Question 3
(a) Sketch the symbol displayed on a smart phone screen when set to the following modes:
(i)Call divert;
(i)Silent;
(i)Flight.
(b) A mobile phone displays no signal when powered ON. Give three reasons for this error message.
(c)List four components found in the network section of a mobile phone PCB
Candidates performance on this question was very good as they were able to respond to the questions appropriately as required except for the last part where candidates could not list the correct components found in the network section of the mobile phone.
Observation
The expected answers are:
(b) Reasons for ‘no signal’ error displayed on a mobile phone
- Faulty antenna
- Faulty network IC / Radio Frequency (RF) IC / Hagar IC
- Object interference
- Active network jammer
- Faulty/no network coverage
- Faulty SIM card
- Corrupt International Mobile Equipment Identity (IMEI)
- Corrupt Operating System (OS)
- Faulty network cable
- Faulty antenna socket / connector
- Faulty antenna switch
- Faulty Power Frequency Oscillator (PFO) / Power Amplifier (PA)
(c) Components found in the network section of a mobile phone PCB
- Antenna switch
- Power Frequency Oscillator (PFO) / Power Amplifier (PA)
- Network IC / Radio Frequency (RF) IC / Hagar IC
- 26 MHz Crystal Oscillator
- Voltage Control Oscillator (VCO)
- Rx filter / Rx Processor
- Tx filter / Tx Processor
- Mutual Coupler
- Antenna socket/connector
- Baseband processor