How do you simulcast AM and FM radio on a single transmitter?

Question

we're required to make a prototype of a transmitter that can send AM and FM signals simultaneously. Our professor gave us a hint that we may use harmonics, yet we're still clueless...we hope yahoo answers can help us build our prototype. Thank you.

Answer 1

AM (amplitude modulation) is where the amplitude of the signal is modulated by making the signal stronger and weaker at the frequency of modulation. FM (frequency modulation) is where the frequency of the signal is modulated by increasing and decreasing the frequency of the carrier signal at the frequency of modulation.

What you need to do is have the signal go through a frequency modulator and then modulate the amplitude of the signal at the modulation frequency. And, you'll probably want to use two different modulation frequencies (say, 1 kHz and 2 kHz), so you can tell them apart on the receive end.

Regarding the harmonics, what your professor might be getting at is how you then have separate receivers at separate frequencies, one being an AM receiver and one being an FM receiver, both simultaneously receiving the single transmitted frequency.

Whenever you transmit an RF carrier signal, you produce harmonics of that carrier that are reduced in amplitude, but still contain the modulation information. So, if you generate a 100 MHz carrier, you will generate harmonics at half of that frequency and double that frequency. That means you will have a lower-amplitude carrier that is generated at 50 MHz and another one at 200 MHz.

If the RF carrier at 100 MHz is strong enough in amplitude, the harmonic carriers should be at a great enough amplitude to be detected and demodulated. So, tune one reciever (AM or FM) to 100 MHz, and tune the other receiver to 50 MHz or 200 MHz. Then adjust the amplitude of the 100 MHz carrier until your receiver at the other frequency can pick up the harmonic carrier frequency.

Answer 2

TV broadcast is the example.The video is AM and the sound is FM(sub-carrier 6.5 or 5.5 for mono and 5.74MHz for stereo).Any way, you can make a AM modulation to a FM transmitter since the FM receiver has a AMPLITUDE limiter for demodulation.

Answer 3

the different solutions anticipate you mean a million transmitter that operates in the two the AM frequency band 540-1640 khz and the FM frequency band, 88-108 mhz. in case you mean what happens in case you attempt to AM and FM modulate on a similar service frequency, then you certainly get the two partial or complete cancellation of one of the sidebands. this is the so-noted as 0.33 technique of single-sideband modulation.

Answer 4

panda750's right.
u dont

Answer 5

you dont