# Homework Help: Cellular radio systems questions

1. Dec 3, 2012

### Mickydawg25

With regards to cellular radio systems

1. how many bits of information does each cycle of a sinewave carry on a minimum channel?

modulator characteristics
2. A system has narrowband fm characteristics.. name me a rule which is an approximate technique to find the necessary freqeuncy deviation?

3 What formulae gives the noise figure of a low noise amplifier?

Last edited: Dec 3, 2012
2. Dec 3, 2012

### the_emi_guy

1. Bits per cycle does not make any sense. Bits/s per Hz of bandwidth is a typical metric for spectral efficiency.

2. A low noise amplifier will have noise figure on its datasheet. Do you have some other noise metric such as nV/sqrt(Hz), that you are trying to convert to NF?

Last edited: Dec 3, 2012
3. Dec 3, 2012

### the_emi_guy

In the case of single carrier modulation you could say that a spectral efficiency of 1b/s per Hz is equivalent to 1 bit per carrier cycle. Is this what you were looking for?

4. Dec 3, 2012

### Mickydawg25

OK this is the system

1200Hz analogue signal encoded using 8 level PCM
This spec results in a bit rate of 6600 bit/s
Signal transmitted over 1100m, 1200Hz bandwidth, FM carrier.
Carrier freq is 875000000Hz.
Allowed 1W carrier Pt and Pr.
antennas - omnidirectional.
antenna feeders=low loss, max 0.1 dB atten.

On a min. bandwidth channel each cycle of each sinewave carries how many bits of
information?

In order to define the modulator characteristics, FM modulator freq dev is computed.
System has narrowband FM characteristics so that the necessary frequency deviation can be obtained by an approximate technique such as what?