Is a series of articles written by Steve Epstein and will be
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CBNT Review, pt1
CBNT Review, pt1
As I was one of the first to take the CBNT test, I
thought this column might be a good place to cover that info in a tutorial. Your
feedback is welcome (steve@broadcastbuyersguide.com).
Reviewing the material for the test, it appears that several areas of knowledge
are covered: General Electronics, x86 PCs, the DOS/Windows OS, and Networking.
Rather than jump right into Networking we will start with the basics and move
quickly into the other areas over the next few months.
Starting with the PC, let’s look at some basics. First, PCs in a broadcast or
mission critical environment need to be protected from surges, spikes, brownouts
and complete power failures. The best way to do this is with a UPS
(uninterruptible power supply) that offers surge and spike protection. At a
minimum, UPSs need to be sized so that upon complete loss of power the PC can be
properly shutdown. Better yet, size the UPS such that you have about 5 minutes
before shutdown is required. That way, if the power returns in a few minutes,
you can avoid the shutdown completely. UPS capacity is measured in Volt-Amps. A
500VA unit might keep a small PC going for 10 minutes or so. Don’t try to keep
2 small computers going for 5 minutes, as you will likely overload the UPS. When
sizing a UPS look carefully at all the specifications. For maximum reliability,
ensure that you are within specs on ALL parameters. As mentioned in a previous
column, include UPSs in your PM routines—it is easy to forget about them.
A basic PC consists of a power supply, motherboard, memory and one or more disk
drives. Most also include a monitor, keyboard and mouse.
Power supplies are straightforward. As they are usually switching
supplies, replacement is often more cost-effective than repair. Test them with
an oscilloscope or digital meter. Newer units may require connection to a
motherboard before they will power up. One thing that can easily be replaced is
the cooling fan. Fan quality varies, but I have found it best to use only high
quality (ball bearing) replacement fans, and put the installation date on the
outside of the power supply where it is easily read. Often the replacement fan
will outlive the supply. If you know its age, you can make a determination on
whether the fan is worth keeping. The same holds true for the other fans found
in cases and on CPUs. New, and clean fans normally run quieter. Clean fans with
compressed air. Avoid “spinning them up” with the air by sticking your
finger in the blade area (while the blade is stationary). It is not as much fun,
but much easier on the bearings. Better still are cases that provide filters.
Once you are sure the power supply is operational, you can test the motherboard.
With nothing more than a single stick of RAM and a CPU, most motherboards will
offer a series of beeps to let you know they are functional. One short beep
usually means everything in the POST (Power On Self Test) is OK. Check your
motherboard documentation for additional info. Adding a monitor card and monitor
will provide visual details. Next, a drive can be used to boot an operating
system. In the past all systems had a floppy drive that could be used for this,
today CD drives are often used for this role. Floppy drives can be plugged into
the floppy controller found on most motherboards, and CD Drives can be attached
to either the primary or secondary hard drive controller. Needless to say,
maintain a bootable disk in every format ( 3.5” floppy, CD etc. ) required in
your facility. They are indispensable for troubleshooting. Even with this small
amount of hardware, configuration is required.
The computer’s CMOS can usually be accessed using the F1 or Delete key at
startup. If you are using the onboard drive controllers, ensure they are
enabled. Disable them if you have a card mounted controller plugged into the
motherboard. Floppies are normally selected by the cable, The A floppy is
connected using the connector after the twist. Hard drives and CDs are set as
either master or slave using drive-mounted jumpers. The first or only drive is
set as the master, with the second drive set as the slave. Most CMOS settings
today can be left in Auto, as the drives provide the necessary information to
the motherboard.
The information above should be sufficient to determine the basic condition of
any PC. Often a completely dead PC is the result of either a power supply or
motherboard failure. However, I have seen card failures as well as RAM failures
that have left a system in a seemingly dead state. Although I dislike disturbing
multiple components during troubleshooting, I have found that after a few
cursory checks of basic connections and the power supply, taking a “dead”
system down to the minimum is often the quickest way to determine the failed
component. Next month we will cover what is needed to get a system booted up and
on a network.
