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add group delay measurement
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@qrp73
qrp73 committed Oct 4, 2019
1 parent 56b0737 commit e81f4fe
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Showing 2 changed files with 79 additions and 28 deletions.
2 changes: 1 addition & 1 deletion main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1418,7 +1418,7 @@ const struct {
} trace_info[] = {
{ "LOGMAG", 7, 10 },
{ "PHASE", 4, 90 },
{ "DELAY", 4, 1 },
{ "GD", 4, 5 },
{ "SMITH", 0, 1 },
{ "POLAR", 0, 1 },
{ "LINEAR", 0, 0.125 },
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105 changes: 78 additions & 27 deletions plot.c
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Original file line number Diff line number Diff line change
Expand Up @@ -440,6 +440,46 @@ float phase(float *v)
return 2 * atan2f(v[1], v[0]) / M_PI * 90;
}


static inline float unwrap(float a0)
{
if (a0 < -M_PI)
a0 += 2 * M_PI;
if (a0 > M_PI)
a0 -= 2 * M_PI;
return a0;
}

/*
* calculate group_delay = -deltaAngle(gamma) / (deltaf * 360)
*/
float group_delay(float v[101][2], uint32_t* f, int count, int i)
{
float a0, a1, a2;
float delay;
// handle first and last points by accepting assymetry
if (i == 0)
{
a1 = atan2f(v[i][1], v[i][0]);
a2 = atan2f(v[i+1][1], v[i+1][0]);
delay = -unwrap(a2 - a1) / ((f[i+1] - f[i]) * 2 * M_PI);
}
else if (i == count-1)
{
a0 = atan2f(v[i-1][1], v[i-1][0]);
a1 = atan2f(v[i][1], v[i][0]);
delay = -unwrap(a1 - a0) / ((f[i] - f[i-1]) * 2 * M_PI);
}
else
{
a0 = atan2f(v[i-1][1], v[i-1][0]);
a1 = atan2f(v[i][1], v[i][0]);
a2 = atan2f(v[i+1][1], v[i+1][0]);
delay = -(unwrap(a1-a0)/(f[i]-f[i-1]) + unwrap(a2-a1)/(f[i+1]-f[i])) / (2 * 2 * M_PI);
}
return delay * 1000000000.0; // to nanosecond
}

/*
* calculate abs(gamma)
*/
Expand Down Expand Up @@ -489,42 +529,46 @@ cartesian_scale(float re, float im, int *xp, int *yp, float scale)
}


uint32_t
trace_into_index(int x, int t, int i, float coeff[2])
uint32_t trace_into_index(
int x, int t, int i,
float coeff[101][2], uint32_t freq[101], int point_count)
{
int y = 0;
float v = 0;
float refpos = 8 - get_trace_refpos(t);
float scale = 1 / get_trace_scale(t);
switch (trace[t].type) {
case TRC_LOGMAG:
v = refpos - logmag(coeff) * scale;
v = refpos - logmag(coeff[i]) * scale;
break;
case TRC_PHASE:
v = refpos - phase(coeff) * scale;
v = refpos - phase(coeff[i]) * scale;
break;
case TRC_DELAY:
v = refpos - group_delay(coeff, freq, point_count, i) * scale;
break;
case TRC_LINEAR:
v = refpos + linear(coeff) * scale;
v = refpos + linear(coeff[i]) * scale;
break;
case TRC_SWR:
v = refpos+ (1 - swr(coeff)) * scale;
v = refpos+ (1 - swr(coeff[i])) * scale;
break;
case TRC_REAL:
v = refpos - coeff[0] * scale;
v = refpos - coeff[i][0] * scale;
break;
case TRC_IMAG:
v = refpos - coeff[1] * scale;
v = refpos - coeff[i][1] * scale;
break;
case TRC_R:
v = refpos - resitance(coeff) * scale;
v = refpos - resitance(coeff[i]) * scale;
break;
case TRC_X:
v = refpos - reactance(coeff) * scale;
v = refpos - reactance(coeff[i]) * scale;
break;
case TRC_SMITH:
//case TRC_ADMIT:
case TRC_POLAR:
cartesian_scale(coeff[0], coeff[1], &x, &y, scale);
cartesian_scale(coeff[i][0], coeff[i][1], &x, &y, scale);
return INDEX(x +CELLOFFSETX, y, i);
break;
}
Expand Down Expand Up @@ -631,48 +675,53 @@ gamma2reactance(char *buf, int len, const float coeff[2], uint32_t frequency)
string_value_with_prefix(buf, len, zi, S_OHM[0]);
}

