Cellular radio systems questions

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Discussion Overview

The discussion revolves around various questions related to cellular radio systems, including the information capacity of sinewave cycles, characteristics of narrowband FM systems, and noise figures of low noise amplifiers. The scope includes theoretical aspects and technical specifications relevant to cellular radio system design.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the relevance of measuring bits per cycle of a sinewave, suggesting that bits per second per Hz of bandwidth is a more typical metric for spectral efficiency.
  • Another participant proposes that in single carrier modulation, a spectral efficiency of 1 bit per second per Hz could be interpreted as 1 bit per carrier cycle.
  • A participant provides a specific system scenario involving a 1200Hz analogue signal encoded using 8-level PCM, resulting in a bit rate of 6600 bit/s, and asks how many bits of information each cycle of the sinewave carries on a minimum bandwidth channel.
  • The same participant seeks an approximate technique for calculating the necessary frequency deviation for a narrowband FM modulator.
  • There is a mention of the noise figure of a low noise amplifier being available on its datasheet, with a query about converting other noise metrics to noise figure.

Areas of Agreement / Disagreement

Participants express differing views on the measurement of information capacity in relation to sinewave cycles, with no consensus reached on the appropriate metrics or definitions. The discussion remains unresolved regarding the specific calculations and techniques for the outlined scenarios.

Contextual Notes

Participants have not fully defined the assumptions behind their calculations or the context for the noise metrics mentioned. There are unresolved mathematical steps related to the frequency deviation and information capacity calculations.

Mickydawg25
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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?
 
Last edited:
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Mickydawg25 said:
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?
 
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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?
 
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?
 

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