As on Linux, it’s possible to select the audio source and sink on a per-app basis.
This interface is buried in Windows control panel.
The current name is “App volume and device preferences”.
You can set the volume, source (input) and sink (output) for each app.
This is helpful say when an app where one-way high fidelity audio is desired instead defaults to two-way low fidelity audio.
Also, modern Bluetooth devices may have the ability to use two-way audio with high fidelity listening by using A2DP for output with headset microphone input.
There are some very important distinctions between analog & digital trunked radio systems, all of which use
FDD
(frequency division duplexing) and LTE networks, which use FDD or
TDD
(time division duplexing).
For TDD LTE systems, surprising cases of long distance interference are possible due to super-refraction caused by tropospheric ducting.
Other sources of anomalous propagation are important and exhibit frequency dependence as well.
The shortest path may not be the path traveled–implications for optimistic terrain-shielded frequency reuse.
Dual-frequency 240MHz + 2GHz 50km & 140km oversea paths
sometimes 240 MHz does better and sometimes 2.015 GHz propagates better!
240 km LTE interference between Korea and Japan
50 Watt base stations contend with 0.2 Watt devices.
Base station to base station power was nearly -90 dBm over 240 km!
FM and TV broadcasts have long been known to be subject to tropo ducting.
A main motivation to move FM from low-band VHF (42-50 MHz) to 88-108 MHz was to get away from sporadic-E ionospheric skip, which could lead to far more interference from hundreds to thousands of kilometers away along with tropo ducting.
Of course, other transmission modes like aircraft AM are also subject to tropo ducting.
The rise of FM translators has made the general public more aware of tropo ducting, particularly as over the air TV audiences have dwindled, and HDTV limits visibility of interference.
VHF tropo ducting has been known for decades from Hawaii to California–a 4000 km path.
However the antennas required are large and the signals are weak.
In summers repeaters 150 km away can be heard almost every day at certain times of day.
On some days the 150 km distant repeaters were so strong you could hear them on an indoor desktop scanner with internal antenna!
Whether trunked or conventional, the impact of ducting on your VHF system depends on the signal ratio desired/undesired, which should be > 21 dB in a 12.5 kHz analog system.
If two stations wishing communications are more than 50 km (base-base) you may have some issues with ducting interference.
This gets trickier in places like New England with a long highly-populated irregularly shaped coast.
The interference on the repeater input can be the issue, especially with high-power base stations accessing repeaters.
These distant base stations can “jam” portable units into the repeater.
Possible resolve: check other user license.
Are they keeping to legal EIRP/antenna height for their control stations?
DMR: MotoTRBO will change to a new rest channel if interference is detected on the current rest channel.
Tropo ducting of UHF (450MHz) including GMRS is more rare than VHF, but can equally interfere with commercial users when it happens.
We have experienced 300 km distant repeaters on an omni base antenna.
Tropo ducting was a plague when UHF trunking came into vogue on 12.5 kHz “split” channels because for years before, low power mobile operation had been permitted on the repeater input (455-460,465-470) MHz range.
Of course, pretty soon people put base stations on those frequencies and we had to threaten FCC action to get them to stop.
Repeater panels would mark those channels as “last-used”.
Be careful when planning a new trunked system so that the “home” or “collect” frequencies are not plagued by these legacy operators.
LTR trunking on any band has only a single bit “area code” to distinguish co-channel systems – and of course the repeater number and group code.
Perhaps once every year or two where due to tropo ducting a customer would hear someone else on their area code, repeater and talkgroup on LTR.
LTR systems are being rapidly replaced with DMR systems, so these problems hopefully won’t be relevant too much longer.
Passport system color code has 2 bits (?) and with other unique ID measures gave much better resiliency against directly hearing “skip”.
But as an analog system 21 dB D/U was required for good audio quality in the presence of tropo ducting.
800 MHz two-way radio especially suffered from tropo-ducting for co-channel Nextel and two-way radio systems.
A customer was 40 km from the repeater with an omni base antenna would experience several hours per year when they could not access the SMR LTR system on 800 MHz due to tropo skip.
A MultiNet II 800 MHz trunking repeater system would sometimes hear tropo skip on the input frequencies.
For Motorola analog Privacy Plus trunking and AMPS cellular phones, the very limited number of connect / SAT tones meant that after a call was established, an undesired signal could bleed through on Privacy Plus trunking systems or AMPS analog cellular.
Privacy Plus control channels rotate every day (and could be manually encouraged to do so earlier).
900 MHz two-way radio systems are still operating, including 33 cm ham radio.
The nature of 900 MHz propagation made them a little less prone to interference from tropo skip, including fewer systems on 900 MHz overall, despite the 12.5 kHz bandwidth (21dB D/U instead of 17dB D/U required for good audio 12.5 kHz vs. 25 kHz).
