Objective - To add multiple frequencies on sine waves onto a \$24V\$ DC Line.
Each frequency block (\$F_1, F_2, ...\$) generates a sine wave of unique frequency within the given range. When the \$n^{th} \$ frequency block \$F_n\$ is switched on, it's frequency must be added to the 24V line regardless of any frequency present along that line.
I have used bias-tee circuit to combine the frequencies. Each yellow block has a \$100nF\$ coupling capacitor.
Sine wave generation method : Square wave to sine wave converter
Frequency Range : \$8KHz - 24KHz\$
Number of Frequency Blocks \$N\$ : \$10\$
Current\$/\$Frequency Block : \$10mA\$ at \$24V DC\$
L1 Inductor Rating :
- Inductance : \$470\mu H \pm 10\%\$
- DC Current Rating : \$420mA\$
- Self-Resonant Frequency : \$100KHz\$
Coupling Capacitor : \$ 100nF, 50V\$
Issues -
- There is a lot of high frequency distortion when detecting the signal over the power-line. (The power-line wire is \$2\$ core, \$1.5mm^2\$, \$25m\$ between each device) How do I resolve this?
The sine waveform (from one block) gets distorted when more than one frequency block is connected. How do I isolate each block but still allowing the signal to flow through? I have used a buck-converter to convert \$24V - 5V DC\$ within each frequency block. It has huge capacitors in its input. Is that the problem? Will a diode at the input do the trick?
I don't get any sine-waves (added) at the power-line, for more than 2 blocks. Do I need to change the \$L1, C\$ values?
Do I need an end resistor after the \$N\$ blocks, connecting the positive and negative?
If this design could be improved, kindly suggest so.
Thank You.