Monday, May 21, 2012
Until recently I didn't realise just how sensitive DTV (Digital Television) actually was. My experience tells me that an amplifier is highly recommended (unless your dongle/device/set top box is exceedingly good). The thing which has made me particularly curious though is the impact of local electrical appliances (such as power boards, heaters, and even networking devices. Removing or swapping particular devices can have an immediate impact on signal strength/integrity.) and the connections between the tuner, antenna, amplifier, etc... While I admit that some of the equipment in my setup could be of a higher standard the tolerances that we're talking about are borderline absurd. Changing the angle of connections is enough to change the signal strengh/integrity substantially. Moreover, signal integrity issues at certain points are extremely difficult to debug without specialised equipment (I've seen some digital TV strengh metres being sold but I haven't tried one as yet and the cost outweighs the possible gains. Admittedly, there are some signal strength measuring systems in the software itself but this is not ideal as it can not go into an arbitrary position in the pipeline.) and the only real feedback that you get is how 'choppy' the sound/picture is. I've found that moving the amplifier power point on to a less noisy circuit can be extremely helpful as well as changing the angle of the cable the being used to carry the signal into various devices (the amplifier is particularly susceptible to this problem and I've found it best to lay it on a flat surface). I may experiment with Microwave based transmitters (2.4/5GHz range) later on but early indications/reviews say that cable may actually be better. I've also been thinking about using an adapter to carry the signal over a non-coax type cable (or a medium that is less suspectible to issues related to cable bending) to hopefully reduce the impact of these problems but once again its a cost/benefit issue and I've seemed to have found a viable solution as is.
I've figured out that some of my recent problems with LibreOffice may also be due to issues with regards to externally inserted objects (such as images). I've been working on a new document (on 'Internet and Computer Security') and its 225+ pages/67K + words and there have been no random crashes as I've previously experienced when working on larger documents. I guess I'll have to write the text before hand, and add other objects in now from now on (at least until they fix the problem. This should also get me around another problem that I've found when editing text and there are images in the document (they don't move perfectly correctly with the text when cut/pasted.). The other alternative is to switch to another system of document management...
Have a theory about some connectivity issues I've been having lately. While playing around with MTU values has resulted in success I've also noticed something else. Sometimes, there seems to be a noticeable delay at certain critical points as though the traffic almost as though it is being buffered. Also, if there is other web based activity simultaneously this will help to get around the problem of stalls/stops at these particular points. Suspect there may be a timeout value that I may be able to tweak in my browser to help smooth out this intermittent problem (I've been dealing with it by dynamically shifting MTU values (depending on the circumstance) along with using HTTP/206 partial download capabilities but am thinking of building something more robust/automated/finding a better configuration for a more elegant solution.).
Friday, May 18, 2012
Someone recently brought me a laptop which was suffering from 'performance anxiety'. There were some obvious issues. File system fragmentation, low spec (P3 933MHz/768MB RAM/30GB HDD), power management issues (it was underclocking itself to a third of its maximum clock speed even when it was plugged into the local AC point), and general sub-standard upkeep (a lot of unrequired crud was installed on the system). I decided to re-install the system using the existing recovery partition by running D:\RECOVERY.EXE
Somehow, the original owner had managed to delete a critical file though (D:\INSTALL\WATERMRK.JPG) which was required for the program to run. After creating this file the program started but refused to run due to the recovery image being older than the currently installed operating system.
I initially tried to get around this problem by uninstalling SP3 (I discovered early in the piece that physical recovery disks were unavailable and the documentation said that you required a special boot disk to access the necessary files on the recovery partition. I didn't want to go with a clean XP Professional install because it woud be cleaner and more elegant if I could just get the recovery system to run.)(The process is similar to removing a Hotfix but more prolonged for obvious reasons).
However, I discovered that this was not enough (I found out that the recovery image was based on Windows XP Tablet PC Edition SP1) and that I needed to go further. Once SP3 was done removing itself I discovered that it also removed a critical uninstall file though. I tried to get around this through registry modifications of keys from the following two folders (I could only guess how the program was getting its version information because I couldn't load tools on to the system due to the system being so slow and unstable after removing SP3).
My Computer\HKLM\SOFTWARE\Microsoft\Updates\Windows XP\
My Computer\HKLM\SOFTWARE\Microsoft\Windows NT\Current Version\
Obviously, this was unsuccessful so I tried using a standard XP boot disk to boot to, 'Recovery Mode' (its three taps using the digitiser or the F12 button if you have a keyboard to activate the boot menu option). I noticed that changing into the various directories ("Access is denied.") and running D:\RECOVERY.EXE ("Command is not recognized.") was impossible though even though it was a FAT32 based filesystem partition and seemed to use standard PE32 executables on initial view (I expected to at least see the standard, "This program cannot be run in DOS mode." string and even saw this string in the initial header of the executable when viewing it via a text editor.).
user@system:/media/sdd1$ file RECOVERY.EXE
RECOVERY.EXE: PE32 executable for MS Windows (GUI) Intel 80386 32-bit
It seemed obvious that these were not standard executables though. I then tried using a Win 7 32-Bit recovery disk (Windows 7 recovery disks are temperamental with regards to the base system and the disk version (32-bit disk should be used with 32-bit base system) if you're curious). This allowed me to move into the required directory and also run D:\RECOVERY.EXE and kick off the recovery processes. Even though it seems possible or obvious that there may have been some co-operation between Microsoft and Fujitsu it looks as though the recovery process isn't quite as clean as it should be (progress meters aren't perfectly aligned, strange screens for particular processes, and so on). Nonetheless, it did what was required (it deleted/copied files to/from rather than formatting the existing Windows partition interestingly) and copied and ran the correct Windows installation files.
Some notes regarding this platform include the following:
- possible design flaw? On my particular system the power cable was quite simply too loose.
- compared to modern imaging techniques/systems (Norton Ghost) the restoration process was extremely slow.
- Windows Security button is the top left in portrait mode if you don't know. Hold it down for three seconds in order to activate Ctl-Alt-Del sequence on the Windows login screen.
- the left hand side of the screen in portrait mode can warm/heat up substantially as the hard drive is located directly underneath.
- even though it is extremely stylish, it seems to have a tiny battery and a high weight though this is synonymous with Windows tablets of this vintage.
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