static void
trace_get_value_string(int t, char *buf, int len, float coeff[2], uint32_t frequency)
static void trace_get_value_string(
int t, char *buf, int len,
int i, float coeff[101][2], uint32_t freq[101], int point_count)
{
float v;
switch (trace[t].type) {
case TRC_LOGMAG:
v = logmag(coeff);
v = logmag(coeff[i]);
if (v == -INFINITY)
chsnprintf(buf, len, "-INF dB");
else
chsnprintf(buf, len, "%.2fdB", v);
break;
case TRC_PHASE:
v = phase(coeff);
chsnprintf(buf, len, "%.2f" S_DEGREE, v);
v = phase(coeff[i]);
chsnprintf(buf, len, "%.3f" S_DEGREE, v);
break;
case TRC_DELAY:
v = group_delay(coeff, freq, point_count, i);
chsnprintf(buf, len, "%.3f ns", v);
break;
case TRC_LINEAR:
v = linear(coeff);
chsnprintf(buf, len, "%.2f", v);
v = linear(coeff[i]);
chsnprintf(buf, len, "%.3f", v);
break;
case TRC_SWR:
v = swr(coeff);
v = swr(coeff[i]);
chsnprintf(buf, len, "%.2f", v);
break;
case TRC_SMITH:
gamma2imp(buf, len, coeff, frequency);
gamma2imp(buf, len, coeff[i], freq[i]);
break;
case TRC_REAL:
chsnprintf(buf, len, "%.2f", coeff[0]);
chsnprintf(buf, len, "%.3f", coeff[i][0]);
break;
case TRC_IMAG:
chsnprintf(buf, len, "%.2fj", coeff[1]);
chsnprintf(buf, len, "%.3fj", coeff[i][1]);
break;
case TRC_R:
gamma2resistance(buf, len, coeff, frequency);
gamma2resistance(buf, len, coeff[i], freq[i]);
break;
case TRC_X:
gamma2reactance(buf, len, coeff, frequency);
gamma2reactance(buf, len, coeff[i], freq[i]);
break;
//case TRC_ADMIT:
case TRC_POLAR:
chsnprintf(buf, len, "%.2f %.2fj", coeff[0], coeff[1]);
chsnprintf(buf, len, "%.3f %.3fj", coeff[i][0], coeff[i][1]);
break;
}
}
Expand Down Expand Up @@ -805,7 +854,8 @@ void plot_into_index(float measured[2][101][2])
if (!trace[t].enabled)
continue;
int n = trace[t].channel;
trace_index[t][i] = trace_into_index(x, t, i, measured[n][i]);
trace_index[t][i] = trace_into_index(x, t, i,
measured[n], frequencies, sweep_points);
}
}
#if 0
Expand Down Expand Up @@ -1380,7 +1430,8 @@ cell_draw_marker_info(int m, int n, int w, int h)
trace_get_info(t, buf, sizeof buf);
cell_drawstring_5x7(w, h, buf, xpos, ypos, config.trace_color[t]);
xpos += 64;
trace_get_value_string(t, buf, sizeof buf, measured[trace[t].channel][idx], frequencies[idx]);
trace_get_value_string(t, buf, sizeof buf,
idx, measured[trace[t].channel], frequencies, 101);
cell_drawstring_5x7(w, h, buf, xpos, ypos, config.trace_color[t]);
j++;
}
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