2 Introduction: First Contacts For most amateurs, their first solo-contacts tend to be on 2m or 70cm (VHF/UHF respectively)Recall: 2m = MHz & 70cm = MHzOnly basic qualifications requiredAffordable equipment for under $100Relatively simple operating proceduresOffers best introduction to local (established) amateurs
4 Operating: Basic Guidelines Listen, Listen, Listen!No matter what the frequency, ensure that you will not interrupt a contact in-progress before transmittingBy listening first, you learn the established etiquette on-airUse only the minimum power necessary to conduct a contactWhen using a “calling frequency” be sure to QSY once establishedDetermine a mutually agreed frequency and move to it to continue chattingAlways comply with the Radiocommunication Act
5 QSO: Methods of making a contact There are three possible schemes for making a contact:SimplexHalf-DuplexFull-DuplexEach method has benefits and drawbacksEase of implementationCost of hardware associatedEtc..
6 Simplex: The most basic QSO Any method of communication which uses the same frequency for transmission and receptionOnly one person may transmit at a time, otherwise, you are “doubling” over each otherSimplest form of communicationEx: Walkie-Talkies as a kid
7 Duplex: Using different TX/RX Freq. Duplex (half and full) is any method of communication which uses different transmit and receive frequenciesHalf-duplex:As with simplex, only one person may transmit at a time for effective communicationRepeaters commonly operate as half-duplexFull-duplex:Seldom used due to the technical challengesCommon example is the cellular telephone
8 Repeaters: A PrimerRepeaters are a very popular resource in amateur radioFrequently used by local residents to improve their “coverage area”Many local “nets” are hosted on repeaters because of their enhanced coverage areaMay be used to link distant geographic locations viaRFEg. VE2REH network in QuebecInternetIRLP, Echolink147.3 MHz147.9 MHz
9 Repeaters: Major Types What:Any radio station which automatically retransmits an input signal to increase the effective range of the original signalGenerally placed in a highly favourable location such as top of a tall building, mountain-top, etc.SimplexHalf-DuplexFull-DuplexCross-Band--HT → Car → APRS iGateSatellite OperationSame-Band“Parrot-Box”StandardRepeaterWiFi & Digital “repeaters”
10 Repeaters: Privileges Basic licensee:Use any open repeaters with operating frequencies which are within the permitted range of the user (ie. your privileges)Basic (70% < 80%) can use only those repeaters which operate on: 6m, VHF, UHFBasic+ (≥80%) may use any repeaters, even those which theoretically retransmit on HFOwn/operate a cross-band repeaterIn addition to Basic privileges, an Advanced operator mayOwn/operate a same-band repeaterRepeater is generally given its own callsign and the input/output frequency pairs are supposed to be managed by a repeater councilMust conform to all Radiocommunication Act requirementsIe. station identification at least every 30 minutes
11 Repeaters: How It Works Simply take an incoming signal and retransmit at higher power, generally in the same band but on a slightly different frequency (the offset)Generally done with two commercial radios designed for this purpose (100% duty cycle)Repeater is generally controlled via DTMF tones and a controller boardHandles on/off operation, CTCSS tones, identificationWhen operating in the same band, a cavity filter (very high Q) is frequently used so that the same antenna can be used for simultaneous TX/RX
12 Coded Squelch: Preventing Noise Sub audible tones used in (RF) noisy environment to trigger a radio’s squelch only when a signal with the associated coded squelch is presentTwo major code types:CTCSSContinuous Tone-Coded Squelch SystemDCS/DTCSDigitally (Tone) Coded Squelch
13 CTCSS: Most Common As many as 50 sub-audible tones Originally only 32 tones, but was adapted to incorporate PL tones (Motorola)67.0 Hz94.8 Hz131.8 Hz171.3 Hz203.5 Hz69.3 Hz97.4 Hz136.5 Hz173.8 Hz206.5 Hz71.9 Hz100.0 Hz141.3 Hz177.3 Hz210.7 Hz74.4 Hz103.5 Hz146.2 Hz179.9 Hz218.1 Hz77.0 Hz107.2 Hz151.4 Hz183.5 Hz225.7 Hz79.7 Hz110.9 Hz156.7 Hz186.2 Hz229.1 Hz82.5 Hz114.8 Hz159.8 Hz189.9 Hz233.6 Hz85.4 Hz118.8 Hz162.2 Hz192.8 Hz241.8 Hz88.5 Hz123.0 Hz165.5 Hz196.6 Hz250.3 Hz91.5 Hz127.3 Hz167.9 Hz199.5 Hz254.1 Hz
14 DCS: Seldom UsedDCS superimposes FSK data (134.4bps) onto the transmitted signalSimilar to CTCSS, the DCS data serves to prevent squelch opening unless the correct data is receivedHas great potential, however, control boards are more cumbersome to implement
15 Repeaters: How to start To use a repeater, you need some information:Repeater’s TX & RX frequenciesRepeaters are listed by the frequency at which they transmitYou must determine the repeater’s receive (listening) frequency by using the offset for the band the repeater is operating onControl tone(s) (if used)Often used in radio-congested areas to reduce unwanted retransmission of garbageGenerally listed with the repeater’s TX frequency
16 Repeaters: Simple Example Let’s use VE3TWO as an example. It is listed simply as:This is the repeater’s transmit frequencyFollowing convention, we know that repeaters which operate on 2m use 0.6 MHz as the offset value (unless otherwise stated)The (+) means a positive offset frequency for the repeater’s receive frequency so we add 0.6 MHz to determine the “listening” frequency147.3 MHz MHz = MHzVE3TWO MHz (+)
17 Repeaters: Advanced Example Suppose a repeater is listed as:To use the repeater, set your radio to:RX on MHzusing CTCSS tone on receiveTX on MHzusing CTCSS tone on transmit*unless otherwise stated, assume that CTCSS tones are listed as (out/in)VE3FAKE MHz (-) (151.4 / 110.9)*
18 A’s Incoming 70cm RF link locked out by 2m reception (in use) Repeater Linking: RFRepeaters may be linked to each other by an RF link to increase total coverage areaWhen you transmit on repeater A’s input (listen) frequency, all repeaters (including A) retransmit your signal“Hi Tom..”147.4 MHz“Hi Tom..”A’s Incoming 70cm RF link locked out by 2m reception (in use)BBlue = 2m “open repeater” frequencyRed = 70cm “rf link” frequencyyoudistantstation(Tom)PTT is pressedMHzMHzMHz“Hi Tom..”147.4 MHz(-)MHz (+0.6)AC146.3 MHzMHzMHz“Hi Tom..”MHz(-)MHz (-0.6)146.3 MHz(+)MHz (-0.6)
19 Repeater Linking: Internet IRLPInternet Radio Linking ProjectRadio↔ Repeater (A)Repeater (B) ↔ RadioMHz(+)Node: 2001146.7 MHz (-)Node: 2002InternetUsing your radio which is set to: (TX MHz, RX MHz) you would link to the distant repeater by pressing: “2002” on the DTMF keypad while holding the PTT buttonOnce the IRLP link is established, you could then transmit to your local repeater and have the distant repeater (B) retransmit at 146.7MHz
20 Repeater Linking: Echolink Echolink is similar to IRLP with the exception that you can link to distant repeaters directly from a computer, dropping the radio-to-repeater portion of the linkTheoretically possible to have straight echolink-to-echolink contacts without even using a radioNot really radio any more, huh?
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