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G2E

OPERATING PROCEDURES

- Digital mode operating procedures

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G2E011 of 15

Which mode is normally used when sending RTTY signals via AFSK with an SSB transmitter?

Why Amateur RTTY grew out of mechanical teleprinters driving direct FSK, where the mark tone is higher in frequency than the space tone. When you feed audio tones into an SSB transmitter instead, lower sideband inverts the audio so the resulting RF mark and space land in the conventional (non-inverted) order. So the long-standing convention for AFSK RTTY on HF is lower sideband, and using upper sideband instead produces a reversed signal the other station cannot decode.
Watch out Upper sideband is the tempting pick because most other HF digital modes such as PSK31, FT8 and JS8 are run on USB, but RTTY is the classic exception. Double sideband and CW are not SSB transmit modes for feeding audio tones at all.
RTTY is the oddball: everything else digital is USB, RTTY AFSK is LSB. R for Reversed.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E022 of 15

What is VARA?

Why VARA is a software modem developed by EA5HVK that uses OFDM (many parallel subcarriers) to move data over HF, VHF and UHF. It is most commonly paired with Winlink, the radio email system, as a transport protocol alongside older modes like ARDOP and Pactor. VARA HF fits in about 2.3 kHz of SSB bandwidth and adapts its speed to channel conditions, which is why Winlink gateways widely support it.
Watch out The low signal-to-noise weak-signal mode used for EME is JT65 or Q65 from the WSJT-X family, not VARA; VARA is aimed at throughput, not digging signals out of the noise.
VARA and Winlink go together: think 'VARA carries the mail.'
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E033 of 15

What symptoms may result from other signals interfering with a PACTOR or VARA transmission?

Why PACTOR and VARA are ARQ (Automatic Repeat reQuest) modes: the receiving station checks each data frame and acknowledges it, and the sender repeats anything that fails the check. When another signal corrupts frames, the sender keeps retrying and eventually times out, the data flow stalls with long gaps while the stations wait for acknowledgments, and if the interference hits during the initial handshake the link never gets established at all. All three symptoms are just different stages of the same problem, so every listed choice is correct.
Watch out Each single symptom is real, but picking only one misses that interference degrades an ARQ link at every stage, from linking through data transfer.
ARQ = ask again. Interference means retries, stalls, and no connection - so 'all of these' fits.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E044 of 15

Which of the following is good practice when choosing a transmitting frequency to answer a station calling CQ using FT8?

Why FT8 runs on strict 15-second time slots, and stations alternate: if the CQing station transmits in the even slots, your reply goes out in the odd slots. Since your signal only shares the band with other stations transmitting in your slot, the clear spot you need is one that is quiet during the alternate slot, not during the CQ. Watching the waterfall while the calling station transmits tells you nothing about who will be on that audio frequency when it is your turn.
Watch out Looking for a clear frequency during the same slot as the caller checks the wrong half of the cycle, and it is the mirror-image trap answer; that traffic is not what you will be competing with. Calling on the station's own frequency is an option some operators use, but it is not the practice the question is asking about.
FT8 ping-pongs every 15 s: you transmit in the OTHER slot, so hunt for a clear spot in that other slot.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E055 of 15

What is the standard sideband for JT65, JT9, FT4, or FT8 digital signal when using AFSK?

Why Nearly all modern digital modes sent as audio frequency-shift keying through an SSB transmitter use upper sideband, and the WSJT-X family (JT65, JT9, FT4, FT8) is no exception. With USB the transmitted RF frequency equals the dial frequency plus the audio tone frequency, so tones map in the same order on every band and everyone's decoder agrees on the signal's position in the passband. If one station used LSB the tone ordering would invert and the transmission would not decode.
Watch out The choice that says LSB reflects the voice convention on 160, 80 and 40 meters, but that tradition applies only to phone; digital operation stays on USB on all bands. DSB and SSB are not sideband selections a transceiver offers for these modes.
Digital is always Upper, on every band. Voice switches sidebands, data does not.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E066 of 15

What is the most common frequency shift for RTTY emissions in the amateur HF bands?

