I found something!

As test points on the right in the picture are accessible from outside without dismounting the unit, I started with them. Sampling the first one using my PC audio card set to 100,000 HZ sampling frequency, I got this:

Uploaded with

ImageShack.usSampling more or less at the dame time the bluetooth transmission, I got this:

$GPGGA,000436.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*47

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000436.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6C

$GPGGA,000437.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*46

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000437.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6D

$GPGGA,000438.061,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*4B

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000438.061,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*60

$GPGGA,000439.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*48

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000439.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*63

$GPGGA,000440.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*46

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPGSV,3,1,12,20,00,000,,10,00,000,,25,00,000,,27,00,000,*79

$GPGSV,3,2,12,03,00,000,,31,00,000,,24,00,000,,15,00,000,*78

$GPGSV,3,3,12,16,00,000,,05,00,000,,01,00,000,,26,00,000,*7D

$GPRMC,000440.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6D

$GPGGA,000441.062,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*46

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000441.062,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6D

$GPGGA,000442.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*44

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000442.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6F

$GPGGA,000443.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*45

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000443.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6E

$GPGGA,000444.061,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*40

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000444.061,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6B

$GPGGA,000445.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*43

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPGSV,3,1,12,20,00,000,,10,00,000,,25,00,000,,27,00,000,*79

$GPGSV,3,2,12,03,00,000,,31,00,000,,24,00,000,,15,00,000,*78

$GPGSV,3,3,12,16,00,000,,05,00,000,,01,00,000,,26,00,000,*7D

$GPRMC,000445.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*68

$GPGGA,000446.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*40

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000446.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6B

$GPGGA,000447.062,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*40

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000447.062,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6B

$GPGGA,000448.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*4E

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000448.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*65

$GPGGA,000449.050,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*4F

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPRMC,000449.050,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*64

$GPGGA,000450.062,0000.0000,N,00000.0000,E,0,00,,0.0,M,0.0,M,,0000*46

$GPGSA,A,1,,,,,,,,,,,,,,,*1E

$GPGSV,3,1,12,20,00,000,,10,00,000,,25,00,000,,27,00,000,*79

$GPGSV,3,2,12,03,00,000,,31,00,000,,24,00,000,,15,00,000,*78

$GPGSV,3,3,12,16,00,000,,05,00,000,,01,00,000,,26,00,000,*7D

$GPRMC,000450.062,V,0000.0000,N,00000.0000,E,,0.00,060305,,,N*6D

Now it's just a matter of time and patience...