Date   

Re: Frequency for JT4g signals from GB3EDN on 23cm

Richard GD8EXI
 

Andy
 I have been following the correspondence re the best digital code for use by beacons with some interest. Here at my QTH in IO74, roughly the geographic centre of the British Isles, I can with patience see on a waterfall diagram the signals from many VHF and above beacons in the UK and near Continent. However I cannot with a few exceptions decode the JT coding where present. The multiple Doppler shifted versions of the beacon signal appears to be the problem. See attached waterfall diagrams of the Angus 144.453 MHz beacon recorded here in IO74PC beaming SE. The situation on 23cms is of course even worse with the signals being spread outside a 2.5 KHz bandwidth hence no nice pictures. Ideally we need an encoding system, which is not dependant on knowing the exact frequency for the beacon because there is not one, thanks to Doppler shift.
 
 One option would be to use a Chirp type encoding (1,2) where rising and falling frequencies represent zeros and ones. The advantage is that the information is then contained in the frequency change over time rather than the absolute frequency. The decoding would then involve measuring, for example, the frequency change over a one second time period. Put another way you would be looking to see if the lines on a waterfall diagram were either sloping left or right to decide if a zero or one was being transmitted.
 
Such a system should be relatively immune to multiple reflection targets travelling at different but constant speeds. However the decoding would be confused by a reflection from a target, which suddenly changed speed or direction. Fortunately planes or satellites rarely suddenly change velocity but meteors do, so they are a potential problem as is auroral refection.
 
You may ask why I do not beam directly at the beacon to minimize the Doppler shift. Unfortunately in many directions I am surrounded by steep hills so there is no signal on the direct path. Also it appears from the correspondence below that other stations are having trouble getting decodes simply because they cannot find the correct frequency to tune to.
 
References
 
1.   The Chirp Beacon Mode. Phil Harman VK6APH. Dubus page 45, vol 4, 2011.

2.   Chirp Modulation. Phil Harman VK6APH and Andrew Martin VK3OE Radcom Page 32, vol 3, 2012.

73s
Richard
GD8EXI



On 24/01/2014 09:24, "Andy Talbot" <andy.g4jnt@...> wrote:


 
 
   

The plots you (Martin) sent earllier suggest Gb3EDN places teh carrier period in the middle of the tones.  Therefore the correct SSB carrier reference tuning point is going to be 1270Hz below that at 1296.98873MHz
 
If you're confident your rig reads 1400Hz high, that means you need to tune to 1296.99017
 
All this shows the need for two things :
 
1)  A  Good knowledge of your receiver's calibration and a means to check with confidence - that's entirely your affair.
 
2)  Beacon keeps should publish precisely their choice of tone and tuning point.   On microwave beacons using JT4G two standards have appeared.  the one I stated with on the Bell Hill set where Tone zero was defiens as the carrier and reference, so you tune 800Hz beklow this and end up with a "nice sounding" carrier terms for the aural people to listen to.  The Tones spread upwards from this
 
Or the GB3EDm approach where the builders clearly tried to centralise the tone spread, and ended up with the need for two different tuning points depending on weak signal reception of aural listening
 
it really would help is builders could use a scheme where tuning didn't have to change dependign on "how" users wish to receive the signal.
 
Andy
G4JNT
 


 
On 23 January 2014 22:27, Martin A Hall <gorrell77@...> wrote:
 
Hi Dave,
 
I haven’t listened to GB3EDN since last April when I did some tests on JT4G reception, and I don’t have a 23cm antenna up at the moment to check, but my notes lead me to believe my IC-910 was set to a receive frequency on USB of 1296.9895 MHz for JT4G reception.  Having said that, the memory channel on the IC-910 is set at 1296.9916 MHz, so take your pick.  I’ve only ever heard this one via aircraft reflections.
 
Hope this helps.  Good luck!
 
73,
Martin
GM8IEM – IO78HF
 
 
From: Dave <mailto:dave@...>  
Sent: Thursday, January 23, 2014 4:16 PM
To: ukmicrowaves@...
Subject: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm
 
Since the JT4g beacon that Andy put on air is now no longer transmitting I
have been decoding JT4g signals from GB3CSB. These have been fairly regular
as there's plenty of aircraft activity over the path between here and
IO75xx. So, I've turned my attention onto GB3EDN. This is a more tricky
one to detect from here as, on the heading from me to it, there are far
fewer aircraft flying across or along the path and many are quite low to the
ground as well.

