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Data comms

A detailed illustration showing various data communication concepts, including analogue and digital signals, transmission media, and networking technologies, in a modern and engaging style.

Data Communications Mastery Quiz

Test your knowledge and skills in the field of data communications with this comprehensive 85-question quiz! Covering a wide range of topics from analogue and digital signal processing to international standards and multiplexing techniques, this quiz is designed for anyone seeking to deepen their understanding of data communication technologies.

Challenge yourself with questions that include:

Signal Processing
Multiplexing Techniques
Transmission Media
ITU Standards

85 Questions21 MinutesCreated by CodingExpert231

Analogue signals in an analogue system need to have

B. Screened Co-Axial DC Block High Pass filters only

C. Regeneration for the un-balanced working

Regular filters and amplifiers

A. Twisted pair cables regularly filtered and Regeneraters.

Analogue 4 Wire working is better than 2 Wire working because

A. Less Wire is used between Amplifiers.

B. The DC Signaling prevents Harmonic Interference.

D. Harmonic Interference balances out the Signalling Interference.

Less Power is required for the amplification

Echo in Analogue 2 Wire working will

A. Show itself by having your voice repeated back and interfering with signals.

B. Be less of an issue Than 4 Wire working

C. Be reduced with Double Hybrid coils.

D. Be cancelled out by Balanced Regeneration circuits

Impulse noise in Digital Systems comes from

A. The effect of the electrons passing through the component

B. The effect of the electrons passing through the Power Supplies

D. Bad shielding from White noise.

C. Bad shielding of & interference from nearby Relays or Contactors or intermittent arcing in circuits.

Signal to noise ratio in Data communications

A. Can change at any time due to external effects, such as interference.

B. Can only vary at connections if they are not balanced

C. Is constant at all times as illustrated in Nyquists 9th Law.

PSTN was not very suitable for Digital Data communications because

Components in the Amplifiers affect DC Signals

Shannons Law on Signal to noise Ratio means signal levels will be too low

The effects of crosstalk Is constant at all times as illustrated in Nyquists 5th Law.

Kirchoffs Law on Current flow in a circuit prevents Analogue Signalling at low frequencies.

What is a Bearer of Opportunity

A. A ship or aircraft moving to a predetermined destination that has available load capacity.

A data connection using existing infrastructure

B. A data connection that does not require encryption to carry sensitive information.

C. A data connection that requires extra encryption because it passes through civilian infrastructure

What is a Unguided Transmission Media?

A. UHF Line of sight Management Radio

B. Twisted pairs / co axial cables.

C. Multi - Mode Fibre optics

D. Multiplexed Analogue Statistical Time Divided HDB3

Which one of the following refers to Twisted Pair Transmission Media?

A. Multi strand core surrounded by two layers of insulation & a twisted mesh of copper wire.

B. Two Balanced Lines with an insulator around each conductor

C. Unbalanced single conductor wrapped in insulation & Twisted with a shield around it.

D. Unbalanced Multi Stranded conductor wrapped in insulation & Twisted with a shield around it.

Which one of the following refers to Optical Fibre Transmission Media

A. Multi strand core surrounded by a layer of insulation / Kevlar & an insulated twisted mesh of copper wire around it.

B. Two Balanced Lines with Kevlar and Glass strands around each conductor.

C. Balanced Multi strand core surrounded by two layers of insulation & a twisted mesh of copper wire.

D. One or more lines of Glass core wrapped in Kevlar Strands & PVC outer.

Which one of the following refers to Satellite Transmission Media?

A. ELF focussed beam in a line of sight to its Geosynchronous orbiting satellite.

B. Troposphere scatter SHF ¼ Wave Line of Sight Masts for delay of up to 500mS.

C. EHF Line of sight transmission with delays of up to 500mS.

D. EHF focused beam in a line of sight to its compliment tower up to 50km distance.

Which one of the following refers to Infra Red Transmission Media?

A. Near visible Short Distance Line of sight up to 4Mbs.

B. Near visible Short Distance up to 64kbs.

C. Near visible Long Distance Line of sight up to 100Gbs

D. Near visible Long Distance up to 64kbs.

Which one of the following are the four Primary Constants in Transmission Lines?

A. Resistance, Inductance, Reluctance, Capacitance

C. Resistance, Leakance, Impedance, Capacitance.

D. Resistance, Leakance, Insertion, Capacitance.

B. Resistance, Inductance, Leakance, Capacitance.

Which one of the following refers to Insertion losses in Transmission Lines?