When was the last time you looked at a typical signal’s path through your
facility? Does it come in on a digital satellite link, and get recorded on an
analog deck? Or, maybe it is played back digitally through an analog console.
Along the path to the (probably analog) transmitter does it go through a codec
that not only does both an A-D and a D-A, but also includes a good measure of
lossy compression? With today’s signals, all the above and many more are
possible and likely. Some are unavoidable, but most can be ironed out with a
little forethought and planning.
It is safe to say that components that interface with the real world will remain
analog for sometime to come. Items such as microphones and speakers must
interface with the physical world and either produce an electrical signal based
on real-world inputs, or provide a real-world output based on an electrical
signal. In both these cases, regardless of I/O signals, the electrical signals
at the real-world conversion point are analogous
to the physical reality
they represent.
Because they have a longer history, and also because advances made on the
digital side tend to provide benefits, first generation analog signals are
usually better than their digital counterparts. However, as we all are familiar
with, as we add generations, those once pristine analog signals quickly fall
victim to noise and other artifacts. It is in those successive generations that
digital signals really shine.
Returning to the problem at hand, is the signal path through your facility as
conversion-free as possible? Do you immediately convert all analog signals to
the digital house format and keep them there until they leave the facility? Do
you have designated a house format? Conversions from one signal type to another
typically result in artifacts. Those artifacts are cumulative. Each A-D and D-A,
each lossy compression-decompression, and each (video) component-composite
conversion is costly in terms of equipment costs and signal quality. Are you
wasting both unnecessarily?
To address this, first, document the system. Since all our facilities are fully
documented, it won’t take more than a few minutes to pull out that
documentation binder or file and lay it out. Pick a color for each signal type,
and add that to your documentation. If you have neatly defined blocks of color
that are confined to small areas, or just one or two colors, then you are in
good shape. If on the other hand you have run out of colors, and you are only
halfway finished, the problem should be obvious.
Pick a house standard. Preferably something you can migrate to over the next 1-5
years. Gear your budgets and purchases toward that standard. If that is not
possible, work toward those neatly defined blocks. If your consoles are 48kHz
set that as a house standard and try to convert everything to that. Purchase a
few high-quality converters and use them. Avoid adding the latest gadget at an
inappropriate point in the signal path. Find the point in the system where it
makes sense from a system perspective.
Along these same lines, are you getting the most from the control side of the
facility? Is the automation system central to the operation, or is it just there
for emergencies? Do you convert serial control signals to GPI/Os? As engineers,
we operate in a world that few others in our facilities understand. It is up to
us to make sure that we are utilizing our budgets, time and equipment to the
fullest. Purchasing extra equipment to do unnecessary conversions is in no
one’s best interest. The next time you need to add some equipment, do so in a
way the fits both your present and future goals.
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Let’s face it, the biggest investment in computer systems today isn’t
money, it is time. Whether it is the time spent inputting data, or trying to
recover from its loss, we spend plenty of time at a computer keyboard.
I will assume you have a backup system in place that regularly saves critical
data to some sort of backup media. If not, getting that in place needs to be
first on your priority list. Beyond regular
backups, there are numerous things that can be done to reduce the chances
of losing your data or your machine. Let’s start with the uninterruptible power
supply (UPS).
Are your machines protected by a UPS? If so, does it work? I recently had a UPS
that continued to pass AC through it, but when it was needed (power failure) I
discovered the DC side was out of commission. Luckily I was working on a laptop
at the time and its batteries kicked in. Implement a regular routine of checking
all emergency power sources—you regularly check the backup generator at the
transmitter, right? If you have UPSs on your network, make sure that all the
interconnection hardware will also remain powered up. It does little good to
have the client computer and the server remain on after a power failure if the
hub/switch connecting them has lost power.
When
you check your backup systems ensure that you do it in accordance with the
manufacturer’s recommendations. Many UPS systems require a ground connection
to safely endure the switch from utility to backup power. When you simply
“pull the plug” you can cause damage to internal components by removing that
connection to ground. Using the test switch, or throwing the breaker is usually
a safer alternative (make sure nothing important is on that breaker if you
decide to go that route).
