Setting up an SSTV Station

In the past, an Amateur Radio Operator operator needed to have dedicated and expensive equipment to be able to transmit and receive SSTV pictures using his amateur radio transceiver.

But with the advent of the personal computer, it has become very easy to get on the air using this mode of transmission and reception.

Here are the things that you need to have and the steps to take to get going on SSTV - either Digital or Analogue. As a matter of fact these same steps apply when you are setting up your station for RTTY or PSK.

What do I need:-

1: An HF SSB Transceiver

Any HF SSB transceiver with associated antenna and hardware, capable of transmitting a stable, clean, drift free signal on any HF band. Most modern solid state transceivers fit into this category easily. The use of older tube type HF transceivers is not encouraged , but can be made to work.

SSTV is a FULL DUTY CYCLE ( Continuous Key Down) mode. Some HF transceivers are capable of such operation. Check your transceiver specifications. If your transceiver cannot handle FULL DUTY CYCLE operations, you can still use it for SSTV by reducing the power output to approximately half of the rated RF power output when transmitting.

2: A Personal Computer

There are many factors you'll need to look at before forking out your hard-earned cash for a computer. Things like CPU, memory, hard disk space, sound cards are essential factors to consider when selecting the system. This is an exhaustive subject , so will only list some of the key considerations.

What do you intend to use the computer for.

If it is for general applications like word processing, checking E-Mail, etc. then look for a cheap model. If you intend to use the system at home, you may want a more well-rounded PC that can handle multimedia applications and web surfing easily. If you want to play games, you'll need something with a fast processor,lots of RAM, a large hard drive, and good sound and graphics cards. If you're using the computer for professional or business purposes, you will want to get the latest models available, factoring in stability and service support in your decision.

Where will it be used.

If you need to take it all over the place, you'll need a laptop. If you intend to leave it in the office or at home on the desk, then buy a desktop.

Who is going to use it?

If it's for an office or a home with multiple users, you might need one with more memory, hard disk space, better video/sound hardware and the latest Windows operating system. If you will be the only one using it, and mostly for general applications, then Windows XP, Windows 7 Home Premium or Vista Home Basic will serve you well.

What is the cost.

You'll certainly need to consider your budget when selecting a PC. Low-end budget systems will save you lots of money and are suitable for most home users. High-end systems with the latest Athlon 64 or Intel Pentium 4 processors will cost more and be more suitable for business environments, those who want to play the latest 3D games or do heavy video or graphics editing.

What software will you use.

Check the hardware requirement specifications for the software packages you will be using and make sure that you purchase a PC with better specifications than required.

From an Amateur Radio perspective.

Since most Amateurs purchase computers for multiple purposes including using them for amateur operations like keeping LogBooks and transmitting and receiving SSTV - RTTY - PSK signals, a middle end PC with a 3 Ghz CPU - not less than 2 Mb RAM - good Sound/Video hardware - large hard drive and at least the Windows XP operating system would be the best compromise. For SSTV operations, where you will be using Photo Editing software along with other applications, the more memory you can install - the better. Photos can and do take up a lot of space on the hard drive. So again, the bigger the hard drive - the better.

It is important to ensure that your PC has either Serial (COM) or USB ports as these will be needed.

Of course you can purchase the latest hardware with the latest operating system if you can afford it or want to. You may or may not experience problems with the installation of Amateur Radio software with the latest operating system. Some Amateur Radio software was written for the Windows XP platform and will not work with later platforms like Vista and Win 7.

For help in selecting/purchasing a PC, see this Article.

3: A Soundcard Interface.

The soundcard interface is the unit that enables you to:-

Send audio from the computer to the radio to be transmitted.

Receive audio from the transceiver for decoding.

Puts the radio into transmit when you ready to send (PTT).

 

There are many commercially made interfaces on the market at present. Two popular units on the market are the Rig Blaster and SignaLink USB.The best interfaces uses circuitry that isolates the Computer from the Transceiver.

The interface that I presently use was built entirely from junk box parts. The isolation transformers were salvaged from old Dial Up computer modems. Look here for a PHOTO of that unit and here for the Schematic diagram. I made generous use of toroids on all lines of the interface. With this unit, I work the following modes - RTTY - PSK - SSTV - MFSK - CW and it has performed flawlessly for the last 5 years.

If you want to receive pictures only, the simple circuit shown below, which is easy to build, will work great.

Interface

 

If you would like to try your hand at constructing an interface, see W2MU's excellent page on soundcard interfacing.

4: Software for sending and receiving pictures

You will download and install the appropriate software depending on which mode you want to use. Most of these programs are free for use by all Amateur Radio Operators. Make sure that the programs you want to use can work with the operating system that you have installed on the computer.

All of the programs listed below should work with one or more of the following operating systems.

Windows 2000 - Windows XP - Windows Vista - Windows 7

Read the instructions for installing each program and follow them carefully.

A good rule of thumb to follow :-

When installing these programs under Windows 2000 or XP - Install to C:\Program Files\xxxx\ directory.

When installing under Windows Vista or Win7 - Install to C:\xxxx\ directory.

Some problems have been reported by Win 7 and Vista users when they have installed these programs to the C:\Program Files\xxxx\ directory.

Here is a list of the most popular programs in use

For Digital SSTV ( DRM ) - Download the EasyPal Program

For Digital SSTV (Not DRM) - Download the KG-STV Program

For Analogue SSTV - Download the MMSTV Program

For Analogue SSTV - Download the Ham Radio Deluxe Program

For Analogue SSTV - Download the Mix-W Program (Not Free)

 

5: Putting it all together

Audio output from Transceiver. (RX Audio)

It is recommended that you take the audio output from the accessory jack on the rear. This is usually a fixed level output and does not vary when you adjust the AF level control.

