Latest Information:
Feb 12th 2007
Tom:
I recently got
involved in this
issue with PUN due
to QRM it is causing
some HF aeronautical
services that we
use. We were just
told by the FCC this
morning that they
now have a very
accurate DF fix and
have notified the
appropriate
authorities in that
country. Of course,
who knows if those
authorities are
willing/able to do
anything? And they
didn't give us the
QTH. But let's hope
this helps.
Feb 13th, 2007
An FCC contact has verified they know the location of the beacon and already have asked the authorities to correct the problems. They said it appears to be a standard NDB transmitter repeating the same message and CW ID.
Still it is good practice for the next time if we learn to coordinate directional headings! We need directional headings from a different angle.
PUN NDB
PUN is an AM modulated transmission on many illegal frequencies. It has an USB voice ID on all frequencies and Morse code tone modulated ID with approximately 800Hz pitch. It has all the characteristics of a NDB (link). It may or may not be an airport NDB or Non-Directional Beacon.
PUN Carrier frequencies readable here are all multiples of 1752kHz.:
1752x1=1752
1752x2=3504
1752x3=5256
1752x4=7008
1752x5=8760
1752x6=10,512
1752x7=12,264
1752x8=14,016
1752x9=15,760
1752x10=17,520
1752x11=19,272
1752x12=21,024
1752x13=22,776
1752x14=26,280
1752x15=28,032
1752x16=29,784
Some of these frequencies have negative level shift during modulation, but that is a NORMAL occurrence when a stage is severely distorting a signal that is amplitude modulated by an earlier stage. This indicates the base frequency of PUN is 1752 kHz or a division of 1752 like 1752 / 7 = 250.3 kHz (approximately).
Possible base frequencies are any division of 1752, so divide 1752 by 2,3,4,5,6,7,8, or 9 produces a potential main frequency. At this point I feel it is unlikely to be anything less than 1752kHz, but it is quite possible I am wrong.
Identifying Frequency and Modulation
When we tune a modern amateur transceiver in the CW mode, a carrier or an additional tone from amplitude modulating the carrier will be audible and match the CW pitch setting of the transceiver when the dial display indicates the approximate frequency of the signal.
In other words in the CW setting with normal narrow CW filters, if I adjust my receiver to 7008, I will hear a 450Hz tone because I have my receiver setup to use with a 450Hz CW pitch. I will hear another 450 Hz tone that represents the Morse amplitude modulation tone of the transmitter when I tune to 7008.8 (this is the upper sideband) or 7007.2 (this is the lower sideband) or multiples of .8kHz up and down from 7008. The sidebands will have the desired keying information. The carrier may or may not have the negative or image of the desired modulation.
If I use the SSB mode and tune 7008 I will not hear any carrier! The only thing I might hear is the modulation, since it is offset from the carrier.
When we deal with distortion products from an overdriven stage or a device that is clipping the waveform, the sidebands will NOT all be the same level. The characteristics of modulation will often vary considerably on all harmonics. You might find some harmonics that have a predominant upper sideband and some with a predominant lower sideband even if the transmitter is perfectly symmetrical in base modulation.
Most important properly identifying signal characteristics demands you have a very low noise environment compared to the signal's level. At my location the NDB carrier is up to 40dB above background noise. This means I can identify spurious products that are approaching 40dB below the carrier level. I can hear the USB voice transmission on every frequency so long as PUN carrier is 15-20dB out of background noise.
We really must have good signal to noise to identify modulation characteristics properly. Poor or moderate S/N ratio often causes problematic transmitters to get "clean" bills of health. If we are giving a critical or exacting report of spurious signals or modulation we must have a very low background noise level and know how, what, and where to listen!
I am fortunate enough to live in a very rural location without locally generated noise. The noise floor is limited by noise propagated in from the equatorial regions when I listen south. When PUN is very strong compared to my noise floor I can hear several modulation harmonics that are multiples of approximately 800 Hz. If the noise was only 10dB stronger I would not hear many of the modulation products, and I would have an entirely different opinion of the modulation characteristics of this beacon.
Because of wide variations in propagation and local noise and difficulty in identifying products, modulation characteristics are generally not important beyond the first few observations. With poor signal-to-noise it is easy to get the impression there is no modulation or a false impression of modulation characteristics.
Directional Headings
I have an Interferometer system using wide-spaced elements (500-1000 feet apart) for measuring directions. In a matter of seconds I can identify direction within a few degrees on 160 meters. Unfortunately I have never calibrated the array on higher frequencies and so the tolerance is wider than on 160. It probably only rivals a 5 element Yagi for directional heading accuracy above 3 or 4 MHz, so I have to include a tolerance.
The bearing from my location is 180 degrees true:
The bearings including two from from Panama and one from YV4 are (tolerances are unknown):
The FCC so far reports it as being from the general area of northwest South America, and it appears from amateur radio bearings to be near HK0M.
The signal from PUN sounds like this:
Tuned 800Hz off to hear tone on CW.
Tuned USB to hear 40 meter voice on 7008USB
Latest Sound File 12 Feb 2007 very good clarity. This sound file is edited at the end to remove the CW but keep the voice.
Note: Voice recordings have been edited by deleting most CW tones.
From HP1AC:
I have listened
several times to
both mp3 of the
voice ID and can
pick up
PISTA LASTENIA
First I though I was
copying - PISTA LAS
PIÑAS
BUT ...... it
is.....PISTA
LASTENIA
Then ,, could it be
the local airport at
Ingenio Lastenia in
Argentina ???
In Panama somewhere
south east in
Darien, there is a "
Las Piñas airport" ,
but no register of
any NDB found.
From W2GFF
I just listened
again to Tom's
recording and it
seemed much clearer
this
time; I hear it as
VISTA LA PEDRA
Doesn't that
translate into
something like STONE
VIEW ??
From LU4YAO
Cannot be Ingenio
Lastenia in
Argentina as it is
closed since the
90´s, had no
airfield and it was
located very near
the Benjamin
Matiencio airport
from Tucuman city (SANT)
Someone mentioned
Salitrera Lastenia
in Chile (see
http://es.wikipedia.org/wiki/Oficina_Salitrera_Chacabuco),
but that was the
name until 1922 when
it changed to
Salitrera Chacabuco
and close in 1945,
having been during
the military rule a
concentration camp.
Today is a national
historical monument,
in ruins. Jorge -
LU4YAO
Argentina also disagrees with directional headings although there is some possible error in headings from long distances or from calibration.
From HP3XUG
This AM, the 3504
sigs were very
strong (nil on
upper freqs and nil
on 1752!).
(Lack of higher
frequency signals
might mean it is
very close to Louis,
but on skywave.)
Was able to play
Tom's audio files
and with my HP wife
Yari's ears, can
provide some further
insight into this
matter, also a copy
from Bill Zellers
was sent me. I can't
quite make it out,
and W2GFF's msg of
"Vista La Pedra"
is almost correct.
She copies "Vista la
Piedra". In this
context, it can
mean "See the Rock"
, View the Rock,
etc.
From PY2XC on 11th Feb,2007
Has anybody
though about PUNTA
CANA AIRPORT (PUN)
located in República
Dominicana?
73 !
CARLOS - PY 2 XC
Thank you everyone
for the help
identifying the
voice!
Any other reports of
what the voice
sounds like would be
helpful.
Please help us locate PUN. email me at
mycall@mycall.com
my call is W8JI