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Getting the most from
ADSL
It’s a fair bet that most readers of SILICON CHIP enjoy their daily
fix of internet access by courtesy of ADSL. While some readers are
luxuriating with optical fibre – and an unhappy minority are still
using dial-up – most of us owe our ongoing communication to the
distinctly freakish technology of ADSL. But what exactly is ADSL
and what came before it? How does it work and why is it often called
a “freak” technology? Are your internet speeds painfully slow? Can
anything be done to speed them up? Do you curse your ISP? Read on!
By ALAN FORD
M
any of us remember the early days of text-only
bulletin boards (which could be regarded as the
fore-runners to today’s internet), to which we
connected via an acoustic modem.
Bulletin boards were set up in the early 1980s by special
interest groups, some businesses and even altruistic individuals. Most specialised in a particular subject or brand
and we connected to them by dialling a number specific to
that bulletin board. We then carefully inserted the telephone
handset into a contraption of cups and flexible joints.
We laid it on its side to prevent
the carbon granules in the
microphone
from
A
Radio Shack
(Tandy in
Australia) acoustic
modem from the 1980s.
These did not work well
with the carbon microphone used
in Australian telephones at the time.
22 Silicon Chip
coalescing, moved the cat out of the room to prevent the
heavy tread of its paws from interrupting data flow and
settled down to enjoy the lightning fast data transfer speed
of approximately 300 bits per second (bps).
Without delving into the esoteric realms of parity bits,
overhead or consideration of baud versus bits (don’t ask!),
you can take that as about 35 characters/bytes per second
(8 bits = 1 byte). In practice, various factors contributed to
delays (as they do today) and we would usually see text
characters emerging on our computer screens one by one
or in groups of a few at a time.
How did that old acoustic modem work? Computer
binary data streams (well, trickles) would be converted
in the modem (or “modulated”) and transmitted over the
telephone line as frequency shifted audio tones. At the
ISP’s end another modem would convert the sounds to data
(or “demodulated”), or vice versa. In fact, that’s where the
word “modem” comes from: it’s a MODulator/DEModulator.
That was fine for plain text but then along came graphics,
with Microsoft Windows a pioneer (but certainly not the
only one), as well as the World Wide Web. Now we needed
to access the Web with its rich images and sounds as well.
The direct modem
Enter the direct-wired modem, connecting the computer
electrically to the PSTN (Public Switched Telephone Netsiliconchip.com.au
Aaahhh – the way we were! This photo, taken in 1981, shows a youthful Dick Smith talking bits and bytes with an equally
youthful and then-hirsute Leo Simpson. But the main point about this picture is not so much the all-new System 80
computer and its external floppy disk drive, it’s that whizz-bang acoustic modem in which the telephone handset resides.
The problem with this (which obviously Dick and Leo didn’t understand) was that the modem needed to be turned on its
side to work properly, otherwise the carbon granules in the microphone would tend to coalesce – and cause data loss.
work), with much anguish on the part of the telcos (well,
Telecom Australia!).
They (Telecom) even took to placing adverts in the media
warning of the dangers of using unapproved (ie, not supplied by them!), mainly imported modems and the heavy
fines for doing so. It wasn’t too long before they realised the
horse had well and truly bolted so instead started issuing
approvals for imported equipment.
Wired modems used more complicated methods of coding and offered much faster communication than the simple
two-tone system of the acoustic device. Speeds increased
as modulation methods became more clever, until in theory
56kb/s could be reached.
In case you haven’t done the sum, that’s about 187 times
faster than the acoustic modem! Of course, we still were
using the PSTN speech path and bandwidth, so for a time
it was thought that 56kb/s was the limit. But we could now
get our images — even some (jerky) moving ones!
But as well as new Web applications needing
even more speed, there was another big disadvantage to the technology — the engaged line
syndrome. While we were using the ‘net’, the Mother-inlaw received the engaged signal and could not impart any
telephonic wisdom to the family. Neither could the kids
call their friends.