The other big problem is knowing what frequency the beacon is transmitting
on. I've not been able to detect any signals yet, so it's a bit hit and
miss tuning about and waiting for a suitably placed aircraft to come along.

I did a quick check on Beaconspots.eu and these are the last reported
sightings of GB3EDN. I'm going to assume the one on the 3rd September was a
typo...

2013-09-03 14:36 GB3EDN 1296.9000 -13dB TR -13 jt4g io85jw>jo45bo 709 DXC
OZ1FF JO45BO
2013-07-20 10:40 GB3EDN 1296.9900 539 TR 539 167 DXC G4KUX IO94BP21
2013-07-11 05:31 GB3EDN 1296.9900 -13dB TR -13 io85>tr>jo45 709 DXC OZ1FF
JO45BO58
2013-07-08 16:05 GB3EDN 1296.9900 -11dB TR -11 jt4g io85>jo45 709 DXC OZ1FF
JO45BO58
2013-04-17 08:53 GB3EDN 1296.9900 519 TR io85jwio87xj 519 178 DXC GM3UAG
IO87XJ

Most of these appear to be tropo reports, not aircraft reflected, but the
ones spotted by by OZ1FF quotes JT4g but reports the signal as via Tropo,
and the other two look like they are reports of the signal strength and
frequency of the CW signal.

The last quoted report that definately quoted to be for AS was this one.

2011-12-18 11:42 GB3EDN 1296.9907 529 AS io85jwio78hf 529 289 DXC GM8IEM
IO78HF

I'm not sure if thats a dial reading report, and since it was back in 2011,
the frequency may well have moved a bit since then.

Is there anyone, who is closer to GB3EDN or who has more regular aircraft
traffic over their path to the beacon, who can give me their dial frequency
readout for detecting the JT4g signals on 23cm please? I will make the
appropriate adjustment for my set up, and will keep a look out for GB3EDN
via aircraft reflections with a bit more certainty that I'm tuned to roughly
the right frequency.

Thanks - Dave (G0DJA)



 
   



Re: [VHFandUHF] GM4CXM Website

John GM8OTI
 

The Scottish Microwave Round Table information has, to date, been hosted on Ray's website. As Ian notes, the wayback machine has the archive, but we are setting up a new site for the GMRT stuff. This is at

http://www.gmroundtable.org.uk/

and we hope to announce the date for this year next week. Further information will follow and I'll announce here when we have new stuff posted.

The new site also has the photos etc. from previous GMRT events.

73
John GM8OTI


Re: Frequency for JT4g signals from GB3EDN on 23cm [1 Attachment]

Brian Flynn GM8BJF
 

Dear Dave,


The site is not great to the south as the Pentland hills (~2000ft) are in the way and are only a couple of miles from the site. The Antenna is on a 4 storey block but it is basically located in the city here.  I get reports of it in the NE of England but not much else. It is best NW through SE. Get regular reports from Scandinavia as its has a view over the N Sea.   CSB  has a clear shoot south from the Kilsyth hills. Will be very interested if you get decodes!


Brian


Re: Frequency for JT4g signals from GB3EDN on 23cm [1 Attachment]

Dave <dave@...>
 

Thanks for the information Brian,
 
Using GB3CSB as the reference and adding 5kHz on I think I saw a brief line in one period (see attached) and in the next period 2 synch pulses but no decode yet.  There was one aircraft in a reasonable position at the time.

I think the problem is lack of aircraft, high enough and in the correct position for the beacon to illuminate enough for my receiver to detect.

GB3CSB is better positioned and there are several aircraft in good positions and heights to get a more reliable signal.  Just shows what a few degrees away from a main flight path can do.
 
Cheers - Dave (G0DJA)

----- Original Message -----
Sent: Friday, January 24, 2014 9:35 AM
Subject: [ukmicrowaves] Re: Frequency for JT4g signals from GB3EDN on 23cm [1 Attachment]
 
I also know that it is spaced pretty exactly 5 kHz above GB3CSB so is
you are getting decodes off CSB just tune up 5k. CSB is GPS frequecy
locked. ( Was looking at both beacons last night with a SDR Rx ! I
attach a screen shot of the signals. The larger signal is EDN and the
smaller is CSB. A bit of careful reading of the scale shows the spacing
to be pretty exact. Ignore absolute reading as my dongle is not very
accurate!)

73s

Brian GM8BJF


Chipbank request

Michael Scott
 

Hi All
 
As a result of the popularity of Sam's Nacton transverter I have received a lot of requests for components for it. Amongst them is 430R 0805 resistors. A few weeks ago someone told me that they were ordering a reel from Hong Kong and would donate the unwanted stock to the chipbank. Unfortunately I can't find the name in my records and wonder if they actually received the reel and would still be willing to donate some to the chipbank.
 
If so, please could you contact me direct.
 
Many thanks
 
Mike, G3LYP


Re: Frequency for JT4g signals from GB3EDN on 23cm

Brian Flynn GM8BJF
 

I am the keeper for GB3EDN. The frequency is derived from a good quality 15 MHz TCXO. I last checked it about 9 month as ago and it was within 10 Hz of its nominal carrier frequency of 1296.990 when it was transmitting plain carrier.

I am presently at my work qth which co-incidently is also the beacon location. Over the weekend I will decode it at home and I will post up the frequency I tune my Rx to. (It is GPS locked)

I also know that it is spaced pretty exactly 5 kHz above GB3CSB so is you are getting decodes off CSB just tune up 5k. CSB is GPS frequecy locked. ( Was looking at both beacons last night with a SDR Rx ! I attach a screen shot of the signals. The larger signal is EDN and the smaller is CSB. A bit of careful reading of the scale shows the spacing to be pretty exact. Ignore absolute reading as my dongle is not very accurate!)

73s

Brian GM8BJF
--
Dr Brian W Flynn
15 Riselaw Crescent
Edinburgh
EH10 6HN

0131 447 4043


Re: Frequency for JT4g signals from GB3EDN on 23cm

Andy G4JNT
 

The plots you (Martin) sent earllier suggest Gb3EDN places teh carrier period in the middle of the tones.  Therefore the correct SSB carrier reference tuning point is going to be 1270Hz below that at 1296.98873MHz
 
If you're confident your rig reads 1400Hz high, that means you need to tune to 1296.99017
 
All this shows the need for two things :
 
1)  A  Good knowledge of your receiver's calibration and a means to check with confidence - that's entirely your affair.
 
2)  Beacon keeps should publish precisely their choice of tone and tuning point.   On microwave beacons using JT4G two standards have appeared.  the one I stated with on the Bell Hill set where Tone zero was defiens as the carrier and reference, so you tune 800Hz beklow this and end up with a "nice sounding" carrier terms for the aural people to listen to.  The Tones spread upwards from this
 
Or the GB3EDm approach where the builders clearly tried to centralise the tone spread, and ended up with the need for two different tuning points depending on weak signal reception of aural listening
 
it really would help is builders could use a scheme where tuning didn't have to change dependign on "how" users wish to receive the signal.
 
Andy
G4JNT
 


 

On 23 January 2014 22:27, Martin A Hall <gorrell77@...> wrote:
 

Hi Dave,
 
I haven’t listened to GB3EDN since last April when I did some tests on JT4G reception, and I don’t have a 23cm antenna up at the moment to check, but my notes lead me to believe my IC-910 was set to a receive frequency on USB of 1296.9895 MHz for JT4G reception.  Having said that, the memory channel on the IC-910 is set at 1296.9916 MHz, so take your pick.  I’ve only ever heard this one via aircraft reflections.
 
Hope this helps.  Good luck!
 
73,
Martin
GM8IEM – IO78HF
 
 
From: Dave
Sent: Thursday, January 23, 2014 4:16 PM
Subject: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm
 

Since the JT4g beacon that Andy put on air is now no longer transmitting I
have been decoding JT4g signals from GB3CSB. These have been fairly regular
as there's plenty of aircraft activity over the path between here and
IO75xx. So, I've turned my attention onto GB3EDN. This is a more tricky
one to detect from here as, on the heading from me to it, there are far
fewer aircraft flying across or along the path and many are quite low to the
ground as well.

The other big problem is knowing what frequency the beacon is transmitting
on. I've not been able to detect any signals yet, so it's a bit hit and
miss tuning about and waiting for a suitably placed aircraft to come along.

I did a quick check on Beaconspots.eu and these are the last reported
sightings of GB3EDN. I'm going to assume the one on the 3rd September was a
typo...

