Lesson 2 HF Procedures and Practices Overview

Transcription

1 Lesson 2 HF Procedures and Practices Overview

2 On Display QSL Cards

3 On Display Icom IC-7000

4 On Display Buxcomm Rascal Sound card interface: PSK31 SSTV RTTY Packet Digital Voice MFSK16 -more-

5 Operating Techniques What does CQ DX mean? How do you break into a voice conversation? How do you break into a CW or digital conversation?

6 Signal Separation What is the recommended signal separation? CW SSB RTTY PSK Hz Approximately 3 khz Hz Hz

7 Operating Guidelines What is a Band Plan? What is a DX Window?

8 DX Window DX Window 80 Meters

9 Basic Operation How do you call CQ? -Voice - CW/Digital

10 Study Guide Review Why is it important to maintain a log of your contacts?

11 Study Guide Review Why is it important to maintain a log of your contacts? Station Worked Date Time Frequency (or just band) FCC may require info: Control Operator and date or time!

12 Study Guide Review What do you do when you notice increasing interference? Don t Blow Up!

13 Definition of Terms Modes ways of conveying information. Modulation the process of impressing or overlaying information to be conveyed onto the RF carrier wave. RF carrier the radio signal that is sent from the transmitter to receiver. Bandwidth the amount of spectrum required (occupied) to convey the information.

14 Voice Modulation AM Amplitude Modulation SSB Single Side Band FM Frequency Modulation PM Phase Modulation

15 AM Vary the amplitude of the RF carrier in step with the applied voice waveform.

16 Amplitude Modulation Q&A G8 Page 1

17 SSB SSB one sideband is filtered out, as well as the carrier (suppressed when no audio is present).

18 SSB allows for available power to be concentrated into the remaining sideband. Less bandwidth SSB Transmitter Amplitude modulated, double sideband, with carrier Q&A G8 Page 5

19 SSB Receiver The missing sideband is recreated in the receiver as a mirror image of the sideband sent. (through a beat frequency oscillator (BFO) and another mixer)

20 Which Sideband Do I Use? 160M 80M 40M Lower SSB 60M = USB Only! 9 MHz Upper SSB 20M 17M 15M 12M 10M 6M VHF/UHF

21 Frequency Modulation (or) Phase Modulation Frequency is varied in step with the voice waveform. Large amplitude large frequency shift (deviation). Small Amplitude small frequency deviation. Important point voice volume depends on frequency deviation, not amplitude variation.

22 FM = Frequency Modulation No FM Deviation Voice (talking into mic) FM Deviation Q&A G8 Page 3

23 FM/PM The deviation setting between the TX and RX equipment must match for effective operation. TX narrow, RX wide low volume. TX wide, RX narrow splatter, distortion, clipping. Q&A G8 Page 2

24 VOX Operation CQ CQ CQ this is N9CHA N9CHA Hands-Free Operation V O X Voice Operated Transmit Adjustments - VOX Delay - VOX Sensitivity - Anti-VOX

25 CW Data modulation concerns two states, on and off. Morse code is simplest data mode, you turn the RF carrier on and off to form dits and dahs. A BFO in the receiver adds some audio to the dits and dahs so that you hear a tone in the speaker. The Begali Signature paddle, uses magnets for return rather than springs.

26 CW - QSK Can you hear between your signals? C Q To break in, you try and get a dit into the space. Space (quiet) The sending stations transceiver must be QSK-able to hear you. QSK = Full Break In

27 CW Abbreviations K = Over KN = Go Only DE = This is (from) QRS = Send slower QRQ = Send quicker QRV = Ready to copy QSL = Acknowledge receipt CL = Closing station

28 CW Best Practices How fast should I send when answering a CQ? Zero Beat to be sure you are on frequency RST = Readability, Signal Strength, Tone 579 C = Chirp AR = End of Message

29 Data Modulation Techniques FSK (frequency shift keying) AFSK (audio frequency shift keying) PSK (phase shift keying) All techniques depend on one state for on, the other state for off. Techniques used to capture the receiver circuitry to improve signal to noise ratio (and therefore accuracy). All?SK modes are 100 percent duty cycle.

30 Digital Modes Band Plan = PSK = Beacons Auto Operation

31 RTTY Radioteletype Based on a 5 bit code called BAUDOT. Used primarily on HF. Comes from the old mechanical teletype days though now mostly by computer. Uses FSK 170 Hz shift on HF No error correction capabilities.

32 BITS AND BAUDS RTTY ASCII Packet PSK31 5 bit - 45 Baud 8 bit and 300 Baud 8 bit /9600 Baud? Bit - 31 Baud (Varicode) Bit = on/off state of data Baud = complete symbol

33 Baudot - Developed in 1870 by Emile Baudot (Fr) - 5 level (+ start/stop bit), 32 possible combinations START BIT Read Down G 170 Hz Shift SPACE OFF 2125 Hz MARK ON 2295 Hz SPACE OFF 2125 Hz MARK ON 2295 Hz MARK ON 2295 Hz STOP BIT Speed = Baud or 60 WPM

34 MFSK Multi-Frequency Shift Keying MFSK16 uses 16 different tones Narrow bandwidth (300 Hz) Able to withstand fading and distortion No error correction Speed = 42 WPM

35 AMTOR AMateur Teletype Over Radio Two modes of AMTOR ARQ (Automatic Repeat request) FEC (Forward Error Correction)

36 AMTOR ARQ ARQ TX and RX linked by handshaking. Three letters sent at a time with error check. Letters repeated until timeout or received correctly. Almost 100%.

37 AMTOR FEC FEC No handshaking. Three letters sent, then the second 3 letters, then first 3 repeated and so-on. RX compares 3 letter pairs and prints the best copy. Not 100% but better than RTTY.

38 PACTOR PACket Teletype Over Radio Similar to AMTOR but more and variable group length to take advantage of changing band conditions. Code more computer like which allows for easier transmission of computer compatible data. Very good error correction.

39 PSK31 Similar to RTTY in that no handshake between RX/TX. Code is a 7 bit code, therefore more characters (upper and lower case etc.). Error correction allowed by transmitting operation (backspace and delete). Transmission technique requires very little bandwidth. Many, many contacts allowed simultaneously in the same space taken by one voice QSO.

40 Packet Very much like computer communication mode HF and VHF Full error correction Forward and relay capabilities Requires a smart modem (TNC) or specialized software that takes advantage of sound card technology

41 Video SSTV (Slow Scan TV) sending snapshots. Generally an HF mode. Uses SSB for transmission. Gray (color) scale represented by amplitude of the wave, low black, high white. Picture built one line at a time.

42 Emergency Communications Amateur Radio Emergency Service Radio Amateur Civil Emergency Service

43 Emergency Communications As a ham, you are NOT allowed to assist a broadcaster prepare a news production or broadcast. Only in the rare instance when there is a threat to life or property, and if there is no other means of communications possible.

44 Emergency Communications Siren Tornado Aftermath When NORMAL communications are not available, use any means possible. Threat to life or property must be taken seriously. All of the normal rules for amateur radio can be broken! Get assistance!

45 Emergency Communications The FCC may restrict normal frequency operations to RACES members when the War Emergency Powers have been activated by the President of the US.

46 Emergency Communications It s your job to transmit essential communications to facilitate relief actions. Transmit the LOCATION and NATURE of the emergency! Lake Delton, WI June 9, 2008