Today both would use email or even the dreaded text
messaging but we are getting ahead of ourselves. Or if
by chance we had the call-waiting facility activated, the
internet experience would be rudely but soundlessly interrupted; neither the Mother-in-law nor our Net aspirations would be fulfilled. A fortunate few might have had a
separate line installed for Net use but it was not a general
rule for households.
POTS and carriers
Then along came ADSL, really a “freak” technology and
After acoustic modems came direct-connect
modems such as this D-Link DFM-526E 56K. At the
time, everyone thought they were unbelievably fast
compared to acoustic models. But ADSL has consigned
them to the rubbish-heap of history!
siliconchip.com.au
May
ay 2012 23
in some ways it’s surprising it works at all. But it does work
if all or most of a large number of aspects are at or near
optimum, as I shall explain.
Hopefully my words will reduce the total of frustrated
users and prevent many of those newsgroup or forum posts
that sometimes use violent language to blame the ISP for
shortcomings that are entirely outside its control!
To appreciate how ADSL works it is helpful to go right
back to the basic telephone network — the Plain Old
Telephone System (POTS) in the mid part of last century.
At first, most lines were strung overhead, including long
distance lines, before the much later advent of coaxial and
tower-to-tower microwave links. The stringing of a dozen
or so wires between say Sydney and Melbourne was expensive and there were obvious limitations of space as the
bare wires could not be allowed to touch and short in any
foreseeable winds.
To have just a dozen connections between Sydney and
Melbourne seems ludicrous now and in fact it was ludicrous
then. So it was necessary to somehow concentrate several
speech channels down one pair of lines in order that the
best use be made of that expensive (and expensively erected)
copper — even galvanised iron in some places!
The solution was carrier telephony. A number of telephone channels were modulated onto several different
radio frequency (RF) carriers, sent down the overhead
wires and separated and demodulated at the other end.
Normal speech occupies a relatively narrow bandwidth;
typically in those days the speech path was designed for
a bandwidth of 200Hz-3kHz.
But the lines were capable of carrying frequencies of
several hundred kilohertz — radio frequencies but still
carried by line.
A typical carrier system in use in the 1950s was capable
of concentrating 17 RF channels down one pair of wires,
spaced by 4kHz, with the highest being 68kHz. Later systems used even higher frequencies.
ADSL and more carriers
Years later, internet engineers reckoned (correctly) that
they should be able to do the same sort of thing with internet signals. The ADSL method consists of modulating
a large group of separate RF channels, often called bins or
buckets, and sharing the data to be transmitted digitally
amongst them.
That’s the Digital Subscriber Link (DSL) but what about
the A for Asymmetric?
Think about how we typically use the internet. We type
a few characters of a website address and in return we get
pages of visual information and plenty of text too. So most
of the data traffic is downloaded and therefore most of the
bins are allocated to it.
An ADSL2+ capable line carries the normal speech and
telephony (POTS) signals in the first 4kHz of bandwidth,
followed by a guard (unused) band from 4 to 25kHz, and
then a large block of separate frequencies spaced 4.3125kHz
apart (up to 512 of them) above that for the internet data.
These separate channels are the bins and about 5% of them
are used for upload with the rest for download.
The number of bins and the allocation between upstream
and downstream varies according to which version (‘Annex’) of the standard is in use. (And before you pundits
TYPICAL ADSL2+ FREQUENCY ALLOCATIONS (not to scale)
ADSL BINS AT 4.3125kHz SPACING
POTS
0-4kHz
GUARD
UPSTREAM
25kHz
DOWNSTREAM
138kHz 142kHz
26 BINS (25 available)
2.2MHz
479 BINS (446 available)
NOTE: some bins are used for pilots or other special purposes
Here’s how ADSL is arranged on a standard PSTN telephone line. The bottom 4kHz is reserved for your phone calls,
followed by a number of channels (‘bins’) for uploaded data and a much larger number for downloaded data.