2013-09-03 14:36 GB3EDN 1296.9000 -13dB TR -13 jt4g io85jw>jo45bo 709 DXC
OZ1FF JO45BO
2013-07-20 10:40 GB3EDN 1296.9900 539 TR 539 167 DXC G4KUX IO94BP21
2013-07-11 05:31 GB3EDN 1296.9900 -13dB TR -13 io85>tr>jo45 709 DXC OZ1FF
JO45BO58
2013-07-08 16:05 GB3EDN 1296.9900 -11dB TR -11 jt4g io85>jo45 709 DXC OZ1FF
JO45BO58
2013-04-17 08:53 GB3EDN 1296.9900 519 TR io85jw<tr>io87xj 519 178 DXC GM3UAG
IO87XJ

Most of these appear to be tropo reports, not aircraft reflected, but the
ones spotted by by OZ1FF quotes JT4g but reports the signal as via Tropo,
and the other two look like they are reports of the signal strength and
frequency of the CW signal.

The last quoted report that definately quoted to be for AS was this one.

2011-12-18 11:42 GB3EDN 1296.9907 529 AS io85jw<as>io78hf 529 289 DXC GM8IEM
IO78HF

I'm not sure if thats a dial reading report, and since it was back in 2011,
the frequency may well have moved a bit since then.

Is there anyone, who is closer to GB3EDN or who has more regular aircraft
traffic over their path to the beacon, who can give me their dial frequency
readout for detecting the JT4g signals on 23cm please? I will make the
appropriate adjustment for my set up, and will keep a look out for GB3EDN
via aircraft reflections with a bit more certainty that I'm tuned to roughly
the right frequency.

Thanks - Dave (G0DJA)



QRP Contacts

John E. Beech
 

Tnx to those of you who sent me thir log extracts - I was pleasantly surprised to see more two-way QRP contacts than
I expected. It also made me feel guilty that I haven't been on myself. Since the xyl started talking about moving house,
I started taking down my antennas, so have nothing working above 144 MHz. Also I think my 23 cms TVTR may be
faulty as I didn't hear much the last time I used it- its been over two years ago now.

de John G8SEQ


Re: [uk-vhf-contesting] RE: [VHFandUHF] GM4CXM Website

Conrad Farlow <conrad@...>
 

Ray you can put it on on g0ruz.com free of charge. I should be able to port it over no problem. I have an old blog on there which I intend to resurrect shortly.

73

Conrad. G0RUZ

Ian White wrote:

 


>-----Original Message-----
>From: gm4cxm
>
>> I haven't updated my personal website at www.rayjames.biz/gm4cxm for
>a number
>> of years so have decided to put the annual hosting costs to other
uses so it
>> will come down on 22/2. I may look at free hosting options in the
future.
>

On VHFandUHF@..., Lawrence GJ3RAX replied:

>For a limited amount of information you could use your QRZ page.

Along with literally billions of others, Ray's website has already been
copied and archived by The Wayback Machine at

So if you post the following link on your QRZ page, Ray, people can
still have permanent access to all the useful information:

28.html>

That link goes directly to your Aircraft Scatter page, which has
accurate links to all the other pages as well.

73 from Ian GM3SEK


--
Sent from my Android device with K-9 Mail. Please excuse my brevity.


Re: Frequency for JT4g signals from GB3EDN on 23cm

Martin A Hall <gorrell77@...>
 

Lack of aircraft on the path to Edinburgh from here is also a problem – there are many more flying slightly to the west which get me into Glasgow.  However, due to the position of the jet stream in recent months there have been even fewer suitable aircraft than usual, since they’ve taken more southerly flight paths.  They do say patience is a virtue!
 
73,
Martin
GM8IEM – IO78HF
 

From: Dave
Sent: Thursday, January 23, 2014 11:10 PM
Subject: Re: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm
 



Sorry, I meant 1.4 of course.

If that doesn't work, I'll give 991.6 plus 1.4 a go...
 
Looking at the path plot, EDN has some seriously steep rising ground in front of it in my direction as well.

Dave (G0DJA)
 
----- Original Message -----
From: Dave
Sent: Thursday, January 23, 2014 11:02 PM
Subject: Re: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm
 
Thanks Martin,
 
I'll give 990.9 a go (your 989.5 plus my 1.3 offset and then 993 as well.

The big problem is getting the frequency right as, over the path between me and it, there's not that many aircraft in the right place...

Cheers - Dave
----- Original Message -----
Sent: Thursday, January 23, 2014 10:27 PM
Subject: Re: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm
 
 

Hi Dave,
 
I haven’t listened to GB3EDN since last April when I did some tests on JT4G reception, and I don’t have a 23cm antenna up at the moment to check, but my notes lead me to believe my IC-910 was set to a receive frequency on USB of 1296.9895 MHz for JT4G reception.  Having said that, the memory channel on the IC-910 is set at 1296.9916 MHz, so take your pick.  I’ve only ever heard this one via aircraft reflections.
 
Hope this helps.  Good luck!
 
73,
Martin
GM8IEM – IO78HF


Re: Frequency for JT4g signals from GB3EDN on 23cm

Dave <dave@...>
 


Sorry, I meant 1.4 of course.

If that doesn't work, I'll give 991.6 plus 1.4 a go...
 
Looking at the path plot, EDN has some seriously steep rising ground in front of it in my direction as well.

Dave (G0DJA)
 

----- Original Message -----
From: Dave
Sent: Thursday, January 23, 2014 11:02 PM
Subject: Re: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm

Thanks Martin,
 
I'll give 990.9 a go (your 989.5 plus my 1.3 offset and then 993 as well.

The big problem is getting the frequency right as, over the path between me and it, there's not that many aircraft in the right place...

Cheers - Dave
----- Original Message -----
Sent: Thursday, January 23, 2014 10:27 PM
Subject: Re: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm

 

Hi Dave,
 
I haven’t listened to GB3EDN since last April when I did some tests on JT4G reception, and I don’t have a 23cm antenna up at the moment to check, but my notes lead me to believe my IC-910 was set to a receive frequency on USB of 1296.9895 MHz for JT4G reception.  Having said that, the memory channel on the IC-910 is set at 1296.9916 MHz, so take your pick.  I’ve only ever heard this one via aircraft reflections.
 
Hope this helps.  Good luck!
 
73,
Martin
GM8IEM – IO78HF


Re: Frequency for JT4g signals from GB3EDN on 23cm

Dave <dave@...>
 


Thanks Martin,
 
I'll give 990.9 a go (your 989.5 plus my 1.3 offset and then 993 as well.

The big problem is getting the frequency right as, over the path between me and it, there's not that many aircraft in the right place...

Cheers - Dave

----- Original Message -----
Sent: Thursday, January 23, 2014 10:27 PM
Subject: Re: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm

 

Hi Dave,
 
I haven’t listened to GB3EDN since last April when I did some tests on JT4G reception, and I don’t have a 23cm antenna up at the moment to check, but my notes lead me to believe my IC-910 was set to a receive frequency on USB of 1296.9895 MHz for JT4G reception.  Having said that, the memory channel on the IC-910 is set at 1296.9916 MHz, so take your pick.  I’ve only ever heard this one via aircraft reflections.
 
Hope this helps.  Good luck!
 
73,
Martin
GM8IEM – IO78HF


Re: Frequency for JT4g signals from GB3EDN on 23cm

Martin A Hall <gorrell77@...>
 

Hi Dave,
 
I haven’t listened to GB3EDN since last April when I did some tests on JT4G reception, and I don’t have a 23cm antenna up at the moment to check, but my notes lead me to believe my IC-910 was set to a receive frequency on USB of 1296.9895 MHz for JT4G reception.  Having said that, the memory channel on the IC-910 is set at 1296.9916 MHz, so take your pick.  I’ve only ever heard this one via aircraft reflections.
 
Hope this helps.  Good luck!
 
73,
Martin
GM8IEM – IO78HF
 
 

From: Dave
Sent: Thursday, January 23, 2014 4:16 PM
Subject: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm
 

Since the JT4g beacon that Andy put on air is now no longer transmitting I
have been decoding JT4g signals from GB3CSB. These have been fairly regular
as there's plenty of aircraft activity over the path between here and
IO75xx. So, I've turned my attention onto GB3EDN. This is a more tricky
one to detect from here as, on the heading from me to it, there are far
fewer aircraft flying across or along the path and many are quite low to the
ground as well.

