Monday, 17 April 2017

Testing the new JT10 Digital mode

Today I did some first quick test with a new digital mode. This mode, JT10 is derived from JT9.
Below you will find the explanation by Igor UA3DJY

First I have installed the latest version of the JTDX software and list on 20 meter 14080.00 khz.

I checked all the settings in the new (beta) software. some of them didn't work now, but this wasn't problem to start the first transmission on 20 mtr,

After some CQ on 20 I decided to switch to 40 mtr and made some contacts.

Message from Igor JTDX developer.

New mode "JT10" in JTDX 17.8 (coming soon)
Hi All,
JT10 mode is derived from the JT9 mode and has 10 tones where two of them dedicated to synchronization pattern, rest 8 are the message data.
Each tone being transmitted for 6912/12000= 0.576 second, minimal distance between the two neighbouring tones is 4*12000/6912= 6.94(4) Hz.
Frequency bin width is 12000/6912= 1.736(1) Hz, so there is always a gap between the two neighbouring tones.
Whole spectrum occupies 6.94(4)*9 +1.74= around 65 Hz. Fano decoder is used for JT10 mode.
16 tones (8+8) are used for SYNC pattern, 69 tones allocated to the message data, total 85 tones being transmitted per 85*0.576= 48.96 seconds time interval.
There are several ideas behind this approach:
- usage of two tones for SYNC pattern can simplify to distinguish harmonic based signals (JT10b and JT10c), also these QRM-ing signals can be decoded and subtracted from the whole signal in the future SW versions
- wider tone spacing shall bring better resistance to the Doppler frequency spreading in comparison to JT65a mode
- wider tone spacing shall bring better spectra overlapping capacity in comparison to JT65a mode, and more signal density on the band if signal subtraction is used in the software
- relatively narrow bandwidth of JT10 signal will allow to get better band capacity in comparison to the JT65a mode.
So far it is not clear if JT10 will go to the public use, one of the reasons that can stop it's usage is the relatively small SYNC pattern, and there is a long way ahead to make it more attractive one in comparison to the
JT65a mode.
73 Igor UA3DJY

73 Gerard