24 Silicon Chip
siliconchip.com.au
reach for your keyboards, I am simplifying the position for
the benefit of newbies).
Separating the information
How is all the information kept separate? First of all let’s
deal with telephony, because this touches on a great advantage of ADSL — the end of the ‘engaged line’ syndrome!
When ADSL is in use, each telephone should be provided
with a low pass filter that allows the DC signalling (such
as on-hook condition), AC ring current and audio frequencies (such as speech and DTMF dialling) to pass normally.
The filter passes the lowest part of the total passband
(up to 4kHz), to the telephone and keeps it separate from
the RF of the internet connection.
The internet is always connected but the telephone, duly
filtered, operates normally. Whether or not we are using
the net, the phone will still ring if someone is calling and
neither telephone party will hear the internet signals.
Now to the Net connection. All the bins, whether allocated to upload or download, are kept separate by the
special ADSL modem, a complex piece of technology now
relatively cheap. At the telephone exchange end the allocation of the bins is controlled by the Digital Subscriber
Line Access Multiplexer (DSLAM). The Modem-DSLAM
combination does more than keep all those bins separate. It
is also a smart self-training combination, passing information on a per bin basis according to how free of interference
each bin is.
Later we will see why this is one possible reason for a
slow internet connection. Meanwhile you can see that the
provision of a large number of separate but simultaneous
bins (= channels) offers a vastly improved speed.
Are your expectations too high?
It is not good for the blood pressure to pursue the unattainable. Because it involves transmitting RF down a copper pair, with corresponding attenuation and other effects,
your speeds will depend on your cable distance from the
nearest exchange and of course, the cable distance will be
more than the ‘crow flying’ distance.
Because ADSL gets progressively slower as the cable distance rises, it becomes marginal at 4km and will probably
not work at all at 5km, although there can be exceptions.
I am lucky enough to be 167 metres cable length from
my exchange and on ADSL2+ I enjoy at least 10Mbit/s
and sometimes nearly 16Mbit/s download speeds, at the
same time as 0.8Mbit/s upload speed, although the copper
cabling here is not very good.
To put that in perspective, the download speed is up
to over 283 times faster than a dial-up modem and 53,000
times faster than the old acoustic modems!
Because speed varies so much with cable distance and
quality of connection, it is not possible to lay down hard
and fast rules but there are many ISP and other sources
on the net where you can compare your speeds to others
in your area.
There’s a possible fly in the ADSL ointment. You may
be on a telephone line concentrator system, such as a RIM
(Remote Integrated Multiplexer), where many lines are
multiplexed and share a fibre (or even coax) link to the
exchange.
Since ADSL is itself multiplexed there can be clashes
and speed penalties. Your telco will tell you if you are on
a RIM or similar concentrator and whether you can expect
a good ADSL experience.
In fact, when you enquire about ADSL, one of the first
things that happens is that you are asked for your phone
number to check whether you are on a multiplexed system.
Unfortunately, that’s all that is checked – the line is not
physically checked to see if ADSL is possible until you
actually apply for the service.
Low speed, dropouts & throttling
Basically there are two types of trouble you can face
as an ADSL subscriber: low speed and drop-outs. What
about throttling? No, not the person at the ISP help desk,
the speed.
Because this check is so simple it ought to be the first
that you do. Many ISP plans have a data limit, after which
data speeds are deliberately restricted or “throttled”. This
is irritating but you will probably agree that the alternative
of receiving an unexpected bill for excess data usage would
be a tad more annoying! Check via your ISP’s website to
see if you are being throttled.
Telephone line problems
Bearing in mind that ADSL is really a freak technology
where we stuff RF signals down a copper pair that it was
not designed for, for optimum speed and especially for freedom from drop-outs the line needs to be in good electrical
condition. There are many joints in a phone line between
you and the exchange as separate ‘pairs’ of wire are connected at street cabinets or pits. If any of those joints are
faulty you will have problems.
