Tag: jt65

JT65 on 5.357 MHz after dark…

NOTE:- The latest JT65 software uses a dial freq of 5357, in the UK we must not transmit beyond 5358. So if you use a dial freq of 5357 then you must ensure your audio is no higher than 1000.

The alternative is to place your dial on 5355 and then you have access to 3Khz.

The RSGB have placed a some advice on their website.

I was quite surprised to hear so much activity on JT65 this evening. I can often be found working data modes on 5.366.5, but this evening decided to check out the JT65 freq.

Check the UK 5 MHz allocation showing practical usage and dial freq on G3NRW site. Here you can download and review the bandplan is a PDF format.

Using WSJT-X v1.5 by K1JT and the excellent JTAlert program by VK3AMA

I have included some screen shots to show the activity and setup. Using 10 to 15w into my doublet antenna.

Here is the bandscope, showing the audio bandpass, you can see 5 signals have been active. Each horizontal line indicates a 60 second period. You either transmit in odd or even mode, TX for 60 seconds, then receive for 60 seconds.jt65_band_scope

In this window you can decode the stations call sign and signal reports. The program can be configured to show different colours, red indicates your working that station or being called by a station.

You can look up online and see who is receiving your signal using PSK reporter. You will need to open the page and type in your callsign. The reports page will look a little like this.

jt65_band_map

This evening I worked OZ1TMK (Denmark), A45XR (Oman), PA3FMP (Netherlands), 9A6TKS (Croatia), LA1VNA (Norway), 5P1KZX (Denmark)

73 Dave M0TAZ

 

So you want to work VK and JA on 10w ?

One answer is to to learn a low powered digital mode, CW fits the bill but things have moved on in the last 100 years and computers have provided an even better, more robust form of digital communication.

What am I talking about? No not the internet, but low power digital modes like JT65, JT9, Olivia, PSK to name a few… In this article we was going to concentrate on JT65 and JT9, like many modes its hard to know where to start, what software and what frequency should you listen to.

So what is JT65
Its a low power digital mode invented by Joe Taylor K1JT in his original paper and I quote “It is easy to show, however, that neither the encoding nor the modulation of CW is optimum. When every dB of signal-to-noise ratio counts, as it does in amateur meteor-scatter and EME contacts, there are very good reasons to explore other options. Personal computers equipped with sound cards provide a golden opportunity for experimenting with the wide range of possibilities.”

The JT65 protocol uses 65-tone frequency shift keying with constant-amplitude waveforms and no phase discontinuities. The original mode was optimised for EME QSO, but later versions JT65A, B and C had a more HF focus. The mode used in the programs we will look at is JT65A although its usually described as just JT65.

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© 2015 Dave, M0TAZ