SSTV
by Bob
Wexelbaum, W2ILP
Another
mode that can be worked using the same hardware interface as was used in the
previous digital mode work is Amateur SSTV.
The abbreviation “SSTV” is meant to mean Slow Scan
Television, but for Amateur HF use “SSTV” means the ability to send still
pictures on the HF phone bands. It would
be impossible to send television signals that are the same as are used
commercially on HF ham bands. A
compatible analog TV signal requires a bandwidth of 6 MHz and obviously it would
take up more bandwidth than an entire ham band in order to transmit one such TV
signal.
SSTV, as HF hams use it, has evolved from earlier days
where only black and white signals of much poorer resolution could be
transmitted. Amateur SSTV has been around
since 1958. It started long before there
were home PCs. The most popular SSTV
program can now utilize the full colors of modern PC displays that are now available
to computer users. Because of its
limited bandwidth, and thus speed, ham SSTV can not transmit streaming video in
the way that JAVA and other computer formats can. Before PCs were available, sending still
pictures via ham radio was a big development and it required some expensive
equipment to do so. Today it is possible
to post pictures on web sites, which can be visited by all of our friends and
relatives and thus the romance of HF picture communication may have lost its
original impact. It takes ham spirit to
go on expeditions to the South Pole, and it takes some of the same ham spirit
to transmit DX pictures where QSB and QRM might blank out parts of them and
they may appear snowy, even when they don’t come from a polar expedition. The
way SSTV is now used involves first making SSB phone contact on a phone band frequency
and then telling the ham that you are QSOing with to get set to receive a
picture. Then you send the picture. The picture may take a few seconds to a few
minutes to be completely scanned.
You can send any picture file that your PC can store. This
includes scanned pictures from you scanner, pictures from your digital camera,
and pictures that you have received and saved from the Internet or from other
Ham SSTV QSOs.
All you need to do this is the freeware available at:-
There you will get a link to download the latest
version of Mokoto Moro’s, JE3HHT’s, software which is called MMSSTV. Even if you don’t intend to transmit
pictures yourself it might be a good idea to be set up to receive them if you
are an HF phone operator. SSTV is
specifically expected to be used at specific phone frequencies. Don’t look for 2 way QSOs on those
frequencies unless you are equipped for SSTV.
The frequencies that are earmarked for SSTV are 3845,
7171, 14230, 14233, 21340 and 28680 MHz.
That gives one frequency for each on 75 meters, 40 meters, 15 meters and
10 meters. On 2 meters 145.5 MHz is used for ham SSTV on space missions. The most activity is on 20 meters, where 2
frequencies have been allocated.
Although some operators don’t like it, it is possible to use other HF
phone frequencies for SSTV if the designated frequencies aren’t available but
most hams wait to use the listed frequencies.
Early users of SSTV had to use surplus CRTs that were
taken from radically scanning radar systems.
These CRTs had a type P7 phosphor which could glow long enough to
display an entire SSTV picture. Green P1
phosphor CRTs used for oscilloscopes, and P4 phosphor TV picture tubes fade too
fast because of there low persistence to be used for SSTV. This is not a problem now that PCs are used because
the pictures are stored in RAM and can be held as long as needed to scan any
picture. The full color capabilities of
the computer can also be used.
Slow scan TV techniques were used in sending TV
pictures to Earth from the first lunar landing.
At that time the slow frame rate of the SSTV was converted to a normal
TV frame rate by using a scan converter on Earth, which would increase the
frame rate by sending each SSTV picture as many times as needed to have the
same frame rate as conventional TV. When
this was done the lunar landing videos could be broadcast for all TV viewers to
view. Although the moving pictures
produced did not flicker when this method was used, the action appeared jerky
because of the initially slow frame rate.
Hams can also transmit conventional TV signals, which
are called Amateur TV (ATV). They must
be on UHF or microwave ham bands. Since
many people now own camcorders and DVD players setting up an ATV station is not
as expensive as it once was. Cable TV
converters and cable ready TV sets are able to tune to some ham channels. When they are fed by an antenna instead of
the cable they can receive the Ham TV signals.
Modulating a UHF ham transmitter is not expensive because the modulator
can utilize the same hardware that is used to convert audio/video from a VCR or
DVD player to produce TV at a TV set antenna input. ATV has had many enthusiasts and has had
publications devoted to it. If
interested, you can find out more by doing a web search.