The coverage is not as good on 900 MHz as 800 MHz because 12.5 kHz analog FM suffers a 4 dB impairment relative to 25 kHz bandwidth analog FM.
The radio technology available at the time of early 900 MHz systems was a bit rudimentary by even year 2000 standards.
The mobiles had trouble holding frequency accurately, microphonics were more of an issue, and different radio models had distinct compandoring parameters.
Anterix got FCC Report and Order
17-200
authorizing broadband LTE on 900 MHz, which added a more dynamic RF environment.
If Visual Studio was just installed or upgraded,
the Windows SDK may also need to be installed or updated (via the same Visual Studio Installer).
The symptoms of needing Windows SDK install or upgrade with CMake may be upon doing the usual:
cmake -B build
that you get errors like
-- The C compiler identification is MSVC 19.25
-- The CXX compiler identification is MSVC 19.25
-- Check for working C compiler: bin/Hostx64/x64/cl.exe
-- Check for working C compiler: bin/Hostx64/x64/cl.exe - broken
CMake Error at CMakeTestCCompiler.cmake:60 (message):
The C compiler
"bin/Hostx64/x64/cl.exe"
is not able to compile a simple test program.
It fails with the following output:
Run Build Command(s):nmake /nologo cmTC_c0691\fast && "bin\HostX64\x64\nmake.exe" -f CMakeFiles\cmTC_c0691.dir\build.make /nologo -L CMakeFiles\cmTC_c0691.dir\build
Building C object CMakeFiles/cmTC_c0691.dir/testCCompiler.c.obj
bin\Hostx64\x64\cl.exe @AppData\Local\Temp\nmC03F.tmp
testCCompiler.c
Linking C executable cmTC_c0691.exe
"cmake.exe" -E vs_link_exe --intdir=CMakeFiles\cmTC_c0691.dir --rc=rc --mt=CMAKE_MT-NOTFOUND --manifests -- bin\Hostx64\x64\link.exe /nologo @CMakeFiles\cmTC_c0691.dir\objects1.rsp @AppData\Local\Temp\nmC12A.tmp
RC Pass 1: command "rc /fo CMakeFiles\cmTC_c0691.dir/manifest.res CMakeFiles\cmTC_c0691.dir/manifest.rc" failed (exit code 0) with the following output:
The system cannot find the file specifiedNMAKE : fatal error U1077: '"cmake.exe"' : return code '0xffffffff'
Stop.
NMAKE : fatal error U1077: '"bin\HostX64\x64\nmake.exe"' : return code '0x2'
Stop.
Python can control Basler cameras using the official Basler PyPylon API on Linux, macOS, and Windows.
The Raspberry Pi and some other ARM systems are also covered by Basler camera drivers.
Windows users are more likely to have issues with a
locked file
in one program that was used in another program.
This happens in many programs including Python, Matlab and GNU Octave since Windows locks the open file by default.
Matlab symptoms arise from scenarios including:
HDF5 file that was previously accessed in Matlab
.m files and folders that were previously edited in Matlab
If this fails, there could be a bug in Matlab or your code that isn’t closing the file.
This can happen when error catching doesn’t have an fclose() inside the catch stanza.
The last resort workaround is:
completely close all Matlab sessions
move or delete the files that Matlab previously accessed
Citizen science images of aurora and celestial features can often be noisy.
Additionally, consumer and even prosumer cameras manipulate images in ways that typically cannot be completely disabled or even easily quantified in all cases.
To make scientific use of images, the image metadata must include:
Geographic coordinates (e.g. from GPS)
time of image (accuracy ~ 10 seconds for wide angle view, ~ 1 second with < 20 degree FOV).
Stellarium helps manual verification of image calibration.
Stellarium can also be used from the
web browser
without needing any install or plugins.
F11 toggles full screen mode.
Press F12 to toggle Stellarium “scripts” menu.
Stellarium can use
ECMAScript,
which is like a generalized, formal JavaScript.
Scripts have a .ssc or .inc filename extension.
Mayavi may be thought of as a Python layer atop VTK, making common 3-D data plotting tasks easy.
Mayavi is installed via pip or conda.
VTK, Traits, et al have .whl binary wheels, which avoid the previously painful build process.
Because of the large number of prereq packages for Mayavi, we strongly urge installing Mayavi in a seperate virtualenv or Conda environment.
conda install mayavi
Mayavi makes high quality manipulable volume plots.
Create a file scalar_field.py with the content
frommayaviimport mlab
importnumpyasnpx, y, z = np.mgrid[-10:10:20j, -10:10:20j, -10:10:20j]
s = np.sin(x*y*z)/(x*y*z)
scf = mlab.pipeline.scalar_field(x,y,z,s)
mlab.pipeline.volume(scf)
mlab.show()
While ArXiv is among the earliest and best known preprint archives, more focused archives can provide easier access to a targeted audience with good reputation.
Here are a few I’ve come across relevant to geosciences: