Recent wideband interference on 40m
Owen
Over recent months, a wideband pulse type interference has been
frequently heard on 40m and 80m bands. You have probably heard it, or
heard mention of it in WIA News.
To assist in identification, I have posted a 10 sec sound clip of it
at http://www.vk1od.net/PulseInterference.mp3 .
As an experiment, I took some field strength readings of it using FSM
( http://www.vk1od.net/fsm/ ).
The peak field strength in Canberra with a deep fade at the time was
up to 30dBuV/m. (QP about 20dBuV/m, about -85dBm or 10uV or S7 on a rx
with a half wave dipole) That is sufficient to be able to take a
bearing using a smallish untuned loop (say 1m per side square loop).
Taking a bearing on signals reflected by the ionosphere is
problematic, but we should be able to get bearings and field strength
observations from around the country that are convergent.
Anyone up for it?
Owen
--
nos...@novirus.com.au
like the pulses we used to get from the Loran Navigation signal on top
band in the UK in the fifties and sixties. What software do you use to
covert wav files to those that can be sent?
Owen
The clip was extracted from a longer wave file from Glen (4DU), and I
cropped it and save it as an mp3 using SoundForge. SoundForge is
commercial software.
If you want freeware, look for Audacity.
The lowest cost way to convert wave files to mp3 is LAME (Audacity can
use LAME), Google for it.
Owen
--
Owen
It is apparent at 22:30 on 7.045 at a bearing of 350 / 170 True from
Canberra, fading up to 20dBuV/m Peak in 2KHz measurement bandwidth.
Using a dipole, thats about -90dBm or about S6 at the receiver.
That bearing from Canberra passes through Port Moresby (PNG), and
Japan.
IPS shows foF2 around 2MHz over Canberra, but the HAP charts show
propagation to far north Queensland and PNG.
Not apparent here on 80m at this time.
Owen
--
Owen
>
>Over recent months, a wideband pulse type interference has been
>frequently heard on 40m and 80m bands. You have probably heard it, or
>heard mention of it in WIA News.
...
>Taking a bearing on signals reflected by the ionosphere is
>problematic, but we should be able to get bearings and field strength
>observations from around the country that are convergent.
>
>Anyone up for it?
It was there again tonight, stronger than last night, up to S9. I make
it about 340 / 160 deg from Canberra.
A few notes are at http://www.vk1od.net/fsm/cs/case01.htm .
Anyone else got any info?
Owen
--
Alan Peake
> It was there again tonight, stronger than last night, up to S9. I make
> it about 340 / 160 deg from Canberra.
It's been coming in on 80 at 10 over for the last few nights. Looks like
a PW of 5ms and a PRF of 43Hz which would give it an unambiguous range
of a little less than 7000 km. It covers about 100 kHz so a broadband
receiver might be the go for further analysis.
Alan
VK2TWB
Owen
<adp...@killspam.internode.on.net> wrote:
>a PW of 5ms and a PRF of 43Hz which would give it an unambiguous range
Alan, am I going blind, or did you leave a decimal point out of the PW
figure?
Owen
--
Alan Peake
>>a PW of 5ms and a PRF of 43Hz which would give it an unambiguous range
>
>
> Alan, am I going blind, or did you leave a decimal point out of the PW
> figure?
>
> Owen
radars)duty cycle. That's what appeared on the CRO anyway.
Alan
Ed -|-
the Aus (qld) is in Longreach which is off bearing
the fading would indicate further than the HAP charts show as a "grade
1" link distance
all you need now is a x bearing for the source
Owen
>Taking a bearing on signals reflected by the ionosphere is
>problematic, but we should be able to get bearings and field strength
>observations from around the country that are convergent.
>
>Anyone up for it?
Not too many from the look of it!
Owen
--
Brad
"Owen" <ow...@no.where> wrote in message
news:lpjcc1dbpae1o5g9h...@4ax.com...
This isn't the USA, there aren't too many 40m beams on 120ft towers around
here. I can conclusively report that it is a damn nuisance on a dipole.
Unfortunately that's about the best I can offer.
What we need is a friendly Government agency with big old log periodics and
some free time to do some bearing checks for us. Regrettably, most of these
have been torn down in recent years to make way for housing estates. I
wonder what happened to all those beams and towers?
Brad.
kmal...@tpg.com.au
wrote:
>
>... clipped
>
>
>This isn't the USA, there aren't too many 40m beams on 120ft towers around
>here. I can conclusively report that it is a damn nuisance on a dipole.
>Unfortunately that's about the best I can offer.
>
>What we need is a friendly Government agency with big old log periodics and
>some free time to do some bearing checks for us. Regrettably, most of these
>have been torn down in recent years to make way for housing estates. I
>wonder what happened to all those beams and towers?
>
>Brad.
>
>
What's wrong with using one of Owen's square loops?
With Owen's bearings from Canberra, what is needed is a similar set of
numbers from Adelaide or Perth or that general direction (or Auckland
come to that) to both remove the ambiguity from loop bearings and to
provide the intersecting bearing to give an X to mark the spot.
Or is this just too low-tech to be of interest?
Keith G Malcolm
2 Jul 05
Owen
wrote:
>
>"Owen" <ow...@no.where> wrote in message
>news:lpjcc1dbpae1o5g9h...@4ax.com...
>> On Sun, 26 Jun 2005 04:53:20 GMT, Owen <no...@no.where> wrote:
>>
>>
>>>Taking a bearing on signals reflected by the ionosphere is
>>>problematic, but we should be able to get bearings and field strength
>>>observations from around the country that are convergent.
>>>
>>>Anyone up for it?
>>
>> Not too many from the look of it!
>>
>> Owen
>
>
>This isn't the USA, there aren't too many 40m beams on 120ft towers around
>here. I can conclusively report that it is a damn nuisance on a dipole.
>Unfortunately that's about the best I can offer.
>
Thankfully, no this isn't the USA... not just yet anyway.
Brad, I write this to the many "listeners", though I pickup on your
points. References to "you" are not to you personally, but to all of
us.
I don't know what the reference to "40m beams on 120ft towers" is
about. If it is to imply that is what is needed for bearings, no it
can be as humble as the loop that I used (
http://www.vk1od.net/SmallUntunedSquareLoop/loop.jpg ).
It is actually very hard to get a decent bearing from an steerable log
period or rotatable Yagi in my experience, they turn so slowly that it
is difficult to DF a signal with severe fade that is faster than the
antenna moves. That is one of the advantages of the loop, it can move
much faster than the fade, and it can be pointed in three dimensions
rather than two.
The antenna doesn't need more gain than needed to hear the signal
above the receiver noise, and it doesn't need front to back gain if we
get cross bearings, which are needed anyway.
>What we need is a friendly Government agency with big old log periodics and
>some free time to do some bearing checks for us. Regrettably, most of these
>have been torn down in recent years to make way for housing estates. I
>wonder what happened to all those beams and towers?
Ok, apparently we are waiting for someone else to do it.
Frankly, I doubt that the ACMA (new name for the ACA of last week)
will put too much effort into it unless we look like we are really
interested. Do we look like we are really interested?
The web page that I linked in my original post has had over a hundred
hits in the last week, obviously people "just looking". Just looking
isn't going to solve the problem. I showed in that article and the
linked pages that bearings can be obtained with the most simple of
equipment.
How many people have a mobile station, or could throw the '706 on the
front seat of the car powered off the cigarette lighter (you are not
going to transmit for this job) and use a loop like the one I
described. (The reason I am talking about a car, is you cannot get
valid bearings operating the loop in your shack beneath other
antennas, the mutual coupling will distort the perception of where the
signal comes from dramatically (it will come from the nearby antenna,
and will be maximum when the loop is oriented for maximum coupling).
The other key thing about the loop I described, it has a balun, and
regardless of whether you have come to the view that baluns are
unnecessary, a balun is REAL important in this application to ensure
the coax does not pickup signal and skew the loop pattern.
Owen
--
Brad
"Owen" <ow...@no.where> wrote in message
The first thing that came to mind was a line from the film The Castle - You
can overcapitalise, can't you? That's a big aerial.
Meanwhile, point taken. I was thinking along the lines of different DF'ing
procedures, which, considering the business I am in - Avionics - with all
those H field ADF antennas, shows I wasn't thinking too clearly. In general,
the highest frequency a ferrite ADF antenna is capable of operating, or
designed to operate, is 2182. Above that different techniques are used,
yours for example. I don't have any Marine background or perhaps that
thought may have come more naturally to me.
I have been reading your article with interest, but doubt that I could
contribute much to useful bearing measurements, being less than 200km due
North of you. no crossbearings from here.
Brad.
Owen
wrote:
>I have been reading your article with interest, but doubt that I could
>contribute much to useful bearing measurements, being less than 200km due
>North of you. no crossbearings from here.