PRESIDENT’S PAGE
BY
KE2LJ
Last weekend we had some nice weather, and I did some
hiking with XYL Jody (N2OEB) in
Last month I took my Tesla
Coil to the LI Wireless meeting, and did the demo there. It went real well, and
I got a few verbal invitations to do it at some other clubs and societies on
the
With the warm weather here, I
put my tractor/plow back into the shed, and stowed the snow shovels and salt
bags. Sure enough, mid-week, the temperature dropped into the low 40s and we
had snow for about 30 minutes. But, this time of year, it never lasts long. No
shovels needed.
We are also only 2 months
away from our Field Day exercise. Hopefully, we’ll have some volunteers to help
this year. Don’t forget, that I intend to sell my house next Spring (early 2007) and move to
Other than that, there’s not
much new here at the Company. I’m in IT and there are some tight budgets for
some reason. Some early retirements have happened, and people are leaving.
That’s could affect my job situation when I go to
As Bob mentions a few times
in this newsletter, our April meeting will not be at UL, we’ll be at a site in
IMPORTANT:
NOTICE OF CHANGE OF APRIL GARC MEETING LOCATION.
Since
the UL will not be available for the GARC meeting on April 19th,
Jack Cottrell has arranged for the meeting to be held at
Driving
Directions:
From
Sunrise Highway (Rt. 27) turn south on
Also
see GARC website for any possible change.
The location for the May meeting has not yet been determined. Watch for news in the May newsletter or on
the GARC website.
INTERNATIONAL MARCONI DAY
The
Radio Central Amateur Radio Club (RCARC) will again be sponsoring Marconi Day,
which is
PUZZLE
Here is
another cryptogram:
L XF
MSG CGHN FAVGZ AW
X FAVGHO FXQAH-UGOGHXZ,
L’CG LOWAHFXMLAO
CGUGMXJZG XOLFXZ XOV
FLOGHXZ,
L TOAY
MSG TLOUI AW
GOUZXOV, XOV L
PDAMG MSGLH WLUSMI
SLIMAHLEXZ,
WHAF FXHXMSAO
MA YXMGHZAA, LO
AHVGH EXMGUAHLEXZ.
-- Y. I.
ULZJGHM--
Solution
to March’s Cryptogram:
A POET
CAN SURVIVE EVERYTHING BUT A MISPRINT.
–OSCAR WILDE—
[This
was a difficult one. It applies to
careless cryptogram makers as well as poets.]
Page
4
CQ DE WA2LQO APRIL 2005
GRUMMAN AMATEUR RADIO CLUB
MINUTES OF GENERAL MEETING -3/15/2006
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
Two applicants failed Technician exams. 146.745 net not very active.
One applicant upgraded to General. 145.330 repebandplansater is good.
VEs present were AB2NT, KB2QFT, Sunday morning 40-Meter net was poor.
KC2HNN, W2ILP and W2QUV.
NEW BUSINESS:
The
UL will not be available for the next two meetings. Please read the web site or contact other
club members to stay informed about meeting location.
PROGRAM:
Marty,
NN2C, brought a tape of the Braveheart DX Expedition to
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
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.
Page 5
INTERNET LINK OF THE MONTH FOR
INTERNERDS
The internet link for this
month is:- http://www.bandplans.com/index
This is a very useful web
site which gives frequency information for most of the modes now being used by
radio amateurs. If you didn’t find the
frequencies for the digital modes I have discussed here in the newsletter, you
can probably find them by using this site.
There is also information about various net frequencies, which could be
of interest to many of us. For example
there is a new Flying Hams Club net from a newly formed club, which consists
mainly of pilots and hams who are interested in aviation or avionics. I had joined their reflector which is on
Yahoo, after reading about them in QRZ.
This is not the old Flying Hams Club, which was founded by K6BX (sk). Most of these guys are young small aircraft
owners.
It is important to check with
the suggested frequency limits if you operate digital modes. You can start a ruckus if you don’t stay within
in the right frequency ranges. Even W1AW
has recently been strongly criticized for broadcasting on what some hams
believe is a reserved frequency for a differing mode.