You can also take the audio output from the headphone/speaker jack. The only drawback to this method is that the level varies with the adjustment of the AF level control. If you use this method, try to keep the AF level control at a fixed spot which does not overdrive the sound card Input and allows you to hear any traffic on the frequency.

Audio output to the Transceiver. (Xmit Audio)

Again it is recommended that transmit audio be inserted into the radio via the accessory jack on the rear. If this is not possible then use the microphone jack on the front of the transceiver.

P.T.T

Connect the PTT line from the interface to correct pin on either the Accessory jack or the Microphone jack.
Then connect the interface to the computer via the COM or USB port.

Connections as follows:-

Cable Hookup

Audio output line from Radio to the Interface then to Soundcard Line Input on Computer ( Accessory jack)

Soundcard Line Output from Computer to the Interface then to Audio Input of Radio. (Mic. or accessory jack )

PTT Line from the Interface to PTT of Radio (Mic or accessory jack)

Interface connected to computer via serial (COM) or USB port

These are all the connections that are necessary. Always double check to make sure your connections are correct, as incorrect connections could do damage to your transceiver

Have a look at W2MU's page for pinouts of various radios. Your Transceiver manual will be an invaluable aid in figuring out the right pins to connect.

Very Important :- Make sure that your Microphone is muted when you you transmit SSTV or PSK. Some interfaces already incorporate this feature. You can disconnect the microphone each time you transmit (a real PITA) or build a microphone disconnect circuit using a relay to do the job automatically when PTT is asserted.

I have made all my connections to the accessory jack on the back of my FT-950 transceiver . It automatically mutes the microphone when I start to transmit pictures.

Software/Program Setup

Now, turn to your computer and set-up the software as necessary. Follow the instructions carefully for installing the software. Once installed correctly, start the program. Enter callsign and other personal information - Select the correct soundcard - Select the COM port number which will be used for PTT - Select the correct options for the mode you intend to use.

Now you are ready to receive and send pictures.

It is always best practice to try to receive pictures before you transmit any. This gives you a chance to see the program in operation and to play around with it. These settings will vary with the program in use. If you do not understand how to setup the software properly, Please read the help files or ask another Amateur Radio Operator for help. They will gladly assist you.

6: Adjustment of your transceiver

It is important that you adjust your transceiver correctly to avoid any problems.

For reception of pictures, your transceiver should set in the USB mode with a bandwidth of 2.4 Khz. Turn OFF all filters - Noise Reduction filter, Noise Blanker, Notch Filter etc. The use of these filters affects the reception of pictures.

For transmission of pictures, your transceiver should set in the USB mode with a bandwidth of 2.4 Khz. Turn OFF Speech Processors - Compressors - Equalizers etc. The use of these will affect the quality of your transmitted signal and the receiving station may have difficulty to decode your pictures.

Next, adjust the ALC level as set out below:-

For Digital DRM picture transmissions with EasyPal - Little or no ALC is the proper setting

For Digital SSTV picture transmissions with KG-STV - You can have ALC but it must not be excessive

For SSTV picture transmissions with MMSSTV - ALC allowed but not excessive

For SSTV picture transmissions with Ham Radio Deluxe - ALC allowed but not excessive

For SSTV picture transmissions with Mix-W - ALC allowed but not excessive

The ALC adjustment is the most important adjustment that you have to make to ensure you transmit a clean signal.

The way to get the right ALC setting is by adjusting the Sound Card Line Output Level with either the Windows Mixer or the Output Level control on the interface (If there is one).

Remember........... SSTV IS FULL DUTY CYCLE
So if your rig runs 100 watts on ssb, then reduce the audio output from the computer sound card so that your transceiver shows about 50 watts output or less.

Don't use the audio speech processor, turn it OFF.

7: Operating Frequencies

These are the most popular frequencies used for SSTV QSO's
3.845 Mhz
7.173 Mhz (Popular)
14.230 Mhz (Popular- Analogue)
14.233 Mhz (Popular- DRM - Easypal)
21.340 Mhz
28.680 Mhz
145.5 MHz

8: SSTV Edict by VA3MOD

Remember - A picture is worth a thousand words. Many people may be receiving the pictures you send.

1. Before starting to TX a picture on a frequency, ask in PHONE " Is this frequency in use? " Never transmit if you hear any other signals.

2. Never interrupt a SSTV QSO by sending a picture. See #1

3. The suggested spacing for SSTV frequencies is 3kHz.

4. Don't hesitate to help/correct station operators who do not use the right operating procedure. They may not even be aware of it.

5. Try to be original in your pictures! Station related pictures (shack, antennas, QTH, area, family etc) make SSTV really attractive! Please don't transmit pictures containing porno, politics, commercials etc.

6. SSTV is a lot more than a picture. Take time to talk about your pictures between sending. Give out comments about the pictures that you receive.

7. Before you transmit your picture, ask the receiving station if they are ready.

8. When you would like to answer to a CQ, first ask the CQ'ing station in PHONE if they are ready for your picture.

9. 20 meters is really overcrowded (and not only with SSTV!). Try the higher bands.

Now go have as much fun as I have had sending and receiving pictures.

Resources

There are many SSTV resource sites available on the WEB that have a ton of information. You can just Google the word SSTV and a number of sites should pop up.

I will mention a few of them here.

KB4YZ ---- W3WVG ---- G4ZER --- KC1CS ---- VA3MOD ---- N4UJW

G0HWC SSTV INFO

Contains a wealth of information.

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