Changed demapping of TCH and FACCH to conform with GSM 05.02 and 05.03
diff --git a/lib/demapping/tch_f_chans_demapper_impl.cc b/lib/demapping/tch_f_chans_demapper_impl.cc
index a2458f1..719429e 100644
--- a/lib/demapping/tch_f_chans_demapper_impl.cc
+++ b/lib/demapping/tch_f_chans_demapper_impl.cc
@@ -49,16 +49,12 @@
gr::io_signature::make(0, 0, 0)),
d_timeslot(timeslot_nr)
- {
- for(int ii=0; ii<13; ii++)
+ {
+ for (int ii=0; ii<3; ii++)
{
- int startpos = ((int)(ii / 4) * 4);
- d_starts_fn_mod26[ii] = startpos;
- d_starts_fn_mod26[ii + 13] = startpos + 13;
+ d_bursts_stolen[ii] = false;
}
- d_bursts_stolen = false;
-
message_port_register_in(pmt::mp("bursts"));
set_msg_handler(pmt::mp("bursts"), boost::bind(&tch_f_chans_demapper_impl::filter_tch_chans, this, _1));
message_port_register_out(pmt::mp("tch_bursts"));
@@ -79,14 +75,14 @@
uint32_t frame_nr = be32toh(header->frame_number);
uint32_t fn_mod26 = frame_nr % 26;
- uint32_t fn26_start = d_starts_fn_mod26[fn_mod26];
- uint32_t fn26_stop = fn26_start + 3;
+ uint32_t fn_mod13 = frame_nr % 13;
+ bool frames_are_consecutive = true;
int8_t * burst_bits = (int8_t *)(pmt::blob_data(header_plus_burst))+sizeof(gsmtap_hdr);
if(header->timeslot == d_timeslot){
header->sub_type = GSMTAP_CHANNEL_TCH_F;
- if (fn_mod26 == 12 || fn_mod26 == 25)
+ if (fn_mod13 == 12)
{
header->sub_type = GSMTAP_CHANNEL_ACCH|GSMTAP_CHANNEL_TCH_F;
@@ -115,7 +111,7 @@
{
//check for a situation where some bursts were lost
//in this situation frame numbers won't be consecutive
- bool frames_are_consecutive = true;
+ frames_are_consecutive = true;
for(int jj=1; jj<4; jj++)
{
if((d_frame_numbers_sacch[jj]-d_frame_numbers_sacch[jj-1]) != 26)
@@ -136,49 +132,118 @@
}
else
{
- if(fn_mod26>=fn26_start && fn_mod26<=fn26_stop)
+ if (fn_mod13 <= 3)
{
- uint32_t ii = fn_mod26 - fn26_start;
- d_frame_numbers[ii] = frame_nr;
- d_bursts[ii] = msg;
+ // add to b1 and b3
+ d_bursts[0][fn_mod13] = msg;
+ d_bursts[2][fn_mod13 + 4] = msg;
+
+ // set framenumber
+ d_frame_numbers[0][fn_mod13] = frame_nr;
+ d_frame_numbers[2][fn_mod13 + 4] = frame_nr;
// check if stealing bits are set
- // see gsm 05.03
- if (static_cast<int>(burst_bits[60]) == 1 && static_cast<int>(burst_bits[87]) == 1)
+ // see 4.2.5 in gsm 05.03
+ if (static_cast<int>(burst_bits[60]) == 1)
{
- d_bursts_stolen = true;
+ d_bursts_stolen[2] = true;
+ }
+ if (static_cast<int>(burst_bits[87]) == 1)
+ {
+ d_bursts_stolen[0] = true;
}
}
-
- if(fn_mod26==fn26_stop)
+ else if (fn_mod13 >= 4 && fn_mod13 <= 7)
{
+ // add to b1 and b2
+ d_bursts[0][fn_mod13] = msg;
+ d_bursts[1][fn_mod13 - 4] = msg;
+
+ // set framenumber
+ d_frame_numbers[0][fn_mod13] = frame_nr;
+ d_frame_numbers[1][fn_mod13 - 4] = frame_nr;
+
+ // check if stealing bits are set
+ // see 4.2.5 in gsm 05.03
+ if (static_cast<int>(burst_bits[60]) == 1)
+ {
+ d_bursts_stolen[0] = true;
+ }
+ if (static_cast<int>(burst_bits[87]) == 1)
+ {
+ d_bursts_stolen[1] = true;
+ }
+ }
+ else if (fn_mod13 >= 8 && fn_mod13 <= 11)
+ {
+ // add to b2 and b3
+ d_bursts[1][fn_mod13 - 4] = msg;
+ d_bursts[2][fn_mod13 - 8] = msg;
+
+ // set framenumber
+ d_frame_numbers[1][fn_mod13 - 4] = frame_nr;
+ d_frame_numbers[2][fn_mod13 - 8] = frame_nr;
+
+ // check if stealing bits are set
+ // see 4.2.5 in gsm 05.03
+ if (static_cast<int>(burst_bits[60]) == 1)
+ {
+ d_bursts_stolen[1] = true;
+ }
+ if (static_cast<int>(burst_bits[87]) == 1)
+ {
+ d_bursts_stolen[2] = true;
+ }
+ }
+
+ // send burst 1 or burst 2 to output
+ if (fn_mod13 == 3 || fn_mod13 == 7 || fn_mod13 == 11)
+ {
+ int tch_burst_nr = 0;
+
+ if (fn_mod13 == 11)
+ {
+ tch_burst_nr = 1;
+ }
+ else if (fn_mod13 == 3)
+ {
+ tch_burst_nr = 2;
+ }
+
//check for a situation where some bursts were lost
//in this situation frame numbers won't be consecutive
- bool frames_are_consecutive = true;
+ frames_are_consecutive = true;
- for(int jj=1; jj<4; jj++)
+ for(int jj=1; jj<8; jj++)
{
- if((d_frame_numbers[jj]-d_frame_numbers[jj-1])!=1)
+ if((d_frame_numbers[tch_burst_nr][jj] - d_frame_numbers[tch_burst_nr][jj-1]) != 1)
{
frames_are_consecutive = false;
+ // burst 3 has 1 sacch burst in between
+ if (tch_burst_nr == 2 && jj == 4
+ && d_frame_numbers[tch_burst_nr][jj] - d_frame_numbers[tch_burst_nr][jj - 1] == 2)
+ {
+ frames_are_consecutive = true;
+ }
}
}
+
if(frames_are_consecutive)
{
//send bursts to the output
- for(int jj=0; jj<4; jj++)
+ for(int jj=0; jj<8; jj++)
{
- if (d_bursts_stolen)
+ if (d_bursts_stolen[tch_burst_nr])
{
- message_port_pub(pmt::mp("acch_bursts"), d_bursts[jj]);
+ message_port_pub(pmt::mp("acch_bursts"), d_bursts[tch_burst_nr][jj]);
}
else
{
- message_port_pub(pmt::mp("tch_bursts"), d_bursts[jj]);
+ message_port_pub(pmt::mp("tch_bursts"), d_bursts[tch_burst_nr][jj]);
}
}
- d_bursts_stolen = false;
- }
+ d_bursts_stolen[tch_burst_nr] = false;
+ }
}
}
}