AFG/dump1090
3
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Use a lookup table for SNR calculation.

Browse source
This commit is contained in:
Oliver Jowett 2014-09-22 14:53:06 +01:00
parent 2e45a59986
commit 76c958b03e
4 changed files with 30 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

8
dump1090.c
View file

@ -98,6 +98,7 @@ void modesInit(void) {
((Modes.pFileData = (uint16_t *) malloc(MODES_ASYNC_BUF_SIZE) ) == NULL) ||
((Modes.magnitude = (uint16_t *) malloc(MODES_ASYNC_BUF_SIZE+MODES_PREAMBLE_SIZE+MODES_LONG_MSG_SIZE) ) == NULL) ||
((Modes.maglut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) ||
((Modes.log10lut = (uint16_t *) malloc(sizeof(uint16_t) * 256 * 256) ) == NULL) ||
((Modes.beastOut = (char *) malloc(MODES_RAWOUT_BUF_SIZE) ) == NULL) ||
((Modes.rawOut = (char *) malloc(MODES_RAWOUT_BUF_SIZE) ) == NULL) )
{
@ -185,6 +186,13 @@ void modesInit(void) {
}
}
// Prepare the log10 lookup table.
// This maps from a magnitude value x (scaled as above) to 100log10(x)
for (i = 0; i <= 65535; i++) {
int l10 = (int) round(100 * log10( (i + 365.4798) * 258.433254) );
Modes.log10lut[i] = (uint16_t) ((l10 < 65535 ? l10 : 65535));
}
// Prepare error correction tables
modesInitErrorInfo();
}