A. Is a minimal loss that does not affect high frequencies

B. Is a loss that is cumulative and increases with the number of connections in a Transmission line.

C. Is directly proportional to Voltage and decreases with higher frequencies

D. Is Indirectly proportional to Resistance and decreases with higher frequencies.

Which one of the following refers to Characteristic Impedance on wire transmission lines?

A. Is the impedance to signals as governed by the frequency and its voltage.

B. Is the attenuation effect as governed by the efficiency of the earth shielding.

C. Is the attenuation of the higher frequencies because of the Di-Electric breaking down

D. Is the impedance to signals as governed by the four Primary constants.

Which one of the following refers to Reflection of Digital signals in Transmission Lines?

A. Is the effect from incorrect Impedance matching, signals bouncing into each other.

B. Is a attenuation effect from the negative pulses following positive pulses.

C. Is the proportional difference of the negative pulses all added to the positive pulses.

D. Is the Indirectly proportional of the negative pulses all added to the positive pulses.

Which one of the following refers to Di-Electric Losses in Transmission Lines?

A. Is a minimal loss that only affects high frequencies if it is a solid strand centre core.

B. Is a loss that is caused by the heating up & breakdown of the Di-Electric and increases with Voltage and Frequency.

C. Is indirectly proportional to Voltage and Inductance of the Di-Electric and decreases with higher frequencies.

D. Is a loss caused by the heating up of the conductor & varies with the quality and size of the conductor(s).

Which one of the following refers to Insertion Losses in Transmission Lines?

A. Is a minimal loss that only affects high frequencies if it is a Multi Pin Connector.

B. Is a loss that mostly caused by the energy lost in the connections.

C. Is indirectly proportional to Voltage and Leakance effect and decreases with higher frequencies.

D. Is a loss caused by the heating up of the conductor & varies with the quality and size of the conductor(s).

What is the role of the International Telecommunications Union (ITU)?

A. They are the ones that control the way manufacturers produce all equipment so the colours and packaging for distribution are all the same.

B. They Co-ordinate the many issues that affect world-wide communications.

C. They are the organisation that makes sure all communication systems charge the same amount of money for services regardless of currency exchange rates.

D. They are the organisation that makes sure all communication systems charge the same amount of money for services with relation to the different currency exchange rates so value is the same.

What facilities are covered by the ITU-TS Recommendations for the X-series?

A. They are the ones that list the way manufacturers produce all Cross overs and the way they are patched into other power supplies.

B. They Co-ordinate the way the data can be moved in the 1st three layers of the OSI 7 layer model.

C. They Co-ordinate the way the data can be moved within the middle layer of the OSI 7 layer model.

D. They list the voltage levels, pin out data & functions of the connections.

What facilities are covered by the ITU-TS Recommendations for the I-series?

B. They Co-ordinate the way the data can be moved within the middle layer of the OSI 7 layer model.

A. They cover the way the DTE’s can Access the ISDN.

C. They list the voltage levels, pin out data & functions of the connections.

They Co-ordinate the way the data can be moved within the first three layers of the OSI 7 layer model

Which one best explains Frequency Division Multiplexing (FDM)?

A. Many inputs are sampled at their input frequencies and combined to an identical output baud rate.

B. Inputs are sampled and combined to make an aggregate output of a greater baud rate.

C. Many inputs are sampled at their input frequencies and combined to a slower output baud rate.

D. Inputs are given a specific frequency channel within a given Bandwidth.

Which one best explains Statistical Time Division Multiplexing (STDM)?

A. Active inputs are sampled at their input Data Rates and combined with a balanced number of Null characters.

B. Active Inputs are combined and sent out with a header.

C. A ‘bit map’ / header system is used so any Active users data can be sent out as a ‘payload’ with separation Null characters between them.

D. A continuous data stream can be sent out to line with all the data from active Inputs using a ‘Bit map’ system with only one null character between each ‘payload’.

Which one best explains Voice Over Internet Protocol (VOIP)?

A. Passing analogue messages over an analogue network.

B. Passing data files over a dedicated internet link.

C. Passing stored voice communications over the internet as extra bandwidth becomes available.

D. Passing data files over the internet in real time.

Which one best explains Baud Rate?