The other big problem is knowing what frequency the beacon is transmitting
on. I've not been able to detect any signals yet, so it's a bit hit and
miss tuning about and waiting for a suitably placed aircraft to come along.

I did a quick check on Beaconspots.eu and these are the last reported
sightings of GB3EDN. I'm going to assume the one on the 3rd September was a
typo...

2013-09-03 14:36 GB3EDN 1296.9000 -13dB TR -13 jt4g io85jw>jo45bo 709 DXC
OZ1FF JO45BO
2013-07-20 10:40 GB3EDN 1296.9900 539 TR 539 167 DXC G4KUX IO94BP21
2013-07-11 05:31 GB3EDN 1296.9900 -13dB TR -13 io85>tr>jo45 709 DXC OZ1FF
JO45BO58
2013-07-08 16:05 GB3EDN 1296.9900 -11dB TR -11 jt4g io85>jo45 709 DXC OZ1FF
JO45BO58
2013-04-17 08:53 GB3EDN 1296.9900 519 TR io85jwio87xj 519 178 DXC GM3UAG
IO87XJ

Most of these appear to be tropo reports, not aircraft reflected, but the
ones spotted by by OZ1FF quotes JT4g but reports the signal as via Tropo,
and the other two look like they are reports of the signal strength and
frequency of the CW signal.

The last quoted report that definately quoted to be for AS was this one.

2011-12-18 11:42 GB3EDN 1296.9907 529 AS io85jwio78hf 529 289 DXC GM8IEM
IO78HF

I'm not sure if thats a dial reading report, and since it was back in 2011,
the frequency may well have moved a bit since then.

Is there anyone, who is closer to GB3EDN or who has more regular aircraft
traffic over their path to the beacon, who can give me their dial frequency
readout for detecting the JT4g signals on 23cm please? I will make the
appropriate adjustment for my set up, and will keep a look out for GB3EDN
via aircraft reflections with a bit more certainty that I'm tuned to roughly
the right frequency.

Thanks - Dave (G0DJA)


Re: Frequency for JT4g signals from GB3EDN on 23cm

Dave <dave@...>
 

That's what I originally thought Andy, but no decodes as yet here.
 
For my set up, assuming as you say it's the 800Hz system, then my calculation (including my 1.44kHz high RX) is that the frequency setting on my dial should be 1296.990.64.

If the tones are centred on .990 though, that, minus 1.3 but plus 1.44 (for my high RX) gives a dial reading of 1296.990.14
 
I'll try starting at 990 and gradually shift up a few Hz at a time leaving it monitoring for a while between each adjustment and see what happens.
 
Dave (G0DJA)
 

----- Original Message -----
Sent: Thursday, January 23, 2014 5:06 PM
Subject: Re: [ukmicrowaves] Frequency for JT4g signals from GB3EDN on 23cm

 

Dave -
I'm speculating here, but suspect you won't be far out if you subtract 800Hz from 1296.9900MHz and assume they are using a decent frequecny source. A not unreasonable assumption as they clearly have a settable frequency source  
 
If they have followed the 'Tone zero is 800Hz' route, then the lowest tone and the period of carrier (and any on off stuff) will be on the nominated frequency, hence tune SSB reference to 800Hz low.
 
Of course, they could have chosen some totally different grid, and centred the JT4G tones around .99, in which case you may have to set SSB ref approximately 1300Hz lower than 1296.99.  But if you use Tol = 400Hz or 600Hz on WSJT, you will probably be near enough.   Even if not near enough to decode, some tones will show eventually and you can work from that.
 
Andy
G4JNT


 


Re: Frequency for JT4g signals from GB3EDN on 23cm

Andy G4JNT
 

Dave -
I'm speculating here, but suspect you won't be far out if you subtract 800Hz from 1296.9900MHz and assume they are using a decent frequecny source. A not unreasonable assumption as they clearly have a settable frequency source  
 
If they have followed the 'Tone zero is 800Hz' route, then the lowest tone and the period of carrier (and any on off stuff) will be on the nominated frequency, hence tune SSB reference to 800Hz low.
 
Of course, they could have chosen some totally different grid, and centred the JT4G tones around .99, in which case you may have to set SSB ref approximately 1300Hz lower than 1296.99.  But if you use Tol = 400Hz or 600Hz on WSJT, you will probably be near enough.   Even if not near enough to decode, some tones will show eventually and you can work from that.
 