Thanks. You flatter me with the assumption that my bearing (which I
know passes pretty much over your QTH) is correct. Bearings are
usefull from anywhere as confirmation at this point.
Though I see a lot of bearings from single locations that are stated
in terms of the supposed source (eg someone with a four-square who has
identified Indonesia as the "bearing"), bearings in common speak, like
degrees wrt true north, and location of the observer are the basis of
sound evidence which the ACA will need (IMHO) to act.
It is true given Australias population distribution, that we are
likely to get more bearings from along the east coast, and with many
of the casual observations indicating the bearings are north / south,
bearings from more westerly or easterly places would be valuable (eg
Darwin, west coast, ZL.
But, IMHO, a few reliable bearings from the east coast are needed to
confirm the suspicion that it is north of east coast locations. The
loop I described has a very sharp null, and it should be possible to
get a pointing accuracy within about +/- 5 degrees, which is better
than things like four-squares. Notwithstanding all that, DFing
ionospheric paths is a problem, and again a reason by a number of
obervations helps in reducing the error statistically.
Thanks for prompting the discussion Brad. I guess there is more
interest in "logging in" to content free-nets on 40m than there is in
low tech, simple, meaningful observations that should help to protect
our bands by supporting our requests for ACMA (ACA) action with good
evidence, demonstrating our interest and committment, and perhaps
even, worthiness.
Owen
--
Alan Peake
interested in this. Didn't have time to look much further but others are
interested.
The mobile loop is a good idea and I'll make one not too far down the
track. I may be off to Adelaide in a month or so. That would give us
about a 1000km baseline.
Alan
Owen
>On Sun, 26 Jun 2005 04:53:20 GMT, Owen <no...@no.where> wrote:
>It was there again tonight, stronger than last night, up to S9. I make
>it about 340 / 160 deg from Canberra.
>
The WIA intruder watch reports an estimated source location of the
Parcel Islands in the South China Sea at 16.5N 112E.
The bearing from here to 16.5N 112E is 318, which is a little west of
my 340 to 350 observations.
The WIA story is at http://wia.org.au/news/2005/20050727-01.php .
Owen
--
Owen
>On Sun, 26 Jun 2005 04:53:20 GMT, Owen <no...@no.where> wrote:
>It was there again tonight, stronger than last night, up to S9. I make
>it about 340 / 160 deg from Canberra.
>
The WIA intruder watch reports an estimated source location of the
Parcel Islands in the South China Sea at 16.5N 112E.
The bearing from hear to 16.5N 112E is 318, which is a little west of
Owen
>On Sun, 26 Jun 2005 04:53:20 GMT, Owen <no...@no.where> wrote:
>It was there again tonight, stronger than last night, up to S9. I make
>it about 340 / 160 deg from Canberra.
>
The WIA intruder watch reports an estimated source location of the
Parzcel Islands in the South China Sea at 16.5N 112E.
The bearing from here to 16.5N 112E is 318, which is a little west of
Owen
>On Sun, 26 Jun 2005 04:53:20 GMT, Owen <no...@no.where> wrote:
>It was there again tonight, stronger than last night, up to S9. I make
>it about 340 / 160 deg from Canberra.
>
The WIA intruder watch reports an estimated source location of the
Paracel Islands in the South China Sea at 16.5N 112E.
spa...@tpg.com.au
> OThe WIA intruder watch reports an estimated source location of the
> Paracel Islands in the South China Sea at 16.5N 112E.
>
> The bearing from here to 16.5N 112E is 318, which is a little west of
> my 340 to 350 observations.
OK Owen, we got the message
73
Owen
>OK Owen, we got the message
I was trying to work out what you mean't, but I guess your ISP or a
news server in the chain doesn't handle the nntp "cancel" message. I
was having a bad time spotting mistakes after each post was sent...
that or I need new specs.
Anyway, anyone wanting to take a DXpedition to the Paracel Islands,
the CIA site has some intelligence on them. Occupied by the Chinese in
1974, claimed by Vietname and Japan (IIRC). Well, that might just be
the sort of place you might feel insecure and want an OTHR!
Owen
--
nva
> On Fri, 29 Jul 2005 10:49:47 +1000, spa...@tpg.com.au wrote:
>
>
>>OK Owen, we got the message
>
>
> I was trying to work out what you mean't, but I guess your ISP or a news
> server in the chain doesn't handle the nntp "cancel" message. I was having
> a bad time spotting mistakes after each post was sent... that or I need
> new specs.
Most properly-configured servers don't honour cancels nowadays, due to
abuse.