A. The maximum number of signal transitions that can be sent and distinguished at the other end.

B. As Nyquist states it is the maximum number of bits that can be sent.

C. Shannons law explains that the Baud rate can only be half the maximum fundamental frequency of the line.

D. It is as Nyquist states that the Baud rate is at least twice the highest fundamental frequency on the line.

What does SCIDA stand for?

A. Site Co-Ordinating Instrument Design Authority.

B. Station Co-Ordinating Installation Design Authority.

C. Site Co-Ordinating Installation Design Authority.

D. Station Communication Installation Design Authority.

Which one best explains Simplex, Half Duplex and Full Duplex?

A. Simplex is synchronised communications at same time, Half Duplex is able to pass data on same channel one way at a time, Full Duplex is both ways at same time.

B. Simplex is synchronised communications at one way at a time on same channel, Half Duplex is able to pass data on same channel one way at a time, Full Duplex is both ways at same time.

C. Simplex is able to pass data both ways at same time, Half Duplex is able to pass data on same channel one way at a time, Full Duplex is synchronised first both ways at same time.

D. Simplex is able to pass data one way only, Half Duplex is able to pass data on same channel one way at a time, Full Duplex is both ways at same time.

Which one best explains the function of a Modem?

A. A Modem converts analogue signals in to a ‘Shift Keyed’ Modulated output to line altering a carrier by amplitude, frequency or phase.

B. A Modem converts digital signals in to a ‘Shift Keyed’ Modulated output to line altering a carrier by amplitude, frequency or phase.

C. A Modem converts analogue signals in to a ‘Shift Keyed’ Modulated output to line altering a carrier by amplitude, frequency or phase or combinations of them eg, amplitude and phase.

D. A Modem converts digital signals in to a ‘Shift Keyed’ Modulated output to line altering a carrier by DC level, frequency or phase.

RED Networks process information with a protective marking (PM) of ……?

A. Official

B. Top Secret

C. Official-Sensitive

D. Secret

Which one best explains the advantage that PSK has over ASK with relation to the given bandwidth?

A. For a given Bandwidth PSK can use higher carrier frequencies ie, 8khz & above.

B. For a given Bandwidth PSK can use lower carrier frequencies ie, 1khz & below for better harmonic differentiation.

C. For a given Bandwidth PSK can use higher number of Baud per Bit.

D. For a given Bandwidth PSK can use higher number of Bits or changes of phase per Baud.

Using VOIP, how is the destination identified ?

A. A Gateway is used to convert the call-signalling data into a format that the PSTN can understand.

B. A list of IP addresses is kept on a central database.

C. An ATA is used to locate the distant ends physical location.

D. A CODEC is used to convert the distant ends IP address to a PSTN number.

Which one briefly explains ASCII ?

A. For it is a code made from 7 bits so can give 32 combinations

B. For it is a code made from 7 bits so can give 128 combinations

C. For it is a code made from 8 bits so can give 64 combinations

D. For it is a code made from 8 bits so can give 256 combinations.

Which one best explains Asynchronous Communications?

A. Information sent at regular intervals always synchronised to the start of every minute.

B. Information that is sent without any delay or processing.

C. Information that is delayed to it is multiplexed with more than one data stream.

D. Information that is sent, as and when it is needed with a structured header / start / stop, sequence of bit(s).

Which one best explains use of Pulse Amplitude Modulation?

A. A digital signal that has been made from a sampled analogue input to make a 64kb data stream.

B. An analogue output of multiple pulse voltages restricted to 64 levels.

C. A digital data stream sampled from the analogue clock signal of 8khz.

D. Analogue output of 64kb taken from a varying digital telephone handset input.

Which one best explains quantum steps and the binary codes that represent them in the PCM / PAM process?

A. A digital sequence of 8 bits that represent one of 64,000 levels that are sampled at 8khz.

B. Each level of the sampled input has to be rounded up or down to be represented by a digital bit pattern, increasing the number of levels will increase the bandwidth needed.

C. A digital data stream sampled from the analogue clock signal of 8khz .

D. Analogue output of 64kb taken from any one of the 125 steps that have been sampled from a varying digital telephone handset input.

In digital Line formatting which method is the simplest one first used to reduce the DC line build up on the line?

