Welcome to B.A.R.K.’s TECHNICIAN CLASS

1. Welcome to B.A.R.K.’sTECHNICIAN CLASS Your Computer goes Ham Digital # 12

2. Your Computer It is often be argued that Morse code is actually a digital signal because it is a binary transmission, a short and a long tone. Amateurs use the International Morse code.

3. Your Computer Morse code can be sent by three different methods : a straight key, an electronic keyer or by keyboard/ software.

4. Your Computer Amateurs are always at the forefront of technology. When computers first became available they were quickly co-opted into the radio shack. In fact, amateurs invented a system of sending data by radio long before the Internet boom.

5. Your Computer The computer’s sound card takes audio from you transceiver to the microphone input where the received audio is converted to a digital form. Rigblaster Often another piece of hardware, such as a Rigblaster or a Signal Link, is used to control the transceiver microphone switch from the computer as well as transmitting and receiving audio. Signal Link USB

6. Your Computer Amateurs developed their own digital transmission software. The most common types of digital transmissions on the amateur radio bands include, packet radio, PSK31 and MFSK. Most software developed by amateur radio operators is free or shareware. The more intricate software, such as satellite tracking programs, is available for a nominal fee.

7. Your Computer Packet radio was the first digital communication system developed by amateurs. The Tucson Amateur Packet Radio Club played a major role in developing the software and hardware necessary for this mode. Packet radio was considered cutting edge technology during the 1980’s and early 1990’s and large radio networks were built to transmit data across the country. Although still used on the HF bands by packet enthusiasts, packet has significantly waned since the Internet boom. FM packet radio continues to be a common mode for digital satellite communications.

8. Your Computer Packet radio uses an AX.25 packet format. The format requires a terminal node controller (TNC) to interface between a radio and a computer. A TNC assembles and disassembles data packets. TNC’s also have an internal modem to convert baseband digital signals to audio tones. The audio tones are transmitted over the air and then reassembled. They are then converted back to data by a TNC at the receive site.

9. Your Computer • Packet Radio includes some attractive features: • Check sum for error detection • - Packet header which contains call sign of the station • to which the data is being sent • Parity bit- an extra code element used to detect errors • in received data • Automatic repeat request in the case of error

10. Your Computer Before we discuss more digital transmission systems, let’s talk about the problems associated with sending and receiving data by radio frequencies. The ionosphere is the part of our atmosphere that refracts radio waves. The ionosphere is constantly changing in height and depth AND is subject to atmospheric noise. Signal fading and noise is detrimental to digital transmissions. Additionally, RF signals are subject to multiple paths. VHF and UHF data signals that propagate over multiple paths will likely have increased bit error rates (BER).

11. Your Computer In 1998 Phase Shift Keying 31 Baud was introduced. PSK31 is a low rate data transmission mode that has two advantages: - It occupies vary little bandwidth -It is an effective low-power communication method. Digipan PSK31 Software The blue colored signal display is called the “Waterfall”.

12. Your Computer APRS= Automatic Packet Reporting System. APRS is a digital communications protocol for exchanging information between a large number of stations covering a large area. . An amateur station used to connect other APRS stations through the Internet is called a “Gateway”.

13. Your Computer The data propagated by digipeaters may be location reports, local weather information or text messages. Often a GPS is utilized for automatic location reports. Kenwood dual bander plugged into the Avmap G5 GPS position plotter.

14. Your Computer VOIP = Voice Over the Internet Protocol. Amateurs use the Internet to inter-connect repeaters. The two most common VOIP systems are Internet Radio Linking Project (IRLP), and Echolink. You can find active VOIP nodes in the ARRL Repeater Directory.

15. Your Computer Echolink and IRLP- You can connect to other Echolink nodes by through a simplex radio, a repeater or directly from your computer. IRLP node can not be connected to directly by a computer. When using a portable radio select connect to an active IRLP or Echolink node by using your radio’s keypad to transmit the node ID number.

16. Your Computer 16

17. Your Computer Amateur also use fast and slow scan television. The standard television format is NTSC (National Television Standard Code). Also referred to as Never Twice the Same Color!

18. Your Computer Amateurs can use the 6 meter band for remote control of models. Because RC transmitters are not capable of being programmed to send a station identification, they are required to have a label listing the operator’s name, call sign and address affixed to the transmitter.

19. Your Computer The maximum power allowed when transmitting telecommand signals to radio controlled models is 1 watt. Hams can use the 6-Meter Band to radio control a model aircraft.

