If you have the volume too high, you will cause the audio to be distorted, leading to the transmission of spurs and 'garbage', which causes interference. REMINDER: Please be careful on how you adjust your OUTPUT volume on your soundcard/interface to your transmitter.
How much power do you really need to transmit, with JT65A? Here is a calculator to help you figure that out, based on the reports you receive from other JT65A stations. THIS MODE IS DESIGNED FOR WEAK-SIGNAL DETECTION AND SUCCESSFUL TWO-WAY COMMUNICATION! However, it is also true that under many conditions on most HF bands, it is often demonstrated that lower power has been sufficient to accomplish amazing results. It is true that on some bands, under certain propagation conditions, the contact can only be accomplished with 100 watts of power. They only increase the power if no contact is made! You simply should NOT be running 100 watts, UNLESS YOU ABSOLUTELY HAVE TO! By running at 100 or greater power, you MAY cause intense interference to all of the other stations on the same frequency, countering any possible benefit of using this mode! DO NOT RUN HIGH POWER UNLESS YOU KNOW FOR CERTAIN THAT YOU CANNOT COMPLETE THE TWO-WAY CONTACT WITHOUT LOWER POWER! USE ONLY THE POWER NECESSARY TO COMPLETE THE CONTACT! The method suggested is to start all calls with lower power, and only increase the power if you must. Many amateur radio operators have worked the world with a simple dipole antenna and 20 watts. This is a WEAK-SIGNAL digital mode! - You should not run much power, at all. Join the Facebook community for JT65A here:, while the Discussion Group on Facebook for JT65A is here.
It was later realized that this protocol, with some adaptation, would also be very usable for terrestrial HF communications. JT65 includes error-correcting features that make it very robust, even with signals much too weak to be heard. JT65A is actually a "sub-mode" of Joe's original JT65 protocol, which he designed to optimize EME contacts on the HF and VHF bands. Joe has contributed to the amateur radio community in much the same way, changing the playing field for weak-signal operation. Joe, a Professor Emeritus of physics at Princeton University, shares a Nobel Prize with Russell Alan Hulse (ex-WB2LAV) for the discovery of the first pulsar in a binary system as well as the first confirmation of the existence of gravitational radiation in the amount and with the properties first predicted by Albert Einstein. The JT65A communications protocol was conceived and first implemented by Joe Taylor, K1JT. Have you ever wondered how much of the noise you hear on the HF bands is actually comprised of signals too weak to be copied? JT65A is a weak-signal digital mode that allows you to pull great DX out from under the noise on the high frequency spectrum. Introduction to a weak-signal digital mode If thats the case your sound device is OK and FLdigi will work without any issues.Welcome to the JT65A Digital Mode for High Frequency Weak Signal Communications. With aplay -l you can check the actual index and see that the stick is now primary (0).Ĭonnect a microphone or ather audio device and with arecord test.wav create an audio testfile.Īplay test.wav should play it over a headphone or connected speakers. Options snd slots=snd-usb-audio,snd-bcm2835 # This sets the index value of the cards but doesn't reorder. Of course you need a cheap USB sound stick cause the RasPi has no sound input device and additionally this stick has to be accepted by Jessie as the primary soundcard (by default its always secondary)Ĭreate a file with the nano editor in /etc/modprobe.d/ named nf with the following cat /etc/modprobe.d/nf One additional sound issue has to be manually fixed in Jessie for FLdigi ! Just follow it and it instantly brings FLdigi to run on the RasPi. Hence i compiled it from the source which also brings you to the latest and greatest version.
There is an FLdigi package in the repository on Jessie now but here it did not work on the Pi2 and 3
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