technician license course chapter 5.3 & 5

Technician License Course Chapter 5.3 & 5.4

Digital Communications, Power Supplies & Batteries

KI0KK

Text related to a question is in red

Text in Italics is a key term or definition

Links are in blue

Answers to review questions are red and bold in the slide following the question

Slide Information

2/6/2021 2021 Technician License Course - SFTARC 2

5. 3 Digital Communications


Technician HF Digital Privileges


Technician VHF/UHF Digital Privileges


Basic Digital Communication Setup (VHF/UHF)

Why use digital – For error free communications

Computers are a key component on any modern amateur radio station not just for digital modes (logging, sending CW)

Digital data is composed of 1s and Øs that are converted into tones

Combinations of protocols, digital codes and modulation types create a digital mode

Newer SDR radios integrate the Modem/TNC into the radio


Digital Signal Types


Computer Modem/TNC Radio Radio Modem/TNC Computer

Digital (Data

Stream)

Audio Tones Digital

Audio Tones

Modulated RF

Radio Waves (Air Link)

The message is in a different form throughout

the communication system

Example of a RTTY Baudot Code


On an oscilloscope, the digital data stream looks like a series of varying patterns of pulses in time.

HF Digital Communications Setup


A USB sound card

Requires a USB to Serial Adapter on most computers

Possible RF interference

HF • CW, yes it is a digital mode

• RTTY, early mode that started with mechanical teletype

• PSK31, Keyboard-to-keyboard

• WSJT Modes - FT8, FT4 & WSPR, Weak signal and propagation monitoring

• Pactor or Winmor, Winlink system messaging

VHF/UHF • AX.25, Packet radio (145.01 -145.09 Mhz)

• APRS, Automatic Packet Reporting System (144.39 Mhz)

• B2F, Winlink system messaging

• JT65 for Moonbounce and MSK144 fro scatter paths

• IEE 802.11 (WiFi) Amateur use on microwave bands

Digital Modes (Data)


CW - Digital Communications at its Best


Packet Radio

AX.25 data packets consist of a header, data and a checksum

Packet Radio has:

A header that contains the call sign of the address

A checksum that permits error detection

ARQ that detects an error and sends a retransmission request to the sending station

Most AX.25 is via APRS now

Packet Radio information in the ARRL Handbook

Simplex frequencies at 145.01 to 145.09 Mhz, 1200 and 9600 baud


PSK31 Ham Radio Deluxe DM780

PSK –phase shift keying, 31 baud

Popular keyboard-to-keyboard conversational mode

Good weak signal

Replaced older RTTY mode that uses the Baudot code

Now replaced by FT8

Other software; FLDIGI, DIGIPAN

Additional mode info on the web at sftarc.org

See slide 8 for a typical set up


https://sftarc.org/index.php/on-the-air-main-menu/operating-modes-menu/16-digital-modes-article

Automatic Position Reporting System (APRS)

Automatically provides location information, weather or short text

Provides real-time tactical communications in conjunction with a map display

An APRS station is a packet radio station combined with a GPS receiver providing the position data

Most used frequency 144.39 Mhz


https://aprs.fi/!lat=38.572&lng=-94.8937

Wi-Fi and Broadband Hamnet

ARDEN

The organization supporting Broadband Hamnet

Uses available Wi-Fi devices with modified firmware on Ham Bands near WiFi

KC Mesh is the Kansas City group for Hamnet

Local Network Map

Can transmit Video, Email, VoIP many other IP based formats

Limited to short range with no high node


https://www.arednmesh.org/

https://groups.io/g/KCmesh/topics

http://136.35.2.156:8083/meshmap/map_display.php11/38.8226/-94.7348

KIØKK Mesh Devices (Portable)


GL.iNET Devices

Mesh Fixed Node Devices

Ensor 5.9Ghz Ubiquiti Node Rocket Radio


Winlink Internet Gateway

Winlink sends emails over the air

Provides an Internet Gateway via Amateur Radio

Used for email forwarding to the internet


HF • AOR

• Free DV

VHF/UHF • D-STAR (ICOM), limited use in the KC area

• System Fusion (Yaesu C4FM and Wirex-X, KC Room)

