From: Rik Strobbe <rik.strobbe@kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>,
        "rsgb-lf-group@groups.io" <rsgb-lf-group@groups.io>,
        "rsgb_lf_group@yahoogroups.co.uk" <rsgb_lf_group@yahoogroups.co.uk>,
        "600MRG@mailman.qth.net" <600MRG@mailman.qth.net>
Thread-Topic: JT9-5 Drift
Thread-Index: AQHUpYt1wQO5xszDOUu6R2nNd3dssqWiBbNygAAIr84=
Date: Sun, 6 Jan 2019 10:48:03 +0000
Message-ID: <1546771678305.41844@kuleuven.be>
References: <CALb7AV2c+sgBkWvr4Zcs60CJhFLPeEFZJLcLub-4LTwrwr+cKQ@mail.gmail.com>,<1546771383530.99285@kuleuven.be>
In-Reply-To: <1546771383530.99285@kuleuven.be>
Accept-Language: nl-BE, en-GB, en-US
Content-Language: nl-BE
MIME-Version: 1.0
Subject: LF: FW: JT9-5 Drift
Content-Type: multipart/alternative;
	boundary="_000_154677167830541844kuleuvenbe_"
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org

--_000_154677167830541844kuleuvenbe_
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Dear all,


Roger, VK4YB, asked me about JT9-5 frequency stability requirement.

As this might be interesting for others too, my answer below.


73 & HNY


Rik  ON7YD - OR7T


________________________________
Van: Rik Strobbe
Verzonden: zondag 6 januari 2019 11:43
Aan: Roger Crofts
Onderwerp: Re: JT9-5 Drift


?Hello Roger,


as JT9-2 and JT9-5 signals are resampled to JT9-1 to be decoded by WSJT dec=
oder engine it all depends on the drift tolerance of that decoder.

For JT9-2 the frequency stability must be 2.222 times better than for JT9-1=
.

For JT9-5 it must even be 5.926 be better.

As I couldn't find any information about the required JT9-1 stability I did=
 some brief tests with JT9-5:

- At -5 dB level a drift up to 0.35 Hz/min seems acceptable.

- At -15 dB level it is 0.26 Hz/min.

- At -25 dB level it is 0.24 Hz/min

- At -30 dB level it is 0.22 Hz/min

- At -34 dB level (more or less the JT95 limit) it is 0.20 Hz/min

But as said this was just a brief test, these numbers should be handled wit=
h some caution.

Also keep in mind that this numbers represent the combined TX and RX drift =
(according to Murphy TX and RX drift will always be opposite).

If using a transverter the TX drift is the combined drift of the driver TX =
and the transverter.

Furthermore I assumed that the drift was linear over time, for frequency ju=
mps it might be different.?

Another frequency instability source will be the ionosphere, but there is l=
ittle we can do about that (but the more stable TX and RX the more room for=
 ionospheric instabilities).

Based on the above I would suggest to aim for a LO stability of no worse th=
an 0.1 Hz/min, 0.05 Hz/min would be even better for weak signal DX (and tha=
t is what JT9-5 is all about).


Tests over the past weeks have shown that JT9-5 works very well for 136 kHz=
 DX (N1BUG was copied by numberous EU stations).

On 472 kHz K3MF has been reported in Europe (as far as I know by G0LUJ and =
myself).


73, Rik  ON7YD - OR7T?

--_000_154677167830541844kuleuvenbe_
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Diso-8859-=
1">
<style type=3D"text/css" style=3D"display:none"><!-- p { margin-top: 0px; m=
argin-bottom: 0px; }--></style>
</head>
<body dir=3D"ltr" style=3D"font-size:10pt;color:#000000;background-color:#F=
FFFFF;font-family:Tahoma,Geneva,sans-serif;">
<p>Dear all,<br>
</p>
<p><br>
</p>
<p>Roger, VK4YB, asked me about JT9-5 frequency stability requirement.<br>
</p>
<p>As this might be interesting for others too, my answer below.<br>
</p>
<p><br>
</p>
<p>73 &amp; HNY<br>
</p>
<p><br>
</p>
<p>Rik&nbsp; ON7YD - OR7T<br>
</p>
<p><br>
</p>
<div dir=3D"ltr" style=3D"font-size:10pt; color:#000000; background-color:#=
FFFFFF; font-family:Tahoma,Geneva,sans-serif">
<hr tabindex=3D"-1" style=3D"display:inline-block; width:98%">
<div id=3D"divRplyFwdMsg" dir=3D"ltr"><font face=3D"Calibri, sans-serif" co=
lor=3D"#000000" style=3D"font-size:11pt"><b>Van:</b> Rik Strobbe<br>
<b>Verzonden:</b> zondag 6 januari 2019 11:43<br>
<b>Aan:</b> Roger Crofts<br>
<b>Onderwerp:</b> Re: JT9-5 Drift</font>
<div>&nbsp;</div>
</div>
<div>
<p>&#8203;Hello Roger,<br>
</p>
<p><br>
</p>
<p>as JT9-2 and JT9-5 signals are resampled to JT9-1 to be decoded by WSJT =
decoder&nbsp;engine it all depends on the drift tolerance of that decoder.<=
br>
</p>
<p>For JT9-2 the frequency stability must be 2.222 times better than for JT=
9-1.<br>
</p>
<p>For JT9-5 it must even be 5.926 be better.<br>
</p>
<p>As I couldn't find any information about the required&nbsp;JT9-1 stabili=
ty I did some brief&nbsp;tests with JT9-5:<br>
</p>
<p>- At -5&nbsp;dB level a drift up to 0.35&nbsp;Hz/min seems&nbsp;acceptab=
le.<br>
</p>
<p>- At -15&nbsp;dB level it is 0.26 Hz/min.<br>
</p>
<p>- At -25 dB level it is 0.24&nbsp;Hz/min<br>
</p>
<p>- At -30&nbsp;dB level it is 0.22 Hz/min<br>
</p>
<p>- At -34 dB level (more or less the JT95 limit) it is 0.20 Hz/min<br>
</p>
<p>But as said this was just a brief test, these numbers should be handled =
with some caution.<br>
</p>
<p>Also keep in mind that this numbers represent the combined TX and RX dri=
ft (according to Murphy TX and RX drift&nbsp;will always be opposite).<br>
</p>
<p>If using a transverter the TX drift is the combined drift of the driver =
TX and the transverter.<br>
</p>
<p>Furthermore I assumed that the drift was linear over time, for frequency=
 jumps it might be different.&#8203;<br>
</p>
<p>Another frequency instability source will be the ionosphere, but there i=
s little we can do about that (but the more stable TX and RX the more room =
for ionospheric instabilities).<br>
</p>
<p>Based on the above I would suggest to aim for a LO stability of no worse=
 than 0.1 Hz/min, 0.05 Hz/min would be even better for weak signal DX (and =
that is what JT9-5 is all about).<br>
</p>
<p><br>
</p>
<p>Tests over the past weeks have shown that JT9-5 works very well for 136&=
nbsp;kHz DX (N1BUG was copied by numberous EU stations).<br>
</p>
<p>On 472 kHz K3MF has&nbsp;been reported in Europe (as far as I know by G0=
LUJ and myself).<br>
</p>
<p><br>
</p>
<p>73, Rik&nbsp; ON7YD - OR7T&#8203;<br>
</p>
</div>
</div>
</body>
</html>

--_000_154677167830541844kuleuvenbe_--