I experienced an error upon any use of apt with a new Rev. C Beaglebone with the factory Debian install like:
insserv: Starting led_aging.sh depends on rc.local and therefore on system facility ‘$all’ which can not be true!
Fix apt failure
by replacing /etc/init.d/led_aging.sh with:
#!/bin/sh -e
### BEGIN INIT INFO
# Provides: led_aging.sh
# Required-Start: $local_fs
# Required-Stop: $local_fs
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start LED aging
# Description: Starts LED aging (whatever that is)
### END INIT INFO
x=$(/bin/ps -ef | /bin/grep "[l]ed_acc")
if [ ! -n "$x" -a -x /usr/bin/led_acc ]; then
/usr/bin/led_acc &
fi
and then reboot.
A large maximum dynamic disk size for a VirtualBox guest is problematic.
Even if one uses a small portion of that maximum size, the guest OS (especially Windows) will spread itself out.
A 10 GB Windows image will climb to the maximum size of the dynamic VDI file over time (say to 50 GB).
Here’s a fairly painless procedure to fix this, taking less than 1 hour on a modern PC.
I assume your guest OS is Windows, and your host OS is Linux running VirtualBox.
BACKUP THE VDI FILE BEFORE DOING THIS PROCEDURE!
In guest Windows, run Disk Defragmenter.
It’s also possible to zero free disk space with
SDelete.
Shutdown guest Windows, and “insert” the
Gparted ISO file
by right-clicking the CD icon at the bottom of the guest OS VirtualBox window and selecting your ISO file.
Resize guest Windows partition so that you have only say 8 GB free (e.g. original partition 40 GB, only 10 GB used –> resize to 18 GB)
Reboot guest Windows, removing the Gparted ISO file from VirtualBox. You will see Windows automatically runs CheckDisk–this is normal. You will need to reboot guest Windows once more, then shutdown guest Windows
In host Linux Terminal:
vboxmanage modifyhd --compact MyFile.vdi
The VDI file size may shrink significantly.
Defragment in guest Windows can make host VDI file INCREASE in size by the amount of bytes that were moved to defragment.
Repeat steps 1, 2, and 6 of the procedure above when VDI has again grown too large.
Do not make excessively large maximum size Dynamic VDIs to start–this problem will only repeat itself over time.
The 902 MHz
band plan
was adapted to reflect reality in much of the USA with regard to easily adaptable commercial equipment.
FM next to weak signal situation might include:
| band |
discussion |
| 50MHz |
The SSB/CW only and “any mode” meet at 50.3 MHz. Do most FM operators stay about 51MHz? |
| 144MHz |
I assume most weak signal work is at least 100 kHz away from the popular 144.390MHz APRS frequency |
| 220MHz |
Again a case of ~100 kHz spacing between FM and whatever weak signal work may exist |
| 440MHz |
The satellite band with what are typically very directive antennas keep multi-MHz separation between FM and weak-signal |
| 900MHz |
I would expect below 902.080MHz and above 902.120 MHz to have heavy interference for weak signal operators according to the band plan. |
Consider the relevant FCC specifications demand for “off-channel, in-band” emissions.
Is this specified as say -60dB so many kHz from center channel, or with an emission mask?
Is the specification sufficient to protect a weak signal operator within N km of a powerful FM transmitter?
If the specification is not sufficient for weak signal protection from nearby (in range) FM transmitters, do the practical filter implementations used by the most frequently used equipment provide enough protection any way as a corollary to meeting the FCC specification?
Run AGI STK on a Linux PC by using a Windows guest virtual machine.
If STK crashes upon opening a scenario in VirtualBox, shut down the virtual machine.
In the options for that virtual machine, disable 3D acceleration, enable 2D acceleration, and set video memory to at least 64 MB.
Then startup the virtual machine and try STK again.