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Introduction. ~~~~~~~~~~~~~ Hello again. Much has happened since the release of SNARF!.TXT & SNARF2.TXT. I released a file called PAIRINFO.TXT, which provided information on the decoding procedure to be applied once the datastream had been recovered. The major purpose of this Tfile is to set some sort of ISO standard for snarfers, I will also include some additional information that may be useful to budding snarfer builders. DaVeX. July 1995. Proposals ~~~~~~~~~ To enable software to be compatible with all snarfers, I propose the following:- 1} All data recovery to TTL including XOR to be done in hardware. 2} The interface to the PC to be CELLTRAK compatible. Pin 10 = clock Pin 15 = data This will allow hardware to be tested before the software is written. Run up CELLTRAK, and once monitoring of the forward channel is underway, remove the lead from the parallel port and plug in the snarfer hardware with the input tuned to a forward channel too, if normal paging info continues to scroll up the screen and the busy/idle flag on the status bar behaves normally, then you can be 99.9% sure your hardware is werking correctly. 3} Software must recognise inverted data and take the nescessary steps. ( See additional info (1) below.) 4} All snarfer builders following these guidelines pay 100 quid into my swiss bank acc. :-) This will achieve two results, hardware will be relatively simple to test, and it opens the door to all the ace coders without hardware to develop software for snarfing indepently of hardware builders. For those without PC's that are attempting to get snarfing, GO BUY A PC! Additional info ~~~~~~~~~~~~~~~ This is just extra info that may or may not be useful whilst trying to build the hardware. 1} The ETACS and AMPS specifications define a NRZ encoded logic 1 as a LOW to HIGH transition in the center of a databit period. The polarity of the demodulated datastream is dependent on the local oscillator in the receiver being used. 2} Clock recovery extracts an 8 or 10 kHz (ETACS or AMPS) phase locked clock signal from the Manchester encoded datastream. 3} Manchester decoding is achieved by exclusive ORing the recovered Manchester encoded data with the recovered clock. 4} The clock recovery PLL on the reverse control channel has 3.75ms of dotting (ETACS) and 3ms (AMPS) in which to lock, or wordsync will be missed. 5} A transmitted pair (along with the dross) takes 156ms to send. (ETACS). 125ms (AMPS). 6} Snarfing follows an exponetially square qubic variant of sods law, you either get loads or fuck all. Greets ~~~~~~ Alphabetical. Atrocity Cherokee Eck Jono Maelstrom (long live the legend) MiniMaster Neuromancer Phantasm Pulse TuRBo Vladimir C00l B0ards ~~~~~~~~~~~ 1066 AlmostDead DockMaster Duk&Cover The Sprawl Unauthorised Access