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May 2012 25
DSL Glossary
ADSL
Asymmetric Digital
Subscriber Line.
ATM
Asynchronous Transfer Mode.
Authentication
Auto-negotiation
Bandwidth
Cross-talk
A digital subscriber line (DSL)
technology in which the
transmission of data from server
to client is much faster than the
transmission from the client to
the server.
A cell-based data transfer
technique in which channel
demand determines packet
allocation. ATM offers fast
packet technology, real
time, demand led switching
for efficient use of network
resources.
A security feature that allows
access to information to be
granted on an individual basis.
Procedure for adjusting
line speeds and other
communication parameters
automatically between two
computers during data transfer.
The range of frequencies a
transmission line or channel can
carry: the greater the bandwidth,
the greater the informationcarrying capacity of a channel.
Signal currents being induced
into neighbouring wires and
causing errors.
bit
(“BINary digiT”)
A single unit of data, where there
are only two possible states. The
smallest amount which can be
carried/transmitted.
bps
bits per second
A standard measurement of
digital transmission speeds.
Bridge
A device that connects two or
more physical networks and
forwards packets between them.
Broadband
Characteristic of any network
that multiplexes independent
network carriers onto a single
cable. This is usually done using
frequency division multiplexing
(FDM).
byte
DMT
Discrete Multitone
26 Silicon Chip
(usually!) 8 bits = 1 byte; origin
is the number of bits needed to
define one text character.
The leading method of signal
modulation for DSL service.
The usable frequency range is
separated into 512 frequency
bands (or channels) spaced
4.3125kHz apart.
DMT uses the FFT (fast Fourier
transform) algorithm as its
modulator and demodulator.
Downstream rate
The line rate for return messages or
data transfers from the network to
the customer.
DSL
Digital Subscriber Line
A technology for bringing highbandwidth information to homes
and small businesses over ordinary
copper telephone lines.
DSLAM
Digital Subscriber Line
Access Multiplexer
A device at the telephone exchange
which enables connection to
multiple customers simultaneously.
Encapsulation
The technique used by layered
protocols in which a layer adds
header information to the protocol
data unit (PDU) from the layer
above.
FTP
File Transfer Protocol
The Internet protocol (and
program) used to transfer files
between hosts.
HTML
Hypertext Markup Language
The most common page-coding
language for the World Wide Web.
HTML browser
(or web browser)
A browser used to traverse the
world wide web.
http
Hypertext Transfer Protocol. The
protocol used to carry world-wide
web (www) traffic between a www
browser computer and the www
server being accessed.
Internet address
An IP address assigned in blocks
of numbers to user organizations
accessing the Internet.
Internet
A collection of networks
interconnected by a set of routers
which allow them to function as a
single, large virtual network.
IP
Internet Protocol
The network layer protocol for the
Internet protocol suite.
IP address
The 32-bit address assigned to
hosts that want to participate in a
TCP/IP Internet. Written as four
numbers separated by dots.
ISP
Internet Service Provider
A company that allows home and
corporate users to connect to the
Internet.
LAN
Local Area Network
A data communications network
restricted to a small area (often
within one building or office)
siliconchip.com.au
Last mile
The final connection between
the nearest exchange and the
subscriber (for most people at the
moment a copper pair).
Line rate
The speed by which data can be
transferred over a particular line
type, express in bits per second
(bps).
Loopback
A diagnostic test that returns the
transmitted signal back to the
sending device after it has passed
through a network or across a
particular link. The returned signal
can then be compared to the
transmitted one.
MAC
Media Access Control Layer. A
computer’s interface to a physical
network.
Multiplexer
A device that can send several
signals over a single line. They are
then separated by a similar device
at the other end of the link.
Router
A system responsible for making
decisions about which of several
paths network (or Internet) traffic
will follow.
