_WSJT-X_ supports a number of features designed for use on the VHF and higher bands. These features include: - *FT4*, designed especially for contesting - *FT8*, designed for making fast QSOs with weak, fading signals - *JT4*, particularly useful for EME on the microwave bands - *JT9 fast modes*, useful for scatter propagation on VHF bands - *JT65*, widely used for EME on VHF and higher bands - *QRA64*, another mode for EME - *MSK144*, for meteor scatter - *ISCAT*, for aircraft scatter and other types of scatter propagation - *Echo* mode, for detecting and measuring your own lunar echoes - *Doppler tracking*, which becomes increasingly important for EME on bands above 1.2 GHz. [[VHF_SETUP]] === VHF Setup To activate the VHF-and-up features: - On the *Settings | General* tab check *Enable VHF/UHF/Microwave features* and *Single decode*. - For EME, check *Decode after EME delay* to allow for extra path delay on received signals. - If you will use automatic Doppler tracking and your radio accepts frequency-setting commands while transmitting, check *Allow Tx frequency changes while transmitting*. Transceivers known to permit such changes include the IC-735, IC-756 Pro II, IC-910-H, FT-847, TS-590S, TS-590SG, TS-2000 (with Rev 9 or later firmware upgrade), Flex 1500 and 5000, HPSDR, Anan-10, Anan-100, and KX3. To gain full benefit of Doppler tracking your radio should allow frequency changes under CAT control in 1 Hz steps. NOTE: If your radio does not accept commands to change frequency while transmitting, Doppler tracking will be approximated with a single Tx frequency adjustment before a transmission starts, using a value computed for the middle of the Tx period. - On the *Radio* tab select *Split Operation* (use either *Rig* or *Fake It*; you may need to experiment with both options to find one that works best with your radio). - On the right side of the main window select *Tab 1* to present the traditional format for entering and choosing Tx messages. The main window will reconfigure itself as necessary to display controls supporting the features of each mode. - If you are using transverters, set appropriate frequency offsets on the *Settings | Frequencies* tab. Offset is defined as (transceiver dial reading) minus (on-the-air frequency). For example, when using a 144 MHz radio at 10368 MHz, *Offset (MHz)* = (144 - 10368) = -10224.000. If the band is already in the table, you can edit the offset by double clicking on the offset field itself. Otherwise a new band can be added by right clicking in the table and selecting *Insert*. image::Add_station_info.png[align="center",alt="Station information"] - On the *View* menu, select *Astronomical data* to display a window with important information for tracking the Moon and performing automatic Doppler control. The right-hand portion of the window becomes visible when you check *Doppler tracking*. image::Astronomical_data.png[align="center",alt="Astronomical data"] Five different types of Doppler tracking are provided: - Select *Full Doppler to DX Grid* if you know your QSO partner's locator and he/she will not be using any Doppler control. - Select *Own Echo* to enable EME Doppler tracking of your receive frequency to your own echo frequency. Your Tx frequency will remain fixed and is set to the Sked frequency. This mode can be used when announcing your CQ call on a specific frequency and listening on your own echo frequency. It can also be used for echo testing with Echo mode. - Select *Constant frequency on Moon* to correct for your own one-way Doppler shift to or from the Moon. If your QSO partner does the same thing, both stations will have the required Doppler compensation. Moreover, anyone else using this option will hear both of you without the need for manual frequency changes. - Select *On Dx Echo* when your QSO partner is not using automated Doppler tracking, and announces his/her transmit frequency and listening on their own echo frequency. When clicked, this Doppler method will set your rig frequency on receive to correct for the mutual Doppler shift. On transmit, your rig frequency will be set so that your QSO partner will receive you on the same frequency as their own echo at the start of the QSO. As the QSO proceeds, your QSO partner will receive you on this starting frequency so that they do not have to retune their receiver as the Doppler changes. Sked frequency in this case is set to that announced by your QSO partner. - Select *Call DX* after tuning the radio manually to find a station, with the Doppler mode initially set to *None*. You may be tuning the band looking for random stations, or to a frequency where a station has been seen on an SDR display. It is usually necessary to hold down the Ctrl key while tuning the radio. From the moment *Call DX* is pressed, your transmit frequency is set so that your echo will fall on the same frequency you (and the DX station) are listening. - See <> for details on the quantities displayed in this window. === JT4 JT4 is designed especially for EME on the microwave bands, 2.3 GHz and above. - Select *JT4* from the *Mode* menu. The central part of the main window will look something like this: image::VHF_controls.png[align="center",alt="VHF Controls"] - Select the desired *Submode*, which determines the spacing of transmitted tones. Wider spacings are used on the higher microwave bands to allow for larger Doppler spreads. For example, submode JT4F is generally used for EME on the 5.7 and 10 GHz bands. - For EME QSOs some operators use short-form JT4 messages consisting of a single tone. To activate automatic generation of these messages, check the box labeled *Sh*. This also enables the generation of a single tone at 1000Hz by selecting Tx6, to assist in finding signals initially. The box labeled *Tx6* toggles the Tx6 message from 1000Hz to 1250Hz to indicate to the other station that you are ready to receive messages. - Select *Deep* from the *Decode* menu. You may also choose to *Enable averaging* over successive transmissions and/or *Enable deep search* (correlation decoding). image::decode-menu.png[align="center",alt="Decode Menu"] The following screen shot shows one transmission from a 10 GHz EME QSO using submode JT4F. image::JT4F.png[align="center",alt="JT4F"] [[VHF_JT65]] === JT65 In many ways JT65 operation on VHF and higher bands is similar to HF usage, but a few important differences should be noted. Typical VHF/UHF operation involves only a single signal (or perhaps two or three) in the receiver passband. We recommend that you check *Single decode* on the *Settings -> General* tab, and do not check *Two pass decoding* on the *Advanced* tab. With VHF features enabled the JT65 decoder will respond to special message formats often used for EME: the OOO signal report and two-tone shorthand messages for RO, RRR, and 73. These messages are always enabled for reception; they will be automatically generated for transmission if you check the shorthand message box *Sh*. *Deep* on the *Decode* menu will be automatically selected. You may optionally include *Enable averaging*, *Enable Deep search*, and *Enable AP*. The following screen shot shows three transmissions from a 144 MHz EME QSO using submode JT65B and shorthand messages. Take note of the colored tick marks on the Wide Graph frequency scale. The green marker at 1220 Hz indicates the selected QSO frequency (the frequency of the JT65 Sync tone) and the *F Tol* range. A green tick at 1575 Hz marks the frequency of the highest JT65 data tone. Orange markers indicate the frequency of the upper tone of the two-tone signals for RO, RRR, and 73. image::JT65B.png[align="center",alt="JT65B"] === QRA64 QRA64 is designed for EME on VHF and higher bands; its operation is generally similar to JT4 and JT65. The following screen shot shows an example of a QRA64C transmission from DL7YC recorded at G3WDG over the EME path at 24 GHz. Doppler spread on the path was 78 Hz, so although the signal is reasonably strong its tones are broadened enough to make them hard to see on the waterfall. The triangular red marker below the frequency scale shows that the decoder has achieved synchronization with a signal at approximately 967 Hz. image::QRA64.png[align="center",alt="QRA64"] The QRA64 decoder makes no use of a callsign database. Instead, it takes advantage of _a priori_ (AP) information such as one's own callsign and the encoded form of message word `CQ`. In normal usage, as a QSO progresses the available AP information increases to include the callsign of the station being worked and perhaps also his/her 4-digit grid locator. The decoder always begins by attempting to decode the full message using no AP information. If this attempt fails, additional attempts are made using available AP information to provide initial hypotheses about the message content. At the end of each iteration the decoder computes the extrinsic probability of the most likely value for each of the message's 12 six-bit information symbols. A decode is declared only when the total probability for all 12 symbols has converged to an unambiguous