Sweeping carrier in the HF bands
Charlie Thompson
passing through the HF bands. It appears both in the
amateur HF bands and other HF frequencies as well.
It sounds just like someone spotting their VFO
as they spin the VFO dail up or down the band.
At first I assumed this was someone with bad
operating practices but after I noticed it on the
non-ham portions of the HF band I figured it was
some military station with annoying operating
practices.
I now belive that none of the above explanations
apply. I think this sweeping carrier is some sort
of HF propogation sounder. It probably is finding
the MUF and collecting data relating to HF
propogation vs. frequency vs. time. If this is
true how can the FCC license such an obnoixous
thing?
Anybody have any explanations?
Thanks in advance,
C. Thompson WB4HVD
Bob Parnass, AJ9S
> I have noticed (for some time now) a sweeping carrier
STRANGE HF SIGNALS MAY BE PROPAGATION SOUNDERS
by Bob Parnass, AJ9S
Many scanner and shortwave listeners are curious by nature,
and want to know the identity of stations they hear. Pirate
broadcast stations have a cult following, as do "spy
numbers" and military transmissions.
But, some signals seem to defy explanation. They are nei-
ther voice nor data. What are those clicks, tweets, and
bursts one hears on the shortwave bands? Perhaps you stum-
bled upon signals from over the horizon radar, or even an RF
induction heating oven. There is another source of these
puzzling signals -- your receiver may have intercepted a
sounder system used for propagational studies.
A recently released U. S. Navy report gives us a peek at
several such radio sweeper systems: HF Maximum Usable Fre-
quency (MUF) Model Uncertainty Assessment, Technical report
1184, by T. N. Roy and D. B. Sailors. June 1987. Naval
Ocean Systems Center, San Diego, CA.
Basically, a sounder system consists of a transmitter that
emits signals sequentially on several frequencies, and a
distant receiver which is programmed to follow the
transmitter frequency and measure the signal strength at
each channel.
Navy Tactical Sounder System
The Navy has used a system of several shore-based AN/FPT-11
(XN-1) sounder transmitters and shipboard and land based
AN/UPR-2 receivers to determine propagation conditions.
Known as the Navy Tactical Sounder System (NTSS), the FPT-11
transmits a double, biphase pulse sequence every minute on
each of 80 frequencies between 2 and 32 MHz. The 80 fre-
quencies are spaced in 100 kHz increments between 2 and 4
MHz, 200 kHz increments between 4 and 8 MHz, 400 kHz incre-
ments between 8 and 16 MHz, and 800 kHz increments between
16 and 32 MHz.
Both receivers and transmitters are synchronized to WWV so
the receivers can follow the transmitter frequency sequence.
Granger Model 900 Sounder
The Stanford Research Institute has used a different system
to study propagation. Their equipment consists of Granger
Associates Model 900 sounders, which cover the 4 to 64 MHz
range in four bands of 40 linearly spaced channels each.
The Granger sounders are high power, and transmit 30 kW peak
pulses of 0.1 ms or 1.0 ms. The scan sequence takes 29
seconds to complete, and is repeated every 20 minutes.
A search of FCC records shows SRI may also be using linear
sweepers. SRI was granted license KA2XNH as an experimental
contract station to fullfull U.S. Navy contract N00014-83-
C-0267. This license permits a 50 watt SRI transmitter to
sweep the 2-32 MHz band in 1 Hz increments not more than 3
times per hour at a sweep rate of not less than 5 minutes
sweep for the entire band.
Other Systems
Another sounder system consists of a device called a C-3
iosonde, which transmits 0.1 ms pulses and is swept linearly
between 2 and 25 MHz.
The BR Communications HF Chirpsounder System takes 5 minutes
to sweep between 2 and 30 MHz, and the sweep is repeated
every 15 minutes.
Sights and Sounds
It's tough to follow frequency agile signals using only
shortwave receiver. Connecting a panoramic display (pana-
daptor) makes it easier to identify sounders. One can actu-
ally see the sweeper signals moving up the band.
--
============================================================================
Bob Parnass, AJ9S - AT&T Bell Laboratories - att!ihuxz!parnass (708)979-5414
John Spencer
about the sweeping signals. It just so happens that I brought home a
.01-1500MHz spectrum analyzer this weekend to investigate the SW bands. I
noticed a carrier that swept up in frequency at a 100kHz/second rate and had a
period of five minutes. Since I live near WWV in Fort Collins, I thought this
might be a service of the NBS. My first thought was one might be able to
determine the wavelength given the time the signal passes the monitored
frequency. There are several different strength signals being transmitted all
a few seconds apart in time. The following is the times the signal was
observed at 16Mhz.
Time UTC
20:45:13
20:46:30
20:46:38
20:46:50
20:47:12
20:48:12
20:49:30
20:49:50
20:51:10
20:51:38
20:52:50
20:53:05
20:53:35
20:54:10
20:55:10
20:56:38
20:57:10
20:58:30
20:58:50
21:00:38
21:01:30
21:01:50
21:02:10
21:03:10
21:04:30
21:04:38
21:04:50
21:05:10
At 6MHz, 11MHz, and 21MHz there was a similar patterns, although at 6MHz the
sweeps were less frequent than those above 10MHz.
