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Speed up acquisition time by removing multiple delay() calls... #9

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Speed up acquisition time by removing multiple delay() calls... #9

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424526d
Speed up acquisition time...
etchorner Jan 31, 2017
eb3c784
Compensation/calibration routines
etchorner Feb 2, 2017
b4a897f
Refined compensation routines, prettified the display, and code cleanup
etchorner Feb 3, 2017
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107 changes: 60 additions & 47 deletions Firmware/standard_firmware/standard_firmware.ino
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
Expand Down Expand Up @@ -38,11 +38,22 @@ long Fstart = 1000000; // Start Frequency for sweep
long Fstop = 30000000; // Stop Frequency for sweep
unsigned long current_freq; // Temp variable used during sweep
long serial_input_number; // Used to build number from serial stream
long num_steps = 1001; // Number of steps to use in the sweep
long num_steps = 101; // Number of steps to use in the sweep
char incoming_char; // Character read from serial stream
byte mode_pressed = 0;
int mode = 1;

// CALIBRATION VALUES
// set AD9850 to zero output, measure FWD and REV over a long period for these values. If not, set both equal to 0.
int fwdOffset = 6; //6 compensates for idle noise on the fwd diode and amplifier
int revOffset = 4; //4 compensates for idle noise on the fwd diode and amplifier
// Short the antenna port to ground, measure FWD and REV over a sweep for this ratio (REV/FWD). If not, set equal to 1.
// see comments in PerformSweep() about alternative compensation schemes....there is a frequency dependent noise component.
double diodeComp = 0.9414309839;
// Short the diode cathodes together, measure FWD and REV over a sweep for this ratio (FWD/REV). If not, set both equal to 1.
// see comments in PerformSweep() about alternative compensation schemes....there is a frequency dependent noise component.
double gainComp = 0.995193251;

void setup() {
// set up the LCD's number of columns and rows:
lcd.begin(16, 2);
Expand Down Expand Up @@ -147,7 +158,7 @@ void loop() {
}
num_steps = 1000;

switch(mode){
switch (mode) {
case 1:
// Full sweep 1-30 MHz
lcd.clear();
Expand Down Expand Up @@ -236,58 +247,58 @@ void loop() {
Fstart = 28000000;
Fstop = 30000000;
break;

}
}
}

void Perform_sweep() {
int FWD = 0;
int REV = 0;
int REV_nosig = 0;
int FWD_nosig = 0;
double VSWR;
double minVSWR;
long minFreq;
long Fstep = (Fstop - Fstart) / num_steps;
minVSWR = 999;
minFreq = Fstart;

// Reset the DDS
digitalWrite(RESET, HIGH);
delay(1);
digitalWrite(RESET, LOW);
delay(10);
SetDDSFreq(Fstart);
delay(100);

// REV_nosig = analogRead(A0);
// FWD_nosig = analogRead(A1);
// if(mode==0){
// Serial.print("FWD ");
// Serial.print(FWD_nosig);
// Serial.print(", REV ");
// Serial.println(REV_nosig);
// Serial.flush();
// }



// Start loop
for (long i = 0; i <= num_steps; i++) {
// Calculate current frequency
current_freq = Fstart + i * Fstep;
current_freq = Fstart + i * ((Fstop - Fstart) / num_steps);

// Set DDS to current frequency
SetDDSFreq(current_freq);
delay(1);

//discard a few measurements
for (int j = 0; j < 19; j++) {
analogRead(A1);
analogRead(A0);
}

// Wait a little for settling
if (digitalRead(BAND) == LOW) {
mode_pressed = 1;
}
delay(10);
// Read the forawrd and reverse voltages
REV = analogRead(A0);
FWD = analogRead(A1);

// Average the reverse and foward voltages and calibrate them
for (int k = 0; k < 50; k++) {
REV += (analogRead(A0) - revOffset);
FWD += (analogRead(A1) - fwdOffset);
}
FWD /= 50;
REV /= 50;

// Mean compensation values
// FWD = diodeComp * FWD;
// REV = gainComp * REV;

// Linear compensation equatiions
// FWD = FWD * (2e-9 * current_freq + 0.9231) ;
// REC = REV *(2e-10 * current_freq + 0.9916);

// Polynomial compensation equations
FWD = FWD * (8.9070e-17 * current_freq * current_freq - 8.1425e-10 * current_freq + 0.9832);
REV = REV * (-2.7626e-18 * current_freq * current_freq + 3.1516e-10 * current_freq + 0.9912);

if (REV >= FWD) {
// To avoid a divide by zero or negative VSWR then set to max 999
Expand Down Expand Up @@ -320,24 +331,26 @@ void Perform_sweep() {
Serial.print("Freq ");
Serial.print(minFreq);
Serial.print(", VSWR ");
Serial.println(minVSWR);
Serial.println(minVSWR, 3);
Serial.flush();
}

lcd.setCursor(15, 1);
lcd.print(".");
delay(100);
lcd.setCursor(15, 1);
lcd.print(" ");
// display results
lcd.setCursor(0, 1);
lcd.print(minFreq);
lcd.print(",");
lcd.print(minVSWR);
lcd.print(":1 ");

digitalWrite(13, HIGH);
//delay(10);
digitalWrite(13, LOW);
lcd.print("F:");
if (minFreq < 10e6) {
lcd.setCursor(3, 1);
}
else
lcd.setCursor(2, 1);
lcd.print(minFreq / 1e6, 3);
lcd.setCursor(9, 1);
lcd.print("V:");
if (minVSWR > 1)
lcd.setCursor(11, 1);
else
lcd.setCursor(10, 1);
lcd.print(minVSWR, 3);
}

void SetDDSFreq(long Freq_Hz) {
Expand All @@ -346,7 +359,7 @@ void SetDDSFreq(long Freq_Hz) {

// Send one byte at a time
for (int b = 0; b < 4; b++, f >>= 8) {
// SPI.transfer(f & 0xFF);
// SPI.transfer(f & 0xFF);
send_byte(f & 0xFF);
}

Expand Down