2007 HamVention - SSTV Forum Presentation

Presentation by Dave Jones - KB4YZ


Operating Digital Radio Mondiale (DRM) with EasyPal Lite Software






I will be reviewing the 8 April version of EasyPal Lite - Beta.

EasyPal Lite is the work of Erik VK4AES from Australia. Erik has discontinued work on his HamPal program and is now working on the new EasyPal Lite. This software uses the DRM (Digital Radio Mondiale) encoding to allow the sending of image files over an HF voice channel. This is known as Digital SSTV.

The GUI was written with Delphi and compiled on a Windows Vista system. It works best when run on a two GHz or faster CPU with Windows Vista. Although less stable, it should run on most fast PC's with Windows XP. It is designed to be easy to setup and use. Keep in mind that it is still in beta testing.





Links for downloading the latest version are available at this URL: http://kb4yz.ham.org

The download is a two MB ZIP file that contains only one file: "EasyPal_Lite.exe". This file should be placed into it's own folder and a shortcut to it should be put on the desktop.

Help from other users is available from the Yahoo Groups newsgroup Here is the URL: http://groups.yahoo.com/group/digsstv

Setup - Use this drop down menu to make your selections for Callsign, Soundcard, and CommPort.





The setup for CommPort includes options for "FAC Green". Using an external circuit, this option can be used to mute the speaker while receiving the digital signal.

It is recommended that you close the program and re-start after setting up or making changes to the soundcard settings.





EasyPal Lite normally runs in a window that is 925x566. The user may optionally select the "Expanded GUI" which will resize the window to fill out the available space on screen.

Here is the normal window size.





HiRes - Allows loading of images larger than 640x480 and keeping the original size when converting to JPEG2000.

Send Text - Turns the TX window into a text editor for the sending of text. Text may be typed, pasted, and edited prior to transmitting.



Callsign - The callsign of a transmitting station will appear in the upper left corner while receiving an DRM transmission.

RX input bargraph - There will be more green in this area with increasing audio amplitude.

Signal Quality bargraph - There will be more green in this area with increased signal quality.

Total - "Total" is the number of segments in the image file being received.

OK Segments - "OK Segments" is the number of segments successfully decoded so far.

Position - "Position" is the segment number that was last decoded.

Missing Segments - This is the number of segments that still need to be received.

TX - The inital DRM Mode is Mode B, Bandwidth 2.5 KHz, Error Protect HI, QAM 16, and LeadIn 24. These settings are the best choices for general use on the HF bands.

To make changes, place mouse pointer over the name of the setting and click the mouse to toggle through the available choices. Any changes to the mode are saved for future sessions when the program is closed.

RX - Is for the DRM mode received. FAC must be green before the mode can be detected and the callsign decoded. In addition to those mode settings that may be changed on transmit, the RX will also reveal the interleave setting. Lng for long and Sht for short. The receive mode settings are automatic and do not require the operator to make any changes for receiving any DRM mode.

Red/green bars: Green light by "IO" indicates Soundcard is active. Green light by Time - Time Sync locked Frame - Frame Sync locked FAC - FAC locked (Fast Access Channel) MSC - MSC locked (Main Service Channel)

Data cannot be decoded until the MSC has a lock. So the MSC must be green before you will be able to copy anything.

TRANSMIT - Starts the transmission of the DRM encoded picture file.

BSR - "Bad Segment Report" Starts the transmission of a short text file that lists the segment numbers that were missing on the last received file.

The type of BSR sent is a bit different from the BSR format used in the past. It is called a "Fast BSR" because it uses a form of shorthand to reduce the size of the BSR transmission.

One drawback to the use of the new "Fast BSR" is that older programs such as HamPal may not recognize all the segments required and if there are many, HamPal may only be able to send fixes for two or three segments at a time. This is only a problem when pictures are sent from HamPal to EasyPal Lite.



FIX - After receiving an BSR, a message will appear in the title bar.

If there is no message in the title bar and you got the BSR File OK, and you think that you should be able to send the FIX, go ahead and try to send the FIX anyway. It may work!

If you load another image before you receive the BSR, here is no need to reload the previous image to fix someone.

ABORT - Allows for stopping a picture, BSR, or FIX transmission.