A. AMD3

B. RTZ

C. UniPolar +/- 12V.

D. PSK

On a V.24 interface DSR is:

A. Asserted by a modem to tell the DTE when its receive buffers are not full.

B. Asserted by a terminal to tell the DCE that it is powered up and not in test mode.

C. Asserted by a terminal to tell the DCE when its receive buffers are not full.

D. Asserted by a modem to tell the DTE that it is powered up and not in test mode.

What is the obvious difference from a V35 compared to a X21 interface?

A. X21 is a 25 way connector the V35 is a 15 way.

B. V35 is a 34 way connector the X21 is a 25 way.

C. V35 is a 34 way connector the X21 is a 15 way.

D. It is only the voltage levels and pin out numbers that are different.

What is in the ITU recommendation for G732?

A. It states that 128Mbs PCM signalling is used in all of the 32 Time slots available.

B. It states that AMD3 signalling and coaxial 50 cable should be used.

C. It states that the Data Frame should contain 32 data channels 2 of them are for synch & signaling.

D. It states that sixteen signalling/synchronisation Time slots are allocated and unavailable for voice data.

What is in the ITU recommendation for X25?

A. It states that data is sent down the line in a 25 way connector so as to maintain noise immunity.

B. It states how data is sent down the line and lists the protocols as to how the data is ‘packaged’ for re transmission between the Network layer, Data Link Layer & the Physical Layers.

C. It states that the data is sent down two TX lines so the data can be duplicated to enable copies to be made for security

D. It states that 25 way ‘D’ Type connectors are used at DTE equipment only.

How is PDH made up?

A. Layers of multiplexers in groups of 8 in each layer with 30 inputs at the bottom stage..

B. Layers of multiplexed inputs with 30 channels in the 1st & then grouped in layers of four at a time from then on.

C. Layers of four inputs at a time starting with 64 inputs at the bottom stage.

D. A single layer of High speed command and control drag & drop type multiplexer.

What advantage does SDH have over PDH?

A. SDH Has the ‘Multiplexer Mountain’ so it has better management and control capabilities.

B. SDH uses dual frequency matched back up facilities so it can copy signals to alternate destinations.

C. SDH does not have the PDH ‘multiplexer mountain’. SDH has greater capability for management & control data to be sent in the header also.

D. SDH sends data in a continuous stream so as to prevent ‘eavesdropping’ when any ‘call’ is started.

How is Fibre optics better than Copper? Eg, Twisted Pair (Cat5)?

A. Fibre Optics uses light so it can use a narrower Bandwidth & cost less than copper to send data.

B. The Low noise and greater security and narrow bandwidth allows a cost effective way to transmit data.

C. Because FO is a very low loss / long haul system it allows a wide bandwidth and high data rate for a small physical size.

D. Because FO is a large size narrow bandwidth system it can send data in a secure way because it is more rugged than copper

In Fibre Optics, what is the best explanation as to why Lasers are used?

A. To overcome Chromatic Dispersion within Fibre Optic cables.

B. To overcome Spatial Coherence in the Fibre Optic cables.

C. For easy Maintenance.

D. To generate Low Power modulated light signals.

In Fibre Optics, what is the minimum recommended bend radius for a fibre cable, before permanent damage is likely ?

A. 8 Times the Diameter of the cable.

B. 12 Times the Radius of the Cable.

C. .8 Times the Diameter of the Cable.

D. 12 Times the Diameter of the Cable.

In Fibre Optics, what is the best way to overcome Modal Dispersion?

A. Use Stepped Index Fibre.

B. By using ‘On-Chip Slice Edge’ LED’s

C. Use 650 nm Wavelength Light.

D. Use Graded Index Fibre.

Analogue 4 Wire working is better than 2 Wire working because:-

A. More DC Balance is achieved.

B. Crosstalk is reduced.

C. Balanced DC Signalling Filters the Inaudible Voice.

D. Hybrid coils are no longer needed.

Which one best explains Voice Over Internet Protocol (VOIP)?

