mordae/pico-sdr
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Signed-off-by: Jan Hamal Dvořák <mordae@anilinux.org>
This commit is contained in:
Jan Hamal Dvořák 2024-01-14 21:32:53 +01:00
parent f8a744ad48
commit c1adb06029
1 changed files with 36 additions and 3 deletions
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39
src/main.c
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@ -36,7 +36,7 @@
#define CLK_SYS_HZ (250 * MHZ)
#define EXTRA_BITS 3
#define EXTRA_BITS 1
#define NUM_SAMPLES 32
#define RSSI_ALPHA 1
#define LPF_SAMPLES 8
@ -63,6 +63,7 @@ static volatile struct status {
unsigned rssi_max;
unsigned sample_rate;
int frequency;
int angle;
int I, Q;
} status;
@ -280,6 +281,32 @@ static float lo_freq_init(float req_freq)
return freq;
}
inline static __unused int cheap_atan2(int y, int x)
{
static const int deg[2][2] = { { 192, 0 }, { 128, 64 } };
return deg[y < 0][x < 0];
}
inline static __unused int imaskmod(int x, int mask)
{
return (x < 0) ? -((-x) & mask) : x & mask;
}
inline static __unused int cheap_angle_diff(int angle1, int angle2)
{
int diff = angle2 - angle1;
diff = imaskmod(diff, 255);
if (diff > 128)
return diff - 256;
if (diff < -128)
return diff + 256;
return diff;
}
inline static __unused unsigned popcount(unsigned v)
{
v = v - ((v >> 1) & 0x55555555);
@ -390,6 +417,8 @@ static void rf_rx(void)
int delta_watermark = 0;
unsigned prev_transfers = 0;
int angle = 0;
while (true) {
int I = 0, Q = 0;
@ -562,6 +591,8 @@ static void rf_rx(void)
prevQ = Q;
angle = (angle * 7 + cheap_angle_diff(angle, cheap_atan2(I, Q))) / 8;
unsigned ssi = I * I + Q * Q;
const unsigned alpha = RSSI_ALPHA;
@ -572,6 +603,7 @@ static void rf_rx(void)
status.rssi_raw = assi2 / 16;
status.frequency = frequency;
status.sample_rate = CLK_SYS_HZ / (delta_watermark * 32);
status.angle = angle;
status.I = I;
status.Q = Q;
status.mtime = time_us_32();
@ -692,8 +724,9 @@ static void command(const char *cmd)
float rssi_rel = (float)st.rssi_raw / (float)st.rssi_max;
printf("%5.1f dB (%4u) [%5u %+6i] ", 10.0f * log10f(rssi_rel),
(unsigned)sqrt(st.rssi_raw), st.sample_rate, st.frequency);
printf("%5.1f dB (%4u) [%5u %+6i] %+4.0f ", 10.0f * log10f(rssi_rel),
(unsigned)sqrt(st.rssi_raw), st.sample_rate, st.frequency,
360.0f * st.angle / 256.0f);
plot_IQ(st.I, st.Q);
puts("");