BTW If you can get a spectrum analyzer to use for a while, you will be
fasinated with the discoveries you will make.
John R. Spencer (j...@hpesjrs.HP.COM, (303) 229-3271)
Don Liu
>I have noticed (for some time now) a sweeping carrier
>passing through the HF bands. It appears both in the
>amateur HF bands and other HF frequencies as well.
>Anybody have any explanations?
>Thanks in advance,
These are the SPREAD SPECTRUM communication signals. There are
usually two modulating signals. One is the useful signal which
modulates the carrier (HF) in one of the common method. The frequency
deviation caused by the useful signal (like data, audio, etc) is
very small.
The other modulation is much greater and results in a widely
spread frequency spectrum. It is the format of this modulation
that characterize the communication. There are several advantages
of the spread spectrum. The "spreading" format is unique for each
station, and only the authorized recevers know the format. Therefore
the S.S. is very secure. Secondly, since the energy is so weak (in
everage sense) in a 10 KC window (that of a radio), the signal can
hardly be noticed (unless slow formats are used).
Most US spied use S.S., by the way.
Barry McLarnon DGBT/DIP
Right you are. This annoying QRM emanates from a device known as a
"chirpsounder", manufactured by an outfit called BR Communications (there
may be other sources, but I haven't heard of any). The U.S. military (and
Canada, amongst other countries) has a fairly extensive network of these
things to support their HF links. Their gratuitous use of spectrum assigned
to other services is, no doubt, justified on the basis of National Security.
Funny thing though... I would have thought that this justification would
only apply in times of National Emergency. Oh well. The next time you get
jolted out of your chair by that carrier sweeping through your headphones,
try and remember that it's all for the cause of peace 'n freedom, etc. :-)
> C. Thompson WB4HVD
Barry VE3JF
--
Barry McLarnon Communications Research Center Ottawa, ON Canada
Internet: ba...@dgbt.crc.dnd.ca UUCP: ...utzoo!dciem!nrcaer!dgbt!barry
CI$: 71470,3651 PBBS: VE3JF@VE3JF AMPRnet: ba...@bbs.ve3jf [44.135.96.6]
Jeff Carroll
>In article <30...@radio.oakhill.UUCP> cha...@oakhill.UUCP (Charlie Thompson) writes:
>>I have noticed (for some time now) a sweeping carrier
>>passing through the HF bands. It appears both in the
>>amateur HF bands and other HF frequencies as well.
>
Not likely, for reasons I'll give below.
> There are
>usually two modulating signals. One is the useful signal which
>modulates the carrier (HF) in one of the common method. The frequency
>deviation caused by the useful signal (like data, audio, etc) is
>very small.
I know of no HF spread spectrum system in the field today. (This
isn't to say there isn't one. In fact, I've heard rumors. But I've heard
of no production contracts.) The lowest-frequency SS systems I know of
(e.g., SINCGARS) are in the 30-88 MHz band, and are frequency-hopping
rather than carrier-swept or psuedonoise-spread.
>The other modulation is much greater and results in a widely
>spread frequency spectrum. It is the format of this modulation
>that characterize the communication. There are several advantages
>of the spread spectrum. The "spreading" format is unique for each
>station, and only the authorized recevers know the format. Therefore
>the S.S. is very secure. Secondly, since the energy is so weak (in
>everage sense) in a 10 KC window (that of a radio), the signal can
>hardly be noticed (unless slow formats are used).
And a swept carrier would be about the stupidest method you
could use for a SS signal, unless you didn't care about being
detected and intercepted. SS is only secure if the enemy can't find
enough of your signal to figure out what kind of encryption and hop
rate/PN sequence you're using. Sometimes just having your signal
*detected* can be deadly, because the enemy can DF on it and blow you
away.
>Most US spied use S.S., by the way.
Not to mention the Army. And the Air Force. And, soon, your
cellular phone.
Jeff Carroll
car...@atc.boeing.com
Jeff Carroll
I've heard about this kind of thing in my graduate EM classes. Forget
the common name (I'll look it up tonight), but it's essentially an
ionospheric effect.
John Woods
> A search of FCC records shows SRI may also be using linear
> sweepers. SRI was granted license KA2XNH as an experimental
> contract station to fullfull U.S. Navy contract N00014-83-
> C-0267.
Ah, but did they pass a code test? And do they QSL??? ;-)
--
John Woods, Charles River Data Systems, Framingham MA, (508) 626-1101
...!decvax!frog!john, jo...@frog.UUCP, ...!mit-eddie!jfw, j...@eddie.mit.edu
Brian Daly
> In article <30...@radio.oakhill.UUCP> cha...@oakhill.UUCP (Charlie Thompson) writes:
> >I have noticed (for some time now) a sweeping carrier
> >passing through the HF bands. It appears both in the
> >amateur HF bands and other HF frequencies as well.
