One of the "Open Forum" topics discussed at the 2012 EME Conference was the potential desirability of a digital EME mode with shorter T/R sequences than the one-minute standard of the commonly used JT65 modes. Briefly stated: one-minute sequences work very well for everyday use. They provide excellent sensitivity, and QSOs last abut 6 minutes; most users find this a comfortable and pleasant rate for their EME QSOs. In EME contests, however, a higher QSO rate would be desirable. A large proportion of contest QSOs using JT65 modes take place at signal levels many dB above the required minimum. These QSOs could be made using shorter sequences, for example 30 s, if a suitable protocol were used. The maximum QSO rate could then be doubled, from around 10 to 20 QSOs per hour. Responses to these ideas during the EME Conference were uniformly positive, so this message is intended to initiate the next necessary step involving the wider EME community. Revisions 2433 and later of WSJT 9.x have included experimental modes called JT65B2 and JT65C2. These modes use 30 s T/R sequences and are otherwise like modes JT65B and JT65C. (The idea is that on bands where you normally use JT65B, you can use JT65B2 for "2x" QSOs. If you normally use JT65C, e.g. on 23 cm, you should use JT65C2.) Because of the shorter transmissions, sensitivity of the 30-second modes is 3 dB poorer than the one-minute modes. The two new modes have now been implemented in MAP65 v2.4.x, revisions 2571 and later. If a significant number of the EME community would choose to use high-speed (2x) modes in upcoming the 2012 ARRL EME Contest, we need to have some wider discussion about it NOW. Here are some initial thoughts designed to get such discussion started on this reflector. No doubt you will think of other things to comment on, as well. 1. The B2 and C2 modes have been around since May 2011 (all revisions of WSJT9 since r2433). However, as far as I know the fast modes have been used and tested by only a few. JT65B2 and JT65C2 are now available also in MAP65. If you are interested in their use for contests, please give them a try and report your results! 2. Other than this request for on-the-air tests, I am NOT suggesting that the 30-second modes should replace the more familiar one-minute modes for everyday use. I DO suggest their use in EME contests, some of the time, if many of your EME contest QSOs take place at S/N around -21 dB and higher. You will surely want to do some of your contest operating with the one-minute modes, as well, so that you can work smaller, weaker stations. 3. Note that when you're operating in JT65B2 mode, the software will not decode JT65B signals, and vice-versa. Therefore, I suggest that on 2 meters it may help to have JT65B2 operations concentrated in a smaller portion of the digital-EME sub-band, such as 144.100 to 144.115, rather than being spread over the full range 144.100 to 144.160. This should help to minimize QRM between users of the different modes, and make it easier to find QSO partners. 4. JT65B2 should work well on 432 MHz and JT65C2 on 1296 MHz. However, the level of digital EME activity on these bands may not yet be high enough to make the fast-QSO modes particularly useful, even in a contest. On these bands, perhaps it would it be less confusing if we do NOT recommend use of the new modes just yet, and stick with JT65B and JT65C for this year's ARRL contest? Your thoughts? 5. Assuming that you make some tests of the JT65B2/C2 modes and find that they work well, would you use them in the ARRL contest this year? ########################################################################### Finally: I have packaged a new release of WSJT (version 9.3, revision 2574) in which JT65B2 and JT65C2 appear as "normal" rather than "experimental" modes. You can download it from this link: http://physics.princeton.edu/pulsar/K1JT/WSJT9_r2574.EXE The new version of MAP65 (v2.4, r2571) with support for JT65B2 and JT65C2 can be downloaded from http://physics.princeton.edu/pulsar/K1JT/MAP65_240r2571.exe As always, it is possible that these programs will have as-yet undiscovered bugs. If you find any, please report them to me! -- 73, Joe, K1JT

This is a follow-up to my posting several days ago concerning WSJT 9.3, MAP65 2.4, and the digital EME modes JT65B2 and JT65C2. A number of EME QSOs have been made over the past several days using JT65B2 on 2 meters. One example: Earlier today I worked PA3FPQ by arrangement, followed by random QSOs with DL8GP, I3MEK, PI9CM, and YO2LAM. Five QSOs in less than 20 minutes, without breaking a sweat. We can confirm that JT65B2 works very well. Several bugs in the early release have been fixed: see below. The JT65B2/C2 modes use 30-second sequences and permit you to make QSOs in half the time required for JT65B/C. The shorter transmissions imply a 3 dB penalty in sensitivity. JT65B decodes reliably at SNR -24 dB and higher (KV decoder); the threshold for JT65B2 is around -21 dB. My tentative recommendation (discussed at the 2012 EME Conference) is that participants in the upcoming ARRL EME contest (Nov 3-4 and Dec 1-2) may wish to use JT65B2 at least some of the time, for working stronger stations. A further tentative recommendation is that JT65B2 should be concentrated between 144.100 and 144.115, leaving 144.115 to 144.160 for JT65B. Public discussion of these recommendations is strongly encouraged! Relevant links on the WSJT Home Page http://physics.princeton.edu/pulsar/K1JT/index.html http://physics.princeton.edu/pulsar/K1JT/wsjt.html http://physics.princeton.edu/pulsar/K1JT/map65.html have been updated with information about the fast modes. Click on these direct links to download WSJT 9.3 and MAP65 2.4.1: http://physics.princeton.edu/pulsar/K1JT/WSJT9_r2574.EXE http://physics.princeton.edu/pulsar/K1JT/MAP65_241r2584.exe A few additional details: 1. JT65B2 and JT65C2 use the same tone spacing as JT65B and JT65C, respectively. They are keyed at twice the rate, and T/R sequences are 30 seconds rather than one minute. Sensitivity of the fast modes is 3 dB worse than the standard modes. The B2 and C2 modes allow EME contest QSOs to be made at twice the rate, up to about 20 QSOs per hour. 2. If you recently downloaded MAP65 v2.4.0 r2571, you should upgrade to v2.4.1 r2584 (the link given above). Several operational bugs in the B2/C2 modes have been corrected. 3. In addition to JT65B2 and JT65C2, Users of WSJT 9.3 will find new entries ISCAT-A and ISCAT-B on the Mode menu. ISCAT-B is the original ISCAT mode with total bandwidth 1809 Hz. ISCAT-A runs at half the rate, uses half the bandwidth, and (for average decodes on steady signals) is about 1 dB more sensitive. It has been found very effective for making aircraft scatter QSOs at 10 GHz. ISCAT-B probably remains the best mode for 6 meters, but as always, experimentation is encouraged! -- 73, Joe, K1JT