A. Passing data files over the internet in real time.

B. Passing data files over a dedicated internet link.

C. Passing stored voice communications over the internet as extra bandwidth becomes available.

D. Passing analogue messages over an analogue network.

White noise in Digital Systems comes from:-

A. The effect of the Analogue Signals interfering with the Power supplies.

B. The effect of the electrons passing through the component and it heating up.

C. The effect of the Power supplies Transformers at mains voltage frequencies only.

D. Bad shielding from atmospheric radiation.

Signal to noise ratio is:-

A. The Ratio between the wanted signal power over the unwanted signal power.

B. The Ratio between the unwanted signal power over the wanted signal power.

C. Only an issue in Analogue Signalling.

D. Only an issue in Digital Signalling.

White noise in Data communications:-

A. Will not be amplified in Analogue systems.

B. Can only be removed by filters.

C. Will be mostly removed from the input signal each time in Digital regeneration.

D. Can only be removed by Analogue Amplifiers.

PSTN was not very suitable for Digital Data communications because:-

A. The effects of crosstalk Is constant at all times as illustrated in Nyquists 5th Law.

B. Shannons Law on Signal to noise Ratio means signal levels will be too low.

C. It was designed for Analogue Voice.

D. Kirchoffs Law on Current flow in a circuit prevent Analogue Signalling at low frequencies.

Which of these are a Guided Transmission Medium?

A. Focused Micro wave beam.

B. UHF Waveguide.

C. LF Sub Ocean Broadcast.

D. VHF Line of sight Management Radio.

Which one of the following refers to Twisted Pair Transmission Media?

A. Multi strand core surrounded by two layers of insulation & a twisted mesh of copper wire.

B. An Unbalanced Single Line with metal foil over copper strands.

C. Unbalanced single conductor wrapped in foil / insulation & A twisted shield around it.

D. A Single conductor or Multi Strand core wrapped in insulation & Twisted with another of the same type.

Which one of the following refers to Co Axial Transmission Media?

A. A single or Multi strand core surrounded by a layer of insulation & a twisted mesh of copper wire around it with insulation around it.

B. Two Balanced Lines with an insulator around each conductor.

C. Balanced Multi strand core surrounded by two layers of insulation & a twisted mesh of copper wire.

D. Multi Cored Cable of six or more Multi Stranded conductors each wrapped in insulation & Twisted with a shield around it.

Which one of the following refers to Microwave Transmission Media?

A. ELF focused beam in a line of sight to its compliment tower.

B. Troposphere scatter SHF Twin Dipole- Dish Line of Sight Masts for distances up to 5km.

C. ¼ Wave Di-Pole VHF Line of sight Tower to Tower communications.

D. EHF focused beam in a line of sight to its compliment tower.

Which one of the following refers to HF Transmission Media?

A. 3MHz-30MHz omni-directional Antenna transmission.

B. 300Hz–3kHz omni-directional Antenna transmission.

C. 20Hz-20kHz omni-directional Antenna transmission.

D. 30GHz-300GHz omni-directional Antenna transmission.

Which one of the following refers to principles of Transmission Line Propogation?

A. Co-Axial, Twisted Pair use Electromagnetic & Fibre Optic uses Electrostatic energy.

B. Co-Axial, Twisted Pair use Electrostatic & Fibre Optic uses ElectroKinetic energy.

C. Co-Axial, Twisted Pair use ElectroKinetic & Fibre Optic uses Optical energy.

D. Co-Axial, Twisted Pair use Electromagnetic & Fibre Optic uses Optical energy.

Which one of the following refers to Di-Electric losses in Transmission Lines?

A. Can be called the V2R Losses, is directly proportional to Voltage across the conductors and also increases with higher frequencies.

B. Can be called the I2R Losses, is Indirectly proportional to Resistance across the conductors and also increases with higher frequencies.

C. Can be called the V2R Losses, is Indirectly proportional to Voltage across the conductors and also increases with higher frequencies.

D. Can be called the I2R Losses, is directly proportional to Resistance of the conductors and also increases with higher frequencies.

Which one of the following refers to Characteristic Impedance and power transfer on wire transmission lines?

A. Is always best to have the load at half the impedance to the source & Line.

B. Is always best to have the load the same impedance to the source & Line.

C. Is always best to have the load at twice impedance to the source & Line.

D. Is always best to have the load at the same impedance to the source regardless of the line.

Which one of the following refers to Copper Losses in Transmission Lines?

A. Is a minimal loss that only affects high frequencies if it is a solid strand centre core.

B. Is a loss that is caused by the heating up & breakdown of the Di-Electric and increases with Voltage and Frequency.

C. Is directly proportional to Voltage Capacitance of the Di-Electric and decreases with higher frequencies.

D. Is a loss caused by the heating up of the conductor & varies with the quality and size of the conductor(s).

Which one of the following refers to Radiation Losses in Transmission Lines?