Beyond
the UPS, do you have an up-to-date “emergency repair disk” for each of your
Windows systems? Each Microsoft OS handles creation and use of an emergency
repair disk differently. Having one is critical to properly rebuilding a machine
without having to wipe the drive and reinstall everything. You will find some
information about emergency repair disks here: http://labmice.techtarget.com/troubleshooting/ERD.htm.
The time to make one is now, while the systems are functional, not after they
have crashed.
Other
items to include in your regular computer PM are cleanup of temporary and old
files, hard disk defragmentation, and ensuring the latest updates are installed,
especially security updates.
All
of us are familiar with preventive maintenance for broadcast systems, but PM for
computer systems may not be part of our daily routine. Take the time to properly
PM your computer systems. Doing so will likely keep those systems running
properly, and may even keep the next round of viruses out of your facility.
Posted February
23, 2004, email from Steve
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By
Steve Epstein
I am always amazed at how many users (both novice and experienced) have trouble
with the path through a computer’s directory structure. Before you jump to the
conclusion that Windows has eliminated the need to understand this structure,
remember that HTML is essentially based on command lines. Images, files and even
URLs are all referenced using the path. Microsoft uses the backslash (\) to
distinguish directories, while Unix uses the forward slash(/). For the most
part, what follows applies to both OSs as long as the proper slash (front or
back) is substituted.
The base, or root, of the directory tree is the /. Type the command "prompt
$p$g” to display the current drive and path ($p) followed by the > symbol
($g) on an MS-DOS machine. The command “cd /” will take you to the root
directory from anywhere on the drive. Typing “dir” will show all the
directories and files in the current directory. All directories except the root
will show a “..” directory, which is the parent directory of current
directory. Typing “cd ..” will take you one directory closer to the root
(/). For instance if you were in the /shop/plans/assets/images directory and you
typed “cd ..” it would take you to the /shop/plans/assets directory. Typing
it three more times would take you all the way to the root. If the assets
directory mentioned above contained an images directory as well as a sounds
directory, typing “cd ../sounds” would move you from the images directory to
the sounds directory.
Commands used on the command line can vary based on where you are in the
directory structure. The following commands all do the same thing; move the
test.txt file from the images directory to the sounds directory. The first uses
a full path and works from anywhere on the drive:
copy /shop/plans/assets/images/test.txt /shop/plans/assets/sounds
The next command will work from the images directory:
copy test.txt ../sounds
This command works from the sounds directory:
copy ../images/test.txt
The previous command assumes the destination to be the current directory, while
the second command assumes the file to be copied is in the current directory.
Although similar, *nix machines have a few “gotchas” to be aware of. With
DOS, if you cd to a directory, you can start any program in that directory
simply by typing the program name and “enter”. With *nix, only programs
found in the path will start. To start a program that is not in the path, either
type the full path (starting with the “/”) or type ./program name. If you
have a lot of programs in a directory outside of the path, consider adding that
directory to the path. For safety, never make “.” (the current directory)
path of the system administrator’s (root’s) path. Something else to be aware
of on a *nix machine is the lack of drive letters. Everything is located on a
single directory tree. Individual drives or partitions are mapped to directories
through the “mount” command. “Mount” is too much to cover here, but will
be covered in an upcoming column.
Gaining a good understanding of the drive structure and using the command line
can typically make troubleshooting easier and faster on any computer-based
system.
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By Steve
Epstein, CPBE, CBNT
Recently, while working on a remote internet server, I could not FTP into
the box. Although I had not tried to log in to this particular box for several
weeks, I used FTP on other boxes daily. As we went through the various
parameters, we realized that I had changed ISPs since the last time I logged in.
The techs at the server location could get in, others in the KC area could get
in, but I could not. The assumption that the problem was on my end could easily
be proven false because I could FTP to several other servers. Suggestions were
made concerning my FTP client, so I tried several others, still no luck. So
where was the problem?
On most *nix networked computers there are two files you should be aware of.
