Cellular radio systems questions

[Mickydawg25]

With regards to cellular radio systems1. 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?

 

[the_emi_guy]

With regards to cellular radio system top level design1. 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?

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?

 

[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?

 

[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?

 

[rezeew]

I would like to provide the following response to these questions regarding cellular radio systems:

1. The number of bits of information carried by each cycle of a sinewave on a minimum channel depends on the modulation scheme used. For example, in binary phase shift keying (BPSK), each cycle can carry 1 bit of information, while in quadrature amplitude modulation (QAM), each cycle can carry multiple bits of information. Therefore, it is not accurate to specify a specific number of bits for all cellular radio systems.

2. A common rule for determining the necessary frequency deviation in narrowband FM systems is to use Carson's rule. This rule states that the bandwidth of an FM signal is approximately equal to 2 times the sum of the maximum frequency deviation and the highest modulating frequency. By rearranging this equation, we can estimate the necessary frequency deviation for a given bandwidth and modulating frequency.

3. The noise figure of a low noise amplifier (LNA) can be calculated using the formula:

Noise Figure (NF) = (Signal-to-Noise Ratio at the input of the LNA) / (Signal-to-Noise Ratio at the output of the LNA)

This formula takes into account the noise contributed by the LNA and compares it to the noise present at the input. A lower noise figure indicates a better performing LNA with less noise added to the incoming signal.