HELLSCHREIBER
By Bob
Wexelbaum, W2ILP
In my digital mode lecture series at GARC the forth
mode covered was Hellschreiber. I am again presenting it here. There are now other digital modes that can be
run with the same hardware interface which I may cover in future newsletters. .
March 2006 VOL. 79, NO. 3
CIR 120
There were not enough Morse operators to fill military
needs during WW II. The
Now we are able to use the Hellschreiber concept in a
much more modern way. We can use a
personal computer and the same interface to a HF SSB transceiver as was used
for RTTY, PSK-31, MFSK-16, etc. We only
need to down load the freeware for Hellschreiber and we will be ready to
operate. The freeware is available from
IZ8BLY’s web site:-
Http://xoomer.virgilo.it/aporcino/Hell/index.htm
Hellschreiber differs from all of the other digital
modes in that the received signal is not decoded to be an ASCII font in order
to be displayed. Hellschreiber actually
sends a strip of a TV like display directly to the computer monitor. Let us compare Hellschreiber to the old black
and white analog TV. The analog TV
signal contains synchronization (synch) pulses and a video signal. The video signal is Amplitude Modulated (AM)
and the amplitude of the signal determines if the spot intensity on a CRT is
going to be white, black or a shade of gray.
The TV picture tube (CRT) is scanned at a horizontal rate of 15,750 Hz,
and a vertical rate of 60 Hz. In order
to reduce flickering alternate frames are interlaced.
HELLSCHREIBER (continued)
The TV synch pulses determine when the scan will start
both horizontally and vertically for each frame. By contrast in Hellschreiber there is no gray
scale, so that Hellschreiber only needs to transmit black and white. In fact it only sends black. Key down is black and key up is white. This is thus true digital of the simplest form.
. According to IZ8BLY the software has the option of providing for gray pixels,
but that option is not being utilized at present as all keyboard characters can
be shown in only black and white. The
principal of Hellschreiber operation is not unlike Wirephoto or FAX without any
gray scale. When the key is up there is
nothing being transmitted so the display either sends white pixels or the blank
background noise level. The noise level
might appear gray or white depending on the noise level just as it randomly appears
in waterfall displays. The black key
down pulses transmit black digital pixels that are equivalent to the TV
video. The software actually shapes the
black pixel pulses somewhat. It rounds
them off a bit just as a key click filter might. This is done to prevent differentiation
(overshoots) of the fast step function that is caused when we send pulses. An interesting feature of Hellschreiber is
that it needs no sync pulses, as it uses no synchronization technique. The vertical scan frequency is derived from
the PC’s clock, as is the horizontal rate at which the strip of signal moves
across the screen from left to right.
The system does not require vertical sync because the characters are displayed
twice. What you see is either two lines
of the same text or one line and a part of a line above it and the remaining
part below it. Thus there is always at
least one complete line that is readable..
The resolution of the characters received is determined by a 7 by 7
matrix of pixels. This enables viewing
of all keyboard characters, both capitals and small case. Again the software can optionally work with
matrixes of other dimensions…but the 7 by 7 matrix is what is presently being
used. The characters appear smooth and solid, except when greatly
enlarged. When the display is projected on
a large screen for demonstrations, it is possible to see the pixel resolution as
steps on curved character parts. If the
characters appear slanted the cause would be that the transmitted vertical scan
rate is not the same as the receiving PC’s vertical scan rate. This can be adjusted for by using software adjustment, but it is seldom
required, as PC clocks are normally sufficiently accurate. Hellschreiber messages can be read in a high
noise level in spite of the fact that the signal is close to the noise. This is because we read using whole word
recognition and we can recognize familiar words even when some pixels are
missing. Our eyes and brains do the
recognition job when we receive Hellschreiber messages and not a computer sound
card’s decoder/encoder. There are 49
pixels per character. 150 Characters (30
words) are transmitted per minute. Each pixel pulse is 8.164 ms long. What I described thus far is called Feld
Hell. There are other versions of
Hellschreiber. There are various
multi-tone versions, frequency shift and FM versions. Normally hams will use Feld Hell when calling
CQ and may change mode after contact is established. Feld-Hell has a BW of 300-350 Hz. FM-Hell’s BW is only 150 Hz
Page 2
HELLSCHREIBER (continued)
Hellschreiber is less popular than other digital
modes. I don’t know why this is so
because it works well for DX contacts and there are lots of DX stations using
it. It can be used legally in any part
of the CW portions of all ham bands but it is most popular on 20 Meters between
14.065 and 14.080 MHz. Serious
Hellschreiber users join a reflector and find out when and where activity is to
occur. There are also Hellschreiber
Activity Days (HADS) when hams that use Hellschreiber are encouraged to go on
the air. These occur at the end of every
other month. Be sure to check with
others before transmitting, as the CW and other digital mode specialists are
very touchy about seeing Hellschreiber signals where they don’t want them to
belong.. It has recently become a turf
war for sub bands and it is hoped that the FCC rules will clear up sub band
problems by defining signals by their required bandwidths rather than their mode. Standardizing to only a few modes would seem
any easy solution but this does not lend itself to encouraging
experimentation. The FCC rules require
that any codes used must be made available at no cost. This is why there is always some
freeware. There is also software that
must be paid for for the same modes, but I have been told that the costly
software is no better than the freeware for the modes I have described.