SNMP
Simple Network
Management Protocol
The network management
protocol of choice for
TCP/IP-based internets.
Split pair
Where the earth leg of one
twisted pair is inadvertently
swapped with the earth leg of
another during jointing, leading
to the noise cancelling effect of
the twist being defeated.
Spoofing
A method of fooling network end
stations into believing that keepalive signals have come from
and return to the host. Polls are
received and returned locally at
either end of the network and are
transmitted only over the open
network if there is a condition
change.
Synchronous connection
During synchronous
communications, data is not sent
in individual bytes, but as frames
of large data blocks.
TCP
Transmission Control Protocol
The major transport protocol in
the Internet suite of protocols
providing reliable, connectionoriented full-duplex streams.
NAT
Network Address Translation.
Allows multiple computers to share
one IP address.
Packet
The unit of data sent across a
packet switching network.
PAP
Password Authentication Protocol.
Pair
The pair of copper wires making up
an individual telephone circuit.
UTP
Unshielded Twisted pair
Port
The abstraction used by Internet
transport protocols to distinguish
among multiple simultaneous
connections to a single destination
host.
Two insulated copper wires
twisted together to reduce
potential signal interference
between the pairs.
Upstream rate
The line rate for message or data
transfer from the source machine
to a destination machine on the
network. Also see downstream
rate.
VC
Virtual Connection
A link that seems and behaves
like a dedicated point-to-point line
or a system that delivers packets
in sequence, as happens on an
actual point to point network.
In reality, the data is delivered
across a network via the most
appropriate route.
WAN
Wide Area Network
A data communications network
that spans any distance and is
usually provided by a public
carrier (such as a telephone
company or service provider).
POTS
Plain Old Telephone Service
Also known as PSTN – the public
switched telephone network.
PPP
Point-To-Point-Protocol.
Provides router-to-router and hostto-network connections over both
synchronous and asynchronous
circuits.
Protocol
A formal description of messages
to be exchanged and rules to be
followed for two or more systems
to exchange information.
RIM
Remote Integrated Multiplexer
Where many lines are locally
multiplexed and share a link to the
exchange. Often precludes ADSL.
Route
The path that network traffic takes
from its source to its destination.
siliconchip.com.au
May 2012 27
vals, it turned out to be a paging alarm system on another
subscriber’s line, with, you guessed it, a split pair.
Local RF Interference
Flat patch lead at top and standard UTP (unshielded
twisted pair) below. The twisted pair lead is preferable for
minimising noise and interference.
Pick up your phone and dial 1. In the few seconds before
the “number unobtainable” tone kicks in you should have
absolute or very near silence (possibly a very faint steady
hiss with some types of phone). There should definitely
be no intermittent crackles (caused by bad joints) and no
cross talk from other telephone users. Cross talk or hum
may indicate a split pair somewhere on the route between
you and the exchange. Is a split pair the same as split end?
A split pair is where the technician has in error used
someone else’s telephone earth line instead of yours. The
phone still works because all the earth wires are connected
together at the exchange but it is noisy, and ADSL does not
like noise. The pair of telephone wires that make up your
normal connection are twisted together in the multi-way
cable that usually runs underground in ducts. The twists in
the pair go a long way towards minimising noise because
the noise currents in the adjacent wires balance out. But
if by error your earth wire is really someone else’s, it is no
longer twisted with your other wire. The pairs are split
and noise will result.
Returning to crackly joints, these are often far worse in
extreme weather, by which I mean excessive heat or cold,
or heavy rain. If you hear line noise, even when all other
equipment is removed from your phone connection, there
is a problem either inside or outside your premises. If
inside you will need the services of a competent licenced
cabler. If outside, your approach needs to be to Telstra or
any other line retailer involved. Be careful here. You may
be slugged with a charge if no faults are found, so do the
other checks first. Also, you may be unlucky with your
technician. Many a case has been marked as ‘no fault found’
when there was a glaring one. I have no magic solution to
this human problem.
