how to canculate data rates of an modulation technique if frequency of carrier and modulation technique is kno

Question

iam using FSK with 315MHZ frequency and the data rates is 9.6kbps i dont know how they calculated,whether bandwidth matters?

Answer 1

The carrier frequency doesn't directly come into play. Note that I say "directly".

Consider the three characteristics: bandwidth, data rate, and modulation type. If you know two of them you can probably come up with the third. Though if the modulation type is unknown it could be a little trickier.

In your case, FSK, and here I assume you mean binary FSK, the bandwidth should be twice as wide as the data rate. FSK in terms of bandwidth utilization looks much like two PSK carriers side by side. Thus if the FSK system is implemented with two sub-carriers, a good rule of thumb is to place them just so the PSK bandwidths don't overlap. Of course placing them tighter would make the demodulation process more difficult, if not impossible. Spacing them wider apart may be necessary depending on the demodulation filters used. But much wider may just be wasting bandwidth.

The carrier frequency is only a consideration in that it needs to be large enough to support the required bandwidth. But it does not lay directly into any calculation of the bandwidth or data rate.

Answer 2

In telecommunications, modulation is the technique of various a periodic waveform, i.e. a tone, so as to apply that sign to place across a message, in an identical way as a musician might modulate the tone from a musical device by ability of various its quantity, timing and pitch. generally a severe-frequency sinusoid waveform is used as service sign. the three key parameters of a sine wave are its amplitude ("quantity"), its area ("timing") and its frequency ("pitch"), all of which could be changed in accordance with a low frequency advice sign to acquire the modulated sign.