A. Is a minimal loss that only affects high frequencies if it is a Multi strand centre core.

B. Is a loss that is caused by the heating up & breakdown of the Di-Electric and increases with Voltage and Frequency.

C. Is indirectly proportional to Voltage and Inductance of the Di-Electric and decreases with higher frequencies.

D. Is a loss caused by the energy being emitted from the conductor & varies with the quality of the materials & shielding.

What facilities are covered by the ITU-TS Recommendations for the V-series?

A. They are the ones that list the way manufacturers produce all equipment so the colours and packaging for distribution/shipping are all the same.

B. They Co-ordinate the number of different power supply options and voltages that equipment can be plugged into.

C. They are the organisation that makes sure all communication systems charge the standby power supply backups in communication equipments.

D. They list the voltage levels, pin out data & functions of the connections.

What facilities are covered by the ITU-TS Recommendations for the G-series?

A. They cover the way the Frame format is including time slot allocation & Line Coding.

B. They Co-ordinate the way the data can be moved within the middle layer of the OSI 7 layer model.

C. They Co-ordinate the way the data can be moved within the first three layers of the OSI 7 layer model.

D. They only list the voltage levels, pin out data & functions of the multi 15 way connections.

Why Multiplex?

A. It is the best way to maximise the bandwidth available.

B. Multiplexing is the best way of combining analogue and digital signals on the same Media.

C. As per the OSI 7 Layer Model, Multiplexers can be used to change analogue to digital.

D. Use Multiplexers to convert digital signals if they need to be converted into analogue for transmission to lines.

Which one best explains Time Division Multiplexing (TDM)?

A. Many inputs are sampled at their input frequencies and combined to make an identical output baud rate to the Input rate.

B. Inputs are sampled and combined to make an aggregate output of a greater baud rate to line.

C. Many inputs are sampled at their input frequencies and combined to a slower output baud rate to line.

D. Inputs are sampled and combined to make an aggregate output that is identical to the baud rate it of each input.

Which one best explains Circuit Switching?

A. For each ‘call’ a circuit path is made through the shortest route through the system.

B. For each ‘call’ a circuit path is made through the ‘best available’ route and remains in force for the next time the same source / destination wish to ‘call’

C. When a ‘call’ is set up the path can take any available route through the system.

D. When a ‘call’ is set up through the system it always takes the ‘best available’ route and has a backup route set to copy the data so nothing is lost.

Which one best explains Packet Switching?

A. For each ‘Message’ it is ‘chopped up’ into many ‘packets’ and each of them can take any path through the system to be ‘put back together in the correct order at the destination.

B. For each ‘Message’ it is ‘chopped up’ into many ‘packets’ and they all go sequentially through the system via the same route to be ‘put back together in the correct order at the destination.

C. For each ‘Message’ a path is made for the ‘Packets’ to follow through the ‘best available’ route in reverse sequence.

D. For each ‘Message’ a path is followed through the ‘best available’ route is stored each time so if it has to be copied to another destination it can do so at any time.

What is the minimum separation between BLACK, RED and BLUE copper cables?

A. 50cm

B. 10cm

C. 1m

D. 2m

Which one best explains Bit Error Rate?

A. The number of Bits sent - The bit errors that can be distinguished at the other end.

B. It is the number of bits that can be sent / The number of Bit errors that can be distinguished at the other end. .

C. It is the number of bit errors recieved - The number of Bits sent.

D. It is the number of bit errors received / The number of Bits sent.

Which one best explains Bit Rate & Baud rate?

A. Bit Rate is the number of bits per Baud. Baud Rate is the maximum number of signal transitions that can be sent and still be distinguished at the other end.

B. Bit Rate is always the same as Baud rate it is the number of bits that can be sent.

C. Baud Rate is the number of bits per Baud so Baud rate is always larger than the Bit Rate, the Bit Rate is the maximum number of signal transitions That can be sent and still be distinguished at the other end.

D. Bit Rate is the number of bits that can be sent, Baud Rate is the maximum number of signal transitions that can be sent and still be distinguished at the other end.

Which one best explains the function of an Amplitude Shift Keying Modem?

A. A Modem converts Analogue signals in to a ‘Shift Keyed’ Modulated output to line by altering a carrier by its Amplitude.

B. A Modem converts Digital signals in to a ‘Shift Keyed’ Modulated analogue output to line by altering a carrier by its Amplitude.

