Low power (QRP) Slow Scan Television, SSTV, is another mode that I enjoy using. This mode allows an amateur to send and receive video pictures worldwide via 2 way radio on the HF ham bands. The video quality of the
pictures can be quite impressive.

Most slow scan pictures are transmitted and received using a home computer and suitable software. The computer is then interfaced to the radio equipment. The picture is transmitted as a series of tones and is received and displayed on the computer screen on the other end. Software for SSTV is abundant and can be found as "Freeware" or "Shareware", so you don't have to spend a lot of money to become involved with this mode.

The SSTV modes Martin 1 and Scottie 1 are the most commonly used modes.

         SSTV Transmission Modes
   Mode         Mode    Color   Time    Scan    
   Family       Name    Type    (sec)   Lines   Notes
   ------       ----    ----    -----   -----   -----
   AVT          24      RBG     24      120     d
                90      RGB     90      240     d
                94      RGB     94      200     d
                188     RGB     188     400     d
                125     BW      125     400     d

   Martin       M1      RGB     114     240     b
                M2      RGB     58      240     b
                M3      RGB     57      120     c
                M4      RGB     29      120     c
                HQ1     YC      90      240
                HQ2     YC      112     240

   Pasokon TV   P3      RGB     203     16+480
   High         P5      RGB     305     16+480
   Resolution   P7      RGB     406     16+480

   PD           PD 240  YC      248     480
                PD 180  YC      187     480
                PD 160  YC      161     384
                PD 120  YC      126     480
                PD 90   YC      90      240

   Robot        8       BW      8       120     a, e
                12      BW      12      120     e
                24      BW      24      240     e
                36      BW      36      240     e

                12      YC      12      120     
                24      YC      24      120
                36      YC      36      240
                72      YC      72      240

   Scottie      S1      RGB     110     240     b
                S2      RGB     71      240     b
                S3      RGB     55      120     c
                S4      RGB     36      120     c
                DX      RGB     269     240     b

   Wraase SC-1  24      RGB     24      120     c
                48      RGB     48      240     b
                96      RGB     96      240     b

   Wraase SC-2  30      RGB     30      128
                60      RGB     60      256
                120     RGB     120     256
                180     RGB     180     256

There are also some experimental modes implemented in only
one or two systems.  Some are still evolving, some will be
phased out.  Information here might not be accurate.  Whether 
others decide to add them remains to be seen.

   ProSkan      J120    RGB     120     240

   WinPixPro    GVA 125 BW      125     480     
                GVA 125 RGB     125     240
                GVA 250 RGB     250     480

   "J.A."       ?       ?       ?       480

   MSCAN        TV1     ?       ?       ?
                TV2     ?       ?       ?

Color Type:

RGB - Red, Green, and Blue components sent separately.
YC - Sent as Luminance (Y) and Chrominance (R-Y and B-Y).
BW - Black and White.


a - Similar to original 8 second black & white standard.
b - Top 16 lines are gray scale.  240 usable lines.
c - Top 8 lines are gray scale.  120 usable lines.
d - AVT modes have a 5 second digital header and no
    horizontal sync.
e - Robot 1200C doesn't really have B&W mode but it can send 
    red, green, or blue memory separately.  Traditionally, 
    just the green component is sent for a rough approximation
    of a B&W image. (Courtesy John Langner)

HF SSTV Frequencies

  • 3.845 MHz

  • 3.857 MHz

  • 7.171 MHz

  • 14.230 MHz

  • 14.233 MHz

  • 21.340 MHz

  • 28.680 MHz

  • Software is available for DOS as well as Windows. Some of the programs available use a simple RS-232 interface to interface the computer to the radio. Other programs can use a computer's sound card. I use a homebrew RS-232 Interface myself. I have made up my own design for a printed circuit board layout, as well as a parts list and parts placement diagram for a popular RS-232 interface called a HAMCOMM modem. This modem is compatible with several different computer programs.

    *Note This circuit board layout is to be used for non-profit amateur radio use only!

    The schematic for this modem can be found by downloading a DOS program called "Hamcomm", a CW, RTTY and AMTOR program and installing it on your computer.The schematic is located in the manual documentation.

    My favorite SSTV program is a DOS program called "Pasokon Lite". There is also a "Freeware" version of this program called "EZSSTV". It is well worth paying the small fee to obtain the full functioning version of this software. It has a lot of nice features.




    Have a look at the links below!


    Slow Scan Links


    Try Listening To Some.....

    Weather Fax (Wefax) Satellite Image Frequencies

    NOAA-14 transmits APT on 137.620 MHz
    NOAA-12 and 15 transmit APT on 137.500 MHz
    NOAAs transmit beacon data on 137.85 MHz when in sunlight
    RESURS-O (1-4) transmits APT on 137.300 MHz
    OKEAN-4 and SICH-1 sometimes transmit briefly on 137.400 MHz
    GOES-E and GOES-W use 1691.0 MHz for WEFAX

    For the reception of WEFAX pictures I use a Windows computer program called WXSat. This is a FREEWARE program that decodes the weather pictures using your computer's sound card. Audio from the receiver is fed into the line input of the sound card. I use a 14 element cross-yagi antenna with a modified Systcoms radio.


    Below are a couple of images received from the NOAA weather satellites.
    These images are just a small portion of a continuous "strip" of data sent.

    Image received using WXSat WEFAX Software and modified Systcoms radio.


    This image also received using WXSat WEFAX Software and modified Systcoms radio.





    Send mail to VA6CW


    I occasionally work SSTV on 21.340 MHz, 14.230 MHz, and 14.233 MHz - 73, VE6BPR