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Questions and Answers
What is the typical range of communication between two portable 25W VHF sets?
What is the typical range of communication between two portable 25W VHF sets?
What is the typical power source for fixed 25W VHF sets?
What is the typical power source for fixed 25W VHF sets?
What is the purpose of a feeder cable in VHF communication?
What is the purpose of a feeder cable in VHF communication?
What is the specification for a digital 25W VHF set in Indian Railways Telecom Manual?
What is the specification for a digital 25W VHF set in Indian Railways Telecom Manual?
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What is the typical communication range between two walkie-talkie sets?
What is the typical communication range between two walkie-talkie sets?
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What type of antenna is typically used with fixed 25W VHF sets?
What type of antenna is typically used with fixed 25W VHF sets?
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What is the purpose of a license in VHF communication?
What is the purpose of a license in VHF communication?
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What type of coaxial cable is used as a feeder cable in VHF communication?
What type of coaxial cable is used as a feeder cable in VHF communication?
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What is the primary purpose of adjusting antenna height and orientation in VHF communication?
What is the primary purpose of adjusting antenna height and orientation in VHF communication?
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What is the impedance of the feeder cable used in VHF communication?
What is the impedance of the feeder cable used in VHF communication?
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Who is responsible for obtaining frequency authorization and license from Wireless Planning Commission?
Who is responsible for obtaining frequency authorization and license from Wireless Planning Commission?
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What is the purpose of connecting a 12V/80-120 AH battery to the VHF set?
What is the purpose of connecting a 12V/80-120 AH battery to the VHF set?
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Who is responsible for distributing VHF walkie/talkie sets among various departments and units?
Who is responsible for distributing VHF walkie/talkie sets among various departments and units?
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What is the purpose of earthing the antenna and feeder cable in VHF communication?
What is the purpose of earthing the antenna and feeder cable in VHF communication?
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Who is responsible for procurement and condemnation of VHF sets?
Who is responsible for procurement and condemnation of VHF sets?
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What is the purpose of using a pool system for distributing VHF walkie/talkie sets?
What is the purpose of using a pool system for distributing VHF walkie/talkie sets?
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What is the maximum range of VHF communication due to the requirement of line of sight?
What is the maximum range of VHF communication due to the requirement of line of sight?
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What is the reason for dark zones occurring in VHF communication?
What is the reason for dark zones occurring in VHF communication?
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What is the advantage of Digital Mobile Radio (DMR) over analog sets?
What is the advantage of Digital Mobile Radio (DMR) over analog sets?
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Why is it essential to have line of sight for point-to-point communication in VHF installation?
Why is it essential to have line of sight for point-to-point communication in VHF installation?
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How is the antenna height decided at both locations for VHF installation?
How is the antenna height decided at both locations for VHF installation?
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What is the advantage of using Digital Walkie-Talkie sets over analog sets?
What is the advantage of using Digital Walkie-Talkie sets over analog sets?
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Why do VHF sets consume more power?
Why do VHF sets consume more power?
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What is the significance of the Digital Mobile Radio (DMR) standard?
What is the significance of the Digital Mobile Radio (DMR) standard?
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Who is responsible for providing funds for the procurement and annual renewal of VHF license?
Who is responsible for providing funds for the procurement and annual renewal of VHF license?
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What is the frequency of measuring VHF set's transmitting power at different frequencies/channels?
What is the frequency of measuring VHF set's transmitting power at different frequencies/channels?
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Who is responsible for inspecting fixed VHF installations every month?
Who is responsible for inspecting fixed VHF installations every month?
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What is the frequency of reporting monthly statements of VHF system's failure?
What is the frequency of reporting monthly statements of VHF system's failure?
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What should be done with unserviceable handsets?
What should be done with unserviceable handsets?
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Who is responsible for arranging for repair/replacement of defective VHF sets?
Who is responsible for arranging for repair/replacement of defective VHF sets?
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What is the purpose of keeping spare sets at site or a suitable location?
What is the purpose of keeping spare sets at site or a suitable location?
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What is the frequency of inspecting fixed VHF installations by SSE?
What is the frequency of inspecting fixed VHF installations by SSE?
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What is the primary objective of radio communication?
What is the primary objective of radio communication?
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What is the frequency range of the VLF spectrum?
What is the frequency range of the VLF spectrum?