Andy
G4JNT


 

On 23 January 2014 16:16, Dave <dave@...> wrote:
 

Since the JT4g beacon that Andy put on air is now no longer transmitting I
have been decoding JT4g signals from GB3CSB. These have been fairly regular
as there's plenty of aircraft activity over the path between here and
IO75xx. So, I've turned my attention onto GB3EDN. This is a more tricky
one to detect from here as, on the heading from me to it, there are far
fewer aircraft flying across or along the path and many are quite low to the
ground as well.

The other big problem is knowing what frequency the beacon is transmitting
on. I've not been able to detect any signals yet, so it's a bit hit and
miss tuning about and waiting for a suitably placed aircraft to come along.

I did a quick check on Beaconspots.eu and these are the last reported
sightings of GB3EDN. I'm going to assume the one on the 3rd September was a
typo...

2013-09-03 14:36 GB3EDN 1296.9000 -13dB TR -13 jt4g io85jw>jo45bo 709 DXC
OZ1FF JO45BO
2013-07-20 10:40 GB3EDN 1296.9900 539 TR 539 167 DXC G4KUX IO94BP21
2013-07-11 05:31 GB3EDN 1296.9900 -13dB TR -13 io85>tr>jo45 709 DXC OZ1FF
JO45BO58
2013-07-08 16:05 GB3EDN 1296.9900 -11dB TR -11 jt4g io85>jo45 709 DXC OZ1FF
JO45BO58
2013-04-17 08:53 GB3EDN 1296.9900 519 TR io85jwio87xj 519 178 DXC GM3UAG
IO87XJ

Most of these appear to be tropo reports, not aircraft reflected, but the
ones spotted by by OZ1FF quotes JT4g but reports the signal as via Tropo,
and the other two look like they are reports of the signal strength and
frequency of the CW signal.

The last quoted report that definately quoted to be for AS was this one.

2011-12-18 11:42 GB3EDN 1296.9907 529 AS io85jwio78hf 529 289 DXC GM8IEM
IO78HF

I'm not sure if thats a dial reading report, and since it was back in 2011,
the frequency may well have moved a bit since then.

Is there anyone, who is closer to GB3EDN or who has more regular aircraft
traffic over their path to the beacon, who can give me their dial frequency
readout for detecting the JT4g signals on 23cm please? I will make the
appropriate adjustment for my set up, and will keep a look out for GB3EDN
via aircraft reflections with a bit more certainty that I'm tuned to roughly
the right frequency.

Thanks - Dave (G0DJA)



Frequency for JT4g signals from GB3EDN on 23cm

Dave <dave@...>
 

Since the JT4g beacon that Andy put on air is now no longer transmitting I have been decoding JT4g signals from GB3CSB. These have been fairly regular as there's plenty of aircraft activity over the path between here and IO75xx. So, I've turned my attention onto GB3EDN. This is a more tricky one to detect from here as, on the heading from me to it, there are far fewer aircraft flying across or along the path and many are quite low to the ground as well.

The other big problem is knowing what frequency the beacon is transmitting on. I've not been able to detect any signals yet, so it's a bit hit and miss tuning about and waiting for a suitably placed aircraft to come along.

I did a quick check on Beaconspots.eu and these are the last reported sightings of GB3EDN. I'm going to assume the one on the 3rd September was a typo...

2013-09-03 14:36 GB3EDN 1296.9000 -13dB TR -13 jt4g io85jw>jo45bo 709 DXC OZ1FF JO45BO
2013-07-20 10:40 GB3EDN 1296.9900 539 TR 539 167 DXC G4KUX IO94BP21
2013-07-11 05:31 GB3EDN 1296.9900 -13dB TR -13 io85>tr>jo45 709 DXC OZ1FF JO45BO58
2013-07-08 16:05 GB3EDN 1296.9900 -11dB TR -11 jt4g io85>jo45 709 DXC OZ1FF JO45BO58
2013-04-17 08:53 GB3EDN 1296.9900 519 TR io85jw<tr>io87xj 519 178 DXC GM3UAG IO87XJ

Most of these appear to be tropo reports, not aircraft reflected, but the ones spotted by by OZ1FF quotes JT4g but reports the signal as via Tropo, and the other two look like they are reports of the signal strength and frequency of the CW signal.

The last quoted report that definately quoted to be for AS was this one.

