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VK7AX > SSTV 25.07.08 04:39l 384 Lines 14932 Bytes #999 (0) @ WW
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To : SSTV@WW
There are 7 messages in this issue.
Topics in this digest:
1. MMSSTV and SiglaLink USB
From: carl.linda
2a. Re: SSTV ANTENNA AND FREQUENCY BAND
From: David Ackrill
2b. Re: SSTV ANTENNA AND FREQUENCY BAND
From: sid.adeel
2c. Re: SSTV ANTENNA AND FREQUENCY BAND
From: Master Ice
2d. Re: SSTV ANTENNA AND FREQUENCY BAND
From: David Ackrill
2e. Re: SSTV ANTENNA AND FREQUENCY BAND
From: David Ackrill
3a. Re: SSTV Satellites
From: David Ackrill
Messages
_____________________________________________________________________
1. MMSSTV and SiglaLink USB
Posted by: "carl.linda" carl.linda(AT)yahoo.com carl.linda
Date: Wed Jul 23, 2008 10:38 am ((PDT))
Still need help getting my MMSSTV program to receive. See message 8289.
No solution yet. I have a TS-440S to a SignaLink to a computer
running MMSSTV. Need help from MMSSTV users who use the SignaLink USB
with built-in soundcard.
Thanks and 73,
Carl
Messages in this topic (1)
________________________________________________________________________
________________________________________________________________________
2a. Re: SSTV ANTENNA AND FREQUENCY BAND
Posted by: "David Ackrill" dave.g0dja(AT)tiscali.co.uk g0dja
Date: Wed Jul 23, 2008 12:31 pm ((PDT))
sid.adeel wrote:
> > No Dave am interested in receiving single pictures sent over the
> > Amateur Radio bands.
> > And waiting for good Antenna description from technically sound people
> > like you.
> > Regards
OK Adeel,
When you said "F band" I wondered if you meant the F type plugs on the
satellite receivers.
For HF the simplest antennas are usually half wave dipoles. You can
connect several together to make a multi-band dipole, see
http://www.hamuniverse.com/multidipole.html for details.
The most active band is 20M (14MHz) and, if you only put up one antenna
to start with, I would suggest that this is a good band because there is
usually a lot of stations using it. Most SSTV activity is on 14.230MHz
using Upper Sideband (USB).
When you have MM-SSTV installed, I would suggest calibrating your PC
soundcard, using the following method.
Tune your radio to WWV on 10MHz (or any of the other WWV transmissions
if you cannot hear the 10MHz transmission. Even with a dipole for 20M
you should be able to hear something.)
1 Go to "Option" and then "MMSSTV Setup"
2 Select the "Misc" tab and push "Adj" button near the bottom left
3 Select full screen for best resolution. The screen should be mostly
all black to start..
4 Right clicking the screen anywhere near the white line will put a
green dotted line to help with the alignment .
5 Single click on the very bottom of the line and then again at the very
top of the line. The dialog box should close and a new clock number will
be set.
That will set your soundcard up for receiving.
Dave (G0DJA)
Messages in this topic (12)
________________________________________________________________________
2b. Re: SSTV ANTENNA AND FREQUENCY BAND
Posted by: "sid.adeel" sid.adeel(AT)yahoo.com sid.adeel
Date: Wed Jul 23, 2008 10:56 pm ((PDT))
Thanks a lot david
any SSTV Satellite in VHF or UHF band?
(Asking for reduce antenna size :P)
Hope I will start practical work for SSTV reception soon
Regards
Adeel
--- In MM-SSTV(AT)yahoogroups.com, David Ackrill <dave.g0dja(AT)...> wrote:
> >
> > sid.adeel wrote:
>> > > No Dave am interested in receiving single pictures sent over the
>> > > Amateur Radio bands.
>> > > And waiting for good Antenna description from technically sound people
>> > > like you.
>> > > Regards
> >
> > OK Adeel,
> >
> > When you said "F band" I wondered if you meant the F type plugs on the
> > satellite receivers.
> >
> > For HF the simplest antennas are usually half wave dipoles. You can
> > connect several together to make a multi-band dipole, see
> > http://www.hamuniverse.com/multidipole.html for details.
> >
> > The most active band is 20M (14MHz) and, if you only put up one antenna
> > to start with, I would suggest that this is a good band because
there is
> > usually a lot of stations using it. Most SSTV activity is on 14.230MHz
> > using Upper Sideband (USB).
> >
> > When you have MM-SSTV installed, I would suggest calibrating your PC
> > soundcard, using the following method.
> >
> > Tune your radio to WWV on 10MHz (or any of the other WWV transmissions
> > if you cannot hear the 10MHz transmission. Even with a dipole for 20M
> > you should be able to hear something.)