Patch leads & RJ plugs
How long is the patch lead joining your modem/router to
the telephone point in your house? Such leads are usually
not twisted, probably because it is cheaper to make flat ones.
Although it’s a comparatively short run, the interferencecancelling effect of a flat pair is much less than a twisted
pair. I would recommend that patch leads be no longer
than two metres. While we are considering the patch lead,
internet problems may also be due to a loose RJ plug on
the patch lead, where it has not been fully pressed home
in the modem or telephone point.
Problems at given times
Internet users often experience drop-outs at specific intervals (every four hours is common) and these have turned
out to be Securitel or similar auto-paging alarm units on the
same line. For optimum internet speed and freedom from
drop-outs, it is best to have only telephones (and possibly
faxes), all with filters, on a line that is to carry ADSL traffic.
In one recent case of drop-outs exactly at 4-hourly inter28 Silicon Chip
In one case I assisted with, the user experienced a dramatic reduction of internet speed at 6PM every evening.
He was convinced that his ISP was deliberately throttling
his speed at peak times, that there were insufficient ISP
servers etc.
Fortunately, he was not one to rush into un-researched
blame and in due course he found by experiment that the
problem was his new plasma TV which was switched on
at 6PM for the news each evening. The switch-mode power
supply was poorly screened and filtered (as is often the
case) and it radiated pulses throughout the house and into
his untwisted patch lead.
RF interference can even be caused by a faulty lamp,
including an incandescent one that is ‘singing’ just before
failing. To test for this, appliances should be completely
disconnected one by one (not just switched to standby).
(But do not emulate a certain friend who noted that if he
switched off at his main fuse panel, the interference certainly stopped — but along with everything else…).
The sheer field strength of a nearby radio or TV broadcaster will result in some induced signals in nearby telephone lines. Your telephones are fitted with capacitors to
reduce or eliminate rectified audio currents from interfering
with normal telephony but the RF itself will often interfere
with ADSL.
Why does RF interference matter?
We’ve looked at the modem/DSLAM combination and
how it dynamically negotiates the best use of the big block
of bins available to it. If there is interference on one or
more of these bins, caused by harmonics or fundamental
frequencies, the modem/DSLAM will agree together not to
use it/them and so the total number in use reduces, leading
to reduced overall speed.
Power interruptions
Some time ago, I was puzzled about drop-outs that I was
suffering after upgrading from ADSL1 to ADSL2+ (a more
‘fussy’ technology, because the frequencies are higher).
Previously, if power visibly failed for a few seconds (as it
often did in thunderstorms), the modem would reset itself
and consequently there was delay. This I understood but
since the upgrade to ADSL2+, the drop-outs also happened
at times when there was no flicker of the lights.
A small Uninterruptible Power Supply (UPS) for the
modem and router solved this problem. Indeed, almost
immediately after fitting the UPS it went into alarm mode
several times, although the lights did not blink.
Here was the solution: power occasionally dipped for a
few milliseconds, not enough for an incandescent lamp to
flicker (because of thermal inertia) but certainly enough to
cause the modem and router to reset.
Modems and routers
Although I have been lucky myself, there are many reported cases of these units becoming flaky. There is a tendency
to leave them on continuously and thus heat fatigue may
occur, particularly when there are underrated electrolytic
capacitors fitted, which is the case with much overseas
siliconchip.com.au
equipment or when the mains voltage is abnormally high.
Modem and router firmware may need upgrading as
manufacturers discover shortcomings in current versions.
Sometimes settings may be lost for one reason or another
and the modem or router may have to be reset to the factory configuration.
Although it is not always practical, the best way of eliminating the modem or router from your list of suspects is to
borrow another; as long as you are quite sure you have set
it up properly. Sometimes when the Net connection fails
it is necessary only to perform a simple power reset of the
modem/router, where you disconnect the low voltage power
for 20 seconds or so (to let the electrolytics discharge) and
then power it up again.
