Below the Noise Floor — Episode 9: "FT8: Making Your First Digital Contact"

FT8 is often the easiest path to a first HF contact - no microphone nerves, no real-time conversation pressure. This episode covers the full transmit setup: audio routing from WSJT-X through AetherSDR, CAT control, the FT8 contact workflow from first call to logged QSO.

Transcript

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In the last episode, we talked about making a voice contact, the CQ call, the exchange, the sign-off. Voice operating is the heart of HF for a lot of operators, and eventually it will be for you too. But for a first contact, FT8 has some real advantages worth considering. There's no microphone, no real-time conversation to manage, no worrying about how your audio sounds, or whether you are speaking too close or too far from the mic. The software handles the exchange automatically once you initiate it. You click a call sign on a decoded signal, the software sends your call sign back, they respond, the software answers, and a minute and a half later, you have a logged contact with a station somewhere in the world. The whole thing is orchestrated by the timing engine in WSJTX. For a first transmission on HF, that reduction in complexity is genuinely valuable. You can focus on understanding what is happening rather than managing a real-time conversation. And because FT8 contacts are made at signal levels that would be inaudible to voice, your first contact may well be with a station in another continent on modest power. In episode 6, we covered receive-only setup for WSJTX, routing audio from Ether SDR into WSJTX through a virtual audio cable or loopback device. This episode builds on that. We are going to add the transmit side, routing audio from WSJTX back into Ether SDR so the software can key the radio and transmit your FT8 signal, and we are going to add cat control so WSJTX and Ether SDR stay on the same frequency automatically. Let me start with the audio routing for transmit because it is the piece that is new. In receive only mode, audio flows one direction. EtherSDR receives RF, converts it to audio, and sends that audio to WSJTX for decoding. For transmit, you need the reverse path as well. WSJTX generates the FT8 audio tones and sends them into Ether SDR, which then transmits them as RF. On Linux, this is handled through the same pulse audio or pipewire loopback setup you used for receive, extended to carry audio in both directions. You need a second loopback, one for receive audio going into WSJTX, one for transmit audio coming out of WSJTX into Ether SDR. The Ether SDR documentation and the WSJTX Linux setup guides both cover this configuration. Once both loopbacks are in place, set WSJTX audio output to the transmit loopback and set Ether SDR's microphone input to that same loopback. On Windows, VB Audio Virtual Cable provides one virtual audio device. For a full duplex FT8 setup, where you need separate paths for receive and transmit audio, the free version of VB Audio provides one cable. A second cable requires either the paid VB Audio product or a different virtual audio solution. Many Windows operators use Voicemeter, also from VB Audio, which provides multiple virtual routing channels in a single application. The WSJTX Windows setup documentation walks through VoiceMeter configuration specifically. On Mac OS, Black Hole supports multiple channel counts and can be configured to carry both directions of audio without a second driver. The specifics depend on which Black Hole variant you install. The two-channel version handles most FT8 setups cleanly. The key principle, regardless of platform, WSJTX audio output goes to a virtual device, and Ether SDR's audio input, the same input that would normally receive your microphone, is set to receive from that same virtual device. When WSJTX generates FT8 tones to transmit, those tones arrive at Ether SDR exactly as microphone audio would, and Ether SDR transmits them. Now CAT control. CAT stands for Computer Aided Transceiver. It is the protocol that lets software control a radio's frequency, mode, and other settings remotely. Without CAT control, WSJTX and Ether SDR operate independently. You tune Ether SDR to 14.074 MHz, and WSJTX has to be manually told it is on 20 m FT8. If you change bands in EtherSDR, WSJTX does not know. Cat control links them so WSJTX always knows what frequency EtherSDR is on and can set the correct operating parameters automatically. EtherSDR supports CAT control via a virtual serial port. It emulates a Kenwood TS2000 compatible interface that WSJTX knows how to talk to. To set this up, enable the CAT interface in EtherSDR settings and note the virtual port name it creates in WSJTX under File, then Settings, then Radio, set the rig type to Kenwood TS2000 and point it at the virtual serial port EtherSDR created. Set the baud rate to whatever Ether SDR specifies, typically 9600 or 115200. Once configured, WSJTX will read frequency and mode from EtherSDR automatically and control PTT through the same interface. PTT through CAT is the cleanest option for FT8 because it does not require a separate hardware PTT connection. When WSJTX is ready to transmit, it sends a PTT command over the CAT link, EtherSDR keys the radio, WSJTX transmits the audio tones, and when the transmission ends, WSJTX sends another CAT command to unkey. The whole sequence is synchronized by WSJTX's timing engine and requires no manual intervention. There is one important audio level check before your first FT8 transmission. The ALP audio level