Why Amateur HF RTTY uses frequency shift keying, where the transmitter alternates between two tones, mark and space. The separation between those two tones is the shift, and the amateur standard on HF is 170 Hz paired with 45.45 baud Baudot code. Your mark and space filters in the decoder must match that shift or the signal will not print.
Watch out 850 Hz was the older wide shift used in commercial and military teleprinter circuits and is still seen in some legacy gear, but it is not the amateur HF norm; 85 Hz and 425 Hz are narrow and commercial shifts not standard for ham RTTY.
Ham RTTY = 170 Hz shift at 45 baud. Think "170/45"; 850 Hz is the old wideband commercial shift.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E077 of 15

Which of the following is required when using FT8?

Why FT8 is a strictly time-synchronized mode: transmissions start at the top of each 15-second interval, and the decoder searches only a narrow window around that expected start time. Every station therefore needs its PC clock synced to UTC, typically with an internet time service (NTP) or GPS, to within roughly a second. The audio modulation and demodulation are done in software by programs like WSJT-X, so no external hardware modem is needed, just a sound card interface.
Watch out The special hardware modem choice describes older packet or RTTY setups using a TNC; FT8 does all of that in software. Antenna polarization and receiver attenuator settings have nothing to do with the protocol, though keeping received audio at a modest level does help decoding.
FT8 = 15-second slots, so keep the clock within about 1 second. Sync the PC, not the antenna.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E088 of 15

In what segment of the 20-meter band are most digital mode operations commonly found?

Why By long-standing band plan convention, the digital data modes on 20 meters cluster just above the RTTY/CW portion, in the 14.070 to 14.100 MHz range. That is where you find PSK31 near 14.070 MHz and FT8 at 14.074 MHz, with the segment ending at 14.100 MHz where the NCDXF international beacons operate. These are voluntary band plans, not FCC rules, but everyone follows them so digital signals can find each other.
Watch out The 14.230 MHz choice is the well-known SSTV calling frequency in the phone segment, and 14.325 MHz is voice as well, so neither is where keyboard-to-keyboard or FT8 traffic lives.
20 m digital: 14.070 to 14.100. Remember 14.074 for FT8 and 14.100 for the beacons that cap the segment.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E099 of 15

How do you join a contact between two stations using the PACTOR protocol?

Why PACTOR is an ARQ (automatic repeat request) mode: the two stations establish a handshaked link in which the receiving station acknowledges each data frame and the sender repeats anything that arrives corrupted. That handshake is addressed between exactly two call signs, so there is no mechanism for a third station to be added to the link. Others can listen in monitor mode, but they cannot join the QSO; they must wait until the link is cleared and then call.
Watch out Sending a NAK, or any transmission on the frequency, only corrupts the linked pair's frames and forces retries; NAK is part of the internal ARQ handshake, not a way to break in. A steady carrier is deliberate interference and does not create a connection for you.
PACTOR is a handshake, not a roundtable: two stations only. Monitor if you like, but you cannot join.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E1010 of 15

Which of the following is a way to establish contact with a digital messaging system gateway station?

Why Digital messaging gateways such as Winlink RMS stations publish their operating frequencies and mode in station lists, and you reach them over the air by sending a connect request (for example a packet or ARDOP/VARA connect) on that frequency. The gateway is automated: it answers the connect frame and then negotiates the link, so no voice or CW calling is involved. Your software just needs the gateway's callsign and its published channel.
Watch out Emailing the control operator is backwards, since the whole point of the gateway is to pass your email over radio, and QRL in Morse simply asks whether a frequency is busy. Gateways do not broadcast an SSID for you to answer; an SSID is only a suffix that distinguishes multiple stations under one callsign.
Look up the published frequency, then send a connect request. Radio link first, email later.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E1111 of 15

What is the primary purpose of an Amateur Radio Emergency Data Network (AREDN) mesh network?

