This power
meter is now finished. A port is LTC5532 and port B and C is classic AD8307. I
make my own PCB for this, today you can by AD8307 from Ebay sold for a few
dollar.
I connected
a LCD display and Encoder. Draw 5V from Arduino Uno to all tree PM boards.
Output from A to A0, B to A1 and C to A2.
Then little
sw doing the work.
LTC5532 can’t
find a formula so I use my generator for input and read levels by ADC and put a
table on my serial port than past in to the code, like this.
if(u0>3.4604)
P1 = 8.0;
else if(u0>3.3822)
P1 = 7.8;
else if(u0>3.3040)
P1 = 7.6;
…………..
else
P1= -21.2;
Then port A
is working.
Port B and
C. use my generator put in 0dBm and -40dBm read the level in V0 – V40/40 = x V/dB
around 23 – 37 mV/db, put it in the code.
if(port==1) //Cal Port B
{
for(int i=0; i<10; i++)
a1 = a1 + analogRead(A1);
u1= a1/10;
u1 = 5.0 * u1 /1023;
pmSet.cal1 = u1;
}
To get
stabile values I average 10 times.
P2 = (u1 - pmSet.cal1)/0.0242 + pmSet.atten[1] +
freqComp[1][pmSet.freq[1]];
pmSet.cal1 = u1 att 0dBm input, calibrated in menu.
pmSet.atten = attenuation infront off power meter 0 –
many dB integer values, set in menu.
freqComp[1][pmSet.freq[1]] = freq compensation set in
code, measurd by generator @ 0dBm on varying frequencys (16 pcs.).
double freqComp[3][16] =
{{0,0,0,0.3,0,-0.2,-0.1,-0.4,0.1,2.9,1.4,4.0,3.8,6.7,12.5,10.4},…….
Unit can be set dBm or W, in menu. Convert to W
if(pmSet.unit == 1) //Unit W
{
P2 = pow(10,(P2-30)/10);
}
Jumping over to new project,
magnetic compass and PA 1296 MHz, stay tuned.
