What kind of questions are asked in interviews for Electronics Engineer?
Some good questions for B-Tech (EC) folks, might be:
1. What is CDMA?
CDMA stands for Code Division Multiple Access which uses digital format. In CDMA systems several transmissions via the radio interface take place simultaneously on the same frequency bandwidth. User data is combined at the transmitter’s side with a code, then transmitted. On air, all transmission get mixed. At the receiver's side the same code is used as in the transmitter’s side. The code helps the receiver to filter the user information of the transmitter from incoming mixture of all transmissions on the same frequency band and same time.
2. Explain Bluetooth
Bluetooth is designed to be a personal area network, where participating entities are mobile and require sporadic communication with others. It is omni directional i.e. it does not have line of sight limitation like infra red does. Ericsson started the work on Bluetooth and named it after the Danish king Harold Biuetooth. Bluetooth operates in the 2.4 GHz area of spectrum and provides a range of 10 metres. It offers transfer speeds of around 720 Kbps.
3. What are GPRS services?
GPRS services are defined to fall in one of the 2 categories:
- PTP (Point to point)
- PTM (Point to Multipoint)
Some of the GPRS services are not likely to be provided by network operators during early deployment of GPRS due in part to the phased development of standard. Market demand is another factor affecting the decision of operators regarding which services to offer first.
4. What are the advantages of CDMA?
Advantages of CDMa are:
- Frequency diversity: Transmission is spread out over a large bandwidth due to that less affected by noise. If bandwidth is increased S/N ratio increases, which means noise will be reduced
- Multiplication Resistance: Chipping codes used for CDMA not only exhibit low correlation but also low autocorrelation. Hence a version of the signal that is delayed by more than one chip interval does not interfere with dominant signal as in other multipath environments
- Privacy: Due to spread spectrum is obtained by the use of noise like signals, where each user has a unique code, so privacy is inherent
- Graceful Degradation: In CDMA, more users access the system simultaneously as compared to FDMa, TDMA
5. What are the advantages of spread spectrum?
Spread spectrum has the following advantages:
- No crosstalk interference
- Better voice quality/data integrity and less static noise
- Lowered susceptibility to multipath fading
- Inherent security
- Longer operating distances
- Hard to detect
- Hard to intercept or demodulate
- Harder to jam than narrow bands
- Use of ranging and radar
6. Explain the steps involved in demodulating a signal
Once the signal is coded, modulated and then sent, the receiver must demodulate the signal. This is usually done in 2 steps:
- Spectrum spreading (e.g., direct sequence or frequency hopping) modulation is removed
- The remaining information bearing signal is demodulated by multiplying with a local reference identical in structure and synchronised with received signal
7. List some advantages of GSM
Here are some advantages of GSM:
- GSM is mature, this maturity means a more stable network with robust features
- Less signal deterioration inside buildings
- Ability to use repeaters
- Talk time is generally higher in GSM phones due to pulse nature of transmission
- The availability of Subscriber Identity Modules allows users to switch networks and handset at will
- GSM covers virtually all parts of world so international roaming is not a problem
8. What are the various types of numbers for network identity?
Various types of number for network identity are as follows:
- MSISDN (Mobile station ISDN) Number: It is international mobile subscriber number which is normally called mobile number. It is unique worldwide
- MSRN (Mobile Subscriber Routing Number): MSRN is used during mobile terminate trunk call to provide location of mobile subscriber
- HON (Hand Over Number): HON is used for providing information required to transfer call from one B?SC to another BSC or to another MSC
- ISMI (International Mobile Subscriber Identity Number): Purpose of ISMI is for location update and authentication
- TMSI (Temporary Mobile Subscriber Identity): TMSI is used instead of IMSI to improve security efficiency of network
- IMEI: International Mobile Equipment Identity
9. What is analog-to-digital conversion of signals?
A discrete-time signal is defined by specifying its value only at discrete times, called sampling instants. When the sampled values are quantised and encoded, a digital signal is obtained. A digital signal is obtained from the analog signal by using an analog-to-digital converter. This entire process is referred to as the conversion of signals from analog to digital form.
Some other question can be:
- What is simulator programme?
- In C programming language, how many parameters can be passed to a function ?
- Which filter has the highest Q factor?
- What is multiplexing? Explain its primary advantage.
- What is SSB modulation?
- How can we remove unwanted sideband from SSB modulation?
- How many channels are there in 2MB pulse code modulation?
- What is cut off frequency?
- Differentiate between pass band and stop band.
- Explain Shanon-hartley law.
- Why interlacing is used in television?
- Which type of modulation is used in TV transmission?
- What is attenuation?
- Differentiate between transducer and transponder.
- What is op-amp?
- Differentiate between conductor and inductor.
- What is meant by pre-emphasis and de-emphasis?
- Which semiconductor device is used as a voltage regulator and why?
- What are monitoring methods for Electronics activities?
- What is an interrupt?