• DMR (Digital Mobile Radio, BackYard Repeater Group)

• P25

Covered in more detail in Chapter 6

Digital Modes (Voice)


http://www.dstarinfo.com/home.aspx



http://www.icomamerica.com/en/products/amateur/dstar/dstar/default.aspx

https://www.youtube.com/watch?v=FiQcmAb_e70

http://www.kansascityroom.com/

https://www.youtube.com/watch?v=5FAFt1QCtC0

http://c5.byrg.net/WP_BYRG_WWW/dmr-info-page/

Regional Fusion Repeaters


KC Room KS/MO Fusion

5.4 Power Supplies & Batteries


Review Questions Section 5.3 – Digital Communications


A. For logging contacts and contact information

B. For sending and/or receiving CW

C. For generating and decoding digital signals

D. All of these choices are correct

How might a computer be used as part of an

amateur radio station?


T4A02 HRLM (5-11)

A. For logging contacts and contact information

B. For sending and/or receiving CW

C. For generating and decoding digital signals


How might a computer be used as part of an

amateur radio station?


T4A02 HRLM (5-11)

A. Baudot

B. Hamming

C. International Morse


What code is used when sending CW in the

amateur bands?


T8D09 HRLM (5-11)

A. Packer radio

B. IEE 802.11

C. JT65


Which of the following is a digital

communications mode ?


T8D01 HRLM (5-11)

A. An amateur-radio-based data network using

commercial Wi-Fi gear with modified firmware

B. A wide-bandwidth digital voice mode employing

DRM protocols

C. A satellite communications network using

modified satellite TV hardware

D. An internet linking protocol used to network

repeaters

Which of the following best describes

Broadband-Hamnet™, also referred to as a

high-speed multi-media network?


T8D12 HRLM (5-12)

A. Moonbounce or Earth-Moon-Earth

B. Weak-signal propagation beacons

C. Meteor scatter

D. All of the above choices are correct

Which of the following operating activities is

supported by digital mode software in the

WSJT-X suite


T8D10 HRLM (5-12)

A. A wideband FM voice mode

B. A digital mode capable of operating in low signal-

to-noise conditions that transmits on 15-second

intervals

C. An eight channel multiplex mode for FM repeaters

D. A digital slow scan TV mode with forward error

correction and automatic color compensation

What is FT8?


T8D13 HRLM (5-12)

A. A wideband FM voice mode

B. A digital mode capable of operating in low

signal-to-noise conditions that transmits on

15-second intervals

C. An eight channel multiplex mode for FM repeaters

D. A digital slow scan TV mode with forward error

correction and automatic color compensation

What is FT8?


T8D13 HRLM (5-12)

A. A check sum that permits error detection

B. A header that contains the call sign of the station

to which the information is being sent

C. Automatic repeat request in case of error


Which of the following may be included in

packet transmissions ?


T8D08 HRLM (5-12)

A. A special transmission format limited to video

signals

B. A system used to encrypt command signals to an

amateur satellite

C. A digital scheme whereby the receiving station

detects errors and sends a request to the sending

station to retransmit the information

D. A method of compressing the data in a message

so more information can be sent in a shorter time

What is an ARQ transmission system ?


T8D11 HRLM (5-13)

A. A special transmission format limited to video

signals

B. A system used to encrypt command signals to an

amateur satellite

C. A digital scheme whereby the receiving

station detects errors and sends a request to

the sending station to retransmit the

information

D. A method of compressing the data in a message

so more information can be sent in a shorter time

What is an ARQ transmission system ?


T8D11 HRLM (5-13)

A. Pulse Shift Keying

B. Phase Shift Keying

C. Packet Short Keying

D. Phased Slide Keying

What does the abbreviation “PSK” mean ?


T8D06 HRLM (5-13)

A. Automatic Packet Reporting System

B. Associated Public Reporting System

C. Auto Planning Radio Set-up

D. Advanced Polar Radio System

What does the term “APRS” mean ?


T8D02 HRLM (5-13)

A. The vehicle speedometer

B. A WWV receiver

C. A connection to a broadcast FM sub-carrier-

receiver

D. A Global Positioning System receiver

Which of the following devices is used to provide data to

the transmitter when sending automatic position reports

from a mobile amateur radio station ?