After a few minutes to let the ADSL connection become
established, you may find that you have normal service.
Computer
My experience was that by far the biggest contributor
to low internet speeds was the state of my own computer.
Running XP it had become somewhat cluttered, with
much software installed or de-installed over the years.
Consequently the machine often ‘froze’. By pressing CTRLALT-DEL on an XP machine you can see its operating state,
via Windows Task Manager. The CPU usage is the critical
figure. If this sits at 100% for more than a few seconds then
the machine is in a virtual ‘locked up’ state and all your
computing will experience considerable delays.
In my case, I had sufficient backups and original software
CDs/DVDs to be able to clean off my hard disk and do a
complete reload of everything. And I had another machine
to work on while this was in progress.
I admit that it took many hours and I know it’s not a luxury
open to all but in my case when it was finished my internet
speeds were revolutionised! When working at the computer
I now make a point of calling up Windows Task Manager
and then minimising it. On the task bar I can then see the
loading of the CPU as a partially green square all the time.
Possibly, you are not able to perform (or risk) a complete
reload from the start but at least, after taking good backups
and verifying them, check your machine for viruses or other
malware. Also, avoid having other applications running
when on the Net and defrag your disk from time to time.
General infrastructure failure
The telephone network that we rely on so heavily can
experience local or even national outages for a number
of reasons. You can be sure that every effort is made to
minimise the effects of this, especially if over a wide area,
because the telco concerned is losing valuable revenue.
A reputable ISP will have a page on its website that will
list outages and general locations (although admittedly this
is of no value when you can’t access it!). Phone help lines
may also be a source of information. (I hear you groan —
but remember that the help-desk jockey is a human being
reading from a script).
We now come to less likely reasons for poor speeds or for
drop-outs. Exchange DSLAMs are very reliable, since they
feed many subscribers, perhaps up to 1,000 or more. If one
is faulty it will give rise to many simultaneous complaints
and is likely to be swapped out quickly.
Exchange congestion is a fairly rare occurrence, though
some remote exchanges are notorious. Again, this is a leaksiliconchip.com.au
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21 automated measurement & waveform math Validate your device operation and identify issues quickly
Data logging capability Find intermittent faults
• TrendPlot™ function
• capturing and replaying up to 100 display screens
or set-up pass/fail waveform limits
The THS3000 series of handheld oscilloscopes is a complete and
comprehensive solution providing you with the ability to make
safe, accurate measurements in both bench and field
environments
Visit TekMark Australia, Booth 5306 in NMW 2012 for
demonstration. Alternatively, contact us on 1300 811 355 or email
enquiries<at>tekmarkgroup.com
age of potential revenue for the telco and the likelihood is
that it will be fixed fairly quickly. Unfortunately, in these
cases ‘fairly quickly’ for a telco may mean a number of
months.
Incompetent or poorly resourced ISPs
I have placed this last because although it is possible I
have never experienced it. I can only think that in this case
subscribers would leave in droves and the ISP concerned
would fold.
How can you tell if your ISP is the guilty party? I would
like to say be guided by forum and newsgroup postings.
Unfortunately this is not completely reliable. In the first
place, among the millions of users there will be many
who are experiencing your problem, even in your own
immediate area, and are convinced they know the causes
(invariably they cite the ISP).
Some posters pop up under cover of a different user
name to their normal one, make a disparaging post and then
disappear, possibly returning under another user name and
agreeing with their own post.
Are they paid stooges from another ISP? Or are they
genuinely frustrated and distressed? There is no way of
checking. You could go by praise but to be fair, praise posts
could also be made by stooges!
I can only be certain about my own experience. To paraphrase a certain person recently in the news, I am a happy
little Vegemite now that I’ve cleaned up my computer and
fixed my power outage problem. And all without any helpdesk jockeys being harmed…
SC
May 2012 29
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