value very close to 1. For EME QSOs some operators use short-form QRA64 messages consisting of a single tone. To activate automatic generation of these messages, check the box labeled *Sh*. This also enables the generation of a single tone at 1000Hz by selecting Tx6, to assist in finding signals initially, as the QRA64 tones are often not visible on the waterfall. The box labeled *Tx6* switches the Tx6 message from 1000Hz to 1250Hz to indicate to the other station that you are ready to receive messages. TIP: QRA64 attempts to find and decode only a single signal in the receiver passband. If many signals are present, you may be able to decode them by double-clicking on the lowest tone of each one in the waterfall. TIP: G3WDG has prepared a more detailed tutorial on using {QRA64_EME}. === ISCAT ISCAT is a useful mode for signals that are weak but more or less steady in amplitude over several seconds or longer. Aircraft scatter at 10 GHz is a good example. ISCAT messages are free-format and may have any length from 1 to 28 characters. This protocol includes no error-correction facility. === MSK144 Meteor scatter QSOs can be made any time on the VHF bands at distances up to about 2100 km (1300 miles). Completing a QSO takes longer in the evening than in the morning, longer at higher frequencies, and longer at distances close to the upper limit. But with patience, 100 W or more, and a single yagi it can usually be done. The following screen shot shows two 15-second reception intervals containing MSK144 signals from three different stations. image::MSK144.png[align="center",alt="MSK144"] Unlike other _WSJT-X_ modes, the MSK144 decoder operates in real time during the reception sequence. Decoded messages will appear on your screen almost as soon as you hear them. To configure _WSJT-X_ for MSK144 operation: - Select *MSK144* from the *Mode* menu. - Select *Fast* from the *Decode* menu. - Set the audio receiving frequency to *Rx 1500 Hz*. - Set frequency tolerance to *F Tol 100*. - Set the *T/R* sequence duration to 15 s. - To match decoding depth to your computer's capability, click *Monitor* (if it's not already green) to start a receiving sequence. Observe the percentage figure displayed on the _Receiving_ label in the Status Bar: image::Rx_pct_MSK144.png[align="center",alt="MSK144 Percent CPU"] - The displayed number (here 17%) indicates the fraction of available time being used for execution of the MSK144 real-time decoder. If this number is well below 100%, you may increase the decoding depth from *Fast* to *Normal* or *Deep*, and increase *F Tol* from 100 to 200 Hz. NOTE: Most modern multi-core computers can easily handle the optimum parameters *Deep* and *F Tol 200*. Older and slower machines may not be able to keep up at these settings; at the *Fast* and *Normal* settings there will be a small loss in decoding capability (relative to *Deep*) for the weakest pings. - T/R sequences of 15 seconds or less requires selecting your transmitted messages very quickly. Check *Auto Seq* to have the computer make the necessary decisions automatically, based on the messages received. - For operation at 144 MHz or above you may find it helpful to use short-format *Sh* messages for Tx3, Tx4, and Tx5. These messages are 20 ms long, compared with 72 ms for full-length MSK144 messages. Their information content is a 12-bit hash of the two callsigns, rather than the callsigns themselves, plus a 4-bit numerical report, acknowledgment (RRR), or sign-off (73). Only the intended recipient can decode short-messages. They will be displayed with the callsigns enclosed in <> angle brackets, as in the following model QSO CQ K1ABC FN42 K1ABC W9XYZ EN37 W9XYZ K1ABC +02 R+03 RRR 73 + NOTE: There is little or no advantage to using MSK144 *Sh* messages at 50 or 70 MHz. At these frequencies, most pings are long enough to support standard messages -- which have the advantage of being readable by anyone listening in. === Echo Mode *Echo* mode allows you to make sensitive measurements of your own lunar echoes even when they are too weak to be heard. Select *Echo* from the *Mode* menu, aim your antenna at the moon, pick a clear frequency, and toggle click *Tx Enable*. _WSJT-X_ will then cycle through the following loop every 6 seconds: 1. Transmit a 1500 Hz fixed tone for 2.3 s 2. Wait about 0.2 s for start of the return echo 3. Record the received signal for 2.3 s 4. Analyze, average, and display the results 5. Repeat from step 1 To make a sequence of echo tests: - Select *Echo* from the *Mode* menu. - Check *Doppler tracking* and *Constant frequency on the Moon* on the Astronomical Data window. - Be sure that your rig control has been set up for _Split Operation_, using either *Rig* or *Fake It* on the *Settings | Radio* tab. - Click *Enable Tx* on the main window to start a sequence of 6-second cycles. - _WSJT-X_ calculates and compensates for Doppler shift automatically. As shown in the screen shot below, when proper Doppler corrections have been applied your return echo should always appear at the center of the plot area on the Echo Graph window. image::echo_144.png[align="center",alt="Echo 144 MHz"] === Tips for EME Current conventions dictate that digital EME is usually done with JT65A on the 50 MHz band, JT65B on 144 and 432 MHz, and JT65C on 1296 MHz. On higher microwave bands typical choices are JT65C or one of the wider QRA64 or JT4 submodes, depending on the expected amount of Doppler spread. JT4 and JT65 offer message *Averaging* -- the summation of subsequent transmissions that convey the same message -- to enable decodes at signal-to-noise ratios several dB below the threshold for single transmissions. These modes also allow *Deep Search* decoding, in which the decoder hypothesizes messages containing known or previously decoded callsigns and tests them for reliability using a correlation algorithm. Finally, JT65 and QRA64 offer _a priori_ (AP) decoding, which takes advantage of naturally accumulating information during a QSO. The following tutorial aims to familiarize you with these program features, all of which are of special interest for EME and other extreme weak-signal conditions. As a starting point, configure _WSJT-X_ as follows: .Settings | General: - *My Call* = W9XYZ - Check these boxes: *Enable VHF/UHF/Microwave features*, *Single decode*, *Decode after EME delay* .Settings | Advanced: - *Random erasure patterns* = 7, *Aggressive decoding level* = 0, *Two-pass decoding* = _unchecked_, *Waterfall spectra* = _Most sensitive_ .Main window menus: - *View* = Message averaging - *Mode* = JT65 - *Decode:* *Deep* selected, *Enable averaging* checked, *Enable deep search* unchecked, *Enable AP* checked .Main window: - *F Tol* = 500, *Rx* 1500 *Hz*, *Submode* = B, *Sync* = 0 - *DX Call*, *DX Grid:* both empty .Wide Graph: - *Bins/Pixel* = 3, *N Avg* = 10 - Adjust the width of the window so that the frequency range extends up to at least 2400 Hz. If you have not already done so, install the sample files available for <>. Select *File | Open* and navigate to ...\save\samples\JT65\JT65B\000000_0001.wav. The waterfall should look something like the snapshot below. A barely visible vertical trace appears at 1300 Hz. This is the synchronizing tone of a simulated JT65B signal with SNR = -26 dB. image::EME_Deep_0.png[align="center",alt="EME_Deep_0"] The decoder recognizes the sync tone of a JT65 signal, but is unable to decode it, producing only this line in the _Single Period Decodes_ panel: 0001 -28 2.5 1300 #* Press *F6* repeatedly, to read subsequent files. When five files have been read your display should look like this: image::EME_Deep_1.png[align="center",alt="EME_Deep_1"] The message `CQ K1ABC FN42` appears in the _Average Decodes_ panel, flagged with the <> `f3`. The label means that decoding was accomplished with the Franke-Taylor algorithm, using the average of 3 transmissions. The _Message Averaging_ window now looks like this: image::EME_Deep_2.png[align="center",alt="EME_Deep_2"] The `$` symbols mark lines corresponding to transmissions used in the most recent attempt toward an average decode. Hit the *F6* key again to read the sixth file. You should now see the message `K1ABC G4XYZ IO91` displayed in the _Average Decodes_ panel, again with the `f3` label. Now pretend you are K1ABC (enter `K1ABC` and `FN42` as *My Call* and *My Grid* on the *Settings | General* tab). Click *Clear Avg* and double-click *Erase* to start with a fresh screen. Open the files 000000_0002.wav and 000000_0004.wav. You should now see the message `K1ABC G4XYZ IO91` in the _Average Decodes_ panel. Its end-of-line flag `a22` indicates that this decode used *My Call* as _a priori_ (AP) information of type 2 (see Table 1 in <>), and is based on the average of 2 transmissions. You might wish to experiment with other combinations of entries for *My Call*, *DX Call*, and *DX Grid*, and with toggling the various options of the *Decode* menu on and off. For best sensitivity, most users will want to use *Deep* decoding with *Enable averaging*, *Enable deep search*, and *Enable AP* all turned on.