the instrument.

cheers, Dan Klinglesmith

63
Connected meters (SQM-LE/LU/LR/DL) / Recover firmware
« Last post by admin on November 10, 2014, 02:44:21 pm »
If your connected SQM experiences a problem after a firmware upload, the unit might be easily recovered back to an operational state.

The firmware upload only writes to the "program" area of the unit. The bootload area, calibration data and serial number are untouched.

For the first 3 seconds after power-up, the unit is waiting for a firmware upload.

You should be able to reload the original firmware as follows:
  • Start up the latest UDM software which you can get from here:  http://unihedron.com/projects/darksky/cd/
  • Press "Find", your SQM should be displayed in the Found-devices window. If no device shows up in the found list, then there is another problem which cannot be fixed by this procedure.
  • UDM may try to read from the device and fail, don't worry about that for now.
  • Go to the firmware Tab, and "Select Firmware" then choose the appropriate firmware for your device. You may have to also select "All Firmware" at the bottom right of the "Open Existing File" dialog since it might automatically be showing other types. Select the desired firmware for your unit (note that SQM-LE files are also used for the SQM-LU).

        Do not press the Load button yet.
  • Unplug the SQM then plug it back in then press the "Load Firmware" button within 1-2 seconds. If the progress bar starts incrementing, then the meter will work fine, otherwise there is likely a hardware issue that needs repair.
  • The firmware should completely load. After the progress bar as completed then press "Find" in UDM to re-find the meter.
64
General Discussion / Light Pollution Map
« Last post by admin on October 17, 2014, 06:08:15 pm »
A new "Light Pollution Map" has been created by Jurij Stare which displays light radiance from NOAA and SQM data from the Unihedron reading database. You can visit the link here:

  http://www.lightpollutionmap.info/


65
Connected meters (SQM-LE/LU/LR/DL) / Re: 2 questions on the LU
« Last post by admin on October 06, 2014, 02:26:57 am »
1) Why is there a log continuous with a measurement interval and Report Interval tab? Are you expecting to have these reports uploaded to a web site?

The "Log Continuous" feature is for gathering readings from the meter and storing them on to the disk in a specified format.

The "Report Interval" tab is used used to set the SQM into a mode were it sends data out at specified intervals without being requested by the "rx" reading request command. There may be very few reasons to use the "Report Interval" feature unless you have some "Listener" software waiting to hear from the device. If you encounter spurious readings under normal reading conditions, it may be that an undesired Reading Interval has been set.

UDM does not currently upload readings to a web site. At the moment,  Knightware SQM-Reader Pro  does this, and our sqm-le_perl-1.3.zip program can also be modifed to do something similar.

2) Is it ok to leave SQM on all the time?

Yes. The SQM-LU draws very little power, so it will not be a big drain on your system.

Some laptop/notebook computers may put the USB port to sleep in a power-down mode. Settings in the Windows control panel power profile section are used to control this behaviour.


You may find more details for both of these questions in our online manual:
  http://unihedron.com/projects/darksky/cd/SQM-LU/SQM-LU_Users_manual.pdf

Please let me know if you have any more questions.
66
Connected meters (SQM-LE/LU/LR/DL) / 2 questions on the LU
« Last post by MgcJim on October 05, 2014, 06:01:46 pm »
1) Why is there a log continuous with a measurement interval and Report Interval tab? Are you expecting to have these reports uploaded to a web site?

2) Is it ok to leave SQM on all the time?


jim

67
Connected meters (SQM-LE/LU/LR/DL) / Re: Change location of log file
« Last post by admin on October 03, 2014, 07:12:05 pm »
I can see the the log file name but cannot change it.

When I click record, it automatically creates a log in a location that I cannot access over my network.

Please indicate how I can change the folder location.

From the UDM top menu, select:
  View
  Directories

Then change the "Logs directory" field by typing or clicking on the file icon.

68
Connected meters (SQM-LE/LU/LR/DL) / Change location of log file
« Last post by MgcJim on October 03, 2014, 02:28:54 pm »
I can see the the log file name but cannot change it.

When I click record, it automatically creates a log in a location that I cannot access over my network.

Please indicate how I can change the folder location.

jim
69
General Discussion / Twilight measurements with the SQM
« Last post by admin on September 15, 2014, 01:17:28 am »
We've had some queries about using the SQM products for measuring light during twilight.
The SQM meters are mainly intended for night time readings and will saturate in daylight. However, with the addition of a Neutral Density (ND) filter over the light sensor, the range of readings can be shifted to be useful in brighter settings.

Here is a page dedicated to some of those questions and applications:
  http://unihedron.com/projects/darksky/twilight/
70
Connected meters (SQM-LE/LU/LR/DL) / FTDI driver installation problems
« Last post by admin on September 03, 2014, 03:46:48 pm »
For some strange reason a recent problem with the installation of the FTDI USB driver for Windows has cropped up. The problem may something to do with cancelling the automatic installation of the FTDI USB VCP driver when connecting a new SQM USB device.

The Windows registry saves old versions and old COM port assignments, and can only be cleaned up with a custom utility provided by the driver manufacturer (FTDI). Here are the steps to solve that problem:

Install this FTDI "CDM Uninstaller" utility:
  http://www.ftdichip.com/Support/Utilities/CDMUninstaller_v1.4.zip

The detailed instructions for its operation are here:
  http://www.ftdichip.com/Support/Utilities/CDM_Uninst_GUI_Readme.html

Here is a summary of the instructions:
  • Remove/unplug the SQM-LU device
  • Start up the CDM uninstaller program
  • Press - Add
  • Press - Remove devices
  • Wait 5 minutes or so until complete
  • Close
  • Re-insert SQM-LU device
  • Wait 5 minutes or so for Windows to install driver and port. If Windows fails to install the driver, it will have to be manually installed with the "setup executable" available from http://www.ftdichip.com/Drivers/VCP.htm (see the comments column on that page for the latest link).
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