communication:fm_improvement_factor
Differences
This shows you the differences between two versions of the page.
| Both sides previous revisionPrevious revisionNext revision | Previous revision | ||
| communication:fm_improvement_factor [2010/06/15 22:39] – rocketboy | communication:fm_improvement_factor [2010/06/15 22:50] (current) – rocketboy | ||
|---|---|---|---|
| Line 1: | Line 1: | ||
| ====== FM Improvement Factor ====== | ====== FM Improvement Factor ====== | ||
| - | The signal to noise ratio (S/N) of an FM data link can be improved by increasing the modulation index (up to a certain point). | + | The signal to noise ratio (S/N) of an FM link can be improved by increasing the modulation index (up to a certain point). |
| * **Frequency Deviation** - Fd - is the change in carrier frequency due to the peak voltage applied to the modulator | * **Frequency Deviation** - Fd - is the change in carrier frequency due to the peak voltage applied to the modulator | ||
| Line 21: | Line 21: | ||
| This is called the FM improvement factor. | This is called the FM improvement factor. | ||
| - | For this to work practically the carrier peaks must be more than the noise peaks - where the RMS power of the carrier is 10dB greater than the channel noise. | + | For this to work practically the carrier peaks must be more than the noise peaks - where the RMS power of the carrier |
| This is called the FM improvement threshold. | This is called the FM improvement threshold. | ||
| + | |||
| + | Thus the improvement for a given transmit power only holds while the received channel noise for the widened channel is 10dB less than the carrier power. | ||
communication/fm_improvement_factor.1276641572.txt.gz · Last modified: 2010/06/15 22:39 by rocketboy