All information and software supplied here is to be used at your own risk. 

Visilink is a simple DTMF menu driven program to add the facility of displaying Video over IP webstreams to most ATV repeaters. It has been written by G7KPM in BBC Basic ( http://www.bbcbasic.co.uk/bbcbasic.html ) and the compiled version is available for download HERE (VisilinkV1_1BETA.zip).

Please note, this software is very BETA and I am probably the worlds worst programmer, so any problems, please Email me (Jason G7KPM) at:

I will try to resolve any issues you may have.

If you are interested in working on Visilink to improve the software or to add additional features then again, please Email me and I will happily supply you with the source code (as long as you promise not to laugh!! ( Hi hi ) ;0)  ...   )

Required Hardware

The hardware is a simple DTMF interface based on the MT8870 DTMF decoder IC. The 4 bit binary value is taken from the MT8870 (Q1 - Q4) to the STATUS pins of LPT1 (Pins 15,13,12 & 10) via transistor buffers. The MT8870 Valid tone detect output is connected to LPT port PIN 11.

Download Visilink DTMF Hardware test program HERE

DATASHEET HERE

Pin	Name	Dir	Description
1	HostCLK		NOT USED
2	data0		Data Bit 0 - REPEATER CONTROL (See Below)
3	data1		Data Bit 1 - REPEATER CONTROL (See Below)
4	data2		Data Bit 2 - REPEATER CONTROL (See Below)
5	data3		Data Bit 3 - REPEATER CONTROL (See Below)
6	data4		Data Bit 4 - Reserved for future use
7	data5		Data Bit 5 - Reserved for future use
8	data6		Data Bit 6 - Reserved for future use
9	data7		Data Bit 7 - Reserved for future use
10	PeriphCLK		MSB (3) data from MT8870 DTMF Decoder
11	PeriphAck		Valid DTMF Tone from MT8870 DTMF Decoder
12	nAckReverse		Bit (2) data from MT8870 DTMF Decoder
13	X-Flag		Bit (1) data from MT8870 DTMF Decoder
14	Host Ack		NOT USED
15	PeriphRequest		LSB (0) data from MT8870 DTMF Decoder
16	NReverse Request		NOT USED
17	1284 Active		NOT USED
18	GND		Signal Ground
19	GND		Signal Ground
20	GND		Signal Ground
21	GND		Signal Ground
22	GND		Signal Ground
23	GND		Signal Ground
24	GND		Signal Ground
25	GND		Signal Ground

4 outputs are also provided to enable the hardware to interface easily to existing repeater logics and these pins change status during program operation. The details of these are:

The above hardware is detected by Visilink at startup and without this connected, will not run. Currently, only LPT1 is supported so it may be necessary to reconfigure your PC hardware to ensure LPT1 is available and free for Visilink to access.

The base address for LPT1 is &378. You can check this in Control Panel > System > Hardware > Ports (COM & LPT).

WARNING

Please ensure to double check all connections and test for shorts etc before connecting the interface to the Parallel port. The port is easily damaged by incorrect interfacing.

Also, ensure the 5v supply to the board is well regulated. A 7805 regulator IC is ideal for this purpose. Exceeding 5v can cause permanent damage to your PC.  

Installation

INTERNET EXPLORER 6 or better is required for Visilink to operate.

Right Click on the above link and select 'Save target as'. Save the downloaded ZIP file into a directory and unzip the contents. It is up to the user where to install the file, but a suitable location would be c:\visilink
The software must be installed on your hard disk as Visilink downloads update files to the directory were it is installed and therefore can not be run from Read only media such as a CD-ROM.

In the directory where the files were unzipped, there should be a file called 'REPEATER_LIST.lst' and 'WEB_REPEATER_LIST.lst'

These files contain the information required for Visilink to operate and consist of the following in TAB seperated values:
Repeater or Station CALLSIGN, Webstream URL & Stream Method.

The end of the file is marked by 3 TAB seperated '#'

When Visilink is first started, the software attempts to download the latest version of 'WEB_REPEATER_LIST.lst' from the GB3GG / Visilink website and this is used by the software by default. This is also downloaded daily when the software is in standby mode. If you wish to add your repeater or personal web-stream to this list, please Email the station callsign and Ustream.TV username to:

We will then add your station to the list. We also require a scanned copy of your amateur radio license and NOV (Where applicable for repeaters). This is to ensure that any web-streams potentially being retransmitted by ATV repeaters are from licensed operators only.

All information supplied are used for status checks only and will not be published in any form. All provided information will be destroyed once the application has been processed.

If you disable the automatic update, Visilink will resort to the file 'REPEATER_LIST.lst' which is user updateable and stored locally on your hard disk. The file can be edited using NOTEPAD from within Windows. Some information is provided in the text file on how to do this to ensure the correct format. This can be used if you wish to create your own menus.

Other required hardware

In order to retransmit the streams selected by Visilink, your PC must have a composite output to allow the connection of the video to your repeater system. Many newer VGA cards such as the Matrox Millennium series have a TV out facility which should be able to support 1024x768 screen resolution. There are also many types of external VGA to composite encoders available which can also be used. Again, the encoder must be able to support 1024x768 screen resolution.

Operation

Above is an example screen shot.

DTMF tones 0 - 9 are used to select required repeater / station

* = delete the selection

# = enter the selection

If no numeric selection has been made and providing there are more than 20 stations in the list, * and  # moves forward and back one page. Also, 0 will place Visilink back into standby mode.

Press ESCAPE at any time to exit the program.