They are the hosts.allow and hosts.deny files. Beyond connectivity, and beyond
firewalls, these two files serve as a last line of defense. They determine who
gets in and who does not. If these files do not exist, or are empty, the default
behavior is to allow all access to all hosts. To be clear, a “host” on a
TCP/IP network is a computer, not the person logged into it.
The basic format of both files is:
service list : host list : action
Each time an external host attempts to access a machine,
these files are scanned (first hosts.allow then hosts.deny) looking for a match.
If no “deny” match is found the host is granted access. The service list
includes services such as http (web), ftp (file transfer), telnet (remote login)
and others. Actions are ALLOW and DENY. Both actions can exist in either file,
but I find it easier to keep each in its own file ( ALLOW actions in the
hosts.allow file and DENY actions in the hosts.deny file). If you have a server
with confidential material on it, one of the first entries you should consider
is ALL : ALL : DENY. That will keep everybody out of the box. Then, as needed,
you can allow individual hosts access.
One very interesting use of these files is to make the machine vanish off the
network automatically when any attempt is made to break into it. As soon as the
first “PING” comes in, all network services are stopped, a DENY entry is
added referencing the offending host, and network services are restarted. By the
time the second ping arrives, the machine knows not to respond. All subsequent
attempts to access the machine fail because they are ignored.
Going back to my inability to FTP, it turns out the machine did have a DENY
entry for the entire block of IP addresses that I had moved to. It seemed
someone had been trying to break into it, and the files had been modified to
prevent access. As there had been no recent activity, the entries were removed
and I was once again able to access it through FTP.
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By Steve
Epstein, CPBE, CBNT
Not all problems within facilities can be properly solved with just hardware or
software. Many times, the problems are workflow or people related. Sometimes the
problems are only viewed within a historical context. Often this means the
underlying causes are unaddressed, and the problems persist despite changes.
Take for instance the introduction of the hard drive as a replacement for tape.
Initially, it was easiest to have disks act like tape machines with functions
such as "play" and "record". Standard transport controls
provided a metaphor for the use of disk drives in audio and video applications.
Although the concepts of "rewind" and "fast forward" do not
really apply to disk drives, most computer "transport" controls
include them.
New opportunities are offered by technology. However, many of us are stuck in
the ways of the past, and our workflow patterns may be as well. Next time,
before throwing hardware or software at a problem, step back. Look at problem
from a fresh perspective. What are the requirements? Has the person that brought
you the problem defined and justified each of the requirements? Have they
separated the “must haves” from “these would be nice”? Instead of
stating "we need three mics for tomorrow's remote" what if they said
“we need to record a piano, singer and acoustic guitar at tomorrow's
remote”. The former may result in 3 handhelds, while the latter will likely
result in a set of mics more appropriate for the situation (maybe even more than
3).
Beyond simply throwing technology at the problem, review the process involved.
The process in use may have been developed when the station was using magnetic
tape and razor blades for editing. Now that you have moved to non-linear editing
on disk drives, do the processes still apply? Often, the person doing the task
was trained by their predecessor, and was simply told “this is how it is done,
don’t change it.” What they are doing may make absolutely no sense today,
but they continue it works. There is an old joke about someone watching a work
crew “plant” trees. Two men drive up with a truck full of trees, one digs a
hole and moves on to dig another. The second fills the open hole in and moves on
to the next hole. When asked, both respond that the worker that puts the trees
in the hole is sick today. When you
realize that both workers are doing exactly what they are trained for, you can
see that each is doing their job, but in reality, nothing is getting done (no
trees are being planted).
Rather than quickly offering solutions make sure the
problem statement is accurate and not a solution in itself. For instance, the
statement "we need a backup system to get the signal to the
transmitter", defines the problem. Whereas, stating “we need a new
microwave system” defines a possible solution rather than the problem.
Glossing over the problem and going straight to the solution can create more
problems than it solves. One obvious problem in this example is that you may not
consider viable alternatives such as fiber or telco. The next time someone comes
to you with a problem make sure they have accurately described the problem
before you (or they) begin to entertain solutions. You may find that more
creative solutions are identified quickly, resulting in better utilization of
current station assets (including your equipment budget).
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