Encode - This encodes the transmitted file with redundant data so that the original file may be created even though not all segments were received. Click to enable.

The Encode uses Reed-Solomon error correction and interleaved redundancy.

Encode changes the extension of the filename sent to .rs plus a number, one through four. Transmission time will be increased by 13% for Encode1. Encode4 will increase the transmission time by 86%.

Use of Encode may reduce the need for BSR's and FIX'es. It compatable only with others running EasyPal Lite.

A stand alone decode program is available from my web page that will allow those not using EasyPal Lite to decode the .rs files manually.

ProgRX - (Progressive Receive) Check to enable viewing the image as it is coming in. Using Progressive RX may increase the chance of program lock-up or other errors.

Replay RX - This will immediately replay the file just received. It will be the same file as the original and the same name.

If the replay is transmitted in the same DRM mode as received, it will also repair any stations that still need segments.

When there are many stations that require FIX'es, it may be more efficient for one station that received the file to do a "Replay RX". This will fix all stations at once.



Tune - This sends the three tone tuning tone for 7 seconds. This is how others may see your tuning tone. The three tones appear directly under the three green dots at the top of the waterfall. These three green dots also mark the proper frequency for the three pilot carriers that are part of the DRM transmission.

Spectrum - Displays the amplitude of the incoming signal across the 2.5 KHz bandwidth.

Waterfall - Displays 30 seconds of signal reception.

LoadPIC - Allows for the loading of an image to be transmitted.

The file will be converted and compressed into a JPEG2000 image. The filename is unchanged except for the extension which becomes ".jp2".

LoadAny - Allows for the loading of most any file type to be transmitted. The file will sent just as original and will not be renamed. This is useful when sending animated GIF files.

Copy - Standard image copy to clipboard from the RX or TX screen.

Paste - Standard image paste from clipboard to the RX or TX screen.




TxModeHelp - This screen serves as a quick reminder for what DRM modes are suitable for different conditions.

TX mode = RX mode This provides a way to quickly change the TX mode to match the DRM mode just received. The mode settings will be copied from here to here.

Full Screen - Image in selected window will be displayed full screen when clicked. The image size remains the same as the original resolution but it is displayed againgt a black background.


WAV - Brings up the "Play Wave File" list. Selecting a WAV file and clicking "TX Now" will immediatelly play the audio from this WAV file. Create the wav files using "W.Fall-Pic", "W.Fall-Text" or another program such as HamPAL or DIGTRX.

W.Fall-Pic - (Waterfall picture) Transforms the image on screen into a grey scale image that becomes analog encoded audio to produce a like image in the waterfall.

W.Fall-Text - (Waterfall text) Transforms text into analog encoded audio to produce the text as an image in the waterfall.

Clear - This will clear the RX or TX screens.

About - Credits.



View - Under the VIEW tab: "Last RX Pictures" - Are thumbnails of the pictures received. These images are JPG copies and are stored in the "RXFiles" folder.

"Last TX Pictures" - Are thumbnails of the pictures transmitted. These images are JPG copies and are stored in the "TXFiles" folder.

Hints - Hints will appear after mouse pointer is placed over selected buttons and areas.



RX tab - Click to view RX screen and RX information line.

Gamma - These buttons allows for some adjustment of the brightness of the received image.

RX Filename - Here the filename of the received image is shown.





TX tab - Click to view TX screen and TX information line.

Secs - This is the number of seconds it would take to transmit this image.

K - This is the file size for the image to transmit. Does not apply to images loaded using LoadAny.

Slider - The setting of this slider changes the level of the JPEG2000 compression that determines the file size.

SET - If the slider has changed position after the image has been loaded, it will be necessary to click the SET button so that the JPEG2000 compression can be reapplied.

TX Filename - The name of the file to be transmitted.

The HamPal program has many more features and may work better for some users but it is no longer being updated. As EasyPal Lite becomes more developed, it should prove to be an easy way for those new to digital modes to get into digital SSTV.

A more detailed guide to EasyPal Lite is available on my web page.




The above was the Dayton HamVention SSTV Forum presentation by Dave Jones, KB4YZ on May 19, 2007. Other speakers were Louis McFadin, W5DID and Mel Whitten, K0PFX.