> >
> > 1 Go to "Option" and then "MMSSTV Setup"
> > 2 Select the "Misc" tab and push "Adj" button near the bottom left
> > 3 Select full screen for best resolution. The screen should be mostly
> > all black to start..
> > 4 Right clicking the screen anywhere near the white line will put a
> > green dotted line to help with the alignment .
> > 5 Single click on the very bottom of the line and then again at the
very
> > top of the line. The dialog box should close and a new clock number
will
> > be set.
> >
> > That will set your soundcard up for receiving.
> >
> > Dave (G0DJA)
> >
Messages in this topic (12)
________________________________________________________________________
2c. Re: SSTV ANTENNA AND FREQUENCY BAND
Posted by: "Master Ice" special(AT)ilizarov.org.uk koyaanisqatsiuk
Date: Thu Jul 24, 2008 4:28 am ((PDT))
Adeel.
As some have already said sstv is mostly on the HF bands and not via
any ham satellite.
As for antennas why not refer to the myriad of good publications by
the ARRL, RSGB et al on the subject?
You could also Google for 'antenna design' on the internet and get
millions of possibilities.
For HF I use a simple long wire for both RX and TX and that works just
fine.
And in the UK on VHF I've never heard a single sstvstation !
Slim G4IPZ
--- In MM-SSTV(AT)yahoogroups.com, "sid.adeel" <sid.adeel(AT)...> wrote:
> >
> > Thanks a lot david
> > any SSTV Satellite in VHF or UHF band?
> > (Asking for reduce antenna size :P)
> > Hope I will start practical work for SSTV reception soon
> > Regards
> > Adeel
Messages in this topic (12)
________________________________________________________________________
2d. Re: SSTV ANTENNA AND FREQUENCY BAND
Posted by: "David Ackrill" dave.g0dja(AT)tiscali.co.uk g0dja
Date: Thu Jul 24, 2008 4:29 am ((PDT))
sid.adeel wrote:
> > Thanks a lot david
> > any SSTV Satellite in VHF or UHF band?
> > (Asking for reduce antenna size :P)
> > Hope I will start practical work for SSTV reception soon
> > Regards
Although the frequencies used by Amateur band satellites are higher, and
the wavelength smaller, which means a half wave dipole for thse bands
are smaller, there are some problems that you will need to read up on
before you start. The following is a very short explanation, please go
to the AMSAT website and read up on how to operate through, or listen
to, signals from Amateur satellites... You might also want to sign up
to a forum that discusses Amateur Satellites to make arrangements to
listen for stations when there is an Amateur satellite in range. This
is another long email from me, on a subject which is only slightly
linked to MM-SSTV, so I hope other people on here will excuse my long
reply again!
1st - Amateur satellites do not 'stop in one location' like TV
satellites appear to do. Although TV satellites *are* moving, they are
in an orbit where they appear, from Earth, to stay in one place. This
means you point a satellite antenna (usually a dish) at one, and you
receive signals. Amateur satellites do not work in this way. They are
in orbits that take them round the Earth. Like the International Space
Sation, they appear to 'fly over' every so many minutes.
2nd - Amateur satellites do not fly over at the same time, nor do they
appear to be in the same place in the sky, every day. You need to use
some way to predict when the satellite will be in range. There are many
computer programs to let you see when the next 'pass' for a particular
satellite will be near to you. One of the better ones, in my opinion,
is Heavens Above. This is free and available at
http://www.heavens-above.com/
3rd - When you have a prediction system, you must keep the variable
figures (known as Kepler elements) up to date or your predictions for
when the satellites will come over will not be correct.
Next, looking at receiving the signals. The 'pass' of an Amateur
satellite may be as short as a couple of minutes up to 15 or 20 minutes,
depending on whether you have hills or buildings in the way and how
'high' above the horizon the satellite will appear to be as it comes
over you. So, for modes like SSTV, you are taking a chance that a)
another SSTV station is on and b) that you both have enough time to send
and receive pictures before the satellite disapears out of your view.
SSTV pictures will not appear to be very good if the signal you receive
is small and there is interference on the signals. They really need
good signal to noise ratios to get reasonable looking results. That then
means that you may want to have a better antenna than a simple dipole on
VHF or UHF, because the signals you get from the satellite may be small.
One way to increase the signals from the satellites is to use an
antenna that is said to have 'gain'. On VHF/UHF these often look like
normal TV antennas and are called Yagi-Uda arrays, or just 'Yagis' for
short. The problem with a Yagi on satellites is that it picks up
signals in a smaller area than a dipole, so you have to keep it pointing
at the satellite. Some people do this by hand, but some people get a
rotator (but even better is two rotators - One to move the antenna
horizontally, the other vertically) and to connect them to a PC to get a
program to point the antenna at the satellite and to track it as it flys
over. These types of rotator are not cheap!