percentage display in WSJTX shows the level of audio being generated for transmission. This should be set so the output is clean but not driving Ether SDR's input into saturation. A common mistake is to have WSJTX output at maximum volume, which overdrives the audio path and produces a distorted FT8 signal. FT8 signals should be relatively low level. The mode is efficient and does not need high drive. Set the WSJTX audio output level to around 50% as a starting point and verify in Ether SDR's transmit meter that peaks are not hitting the top of the scale. Also check your power level in Ether SDR before transmitting FT8. For FT8 specifically, lower power is often better. The mode can make contacts at 5 to 10 watts that would be impossible at any power level with voice. Starting at 25 watts on a 15 meter or 20 meter band during reasonable propagation conditions will result in contacts. You can experiment with lower power after your first few contacts. 5 watts FT8 contacts across an ocean are genuinely achievable with a decent antenna. Now let me walk through the actual workflow of making a contact. Start WSJTX with the audio and cat configured. Tune Ether SDR to 14.074 MHz USB mode. WSJTX should reflect the same frequency automatically if CAT is working. In the WSJTX main window, confirm the mode is set to FT8 and that the band activity panel is populating with decoded signals at the top of each 15-second cycle. If you see decodes appearing, rows of call signs, grid squares, and signal reports, the receive side is working. In WSJTX settings, enter your call sign and your four six-character grid square locator. Your grid square is the maidenhead locator for your location. A four-character version like DMs04 for San Diego is sufficient for most purposes. This information is what gets transmitted in your FT8 signal and what the other station needs to log the contact. To make a contact, look at the band activity panel for a station calling CQ. CQ calls are highlighted differently from other traffic in WSJTX, typically in a different color. Find a CQ call from a station you want to work and double-click it. WSJTX will automatically cue a response to transmit at the next available slot in the sequence. The exchange proceeds automatically from there. At the next transmit slot, WSJTX sends your call sign in Grid Square. The other station software receives it, decodes it, and if they double-click your call sign in their band activity panel, they send back a signal report to you. WSJTX receives their report, sends your signal report back to them, along with a confirmation code, they confirm, and WSJTX logs the contact. The whole sequence is four transmissions over about 90 seconds. Watch the TX watchdog timer and the sequence indicator in WSJTX as the exchange progresses. WSJTX shows which message it is currently transmitting and what it is waiting to receive. If the exchange stalls, if the other station does not respond after two or three of your transmissions, WSJTX will eventually time out. This is normal. Not every CQ caller will respond to every caller. Propagation may have changed between when you saw their CQ and when you responded, simply find another station and try again. When a contact completes, WSJTX logs it automatically to an ADIF log file and to its own internal log. If you have PSK reporter reporting enabled, the contact appears on the PSKI reporter map. If you have connected a logging application such as log40M or Ham Radio Deluxe, the contact can be transferred to your main log automatically. A few things worth knowing about FT8 operating practice, you will see operators calling CQDX in the band activity panel. This means they are looking specifically for contacts outside their own country or region. If you are in the same country as a CQDX caller, it is considered poor form to respond. They are specifically seeking foreign contacts and responding as a domestic station wastes one of their transmit slots. Some operators run FT-8 in what is called Fox and Hound mode during de-expeditions, organized expeditions to rare or remote locations specifically to put that location on the air for other operators to contact. Fox and Hound uses a different procedure and different frequencies from standard FT-8. You will see it explained if you encounter it. For initial operating, standard FT-8 on the regular frequencies is all you need. FT-8 contacts do count for awards including DXCC, the premier DX award requiring confirmed contacts with 100 or more countries or territories. Digital mode contacts, including FT8, are fully valid for most awards. This means that your first few weeks of FT-8 operating, if conditions are reasonable, can log an impressive number of different countries relatively quickly. One more thing. The automated nature of FT-8 sometimes raises questions about how much of the contact the operator is actually doing versus the software. The FCC requires that a licensed operator be present and in control during transmission. Running FT-8 fully automatically while you're away from the station is not compliant with that requirement. Being present and initiating contacts deliberately, even if the exchange itself is automated, is the correct practice. That is the full FT-8 transmit setup. Audio routing for both directions. CAT control linking WSJTX to Ether SDR. Power level set conservatively. Call sign and grid square entered. First contact initiated by double-clicking a CQ call and watching the sequence complete. Next episode, we start phase 3. The Ether SDR deep dive. This is below the noise floor.