The big question is, why have carrier waves in modulation at all? Why not simply use the input signal directly? So why not use it directly? Why are carriers and modulation needed at all? Interestingly, the input signals could be carried without a carrier wave by very low frequency electromagnetic waves.
The problem, however, is that this will need quite a bit of amplification in order to transmit those very low frequencies. The input signals themselves do not have much power and need a fairly large antenna in order to transmit the information.
In order to keep communication cheap and convenient and require less power to carry as much information as possible, carrier systems with modulated carriers are used. This site uses both functional cookies and tracking cookies to help us understand how users interact with the site. You can choose to disable non-functional cookies if you wish, however we will need to set a functional cookie to respect your choice. We use trusted third-party analytics providers to help us improve your experience on this website.
Radio Academy. Login Register Search. View Conferences. Gartner Webinars Expert insights and strategies to address your priorities and solve your most pressing challenges. View Webinars. Related Terms Business Technologist. Digital Assets. Digital Finance. Fusion Team. Sufiyan Ghori Sufiyan Ghori 2, 11 11 gold badges 32 32 silver badges 49 49 bronze badges. However, some combinations are more useful than others. In particular, if you want to, at some remote location, separate the "signal" from the "carrier", then it's useful to not have the "carrier" in the same frequency band as the "signal".
The main purpose of using a "carrier" is to transmit multiple signals of smaller bandwidth over a channel that has much larger bandwidth. Show 1 more comment. Active Oldest Votes. Obviously this is not to scale, but you get the idea. We increase the carrier frequency for the following reasons: Spectrum Availability. You send your signal where the FCC or whatever governing body applies says you can send it. Increased bandwidth. As the answer to your question demonstrated, to send wide-band signals you need higher carrier frequencies.
Practicalities of antennas. It is difficult impossible? An antenna's bandwidth, though, is proportional to its center frequency, so increasing the carrier frequency makes it much easier to make good antennas with wide passbands. Channel characteristics. Different frequencies behave in different ways.
Some frequencies get absorbed by rain and some resist that. Some frequencies bounce off the ionosphere and so can travel farther than "line of sight". Improve this answer. Jim Clay Jim Clay Add a comment. Firas Faham Firas Faham 21 1 1 bronze badge. What would happen if a 1khz signal amplitude modulate a 1khz carrier signal?
Carrier frequencies were , , and Hz, and modulation rates were 2, 5, and 10 Hz. For the two lower carrier frequencies, FM detection tended to be best at the lowest modulation rate while AM detection was best at the highest rate.
For the Hz carrier, both AM and FM detection tended to be poorest at the lowest modulation rate.
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