WEBVTT NOTE Using the Controls 1 00:00:00.000 --> 00:00:01.350 Squelch. 2 00:00:01.350 --> 00:00:08.069 Question. How is squelch adjusted so that a weak FM signal can be heard? 3 00:00:08.969 --> 00:00:16.729 Answer. Set the squelch threshold so that receiver output audio is on all the time. 4 00:00:17.329 --> 00:00:29.775 Just barely open, right at the point where the hiss returns. Anything tighter and weak stations, the ones you most want to hear, are silenced along with the noise. 5 00:00:29.775 --> 00:00:40.083 The instinct is to run squelch tight because hiss is unpleasant. That instinct costs you exactly the contacts that are hardest to make. 6 00:00:40.083 --> 00:00:52.529 Scanning does the opposite job: it tunes through a range of frequencies to check for activity, using the squelch threshold to decide when to stop. Microphone gain. 7 00:00:52.529 --> 00:00:59.572 Question. What is the effect of excessive microphone gain on SSB transmissions? 8 00:01:00.472 --> 00:01:04.672 Answer. Distorted transmitted audio. 9 00:01:05.272 --> 00:01:16.593 On SSB, too much gain overdrives the transmitter and splatters energy into adjacent frequencies, you sound bad and you interfere with neighbours. 10 00:01:16.593 --> 00:01:29.631 On FM the same excess causes overdeviation, which the previous module covered. The fix on FM is to talk further away from the microphone, not to shout from a distance. 11 00:01:29.631 --> 00:01:38.532 Normal conversational level, a couple of inches away, across the microphone rather than into it. Filter bandwidth. 12 00:01:38.532 --> 00:01:47.664 Question. What is the advantage of having a choice of receiver filter bandwidths in a multimode transceiver? 13 00:01:48.564 --> 00:01:56.364 Answer. Permits noise or interference reduction by selecting a bandwidth matching the mode. 14 00:01:56.964 --> 00:02:06.407 Receiver noise power scales with bandwidth, so every hertz of filter wider than the signal is noise admitted for free. 15 00:02:06.407 --> 00:02:16.087 Question. Which of the following receiver filter bandwidths provides the best signal-to-noise ratio for SSB reception? 16 00:02:16.987 --> 00:02:20.627 Answer. 2400 Hz. 17 00:02:21.227 --> 00:02:36.297 An SSB voice signal occupies about 3 kHz, and 2400 Hz captures the intelligible part of it while rejecting a fifth of the noise a 3 kHz filter would admit. 18 00:02:36.297 --> 00:02:53.409 The principle generalises: Mode, CW; Sensible filter, 250 to 500 Hz. Mode, SSB; Sensible filter, 2400 Hz. Mode, FM; Sensible filter, 10 to 15 kHz. Match the filter to the mode. 19 00:02:53.409 --> 00:03:04.882 A CW signal received through an SSB filter is buried in noise that carries no information. Tuning and frequency entry. 20 00:03:04.882 --> 00:03:20.827 A transceiver's operating frequency is entered with the keypad or the VFO knob, and the VFO (Variable Frequency Oscillator) sets the receive and transmit frequency. 21 00:03:20.827 --> 00:03:28.147 Question. What does an FM signal sound like when received slightly off frequency? 22 00:03:29.047 --> 00:03:32.913 Answer. The audio becomes distorted. 23 00:03:33.513 --> 00:03:48.798 Not quieter, not shifted in pitch, distorted. FM demodulation depends on the signal sitting in the middle of the discriminator's range, and off-centre it detects unevenly. 24 00:03:48.798 --> 00:04:04.708 That distinctive muddiness is the sound of being a couple of kilohertz off. On SSB, being off frequency shifts the pitch of the voice instead, and the fix is a dedicated control: 25 00:04:04.708 --> 00:04:16.721 Question. Which of the following controls could be used if the voice pitch of a single-sideband signal returning to your CQ call seems too high or low? 26 00:04:17.621 --> 00:04:22.421 Answer. The RIT or Clarifier. 27 00:04:23.021 --> 00:04:39.022 Receiver Incremental Tuning moves the receive frequency slightly without moving your transmit frequency, so you can correct for the other station's drift without becoming the one who is off. Digital voice configuration. 28 00:04:39.022 --> 00:04:53.488 A DMR "code plug" is configuration data loaded onto your radio to access repeaters and talkgroups. Not a single setting, the whole configuration: channels, talkgroups, colour codes, contacts, zones. 29 00:04:53.488 --> 00:05:02.255 Building one is most of the work of getting on DMR, and shared code plugs for a local area are the usual starting point. 30 00:05:02.255 --> 00:05:12.849 A specific group of stations is selected on DMR by entering the group's identification code, the talkgroup ID. D-STAR takes a different approach. 31 00:05:12.849 --> 00:05:25.781 Your call sign must be programmed into a D-STAR transceiver before transmitting, the call sign is part of every transmission at the protocol level rather than something you say. 32 00:05:25.781 --> 00:05:45.010 What each misadjustment sounds like. Symptom, Cannot hear weak FM stations; Control, squelch too tight. Symptom, Your SSB audio is distorted and splattering; Control, microphone gain too high. 33 00:05:45.010 --> 00:06:00.834 Symptom, Your FM audio drops out on peaks; Control, overdeviation, back off the microphone. Symptom, Received FM sounds muddy; Control, you are off frequency. 34 00:06:00.834 --> 00:06:17.058 Symptom, Received SSB voice sounds too high or low; Control, adjust RIT or clarifier. Symptom, Noise swamps a CW signal; Control, filter too wide. Check yourself. 35 00:06:17.058 --> 00:06:36.487 You cannot hear a station others are working on 2 metres FM. First control to check? Received SSB voice sounds like a chipmunk. Which control? Why is 2400 Hz better than 3 kHz for SSB reception? 36 00:06:42.487 --> 00:06:58.930 Squelch. Open it until the audio is on all the time; weak signals are exactly what a tight squelch removes. RIT or clarifier, it moves your receive frequency without moving your transmit frequency. 37 00:06:58.930 --> 00:07:08.529 It admits less noise while still passing the intelligible part of the voice, so the signal-to-noise ratio improves.