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What is the primary mode of communication used in Indian Railways?
What is the primary mode of communication used in Indian Railways?
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What is the frequency band allocated by WPC for Indian Railways in VHF communication?
What is the frequency band allocated by WPC for Indian Railways in VHF communication?
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What is the wavelength of the HF spectrum?
What is the wavelength of the HF spectrum?
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What is the primary factor affecting communication in the VHF frequency range?
What is the primary factor affecting communication in the VHF frequency range?
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What is the frequency range of the UHF spectrum?
What is the frequency range of the UHF spectrum?
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What is the classification of the frequency range 3-30 MHz?
What is the classification of the frequency range 3-30 MHz?
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What is the primary mode of propagation for VHF communication?
What is the primary mode of propagation for VHF communication?
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What is the frequency band used in Railways for VHF communication?
What is the frequency band used in Railways for VHF communication?
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What type of operation is used in VHF communication?
What type of operation is used in VHF communication?
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What is the primary advantage of using Digital Radio VHF over analog sets?
What is the primary advantage of using Digital Radio VHF over analog sets?
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What is the purpose of using a duplex VHF set in Indian Railways?
What is the purpose of using a duplex VHF set in Indian Railways?
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What is the limitation of VHF communication due to line of sight?
What is the limitation of VHF communication due to line of sight?
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What type of equipment is used in VHF communication for point-to-point communication?
What type of equipment is used in VHF communication for point-to-point communication?
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What is the primary factor affecting communication in the VHF frequency range?
What is the primary factor affecting communication in the VHF frequency range?
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What is the primary purpose of adjusting antenna height and orientation in VHF communication?
What is the primary purpose of adjusting antenna height and orientation in VHF communication?
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What is the impedance of the feeder cable used in VHF communication?
What is the impedance of the feeder cable used in VHF communication?
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Who is responsible for obtaining frequency authorization and license from Wireless Planning Commission?
Who is responsible for obtaining frequency authorization and license from Wireless Planning Commission?
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What is the purpose of connecting a 12V/80-120 AH battery to the VHF set?
What is the purpose of connecting a 12V/80-120 AH battery to the VHF set?
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Why is it essential to earth the antenna and feeder cable in VHF communication?
Why is it essential to earth the antenna and feeder cable in VHF communication?
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What is the advantage of using a pool system for distributing VHF walkie/talkie sets?
What is the advantage of using a pool system for distributing VHF walkie/talkie sets?
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What is the primary responsibility of the S&T department in VHF communication?
What is the primary responsibility of the S&T department in VHF communication?
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What is the specification of the power supply provided with the VHF set?
What is the specification of the power supply provided with the VHF set?
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What is the maximum range of VHF communication due to the requirement of line of sight?
What is the maximum range of VHF communication due to the requirement of line of sight?
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What is the advantage of Digital Mobile Radio (DMR) over analog sets?
What is the advantage of Digital Mobile Radio (DMR) over analog sets?
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What is essential for point-to-point communication in VHF installation?
What is essential for point-to-point communication in VHF installation?
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Why do VHF sets consume more power?
Why do VHF sets consume more power?
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Who is responsible for providing funds for the procurement and annual renewal of VHF license?
Who is responsible for providing funds for the procurement and annual renewal of VHF license?
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What is the reason for dark zones occurring in VHF communication?
What is the reason for dark zones occurring in VHF communication?
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How often should the VHF set's transmitting power at different frequencies/channels be measured?
How often should the VHF set's transmitting power at different frequencies/channels be measured?
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How is the antenna height decided at both locations for VHF installation?
How is the antenna height decided at both locations for VHF installation?
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What is the responsibility of the nodal supervisors of the user department?
What is the responsibility of the nodal supervisors of the user department?
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What is the advantage of using Digital Walkie-Talkie sets over analog sets?
What is the advantage of using Digital Walkie-Talkie sets over analog sets?
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What should be done with unserviceable handsets?
What should be done with unserviceable handsets?
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What is the limitation of VHF communication due to interference?
What is the limitation of VHF communication due to interference?
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Who is responsible for arranging for repair/replacement of defective VHF sets?
Who is responsible for arranging for repair/replacement of defective VHF sets?
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What is the frequency of inspecting fixed VHF installations by SSE?
What is the frequency of inspecting fixed VHF installations by SSE?