Computers keep getting faster and thus lend themselves
to schemes that were previously impossible.
You might say that this is an evolution toward what is now being called
nano technology. It may now be science
fiction but some scientists believe that the only limit to small increments
will occur as we approach the size of subatomic particles.
Hellschreiber served its purpose during WWII and it
can still be used as effectively as Morse CW.
It is really a very high speed CW mode and mathematically it retains the
same advantages as CW, except for its benefit of human recognition by anyone
who can read text but is not trained to copy Morse. Wire photo and facsimile (FAX) were
developed to fit the needs of newspaper correspondents who needed to send still
pictures along with their reports.
Early home computers
were fast enough to generate the 8.164 ms Hell pixel pulses. Modern computers can shape or generate the HF
radio frequency carrier that exists during the pixel pulse time. The computers
of the future will do what might seem impossible now. Hellschreiber is important if it only serves
as an introduction to the whole subject of still picture generation and leads
to the study of moving picture generation.
In the future we will discuss SSTV, which is a method for sending still
pictures by amateur radio on HF. We can
then follow by discussing Amateur Television (ATV), which uses the same standards
as commercial analog TV on UHF ham frequencies. Then we can get to the topic of
scan conversion techniques that have been used for radar displays. There were once large analog scan converters
that used TV cameras to view radar CRT displays. They were large and difficult to adjust. They were replaced by digital scan conversion
that is now used. Displays no longer
depend on the decay of CRT phosphors (persistence) as digital video can be
retained as long as desired in random access digital memories (RAMs). Digital
storage led to the development of digital memory storage oscilloscopes. These same techniques now make HDTV
possible..
Page 3
PRESIDENT’S PAGE
BY
KE2LJ
There's not much in the way of new
things to report to report. We had a group of people working on a pre-proposal
effort to do an upgrade to the venerable B52 bomber. But apparently the
Government cancelled that effort, and the work came to a rapid halt. There were
probably 100 Engineers that will be let go if they don’t find other assignments
in
CQ DE WA2LQO MARCH 2005
GRUMMAN AMATEUR RADIO CLU
MINUTES OF GENERAL MEETING -2/15/2006
Karen KC2OPX
The meeting was called to order at
TREASURERS REPORT – Ed, WB2EAV REPEATERS – Gordon, KB2UB
Finances
continue to be in good shape. Nothing new to report.
VE REPORT – Bob, W2ILP NET REPORT- Zack, WB2PUE
One applicant passed Technician exam. 146.745 repeater is very
weak
A second applicant upgraded to General. 145.330 repeater is good.
VEs present were AB2NT, KC2HNN, Sunday morning 40-Meter net was
good.
W2ILP and W2QUV.
This was the first
VE session held at
NEW BUSINESS:
Ed
Hare, ARRL Lab Manager, will be lecturing on the ills of BPL in Greenlawn on
March 14th. (Unfortunately
the time conflicts with our March VE session).