2011-12-18 11:42 GB3EDN 1296.9907 529 AS io85jw<as>io78hf 529 289 DXC GM8IEM IO78HF

I'm not sure if thats a dial reading report, and since it was back in 2011, the frequency may well have moved a bit since then.

Is there anyone, who is closer to GB3EDN or who has more regular aircraft traffic over their path to the beacon, who can give me their dial frequency readout for detecting the JT4g signals on 23cm please? I will make the appropriate adjustment for my set up, and will keep a look out for GB3EDN via aircraft reflections with a bit more certainty that I'm tuned to roughly the right frequency.

Thanks - Dave (G0DJA)


Re: [VHFandUHF] GM4CXM Website

Ian White
 

-----Original Message-----
From: gm4cxm

I haven't updated my personal website at www.rayjames.biz/gm4cxm for
a number
of years so have decided to put the annual hosting costs to other
uses so it
will come down on 22/2. I may look at free hosting options in the
future.
On VHFandUHF@yahoogroups.com, Lawrence GJ3RAX replied:

For a limited amount of information you could use your QRZ page.

Along with literally billions of others, Ray's website has already been
copied and archived by The Wayback Machine at <www.webarchive.org>

So if you post the following link on your QRZ page, Ray, people can
still have permanent access to all the useful information:

<http://web.archive.org/web/20140123113230/http://rayjames.biz/gm4cxm/id
28.html>

That link goes directly to your Aircraft Scatter page, which has
accurate links to all the other pages as well.


73 from Ian GM3SEK


Re: 1296 Beacon QRT

Dave <dave@...>
 

I've saved all the decodes and non-decodes for several days into a TXT file per day and am importing them into an Excel file.

I'm hoping to see what times of day would be best to try for skeds based on the results.

If I come up with anything that looks interesting I will try to write something up for Scatterpoint but not sure how long that will take me.
 
Dave (G0DJA)

----- Original Message -----
Sent: Wednesday, January 22, 2014 1:47 PM
Subject: [ukmicrowaves] 1296 Beacon QRT

 

I'm turning the 1296 Personal beacon off now (1342 Wed 2014/01/22)

If anyone has worthwhile plots / decodes or other comnparisons betwen
the modes. or ideas or comments, perhaps they could send something in
to John for the RadCom Column and / or to Scatterpoint.


1296 Beacon QRT

Andy G4JNT
 

I'm turning the 1296 Personal beacon off now (1342 Wed 2014/01/22)

If anyone has worthwhile plots / decodes or other comnparisons betwen
the modes. or ideas or comments, perhaps they could send something in
to John for the RadCom Column and / or to Scatterpoint.

I know Dave 'DJA has had appreciable success getting this quite QRP
signal at 280km, mostly due to aircraft up and down the country.

John 'API has monitored consistently, and had the signal which is just
about copiable direct corrupted by aircraft many times as well as
enhanced. Although the path between us s only 50km, there are two
airports in the vicinity, Sounthampton and Bournemouth, as well as
flights to and from the big two crossing all around.

I know several other stationms were monitoring, what did you get ?

Andy
G4JNT


Re: QRV for UKAC tonight on 1296

Peter G3SMT
 

Hello Dave.

I made a number of contacts on 23cm using less than 10W so if you would like the details let me have your email address and I will send them to you.

73

Peter
G3SMT


On 21/01/2014 17:23, Dave wrote:
 



Only for SSB...  :-)
 
Seriously, if anyone does work anyone else, either one way QRP or 2 way, please let me know some details so that I can feed the information to other forums.  I'm sure that John (G8SEQ) would be interested for possible inclusion in SPRAT as well.

Just a reminder, the generally (!) accepted definition of QRP by most of the QRP clubs and organisations is 10W or less for Single Sideband and 5W or less for CW or similar modes. There's arguements about what the power levels for some modes should be, like RTTY, but I *think* - but don't quote me - that PSK is usually taken as under 10W and is counted as a variation of SSB.
 
I'm hoping to be about on CW and I will try reducing my power to 5W from my current 10W ouput.
 
Dave (G0DJA)
 
 
----- Original Message -----
Sent: Tuesday, January 21, 2014 3:47 PM
Subject: Re: [ukmicrowaves] QRV for UKAC tonight on 1296

 

Great so if you work me it will be QRP to QRP :-)

73

Conrad G0RUZ