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What should be kept at site or a suitable location to replace the faulty sets?
What should be kept at site or a suitable location to replace the faulty sets?
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Who is responsible for inspecting fixed VHF installations every month?
Who is responsible for inspecting fixed VHF installations every month?
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What is the primary factor affecting communication in the VHF frequency range?
What is the primary factor affecting communication in the VHF frequency range?
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What is the advantage of using Digital Mobile Radio (DMR) over analog sets?
What is the advantage of using Digital Mobile Radio (DMR) over analog sets?
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What is the primary consideration for VHF antenna setup?
What is the primary consideration for VHF antenna setup?
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What is the frequency range of the VHF spectrum allocated by WPC for Indian Railways?
What is the frequency range of the VHF spectrum allocated by WPC for Indian Railways?
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What is the primary mode of communication used in Indian Railways?
What is the primary mode of communication used in Indian Railways?
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What is the primary objective of radio communication?
What is the primary objective of radio communication?
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What is the limitation of VHF communication due to the requirement of line of sight?
What is the limitation of VHF communication due to the requirement of line of sight?
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What is the primary consideration for VHF power and frequency?
What is the primary consideration for VHF power and frequency?
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Study Notes
Radio Communication
- Radio communication involves the transfer of intelligence from one point to another through space using radiated electromagnetic energy (Radio Waves) in the frequency spectrum of 10 KHz to 30,000 KHz.
Radio Frequency Spectrum
- The radio frequency spectrum can be classified into the following categories:
- VLF (Very Low Frequency): 10-30 kHz, wavelength: 30,000-10,000 m
- LF (Low Frequency): 30-300 kHz, wavelength: 10,000-1,000 m
- MF (Medium Frequency): 300-3000 kHz, wavelength: 1,000-100 m
- HF (High Frequency): 3-30 MHz, wavelength: 100-10 m
- VHF (Very High Frequency): 30-300 MHz, wavelength: 10-1 m
- UHF (Ultra High Frequency): 300-3000 MHz, wavelength: 100-10 cm
- MW (Microwave): 3-30 GHz, wavelength: 10-1 cm
Modes of Communication in Indian Railways
- The modes of communication used in Indian Railways are:
- VHF Communication
- UHF Communication
- M/W Communication
VHF Communication
- VHF communication uses the frequency band of 30 MHz to 300 MHz.
- The frequencies allotted by WPC for Indian Railways are in the band 146.2 MHz to 167.95 MHz.
- Communication in this range of frequencies is mainly due to line of sight, reflection, and scattering of waves.
- VHF sets are used for communication between Guard & Driver, between moving train/vehicle with fixed location (Station) or another moving train/vehicle.
Types of VHF Sets
- There are three types of VHF sets:
- Portable 5W VHF Sets: Used for communication between Guard & Driver, between moving train/vehicle with fixed location (Station) or another moving train/vehicle.
- Portable 25W VHF Sets: Normally used in Loco and vehicles operated on 12V battery set.
- Fixed 25W VHF Sets (Base Stations): Installed at desired locations, mainly at ASM rooms, operating on AC Mains or by 12V battery.
Antennas Used
- The following antennas are used:
- Whip Antenna
- Ground Plane (GP) Antenna
- Dipole
- Low Profile
- Yagi Antenna
Feeder Cable
- A 50 Ohms unbalanced coaxial cable is used as a feeder cable.