20. Let’s Review !

21. T8D09 What code is used when sending CW in the amateur bands?A. BaudotB. HammingC. International MorseD. Gray

22. T8D09 (C)What code is used when sending CW in the amateur bands?A. Baudot B. HammingC. International MorseD. Gray

23. T8D10 Which of the following can be used to transmit CW in the amateur bands?A. Straight KeyB. Electronic KeyerC. Computer KeyboardD. All of these choices are correct

24. T8D10 (D)Which of the following can be used to transmit CW in the amateur bands?A. Straight KeyB. Electronic KeyerC. Computer KeyboardD. All of these choices are correct

25. T8D01 Which of the following is an example of a digital communications method?A. PacketB. PSK31C. MFSKD. All of these choices are correct

26. T8D01 (D)Which of the following is an example of a digital communications method?A. Packet B. PSK31 C. MFSKD. All of these choices are correct

27. T4A06 Which of the following would be connected between a transceiver and computer in a packet radio station?A. TransmatchB. MixerC. Terminal node controllerD. Antenna

28. T4A06 (C)Which of the following would be connected between a transceiver and computer in a packet radio station?A. Transmatch B. MixerC. Terminal node controllerD. Antenna

29. T4A07 How is the computer’s sound card used when conducting digital communications using a computer?A. The sound card communicates between the computer CPU and the video displayB. The sound card records the audio frequency for video displayC. The sound card provides audio to the microphone input and converts received audio to digital formD. All of these choices are correct

30. T4A07 (C)How is the computer’s sound card used when conducting digital communications using a computer?A. The sound card communicates between the computer CPU and the video display B. The sound card records the audio frequency for video displayC. The sound card provides audio to the microphone input and converts received audio to digital formD. All of these choices are correct

31. T8D08 Which of the following may be included in packet transmissions?A. A check sum which permits error detectionB. A header which contains the call sign of the station to which the information is being sentC. Automatic repeat request in case of errorD. All of these choices are correct

32. T8D08 (D)Which of the following may be included in packet transmissions?A. A check sum which permits error detectionB. A header which contains the call sign of the station to which the information is being sentC. Automatic repeat request in case of errorD. All of these choices are correct

33. T8D11What is a "parity" bit?A. A control code required for automatic position reportingB. A timing bit used to ensure equal sharing of a frequencyC. An extra code element used to detect errors in received dataD. A "triple width" bit used to signal the end of a character

34. T8D11 (C)What is a "parity" bit?A. A control code required for automatic position reportingB. A timing bit used to ensure equal sharing of a frequencyC. An extra code element used to detect errors in received dataD. A "triple width" bit used to signal the end of a character

35. T3A11 Which part of the atmosphere enables the propagation of radio signals around the world?A. The stratosphereB. The troposphereC. The ionosphereD. The magnetosphere

36. T3A11 (C)Which part of the atmosphere enables the propagation of radio signals around the world?A. The stratosphere B. The troposphereC. The ionosphereD. The magnetosphere

37. T7B12 What does the acronym "BER" mean when applied to digital communications systems?A. Baud Enhancement RecoveryB. Baud Error RemovalC. Bit Error RateD. Bit Exponent Resource

38. T7B12 (C)What does the acronym "BER" mean when applied to digital communications systems?A. Baud Enhancement RecoveryB. Baud Error RemovalC. Bit Error RateD. Bit Exponent Resource

39. T3A10 What may occur if VHF or UHF data signals propagate over multiple paths?A. Transmission rates can be increased by a factor equal to the number of separate paths observedB. Transmission rates must be decreased by a factor equal to the number of separate paths observedC. No significant changes will occur if the signals are transmitting using FMD. Error rates are likely to increase

40. T3A10 (D)What may occur if VHF or UHF data signals propagate over multiple paths?A. Transmission rates can be increased by a factor equal to the number of separate paths observedB. Transmission rates must be decreased by a factor equal to the number of separate paths observedC. No significant changes will occur if the signals are transmitting using FMD. Error rates are likely to increase

41. T8B11 What is a commonly used method of sending signals to and from a digital satellite?A. USB AFSKB. PSK31C. FM PacketD. WSJT

42. T8B11 (C)What is a commonly used method of sending signals to and from a digital satellite?A. USB AFSK B. PSK31C. FM PacketD. WSJT

43. T8D02 What does the term APRS mean?A. Automatic Position Reporting SystemB. Associated Public Radio StationC. Auto Planning Radio Set-upD. Advanced Polar Radio System

44. T8D02 (A)What does the term APRS mean?A. Automatic Position Reporting SystemB. Associated Public Radio StationC. Auto Planning Radio Set-upD. Advanced Polar Radio System

45. T8D03 Which of the following is normally used when sending automatic location reports via amateur radio?A. A connection to the vehicle speedometerB. A WWV receiverC. A connection to a broadcast FM sub-carrier receiverD. A Global Positioning System receiver

46. T8D03 (D)Which of the following is normally used when sending automatic location reports via amateur radio?A. A connection to the vehicle speedometerB. A WWV receiverC. A connection to a broadcast FM sub-carrier receiverD. A Global Positioning System receiver

47. T8D06 What does the abbreviation PSK mean?A. Pulse Shift KeyingB. Phase Shift KeyingC. Packet Short KeyingD. Phased Slide Keying

48. T8D06 (B)What does the abbreviation PSK mean?A. Pulse Shift KeyingB. Phase Shift KeyingC. Packet Short KeyingD. Phased Slide Keying

49. T8D07 What is PSK31?A. A high-rate data transmission modeB. A method of reducing noise interference to FM signalsC. A method of compressing digital television signalD. A low-rate data transmission mode

50. T8D07 (D)What is PSK31?A. A high-rate data transmission modeB. A method of reducing noise interference to FM signalsC. A method of compressing digital television signalD. A low-rate data transmission mode