first steps in the old nmt900 mobile telephone system ----------------------------------------------------- nmt900 is a mobile telephone standard used in norway,sweden,danmark,switzerland,etc... spells nordic mobile telephone 900 mhz (there is a 450mhz as well). since there is about no documentation available for the non professional i started my own research. the data transmission seems to be a FSK 1200 bd type. unlike the amps system there is a real old fashion modem inside the phone. no manchester, no nrzi coding, simple and slow. my phone uses three 8032 processors running at 11 mhz. one for the display, the second has external ram, rom, and does the data handling. i still did not find out what the third of them does. i opened my old portable phone and connected a printer cable to the data output and clock pins. so i can read in all data the phone transmits. Ive done the read-in and display with the DIGISCOPE software, available for free on this site. ive modified the software sligthly to have this 0101 sequences written to a file. following comes the data of the first word transmitted on the control channel with the phone number set to 111111 (yes, i can do that by tampering the 46C05 eeprom) and beyond the same word with a different phone number. i concentrated on the third digit. compare A word nmt900 mobile to base ------------------------------------ s------es------es------es------es------es------e 111111(22) - 222222(11) ----------------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I00000000II000000IIIII0II0I0I0I0I00I00I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I000III000I0I0III0I0I0 - - - - - -- ---- - -- - - - --- - --- + --- - +-- - --- - ---- - - - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111(22) - 112111(11) ----------------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I000I000II00I0I0000II00IIII00000I0II0000I0II0000I0III0I0I00II000III00000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - --- - + + - + + - 2 1 2 1 2 1 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 113111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I000I000II00I0I0000II00IIII00000I0II0000I0II0000I0III000I00I0000IIII0000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - --- - + - + 2 2 2 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 114111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I000I000II00I0I0000II00IIII00000I0II0000I0II0000I00I00I000III00II0I00000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - --- - - + - + + - 4 1 4 1 4 1 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 115111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I00000I00I00I0I0III00I00I0II0000I0II0000I0II0000I00I000000II000II0II0000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - ---- - - - - + 4 4 4 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 116111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I00000I00I00I0I0III00I00I0II0000I0II0000I0II0000I00II0I0000II00IIII00000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - ---- - - - + + - - + + + - 4 2 1 4 2 1 4 2 1 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 117111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I00000I00I00I0I0III00I00I0II0000I0II0000I0II0000I00II000000I000IIIII0000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - ---- - - - + - - + + 4 2 4 2 4 2 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 118111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I000I000II00I0I0000II00IIII00000I0II0000I0II000000II0000I0IIII00I0I00000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - --- - - ++ - 8 18 1 8 4 2 1 4 2 18 4 2 1 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 119111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I00000I00I00I0I0III00I00I0II0000I0II0000I0II000000II00I0I0II0I00I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - ---- - - - + + 8 8 8 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 - 110111 --------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 0I000I0I00000I00I00I0I0III00I00I0II0000I0II0000I0II000000III000I00III00III00000I0II0000I0II0000I0II00I0I0III0I0I0 - - - - ---- - - - + - ++ + - 8 2 2 18 2 1 - - + - - - -+ + + + 8 4 2 1 4 2 18 4 2 1 111111 bytes test ----------------- 0I000I0I0I0I0I0II0000II00000I0IIIII0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II0000I0II00I0I0III0I0I0 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 0 2 4 F 1 1 1 1 1 1 1 1 1 123456 ------ 0I000I0I000I0I0III00000I0000000IIII0000I0II0000I0III0I0I00I0000III000I00I0II00I0000I0II000II00IIII000I0I0III0I0I0 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 0 2 0 3 1 1 1 2 3 4 5 6 1 BitNumbers counted after sync pattern ------------------------------------- 0000000001111111111222222222233333333334444444444555555555566666666667777777777888888888899999999990000000000 1234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789 0I000I0I000I0I0III00000I0000000IIII0000I0II0000I0III0I0I00I0000III000I00I0II00I0000I0II000II00IIII000I0I0III0I0I0 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 8 4 2 1 0 2 0 3 1 1 1 2 3 4 5 6 1 1. bitnumber 5, 7, 9,11 = 0000 = 0 2. bitnumber 13,15,17,19 = 0010 = 2 3. bitnumber 21,23,25,27 = 0000 = 0 4. bitnumber 29,31,33,35 = 0011 = 3 5. bitnumber 37,39,41,43 = 0001 = 1 6. bitnumber 45,47,49,51 = 0001 = 1 7. bitnumber 53,55,57,59 = 0001 = 1 = ph1 8. bitnumber 61,63,65,67 = 0010 = 2 = ph2 9. bitnumber 69,71,73,75 = 0011 = 3 = ph3 10. bitnumber 77,79,81,83 = 0100 = 4 = ph4 11. bitnumber 85,87,89,91 = 0101 = 5 = ph5 12. bitnumber 93,95,97,99 = 0110 = 6 = ph6 13. bitnumber 101,03,05,07 = 0001 = 1 ph1 to ph6: this is the phone number! every second bit contains unscrambled binary data. i call them odd bits. the even bits seem to be a and of different odd bits. help me to decipher the full message. have phun maria ps: ---- this is a tab length in chars. this is a tab length in tab