Expected Communication Range
- The expected communication range is:
- Walkie-Talkie to Walkie-Talkie: 1 to 2 Km
- Portable Set: 12 Km to 15 Km
- Fixed 25W VHF Set to Fixed 25W VHF Set: up to 25 Kms when antenna used are directional & fixed at the height of 15 to 20 metres
Limitations of VHF Communication
- The limitations of VHF communication are:
- Range limited up to 25 Km maximum due to requirement of line of sight
- Dark Zones occur due to terrain, high-rise buildings, and other structures
- VHF sets consume more power, hence the set may require more than one battery set for long duration usage
- Interference due to other users operating at the same frequency
- Effect of prevailing noise in the surrounding
Digital Radio VHF Sets
- Digital Mobile Radio (DMR) is an open standard that is not proprietary to any single manufacturer
- DMR equipment must be compatible, so a radio will work on any base station or network
- Digital Walkie-Talkie sets have several advantages in terms of Voice Quality, Coverage, Battery Life, Channel Capacity, and Data Capabilities
- Digital sets are preferred over Analog sets and Analog sets are to be phased out gradually
- License-exempted Digital VHF set allowed by WPC may be considered for maintenance purpose (non-crew usage)
Installation of VHF
- Point-to-point communication requires the availability of line of sight
- Antenna height must be decided at both locations by measuring minimum field strength needed for satisfactory communication
- Antenna height and orientation can be adjusted to get a maximum signal strength or voice
- Antenna can be mounted on a tower/Mast of approved design or on a pipe on the roof of a building
- Feeder cable must be of 50 Ohm impedance unbalanced of approved design
- Antenna and its feeder cable must be earthed as per earthing arrangement defined in chapter XXIII
Maintenance of VHF Sets
- Maintenance of VHF sets is the responsibility of the S&T department
- Nodal supervisors of the user department shall inform or handover defective sets to the concerned SSE/Tele
- SSE/Tele concerned shall arrange for repair/replacement of these sets for minor defects departmentally and for major defects through authorized agencies/OEM
- Unsustainable handsets should be expeditiously condemned and payment of license fee for those sets to be stopped
Inspection and Failure Report
- Fixed VHF installation must be inspected every month by JE, by SSE once in six months and by ADSTE/DSTE once in a year
- VHF system’s failure must be reported to the controlling officer daily in the morning
- Monthly statements of failure must be reported in the PCDO to Headquarter
- Spare sets must be kept at site or at a suitable location to replace the faulty sets
Frequencies Allotment
- The Railway Board has decided on frequencies for different uses.
Limitations of VHF Communication
- Range limited to 25 Km maximum due to line of sight requirement.
- Dark zones occur due to terrain, high-rise buildings, and other structures.
- VHF sets consume more power, requiring more than one battery set for long-duration usage.
- Interference occurs due to other users operating at the same frequency.
- Prevailing noise in the surrounding area affects communication.
Digital Radio VHF Sets
- Digital Mobile Radio (DMR) is an open standard, not proprietary to any single manufacturer.
- DMR equipment must be compatible, allowing radios to work on any base station or network.
- Advantages of DMR include improved voice quality, coverage, battery life, channel capacity, and data capabilities.
- Digital Walkie-Talkie sets should be preferred over analog sets, with analog sets to be phased out gradually.
Installation of VHF
- Line of sight availability is essential for point-to-point communication.
- Antenna height must be decided at both locations by measuring minimum field strength needed for satisfactory communication.
Uses of VHF Communication
- Traffic control
- Police duties
- Mobile communication
- Point-to-point communication
- Point-to-multi-point (group) communication
- Disaster management
- Possible uses on Indian Railways include:
- Communication during maintenance and construction blocks
- Yard communication
- Communication in the train between Guard and Driver
- Mobile communication between moving trains/vehicles with fixed locations
- Emergency communication
Specification and Performance Parameters
- Frequency range: 30 MHz to 300 MHz
- Frequency band used in Railways: 146.2 MHz to 167.95 MHz
- One spot frequency used for each channel
- Mode of propagation: line of sight, reflection, and scattering of waves
- Type of operation: simplex or duplex
- Channel capacity: 1/16/128/256 channels
- Voice or low-speed data or both
VHF Walkie/Talkie Sets
- Used in several departments of Railways
- Distribution among departments and units under their jurisdiction
- Maintenance and condemnation of VHF sets done by the S&T department
- Frequency authorization and license obtained from Wireless Planning Commission
- Payment of spectrum charges and license renewal done by the S&T department
Maintenance of VHF Sets
- Responsibility of the S&T department
- Nodal supervisors of the user department inform or handover defective sets
- SSE/Tele arranges for repair/replacement of sets
- Unserviceable handsets condemned and payment of license fee stopped
- Annual checks of transmitting power, spur, and other parameters
Inspection
- Fixed VHF installation inspected every month by JE, every six months by SSE, and every year by ADSTE/DSTE
Failure Report
- VHF system failure reported to controlling officer daily
- Monthly statements of failure reported in PCDO to Headquarters
- Spare sets kept at site or suitable location to replace faulty sets
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Description
This quiz covers the basics of radio communication, including the definition, frequency spectrum, and types of radio waves. It's a crucial chapter in understanding analog and digital VHF communication.
