ZL2AFP Narrow Band OFDM TV

Orthogonal Frequency Division Multiplex (OFDM)
Live analog TV in a voice bandwidth!

Introduction     Transmitting     Receiving     Picture Replay

 Getting Started

There are two separate programs for each mode family, a transmitter program and a receiver program. There are also two viewer programs, used to play back previously recorded reception, at any chosen speed. All these files are included in the one archive.
ZL2AFP OFDM NBTV Software (ofdm_nbtv.zip, 315kB)

The programs in the archive are:

The low resolution transmitter program, RGB colour and B&W.
The low resolution receiver program, RGB colour and B&W.
The modest resolution transmitter program, RGB colour and B&W.
The modest resolution receiver program, RGB colour and B&W.
The faster VHF transmitter program, RGGB colour only.
The faster VHF receiver program, RGGB colour only.
AVI Viewer.exe
The AVI replay program. Plays AVI format files at selected frame speeds with frame averaging.
RGGB Viewer.exe
Special replay program only for RGGB .tv format files.
First download the archive from the link above. Then simply allocate a folder on your computer, and unzip the archive into the folder. The programs will work fine with WIN98™ or WINXP™, and no changes are made to the operating system or registry. The computer should be at least a Pentium™ 500MHz, and must have a good quality sound card, and (for PTT control) a working serial port. USB serial ports are OK.

Make yourself a shortcut to each of the programs, and place them in your menu system, perhaps in a sub-folder 'ZL2AFP NBTV'. If you later wish to remove the programs, simply delete the folder and remove your shortcuts.

Connections to transmitter and receiver are the same as for any other sound card radio mode - audio cables from sound card Line Out to the transmitter microphone input, and from the receiver audio output to the sound card Line Input. Add a cable to the PTT circuit from one of the computer serial ports. The TX programs activate DTR and RTS.

Using the Windows Volume Control applet, enable (unmute) the WAVE output, and set the WAVE volume to about half way. Switch to the Recording Control applet (Options/Properties/Recording from the Volume Control Applet), and select Line In as the source, and adjust the Line In level about half way to start with. The transmit programs provide direct access to the sound card Volume Control applet, and the receivers provide the same access for the Recording Control applet. You may find you need a different audio level on transmit than is required for digital modes. Take care to keep the power down - an indicated 10-20W is as much as the typical 100W transceiver can manage without causing image distortion or excessively wide signals. The peak power will be about 100W even though the average is lower. Don't worry, 10W average power will give good performance as the receiver is quite sensitive.

Separate transmit and receive programs allow the user to operate just one or the other, but you can also use both at the same time in order to monitor your own transmission. In this case, set the receiver Recording Control source to 'Stereo Mix' or 'What U Hear' rather than Line In. If you run both programs, it does not matter which you start first. You may find that the timing is off (pictures slide sideways, contain noise, or are shaded from top to bottom) when running both programs at once. This is especially true on older computers, and the problem is known to be sound card dependent. See the 'Transmitting' and 'Receiving' pages for more information.

Introduction     Transmitting     Receiving     Picture Replay

Copyright © Con Wassilieff and Murray Greenman 2004-2009. All rights reserved.