C. A Modem converts Analogue signals in to a ‘Shift Keyed’ Modulated output to line by altering a carrier by Amplitude and Phase.

D. A Modem converts Digital signals in to a ‘Shift Keyed’ Modulated output to line by altering the carrier by its DC level.

How many stages does the SCIDA engineering change request (ECR) procedure have?

Which one best explains Synchronous Communications?

A. Information sent at regular intervals always synchronised to the start of every minute.

B. Information that is sent in blocks of Data without any delay or processing in bursts with gaps.

C. Information that is structured and or multiplexed so it is in a continuous data stream.

D. Information that is sent as and when it is needed with a structured header / start sequence of bit(s).

Which one best explains use of Pulse Amplitude Modulation, PCM & Quantizing?

A. A Digital signal that has been made from a sampled Analogue input to make a 64bit pattern every 125s.

B. An Analogue signal that is output of multiple pulse voltage levels restricted to 64 levels each 8 bit pattern takes 12.5 s to be sent.

C. Analogue output of 64kb taken from a varying digital telephone handset input with each pulse bit having a duration of 3.9s

D. A Digital data stream of 8 bits made from a sampled Analogue input sampled at a rate of 8khz but rounded up or down to one of 256 levels that takes 3.9s to be sent to line.

Which one best explains quantization noise and how to minimise it in the PCM / PAM process?

A. This is the result of the error from rounding up or down if the sampled input if you have more levels the error is reduced.

B. This is the result of the error from rounding up or down if the sampled input if you reduce the levels by half the error is reduced by half.

C. Quantization noise is an effect generated by the clock signal of 8kHz, decreasing the clock rate to 6.8kHz (This is twice the maximum frequency being sampled) will decrease the Quantisation noise.

D. Quantisation noise is only an issue if a linear scale is used to minimise the quantisation noise the number of steps should be reduced to 64 and use a Logarithmic scale.

In digital Line formatting which method is the one that will reduce the DC line build up on the line and keep timing transitions if you have a long string of ‘Zeros’ sent to line?

A. AMI.

B. RTZ

C. HDB3

D. PSK.

V.11 specifies.

A. Balanced, double-current interface, operating at +/- 10 volts.

B. Unbalanced, double-current interface, operating at +/- 10 volts.

C. Balanced, double-current interface, operating at +/- 25 volts.

D. Unbalanced, double-current interface, operating at +/- 25 volts.

V.28 specifies which aspect of a physical interface?

A. Electrical

B. Mechanical

C. Procedural

D. Functional

What is in the ITU recommendation for X21?

A. It states that data is sent down the line in an unbalanced way so as to maintain noise immunity.

B. It states that data is sent down in phase on two data lines so they can be combined to make a bigger clearer signal at the RX end..

C. It states that the data is sent down two TX lines in anti-phase and the noise is cancelled out when they are both compared at the RX end.

D. It states that two signalling lines are reverse double buffered so the data transmission is to be sent at twice the normal TX data rate.

Where in the OSI seven layer model does X25 operate?

A. Data Link Layer up to the Session Layer.

B. Physical Layer and Data Link Layer only.

C. Physical Layer to the Network Layer.

D. Physical Layer to the Session Layer.

What is SDH?

A. A single multiplexer system that puts a ‘header’ in front of the payload that ‘indexes’ the data.

B. Four matched and synchronised Analogue multiplexers for fibre optic data links.

C. A set of 8 layers of high speed matched multiplexers that send parallel high speed signals.

D. Fibre optic dual frequency Synchronised Digital High speed Analogue multiplexer system.

What does the LASER safety acronym “COFFEE” represent ?

A. Chemical, Optical, Fibre Fragments, Environment and End Caps

B. Chemical, Optical, Fibre Fragments, Environment and Electrical Hazards

C. Chemical, Optical, Fibre Fragments, Environment and Energy Dispersion

D. Chemical, Optical, Fibre Fragments, Environment and Everyone

In Fibre Optics, Patch Leads are used for?

A. Permanent connections between other Fibre Optic cables.

B. For User Communications using an ODTR.

C. To deliberately introduce a 12db loss for testing purposes.

D. To provide a flexible connection for switching or meter connections

What piece of test equipment gives an electronically produced graph of power losses (Measured in db’s) in a Fibre Optic system.?

A. An ODTR.

B. A Calibrated laser Power Source & Matched Laser Power Meter.

C. A Laser Pen.

D. An OTDR.

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