The next problem is something called dopler shift. If you hear a police
car or ambulance with its siren on coming towards you from the distance,
as it comes the noise of the siren seems to change, as it goes by you
will hear the sound change again, and it makes a different sound as it
goes away. This is called Doppler shift. It also affects radio signals
and, as the satellite comes towards you, you have to tune your radio
away from the frequency that the satellite is transmitting on in one
direction, and as it goes away, you have to tune in the other direction.
Only when the satellite is right above you will it appear to be on the
correct frequency and only for a very short time. Again, some people
use computer programs, connected to their radios by a CAT (Computer
Aided Transceive) connection. Some older radios, especially for VHF/UHF
only, do not have a CAT system built in.
For an FM signal, Dopler shift may not be too much of a problem, but on
SSB it is and, if you do not make allowances, the signals will be
distorted and the picture will not look as good as it should. Also,
some Amateur satellites use one frequency to send signals to Earth, and
another to receive signals from Earth. Often these frequencies are on
different bands, perhaps 432MHz up and 144MHz down. That means you need
two antennas, one for each band, and either two radios or a radio that
you can set up to transmit on one band and receive on another.
As I say, applogies for the long reply, but there is a lot to think
about when using Amateur satellites and, you may find that there are not
very many stations sending SSTV through the satellites. If you have not
used SSTV before, it might be better to put up a simple 20M halfwave
dipole (even if it is indoors) and to start to receive pictures on HF.
Then, if you want to try Amateur satellites, read up on how they operate
and find out when they will be coming over your area each day and then
listen for signals to see if there is much SSTV activity on the satellites.
Dave (G0DJA)
Messages in this topic (12)
________________________________________________________________________
2e. Re: SSTV ANTENNA AND FREQUENCY BAND
Posted by: "David Ackrill" dave.g0dja(AT)tiscali.co.uk g0dja
Date: Thu Jul 24, 2008 8:18 am ((PDT))
Master Ice wrote:
> > And in the UK on VHF I've never heard a single sstvstation !
> >
> > Slim G4IPZ
Round here there is activity on 144.525 and 144.550Mhz using FM most
weekends, plus some SSB at times.
It depends on which part of the country you are in, I guess?
Dave (G0DJA)
Messages in this topic (12)
________________________________________________________________________
________________________________________________________________________
3a. Re: SSTV Satellites
Posted by: "David Ackrill" dave.g0dja(AT)tiscali.co.uk g0dja
Date: Wed Jul 23, 2008 12:32 pm ((PDT))
sid.adeel wrote:
> > What are the satellites providing SSTV images for amateur?
> > I only know about
> > AO-10(145.940 Mhz USB for receive),FO-20 and FO-29 (435.880 USB for
> > receive) SuitSat(145MHz)
> >
Suitsat was only operating for a short time. It was an old space suit
onto which a camera and transmitter was attached, and pushed out into
space. For details see
http://science.nasa.gov/headlines/y2006/26jan_suitsat.htm
For other Amateur Satellites, try AMSAT (Amateur Satellite club) at
http://www.amsat.org
APD is a data transmission, based on Packet (AX.25) and it is just a
series of numbers, which can be decoded to give details of various
readings on a satellite. Like this example given by the Laboratory for
Space Systems, Department of Mechano-Aerospace Engineering, Tokyo
Institute of Technology.
4A-51-31-59-54-43-3E-4A-51-31-59-43-5A-3A-D0-30-77-B8-03-16-99
According to an above APD status packet we can obtain information as;
4A-51-31-59-54-43-3E-4A-51-31-59-43-5A-3A : Header(JQ1YTC>JQ1YCZ)
D0 : APD Packet ID (Fixed)
30 : Status Code
APD Status : Operational
HV Status : Set Value = Output Value
Temp Correction : Active
Data Mode : Counter Valid
Detector : APD A
APD Gain : Gain 30
Threshold : 219mV
77 : Temperature
0x77 = 119 -> (119/255)*91.712-48.569 = -5.7 [degC]
B8 : High Voltage
0xB8 = 184 -> (184/255)*396.5 = 286 [V]
03-16-99 : Counter
0x1699 = 5785 -> 5785 * 23 = 46280
Hope this helps explain the difference between SSTV (pictures converted
into a code and decoded back into a picture) and APD.
Regards - Dave (G0DJA)
Messages in this topic (2)
------------------------------------------------------------------------
*******************************************************************
ABOVE IS A CROSS POST TO THE PACKET RADIO NETWORK IN AN EFFORT TO
PROMOTE FURTHER INTEREST IN SLOW SCAN TELEVISION AND PACKET RADIO
Courtesy Tony VK7AX VK7AX(AT)VK7AX.#ULV.TAS.AUS.OC
*******************************************************************
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