Why AREDN (Amateur Radio Emergency Data Network) firmware turns inexpensive commercial Wi-Fi routers into amateur band nodes on frequencies like 2.4 GHz, 3.4 GHz and 5.8 GHz that automatically link to each other in a self-healing mesh. The point is a local high-speed IP network that can carry VoIP, video, file transfer, email and served-agency applications when the internet or other infrastructure is down, or to support a public service event. It is a data infrastructure, not a voice repeater system or a reporting service.
Watch out The propagation-monitoring choice describes systems like WSPR, PSK Reporter or the Reverse Beacon Network, and the spotting choice describes DX cluster networks, both of which are internet-based reporting tools rather than an emergency data network.
Read the name: Amateur Radio EMERGENCY DATA Network. Emergency plus data equals high-speed data in emergencies.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E1212 of 15

Which of the following describes Winlink?

Why Winlink is a worldwide radio email system that lets amateurs pass messages into and out of the internet email system through volunteer gateway stations. On VHF/UHF it commonly runs AX.25 packet radio, and on HF it uses modes such as Pactor, ARDOP, VARA HF and WINMOR, so it operates on both VHF and HF. Since it is a radio email network, is built on packet-style protocols, and works on both VHF and HF, every listed description fits.
Watch out Each single description is true but incomplete; picking just the email one or just the packet one ignores the others, and the pool wants the full picture.
Winlink = radio email, packet based, VHF and HF gateways. Three true statements means take the all-of-the-above choice.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E1313 of 15

What is another name for a Winlink Remote Message Server?

Why Winlink is an email-over-radio system where stations on the air connect to an RMS (Remote/Radio Message Server) that relays their traffic to and from the internet email system. Because it bridges two different networks, RF and the internet, it is called a gateway. Users connect to a gateway with Winlink Express over VHF/UHF packet or HF modes such as VARA or Pactor.
Watch out A Terminal Node Controller is just the modem hardware that turns data into packet tones at an individual station; it does not provide the internet link. RJ-45 is the 8-pin connector used for Ethernet cabling.
RMS bridges radio to internet email, and a bridge between networks is a gateway.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E1414 of 15

What could be wrong if you cannot decode an RTTY or other FSK signal even though it is apparently tuned in properly?

Why FSK decoding requires the receiver and software to agree on three things: which tone is mark and which is space, the signaling rate (45.45 baud for standard amateur RTTY, but other rates exist), and the sideband in use. Getting the mark/space assignment backwards inverts every bit, so the decoder prints garbage; amateur RTTY is normally sent LSB, and choosing USB by mistake reverses the tone sense the same way. A baud rate mismatch means the software samples the bit stream at the wrong intervals, so nothing lines up. Because all three faults produce a signal that looks tuned in but decodes as nonsense, all the listed causes apply.
Watch out Each individual choice is a real failure mode, so picking just one, such as reversed mark and space, misses the fact that the sideband and baud rate errors cause exactly the same symptom.
Tuned in but gibberish? Check the three S's: sideband, speed (baud), and shift sense (mark/space).
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
G2E1515 of 15

Which of the following is a common location for FT8?

Why FT8 uses a set of well-known dial frequencies by band, and on 20 meters that is 14.074 MHz USB. Because each FT8 signal occupies only about 50 Hz and stations spread out across the 3 kHz audio passband, the actual occupied spectrum runs from roughly 14.074 to 14.077 MHz. Sticking to these standard watering holes is what makes the mode work, since everyone must be listening in the same slice to decode each other.
Watch out The 14.110 to 14.113 MHz range is in the digital/data region but is not the FT8 calling segment; historically that area saw other data and automatic operations. FT8 lives in the data segment near the bottom of the band, not in the CW or phone portions.
20 meter FT8: dial 14.074, signals spread to 14.077. Remember 074 and add 3 kHz.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
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