Spectrum Analysis
To make sure that the transmitter is outputting things as we expect, the prototype transmitter I built is connected up to a spectrum analyzer:
In The Schematic:
Measured @ 'Here':
Our carrier frequency is definitely visible with the highest peak at 9dbm (about 10mW) and then harmonic frequencies can also be seen on both sides. Harmonics are always expected in systems that have no filtering.
Zero-Span Power Analysis (Time-Domain)
The final thing to do is see what our power output looks like to make sure governments won't hunt us down for creating something that is too powerful. A single frequency power analysis at the peak is analyzed. Notice the highest power output was actually at 27.142 MHz and not 27.145 MHz. Many factors cause that, however I'm sure all my parts being through-hole and having horrid tolerances doesn't help.
Measured @ 'Here':
The power output wave seen above looks exactly like the square wave we wanted to transmit which is pretty cool given how we're still looking at a mixed signal. This means our receiver should have an easy time distinguishing between the on/off points that hit 7dBm and -25dBm. These transmission strenghts are well within the regualtions of most governments.
To make sure that the transmitter is outputting things as we expect, the prototype transmitter I built is connected up to a spectrum analyzer:
Our carrier frequency is definitely visible with the highest peak at 9dbm (about 10mW) and then harmonic frequencies can also be seen on both sides. Harmonics are always expected in systems that have no filtering.
Zero-Span Power Analysis (Time-Domain)
The final thing to do is see what our power output looks like to make sure governments won't hunt us down for creating something that is too powerful. A single frequency power analysis at the peak is analyzed. Notice the highest power output was actually at 27.142 MHz and not 27.145 MHz. Many factors cause that, however I'm sure all my parts being through-hole and having horrid tolerances doesn't help.
The power output wave seen above looks exactly like the square wave we wanted to transmit which is pretty cool given how we're still looking at a mixed signal. This means our receiver should have an easy time distinguishing between the on/off points that hit 7dBm and -25dBm. These transmission strenghts are well within the regualtions of most governments.