T8D03 HRLM (5-13)

A. Providing real-time tactical digital communications

in conjunction with a map showing the locations of

stations

B. Showing automatically the number of packets

transmitted via PACTOR during a specific time

interval

C. Providing voice over internet connection between

repeaters

D. Providing information on the number of stations

signed into a repeater

Which of the following is an application of

APRS (Automatic Packet Reporting

System)?


T8D05 HRLM (5-14)

A. Providing real-time tactical digital

communications in conjunction with a map

showing the locations of stations

B. Showing automatically the number of packets

transmitted via PACTOR during a specific time

interval

C. Providing voice over internet connection between

repeaters

D. Providing information on the number of stations

signed into a repeater

Which of the following is an application of

APRS (Automatic Packet Reporting

System)?


T8D05 HRLM (5-14)

A. Headphone output

B. Mute

C. Microphone or line input

D. PCI or SDI

Which computer sound card port is

connected to a transceiver's headphone or

speaker output for operating digital modes ?


T4A04 HRLM (5-15)

A. Receive and transmit mode, status and location

B. Antenna and RF power

C. Receive audio, transmit audio and push-to-talk

D. NMEA GPD location and DC power

Which of the following connections might be

used between a voice transceiver and a

computer for digital operation ?


T4A06 HRLM (5-15)

A. Receive and transmit mode, status and location

B. Antenna and RF power

C. Receive audio, transmit audio and push-to-

talk

D. NMEA GPD location and DC power

Which of the following connections might be

used between a voice transceiver and a

computer for digital operation ?


T4A06 HRLM (5-15)

A. The sound car communicates between the

computer CPU and the video display

B. The sound card records the audio frequency for

the video display

C. The sound card provides audio to the radio's

microphone input and converts received audio to

digital form

D. All of these choice are correct

How is a computer’s sound card used when

conducting digital communications ?


T4A07 HRLM (5-15)

A. The sound car communicates between the

computer CPU and the video display

B. The sound card records the audio frequency for

the video display

C. The sound card provides audio to the radio's

microphone input and converts received

audio to digital form

D. All of these choice are correct

How is a computer’s sound card used when

conducting digital communications ?


T4A07 HRLM (5-15)

A. A gateway

B. A repeater

C. A digipeter

D. A beacon

What name is given to an amateur station

that is used to connect other amateur

stations to the internet ?


T8C11 HRLM (5-15)

Power Supplies


Power Supplies

Most modern radios runs on 12 volts DC (13.8V)

Household current is 120 volts AC

A Power supply converts 120 volts AC to 12 volts DC 13.8 volts dc is the common voltage

you will see

This is the charging voltage for vehicles and lead acid batteries


Alinco DM-330MVT

30A $160

Key Power Supply Ratings Input Voltage

Output Voltage

Continuous and Intermittent output current

A power supply Regulator circuit controls changes in the output voltage vs output current Voltage regulation is measured as a percentage of voltage

change between no load and full load

The current rating of the supply must be at least equal to the maximum current of all attached devices

Power Supply Ratings


Measuring the Voltage & Current


+

- Voltmeter

Ammeter

Power

Supply Radio

DC wiring should be as short as

possible and of sufficient gauge

to carry the load with limited

voltage drop. E = I X R

Types of Power Supplies

Linear Heavy and large (physically) More robust Easier to repair

Switching Light weight and small More electronics inside More difficult to repair Can cause radio noise (HF)

Price $100 - $200 Linear are usually more


What do you need?

Regulated

Current Rating

Handie Talkie – At least 2 - 3 A

VHF/UHF mobile – At least 10 - 12 A

HF Radio (12)V– At least 20 A

Some HF Radios have the Power Supply built in.

Practical Power Supply Concerns


Wiring Considerations Fuse in both positive and negative leads at the power

connection

Negative lead to the negative battery terminal or the battery cable ground point to the frame. Watch for vehicle battery monitoring systems.

Use grommets or other protective devices where the wiring passes through the firewall

Don’t assume all metal is connected to the battery negative ground

Alternator whine is caused by noise on the DC power system inside you own vehicle

Mobile Power Wiring


Batteries


Creates current through a chemical reaction

Made up of individual cells (approximately 1.5 to 3.6 volts per cell) connected in series.