This lecture is being presented by the EMC
section of the IEEE. We have learned
that LIPA is going to test BPL in
PROGRAM:
A
presentation was given by Tom Carruba, KA2D who is our ARRL Emergency
Coordinator. He spoke about the role of the Amateur Radio
Emergency Service (ARES). ARES supports
training programs, and coordinates members who are active in
meetings, drills, and marathons. It is
important to join so as to get
on a membership list and be available if and when needed in an emergency of any
kind. While ARES members are not to be first responders, they may be
called when and if needed to coordinate with other
communication services.
The meeting
was adjoined at
GARC NETS:
40 Meters: 7.289 MHz at 7:30 AM EST
Sundays.
20 Meters: The 20 Meter WAG net has been
cancelled because of inactivity.
2 Meters (via repeaters): 146.745
MHz (-.600)at
145.330 MHz (- .600) at
[Tone for
both repeaters is 136.5 Hz]
(ARES/RACES) Mondays
MEETINGS
General Meetings of the GARC
are held on the third Wednesday of each month, starting at
Page 5
GARC WEB SITE
The web site of the GARC can
be found at http://www.qsl.net/wa2lqo/ Webmaster is Pat Masterson KE2LJ. Pictures of GARC activities, archives of
newsletters, roster of members, and other information about the GARC may be found
there.
Internet Link of the Month for Internerds
The internet link for this
month is:- http://www.xs4all.nl/~nl9222/software.htm
This link provides an index
of software for most ham digital modes as well as for some other ham related
functions. This index covers both DOS
and/or Windows operating systems in PCs.
There may be another index elsewhere for the Mac users. You might ask why there is still old DOS
software around when most new computers go directly to Windows. Many of us have old computers that use DOS
and want to dedicate them to our ham station, where they may be adequate and
permit us to free up our new PC with Windows XP for our other home computer
needs. The link is called Amateur Radio
Visual Software. Notice that Dimension 4,
which was previously explained in this column, is also included on this
Index. I would suggest that you use the
software that I suggested for each digital mode, unless you are using a
different operating system. Ham Radio is
a hobby that is designed to promote some experimentation. This includes seeing for yourself what
software is best for you. Be sure you
know how to delete software if you don’t like it, but feel free to try whatever
works best for you.
ED HARE WILL SPEAK ABOUT BPL ON
Ed Hare, ARRL Lab Manager was
scheduled to speak at an IEEE – EMC Society meeting on March 14th. Due to circumstances the meeting had to be
rescheduled for
The meeting will be at
PUZZLE
Here is another cryptogram. This is a short “expert” one, so I’ll give
you a hint. It also applies to
cryptogram printers.
M XZTG
EMJ INQCVCT TCTQAGLVJB
FNG M KVIXQVJG.
–ZIEMQ RVUPT--
Solution to February’s
cryptogram:
WHY SHOULD WE BUY
PRESCRIPTION DRUG INSURANCE FROM COMPANIES THAT LIMIT THE BRANDS OF DRUGS WE
CAN GET? WE DON”T BUY AUTO INSURANCE
THAT LIMITSD THE BRANDS OF CARS THAT CAN HIT US. –BOB WEX--
Page 6
GARC VE SESSIONS We
are continuing to proctor exams for all classes of ham licenses on the second
Tuesday of each month starting at 5:00 PM. The present
exams are: Element 1: 5
WPM CW, Element 2:
Technician Element 3:
General Element 4:
Amateur Extra Class. The fee for
2006 is $14 for all exams taken at one sitting. Applicants
for upgrades should bring a photocopy of their license and their FRN number. New, first
time applicants should be aware that their Social Security number will be
required on their application form. All applicants should bring driver’s license
or other picture ID. Until
further notice, VE exams will be at Room: Briarcliffe
in All
applicants should contact W2ILP to preregister if possible, but walk-ins may
still be accepted. For any information
e-mail: - [email protected]
or phone: - (631)
499-2214 Study
material information is available at the http://www.arrl.org or the http://www.w5yi.org web site. All VECs use
the same Q & A pools. Since the
beginning of the VE program the GARC has provided opportunities to take ham
exams monthly, during all twelve months of every year. Bob
Wexelbaum, W2ILP and
the Grumman VE team. |
CQ de WA2LQO March 2006 VOL.