ED HARE SPEAKS ABOUT BPL ON
Ed Hare, ARRL Lab Manager, lectured
at a meeting of the EMC Society of the IEEE at BAE Systems in Greenlawn on
April 4th. The meeting was
well attended by engineers and hams, as well as hams who are also
engineers. The subject was the
potential of interference by Broad Band over power lines. The subject was well illustrated by power
point projections that Ed had prepared which were based on FCC and vendor measurements,
as well as his own spectrum analysis. There was an actual video/audio program
of Ed’s mobile HF radio while he drove through BPL areas. BPL has been tested in several areas with
mixed results. There is always some
interference to nearby HF receivers but the range of harmful interference does
seem to differ for different systems. A
“plug –in” system intended for BPL within a single building is quite different
than a BPL system coupled to long overhead power lines. BPL on power main lines is the greatest
source of interference over large areas. Notch filters can be used to reduce
some of the worst interference at specific frequencies. Notch filters are not really component type
filters, although effectively they act as lumped constant filters. They are simply the elimination of specific
carrier frequencies. They cost nothing,
but may reduce the broad band system capabilities somewhat. There were no engineers present to represent
either BPL vendors or power companies.
Thus there was no heated debate.
The Part 15 FCC regulations that apply to BPL specify recommended
limits, however if the limits are exceeded there may be no FCC action taken
unless the interference proves to be harmful.
As we had seen when RF field strength measurements had to be taken to
apply radiation hazard limits it is very difficult to accurately measure
electric and magnetic fields at HF frequencies because of antenna near field radiating
characteristics and ground reflections.
Many vendor measurements were taken only one meter above the
ground. Hams who operate from a fixed
location may file complaints against BPL, but mobile ham operators may simply
be asked not to operate in areas where interference is excessive. In other words, if no harm can be proved no
action may be taken. The meeting was
enjoyable as was the pizza and soda that was served. There is a great deal of recognition between
well known engineers and well known hams on Long Island and the informal
chatter after the meeting was enjoyed by all, just as much as the expert
technical questions posed to Ed Hare, who responded with a good sense of humor.
Although many hams have sent e-mails
about BPL interference probabilities to the head of LIPA, it is believed that
BPL testing will begin in Hauppauge in the near future.
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
Treasurer Ed Gellender WB2EAV X02-14
516-575-0013
1Yr Board Member Zack Zilavy WB2PUE Retiree
631-667-4628
1YrBoard Member Dave Ledo
AB2EF
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
This being April, I had considered making this
newsletter an April Fool’s edition. I
decided not to do so. I have to stick to
real facts here. Any fooling around here
has to be done on a non-intentional basis….purely accidental. Anyway one man’s foolishness might be another
mans hobby, and vice versa.
As you can see in the box to the right of
here, the GARC VE sessions will now be given in room:
The GARC has had a long
tradition of holding VE exams on the second Tuesday of each month and club
meetings on the third Wednesday of each month.
We must thank Jack WA2PYK and Pat
KE2LJ for their efforts in finding a meeting place for this month. It wasn’t
easy. Our speaker at the April meeting
will be Frank Fallon, N2FF, ARRL Hudson Division Director.
73,
W2ILP (Intentionally Limiting
Philosophies)
CQ de WA2LQO
April 2006
VOL. 79,
NO. 4
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
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 so as to conferm location, 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.
TECHNICAL
BITS
Early
hams built only CW transmitters but when radiotelephony was being developed
hams began to build Amplitude Modulated (AM) transmitters. Phone operation
required getting a Class A License, which later became the Advanced Class. The basic CW ham license then became a Class
B license, and later a General Class license.
The
most common way to produce AM was to plate modulate the transmitter’s final RF
power amplifier. This required an audio
voltage amplifier to increase the output of a microphone and drive a power modulator. The modulator was thus a high powered audio
amplifier. If the DC plate input of the
final was a kilowatt, then to get 100% modulation the modulator would have to
produce about 500 watts of audio output.
Care would have to be taken so as not to overdrive because if the
modulation exceeded 100% this would lead to both audio distortion and spurious
RF output. The modulator usually was a
push-pull circuit using two power amplifier tubes. These tubes operated in Class B, which means
that each tube amplified half of the audio wave form. The final RF amplifier could operate in Class
C, which means it only needed to amplify half of the RF wave. The RF tank circuit would act as a sort of a
flywheel, causing the wave to become nearly sinusoidal. This method of AM plate modulation is known
as high level modulation. Later methods
permitted modulating the RF section of transmitters at an early stage and thus
not requiring as much audio power as final plate modulation. Hams experimented with other modulation
methods which were sometimes advantageous.
If the RF final amplifier was a pentode or tetrode tube, l screen modulation
could be used.