diff options
Diffstat (limited to 'src/lib/gsm_constants.h')
| -rw-r--r-- | src/lib/gsm_constants.h | 48 |
1 files changed, 42 insertions, 6 deletions
diff --git a/src/lib/gsm_constants.h b/src/lib/gsm_constants.h index ded8cb4..520ff4f 100644 --- a/src/lib/gsm_constants.h +++ b/src/lib/gsm_constants.h @@ -22,10 +22,12 @@ #define FRAME_BITS (TS_PER_FRAME * TS_BITS + 2) // 156.25 * 8 #define FCCH_POS TAIL_BITS #define SYNC_POS 39 -#define TRAIN_POS 58 -#define SAFETY_MARGIN 6 +#define TRAIN_POS TAIL_BITS + DATA_BITS + 5 //first 5 bits of a training sequence +//aren't used for channel impulse response estimation +#define TRAIN_BEGINNING 5 +#define SAFETY_MARGIN 6 // -#define FCCH_HITS_NEEDED (USEFUL_BITS - 4) +#define FCCH_HITS_NEEDED (USEFUL_BITS - 4) #define FCCH_MAX_MISSES 1 #define FCCH_MAX_FREQ_OFFSET 100 @@ -38,9 +40,9 @@ static const unsigned char SYNC_BITS[] = { 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 1 }; -const unsigned FCCH_FRAMES[] = {0,10,20,30,40}; -const unsigned SCH_FRAMES[] = {1,11,21,31,41}; -const unsigned BCCH_FRAMES[] = {2,3,4,5, 12}; //remove 12 +const unsigned FCCH_FRAMES[] = {0, 10, 20, 30, 40}; +const unsigned SCH_FRAMES[] = {1, 11, 21, 31, 41}; +const unsigned BCCH_FRAMES[] = {2, 3, 4, 5}; // Sync : .+...++.+..+++.++++++.++++++....++.+..+.+.+++.+.+...+..++++..+.. // Diff Encoded Sync: .++..+.+++.+..++.....++.....+...+.+++.+++++..+++++..++.+...+.++. @@ -91,6 +93,40 @@ static const unsigned char dummy_burst[] = { 1, 1, 1, 0, 1, 0, 1, 0 }; + +/* + * The frequency correction burst is used for frequency synchronization + * of the mobile. This is broadcast in TS0 together with the SCH and + * BCCH. + * + * Modulating the bits below causes a spike at 62.5kHz above (below for + * COMPACT) the center frequency. One can use this spike with a narrow + * band filter to accurately determine the center of the channel. + */ +static const unsigned char fc_fb[] = { //I don't use this tables, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //I copied this here from burst_types.h because + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, //the description is very informative - p.krysik + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, + 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 +}; + +static const unsigned char fc_compact_fb[] = { + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, + 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0 +}; + //Diff encoded train_seq //TSC0: +.++.+++..+...++..++.+++.. //TSC1: +.+++.++..++...+..++.+++.. |