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Latest Information: Feb 12th 2007 Tom: 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 NDBPUN 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 ModulationWhen 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 HeadingsI 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 From W2GFF
I just listened
again to Tom's
recording and it
seemed much clearer
this 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) 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 From PY2XC on 11th Feb,2007
Has anybody
though about PUNTA
CANA AIRPORT (PUN)
located in República
Dominicana?
Thank you everyone
for the help
identifying the
voice! Please help us locate PUN. email me at mycall@mycall.com my call is W8JI
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