Battery types

Disposable, Non-Rechargeable or Primary

Rechargeable or Secondary

Storage (rechargeable)

Available in different voltages and capacities

Battery Facts


Battery Types


Battery Capacity


Power capabilities rated in Ampere-hours.

Amps x Time

Expressed in: • Amp hours (A-hr)

• milliAmp hours (mA-hr)

600 mA-hr

3000 mA-hr (3 A-hr)

Some batteries can be recharged, some cannot

Use the proper charger for the battery being charged

Batteries will wear out over time

Best if batteries are maintained fully charged. Over-charging will cause heating and could damage the battery

Storage battery chargers must switch to float level once the battery is fully charged

Lead-acid batteries release explosive gasses during charging so provide adequate ventilation

Battery Charging


Storage Battery Charging Tips

Storage Batteries have a lot of energy

Hazardous if acid is spilled

Can be charged with a car in an emergency

Run the engine

If charged or discharged too quickly, a storage battery may:

Overheat

Give off flammable gas

Explode


Battery Tips

Store in a cool, dry place.

Regularly inspect the batteries for leakage.

Accidental short circuiting a battery can cause a fire and damage the battery.

For maximum life, draw current from the battery at the slowest rate needed


Review Questions Section 5.4 Power Supplies and Batteries


A. Efficiency of the transmitter at full power

B. Receiver and control circuit power

C. Power supply regulation and heat dissipation

D. All of the above choice are correct

What must be considered to determine the

minimum current capability for a transceiver

power supply ?


T4A01 HRLM (5-16)

What must be considered to determine the

minimum current capability for a transceiver

power supply ?

A. Efficiency of the transmitter at full power

B. Receiver and control circuit power

C. Power supply regulation and heat dissipation

D. All of the above choice are correct


T4A01 HRLM (5-16)

A. About 12 volts

B. About 30 volts

C. About 120 volts

D. About 240 volts

How much voltage does a mobile

transceiver typically require ?


T5A06 HRLM (5-16)

A. Regulator

B. Oscillator

C. Filter

D. Phase inverter

What type of circuit controls the amount of

voltage from a power supply ?


T6D05 HRLM (5-16)

A. The ignition system

B. The alternator

C. The electric fuel pump

D. Ant0lock braking system controllers

What is the source of a high-pitched whine

that varies with speed in a mobile

transceiver's receive audio ?


T4A10 HRLM (5-17)

A. The ignition system

B. The alternator

C. The electric fuel pump

D. Antilock braking system controllers

What is the source of a high-pitched whine

that varies with speed in a mobile

transceiver's receive audio ?


T4A10 HRLM (5-17)

A. At the battery or engine block ground strap

B. At the antenna mount

C. To any metal part of the vehicle

D. Through the transceiver’s mounting bracket

Where should the negative return of a

mobile transceiver's power cable be

connected ?


T4A11 HRLM (5-17)

A. The battery could over heal, give off flammable

gas or explode

B. The voltage could become reversed

C. The memory effect will reduce the capacity of the

battery

D. All of these are correct

What can happen if a lead-acid battery is

charged or discharged too quickly ?


T0A10 HRLM (5-19)

A. The battery could over heal, give off

flammable gas or explode

B. The voltage could become reversed

C. The memory effect will reduce the capacity of the

battery

D. All of these are correct

What can happen if a lead-acid battery is

charged or discharged too quickly ?


T0A10 HRLM (5-19)

A. Nickel-metal hydride

B. Lithium-ion

C. Lead-acid gel-cell

D. All of the choices are correct

Which of the following battery types is

rechargable


T6A10 HRLM (5-17)

A. Nickel-cadmium

B. Carbon-zinc

C. Lead-acid

D. Lithium-ion

Which of the following battery types is not

rechargable


T6A11 HRLM (5-17)

A. Nickel-cadmium

B. Carbon-zinc

C. Lead-acid

D. Lithium-ion

Which of the following battery types is not

re-chargable


T6A11 HRLM (5-17)

technician license course chapter 5.3 & 5

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