View Single Post
  #11   Report Post  
Old March 23rd 08, 07:33 PM posted to rec.radio.amateur.moderated
Klystron Klystron is offline
external usenet poster
 
First recorded activity by RadioBanter: Jun 2007
Posts: 50
Default WPM to BPS calculation

Paul W. Schleck " wrote:
Klystron writes:


It still seems like an awfully slow data rate. I have seen people
throw 14400 Baud modems in the garbage because they considered them to
be so slow as to be worthless. A data rate of 42 bps is about 3 orders
of magnitude slower than that.



Many types of communications vary over many orders of magnitude of
information rate, yet are considered useful and up-to-date.

For example, the Casio WaveCeptor on my wrist:

http://www.eham.net/reviews/detail/2497

receives a ~ 1 Baud Pulse Position Modulated (PPM) signal from radio
station WWVB in Fort Collins, Colorado, which transmits on 60 kHz. It
takes about a minute to send the complete time code to synchronize my
watch. Slow? Yes. Useful? Yes, very much so, especially when
considering the coverage and reliability that can be obtained from such
a low-bandwidth, groundwave-propagated, Very Low Frequency (VLF) signal.
[...]



In your model, only a single axis of data is transmitted - the time
of day. That seems like a great deal of infrastructure and energy
consumption to transmit a single data quantity. The equivalent
infrastructure for weather transmission (marine and air) is even more
elaborate and expensive. Can you see that is an outrageously inefficient
way to distribute a small quantity of information?


One of the most current and widely used communications technologies
among young people is cellular telephone text messaging:

http://en.wikipedia.org/wiki/Text_messaging

(sometimes also called "Short Messaging System" or SMS)

According to this recent demonstration on the Tonight Show with Jay
Leno:

http://www.youtube.com/watch?v=AhsSgcsTMd4

the realizable data rates are comparable in order of magnitude to that
of fast Morse code that can be sent and received by human operators.
Just try telling a teenager with an SMS-capable cellular telephone that
it should be thrown in the trash because it isn't fast enough, or isn't
of sufficiently novel technology, and see his or her reaction.



My understanding is that they use SMS for fairly trivial
communications, like what they will have for lunch or where they will
meet at the mall. A rough equivalence might be SMS users objecting to
the use of the SMS system by people who are sitting at full-size
computers or by people who have connected keyboards to their phone. If
they were to complain that "typing" pidgin English (like "HOW R U?")
with your thumbs on a tiny telephone keypad was the one true way to use
SMS, then I think I could agree that there was an equivalence.
You might ask those kids why they also use conventional e-mail,
despite having SMS availability.


To give you an amateur radio example, the Automated Position Reporting
System (APRS):

http://www.aprs.org

uses 1200 Baud AFSK packet. Faster, but still an order of magnitude
slower than technologies you imply should be thrown out.
[...]



Again, it is for the exchange of a single axis of data - geographic
location. Please stop tying to pass off these single purpose, dedicated
systems as examples of general purpose communications.


To even give you a Morse code example, consider the simplicity and
effectiveness of the NCDXF beacons running on the HF bands:

http://www.ncdxf.org/beacons.html



My understanding is that Morse-based beacon identifications are read
by computerized devices and are not "copied" by the pilots. I doubt that
you could find very many current pilots who could copy any Morse at all.


[...]
There are even a number of excellent software packages linked from the
NCDXF site above that could automatically monitor the signals, decode
the Morse, and record the quality of the communications paths over time.
One such package is Faros:

http://www.dxatlas.com/Faros/

one of many advanced signal processing software packages for amateur
radio that exploits the ubiquitousness of of inexpensive personal
computers with sound cards in most home ham "shacks."



There is nothing about that that is unique to Morse. Any type of RF
link would be usable in that way.


Focusing simply on information rate disregards other aspects of the
communications and the channel over which it is transmitted. These
important aspects include the bandwidth and propagation characteristics
of the available channel, the complexity of the required transmitting
and receiving equipment, the amount of data that needs to be
transmitted, and how quickly and often it needs to be conveyed.

Single-attribute measuring contests may be fun, even ego-boosting to
some, but are really not very useful or impressive to those who actually
design and use practical communications systems.

It just seems inconsistent with the way
that so many hams have fought tooth and nail to hold onto Morse and to
hinder the move toward digital modes.


I'm not sure that I understand your line of reasoning here. You are
implying cause-and-effect. In other words, use and advocacy of Morse
code somehow directly contributed to the obstruction of other
technologies. Can you give direct evidence of specific examples?



Hams used to deride digital communications as "pulse" and tell tales
about the way that it squandered bandwidth. They made it out to be
something along the lines of spark-gap. Look for articles about "pulse"
communications in old (1960's and 70's) issues of QST and Popular
Electronics. Considering the lead time needed to develop a new mode, I
think it is unreasonable not to go back at least that far. I believe
that the anti-digital curmudgeons delayed the implementation of digital
modes by a matter of decades. It is interesting to note that the most
widely used digital modes (for 2-way radio, not for broadcast) were
developed either in Japan (Icom/JARL DV) or under the auspices of a
police organization that has no ties to radio, except as consumers (APCO
25).


[...]
Furthermore, if the only technologies that you believe should be saved
from being thrown away are those at 14.4 kBaud and up,



Can you point to something in my post that makes such a claim? The
only technology that I have derided as being too slow as to have value
is Morse code that is sent by hand (less than 100 baud). The Navy shut
down its VLF network on the grounds that the data rate was inadequate.
Perhaps it is time for the amateur community to take a similar step.


those
technologies are only practically realizable on amateur radio bands at
high VHF and up. Such bands have been open to licensees without need of
a Morse code test for going on 17 years now. Even before then, these
bands were accessible to Technician-class amateurs since at least
shortly after World War II, with a license that only required a minimal,
5 WPM (essentially individual character-recognition) Morse code test.

If you are saying that someone *else* should have developed these
technologies (other than you, of course), and that since they haven't,
then someone *must* be to blame, well, you can't really dictate how the
world should turn out without taking an active role to help make it that
way.



That last paragraph is incoherent. Could you rephrase it?

--
Klystron