>
> >Anybody have any explanations?
> >Thanks in advance,
>
> These are the SPREAD SPECTRUM communication signals. There are
> usually two modulating signals. One is the useful signal which
>
carrier, as the original article mentions. There are two types of spread
spectrum -- frequency hopping, ans pseudo-random noise. In frequency hopping,
the carrier is "hopped" over many frequencies, not a continuous sweeping. In
PN, the bandwidth of the signal is spread and requires special detection
circuits -- not something that would be picked up be your everyday SW
receiver.
My quess is the continuous sweeping is some sort of OTH backscatter radar.
73's.
--
Brian K. Daly WB7OML @ AG Communication Systems, Phoenix, Arizona
UUCP: {...!ames!ncar!noao!asuvax | uunet!zardoz!hrc | att}!gtephx!dalyb
Phone: (602) 582-7644 FAX: (602) 582-7111
~
Gary Bourgois
>In article <16...@orstcs.CS.ORST.EDU>, li...@guille.ECE.ORST.EDU (Don Liu) writes:
>> In article <30...@radio.oakhill.UUCP> cha...@oakhill.UUCP (Charlie Thompson) writes:
>> >I have noticed (for some time now) a sweeping carrier
>> >passing through the HF bands. It appears both in the
>> >amateur HF bands and other HF frequencies as well.
>>
>> >Anybody have any explanations?
>> >Thanks in advance,
>>
>> These are the SPREAD SPECTRUM communication signals. There are
>> usually two modulating signals. One is the useful signal which
>My quess is the continuous sweeping is some sort of OTH backscatter radar.
Once again, let us put this question to a rest. The sweeping carrier is
a CHIRPSOUNDER. Used to track ionospheric conditions. There are
several locations (All Military) in the world, where these sweeps are
made according to a predefined schedule. The schedule itself is in the
(I believe) lastest issue of Popular Communications.
In addition to reading this newsgroup, anyone with a serious interest in
radio communications should subscribe to Popular Communciations (or get
it at your news stand) and Monitoring Times. Glenn Hauser's two
magazines are probably also very useful, though I have not managed to
part with the subscription fee yet...
To the person who replied to my PockaPock posting (the funny sputtering
sound I noted on 75 meters) I am quite sure that he is right, and that
the sound eminates from frequency hopping radios (military). This
leaves the funny BURST type (Obviously Digital) transmissions that I
regularly hear on 75 meters very early in the morining. I was told that
these are used in conjunction with Radio Navigation for USAF planes,
though none of my friends in the USAF "will confirm nor deny".... It IS
interesting to note though that on the night Norriegga was being ferried
to the USA, that the well known Cuban CW jammer that trashes up the
entire 75m band was out in full force, and making a shambles of 75
meters (though the cuban's fundamental is 3922, his spurs are LOUD on
3950, which also happens to be where I often copy the one second digital
bursts (they are NOT any type of signal I am familiar with, but
obviously ARE digital)...
Where is HAVANA MOON to solve these mysteries... I know he reads this
group......
>73's.
>--
>Brian K. Daly WB7OML @ AG Communication Systems, Phoenix, Arizona
>UUCP: {...!ames!ncar!noao!asuvax | uunet!zardoz!hrc | att}!gtephx!dalyb
>Phone: (602) 582-7644 FAX: (602) 582-7111
>~
--
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== 3.950 Nationwide Amateur Radio Nightly after 0200z=Learning Channel ==
=============== WB8EOH = The Eccentric Old Hippie = WB8EOH ================
mgeiger...@gmail.com
John Reed
wrote in message
news:9e364782-ffdf-4d60...@googlegroups.com...
dxAce
K1QAR
Apparent powerful spread spectrum, covering the entire 75 meter phone band at S8-9, sounding like fast popcorn, effectively shutting down activity in major ham band.
Where is the lobby arm of the ARRL?
Where is law ' n' order, FCC?
Our established tax and membership supported 'system' remedies seem to be occupied elsewhere.
Since its been noticed that a really powerful signal (10-100kW), properly aimed by a wire beam has often shut illegal band intruders off in the past, maybe there is some floks out there who would like to DF and locate this guy, and someone who would help amateur radio survival by "gunning" this guy off the air.
fred k. engels®
Where is the law ' n' order, F¢¢? They are busy ass kissing those
broadcasting shitheads!!!!
Our f¢¢ tax supported 'system' is occupied elsewhere sucking their
broadcasters cock!
"K1QAR" wrote in message
news:af495d76-3787-4e75...@googlegroups.com...
Saturday 7-8 AM, 4/25 Boston area, intruder alert.
Apparent powerful spread spectrum, covering the entire 75 meter phone band
at S8-9, sounding like fast popcorn, effectively shutting down activity in
major ham band.
Where is the lobby arm of the ARRL?
Where is law ' n' order, FCC?