79, NO. 3 EDITOR Bob Wexelbaum W2ILP (631) 499-2214 CONTRIBUTING WRITERS PAT MASTERSON, KE2LJ And all the members of GARC (we hope!) CQ de WA2LQO is published monthly by
the Grumman Amateur Radio Club for its members and friends. Send articles
and amateur equipment advertisements to: KE2LJ or W2ILP ELECTRONIC SUBMISSIONS If you want to
submit articles or amateur equipment ads via e-mail do the following: 1. For
submission direct to editor call him at above number to set up a transfer. 2. For e-mail
transfer: Internet Address Our February VE
session at The FCC has not stated when the CW exams will be
eliminated, although they had stated that they planned to entirely
eliminate the CW requirement. A 5 wpm CW exam remains required for a General Class
license until further notice. It
was expected that the FCC would announce the CW elimination at the Dayton
HamVention, but the latest news is that this will not happen. A new Technician class question pool is now available
at the W5YI.org web site. The exam
seems to be at least as difficult as the previous exam, if not more so,
since it covers more material.
There is a petition to create an easier entry exam, but no action has
been taken on it. It might take the
form of recreating a Novice class but without a CW exam. The new Technician exams will not be given until July
2006. VY 73, W2ILP (I License People)…with the help of the VE team,
a VEC and the FCC. GRUMMAN
AMATEUR RADIO CLUB OFFICERS FOR 2005 President Pat Masterson KE2LJ V01-01 516-346-7125 Vice President Gordon
Sammis KB2UB Retiree 631-666-7463 Secretary Karen
Cefalo KC2OPX 1Yr Board Member
Zack Zilavy WB2PUE Retiree 631-667-4628 1Yr Board Member
Bob Christen W2FPF
2Yr Board Member
Bob Wexelbaum W2ILP Retiree 631-499-2214 2Yr Board Member
Jack Cotterell WA2PYK
Retiree 516-249-0979 Trustee
WA2LQO Ray Schubnel W2DKM Retiree STANDING
COMMITTEE CHAIRMEN Meeting
Programs Contact a Board Member FCC
Exam Coord. Bob Wexelbaum W2ILP 631-499-2214 GRUMMAN
AMATEUR RADIO CLUB OFFICERS FOR 1997 President Pat Masterson KE2LJ B38-111 346-6316 Vice
President Gordon Sammis KB2UB C63-005 575-1846 Secretary Peter Rapelje N2PYV Retiree 676-0694 Treasurer Phil Simonetti N2ZED K10-14 346-8124 2Yr
Board Member Paul Chalson WA2FOF A16-043 224-8153 2Yr
Board Member Howard Liebman W2QUV Retiree 433-7487 2Yr
Board Member Martin Miller NN2C Retiree 423-8153 1Yr
Board Member Zak Zilavy WB2PUE Retiree 667-4628 1Yr
Board Member Hank Niemczyk W2ZZE Retiree 796-3212 Trustee
WA2LQO Ray Schubnel W2DKM C31-005 575-5036 STANDING
COMMITTEE CHAIRMEN Meeting
Programs Contact a Board Member FCC
Exam Coord. Bob Wexelbaum W2ILP 499-2214
EDITORIAL
Treasurer Ed Gellender WB2EAV X02-14 516-575-0013
1YrBoard Member Dave Ledo AB2EF
GRUMMAN AMATEUR RADIO CLUB Sixty Years 1944 -2004
FIRST CLASS
DO NOT DELAY |
TECHNICAL BITS
We
have been talking about HF radio receivers here. Receivers were normally store bought but
transmitters were usually home brewed before Single Sideband became
popular. Many hams started as SWLs,
using general coverage short wave receivers that became part of their first ham
radio set up when they got licensed. A
new license meant getting the parts together to build a transmitter or buying a
transmitter from another ham. There were
few transmitters on the market and most were expensive. CW
transmitters were relatively easy to build and the needed parts were available
in catalogs or for New Yorkers on