FERGUSON BSB/D2MAC BASEBAND DECODER MODIFICATION
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You will require :-

        A Ferguson BSB receiver.

        A D2MAC firmware rom (obtainable from TRAC SATELLITE SYSTEMS for
                around œ39.00 or write your own code to switch the chip
                set in your receiver to D2MAC. Clever sods amongst you
                could write a DMAC/D2MAC code to enable NRK/MARCOPOLO 
                decoding as well!).
        
        A suitable satellite receiver with a clean baseband output (unit 
                tested with a Chaparral Monterey 40 with baseband option
                set for B-EMPHASISED).

        A home built baseband inverter (see text and PCX/GIF diagram).

... and the following components :-

        1 x Small lump of Veroboard (or etch your own PCB)
        1 x BC212 Transistor
        1 x BC182 Transistor
        1 x 10uF Electrolytic Capacitor
        1 x 22uF Electrolytic Capacitor
        1 x 15K ohm Resistor
        1 x 5K6 ohm Resistor
        2 x 100 ohm Resistors
        3 x 1K2 ohm Resistors

        ... and some odd bits of connecting cable.

HACKING
-------

[1]     Start off by making up your circuit. Then unscrew your BSB receiver
        and note where all the screws come from. 

[2]     Remove the 5 screws holding the main PCB of the BSB receiver to the 
        plastic case. 
        
[3]     Now that the PCB is on the desk turn it over and locate the tuner
        unit. Pry off the shield cover to reveal tracks underneath.

[4]     Locate the two feed through pcb connections from the top of the board 
        as indicated in the diagrams (PCX/GIF) supplied with this document.

[5]     From the feed through pcb nearest the IC count up 3 connections.
        Follow the track (see diagram) and cut at marked place.

[6]     Connect the output from your circuit to the un-used pad at the top
        of your cut track.

[7]     Connect your +12 volt supply for your circuit to the 12 volt
        regulator (see diagram). You can also connect the 0v ground conection
        to the centre connection of this regulator if you wish or anywhere
        else that is obviously 0v earth.

[8]     A convenient place to feed your circuit with a baseband input can be
        made by cutting the track connecting the ACM Phono socket to the
        receiver (not used!) and connect your baseband input to this.

Re-assemble unit ... switch on. Supply a clean baseband signal to your now
coverted decoder, sit back and enjoy. If you have a Monterey then you can
feed the now decoded signals from the decoders scart socket back into the 
Monterey (note: remember to change the audio input as well!).

If you have the TRAC rom fitted to your receiver/decoder then the BIT ERROR
RATE indication comes in handy for fine tuning the signal, also the audio
selection still works.

If you have any comments on this peice of hacking then upload a message to
the GOLLY BBS where this file spawned from.

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These notes were written over lunch! so are they are probably full of
spelling mistakes and stuff like that. But if youve got half a brain then 
the circuit diagram will be all that you need anyway ... happy hacking!

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Paul Donald


