There are numerous radars running in the HF bands.
Some of them run continuously.

Frequencies heard in San Diego.
4407
4814
12180 to 12100
13370 to 13450
13500 to 13570
13920 to 13970
26340 to 26190

We can examine their echos too.
I recorded the one at 26190 (a while back) for 60
seconds and ran an autocorrelation.
A plot of it is posted in alt.binaries.alt.
We can see that it echos over great distances,
on the order of the circumferance of the Earth.
(The horizontal scale is time converted to distance
figuring the signal travels at the speed of light.)

--
rb

"Ron Baker, Pluralitas!" wrote in message
...
There are numerous radars running in the HF bands.
Some of them run continuously.

Frequencies heard in San Diego.
4407
4814
12180 to 12100
13370 to 13450
13500 to 13570
13920 to 13970
26340 to 26190

We can examine their echos too.
I recorded the one at 26190 (a while back) for 60
seconds and ran an autocorrelation.
A plot of it is posted in alt.binaries.alt.
We can see that it echos over great distances,
on the order of the circumferance of the Earth.
(The horizontal scale is time converted to distance
figuring the signal travels at the speed of light.)

--
rb

http://www.lazygranch.com/sound/shortwave/4814usb.wav

I recorded this from the SF Bay area in usb. It looks like bursts of
5Khz modulated at 500hz, then of course gated to wait for an echo.

BTW, I think this is codar.
Ron Baker, Pluralitas! wrote:
There are numerous radars running in the HF bands.
Some of them run continuously.

Frequencies heard in San Diego.
4407
4814
12180 to 12100
13370 to 13450
13500 to 13570
13920 to 13970
26340 to 26190

We can examine their echos too.
I recorded the one at 26190 (a while back) for 60
seconds and ran an autocorrelation.
A plot of it is posted in alt.binaries.alt.
We can see that it echos over great distances,
on the order of the circumferance of the Earth.
(The horizontal scale is time converted to distance
figuring the signal travels at the speed of light.)

--
rb

wrote in message
ups.com...
http://www.lazygranch.com/sound/shortwave/4814usb.wav

I recorded this from the SF Bay area in usb. It looks like bursts of
5Khz modulated at 500hz, then of course gated to wait for an echo.

BTW, I think this is codar.

Yeah, Codar seems likely.
I've put some plots from your recording at alt.binaries.alt.
There are some good echos there.
0.02 seconds corresponds to 6000 km.
I think you will find that the signal is sweeping
down from 4820 to 4790 over about 0.5 seconds,
repeating every second.
It is audible when it passes through the passband
of the receiver.

--
rb

What!!!??? No over the horizon Radar!
There's that Johnny Cash movie commercial on my DirecTV Radio thangy
gin.

The tasteeee of lovee is sweetttt,,,,,,,
cuhulin

Interesting. Is there a canned program to take an autocorrelation of a
wav file? I noticed the signal was wide, so I used the 9.5Khz filter,
though clearly that isn't enough if the signal is 30Khz wide. BTW, it
has an interesting sound with FM demod.

I suppose if I had the ability to digitize at a higher bandwidth, I
could sample my 455Khz IF output and get the whole sweep. I did move
the VCO around a bit and couldn't find a center of the signal.

I've been looking at various high speed digitizers for use as a
pan-adapter. This is the most interesting of the bunch:
http://www.universal-radio.com/catal...rxvr/0014.html


Ron Baker, Pluralitas! wrote:
wrote in message
ups.com...
http://www.lazygranch.com/sound/shortwave/4814usb.wav

I recorded this from the SF Bay area in usb. It looks like bursts of
5Khz modulated at 500hz, then of course gated to wait for an echo.

BTW, I think this is codar.

Yeah, Codar seems likely.
I've put some plots from your recording at alt.binaries.alt.
There are some good echos there.
0.02 seconds corresponds to 6000 km.
I think you will find that the signal is sweeping
down from 4820 to 4790 over about 0.5 seconds,
repeating every second.
It is audible when it passes through the passband
of the receiver.

--
rb

In article ,
"Ron Baker, Pluralitas!" wrote:

wrote in message
oups.com...
Interesting. Is there a canned program to take an autocorrelation of a
wav file?

I use Matlab. It is a general purpose math tool. A lot of
people use it to prototype DSP algorithms. There is
a student version for $150. It is good enough.
There is also an open source, free program called Octave
that tries to be compatible with Matlab. Matlab programs
can generally be ported to Octave with more or less work.

Snip

They just got through trying to hit me up for $1000 - $1300 bucks for
versions 12 and 13.

--
Telamon
Ventura, California

"Telamon" wrote in message
...
In article ,
"Ron Baker, Pluralitas!" wrote:

wrote in message
oups.com...
Interesting. Is there a canned program to take an autocorrelation of a
wav file?

I use Matlab. It is a general purpose math tool. A lot of
people use it to prototype DSP algorithms. There is
a student version for $150. It is good enough.
There is also an open source, free program called Octave
that tries to be compatible with Matlab. Matlab programs
can generally be ported to Octave with more or less work.

Snip

They just got through trying to hit me up for $1000 - $1300 bucks for
versions 12 and 13.

Yeouch. At prices like that they are begging for
competition.
That makes me wonder what we are
paying for it at work.

I know a few young engineering students who have the
full version. I suspect they obtained it through...
alternative sources.

--
rb

Of course the $1k price tag stops me from buying it too. There are
cheaper digitizers out there. However, look at a National Instruments
ADC card in that range and a grand sounds cheap.

In the dark ages before such items could be bought at all, we hooked up
an ADC with a few storage registers and a mux to feed the data in
parallel to a logic analyser, which in turn acted like the frame
buffer, then took the data off the logic analyser over the GPIB port.

http://www.octave.org/
I'll give this a shot.


Ron Baker, Pluralitas! wrote:
wrote in message
oups.com...
Interesting. Is there a canned program to take an autocorrelation of a
wav file?

I use Matlab. It is a general purpose math tool. A lot of
people use it to prototype DSP algorithms. There is
a student version for $150. It is good enough.
There is also an open source, free program called Octave
that tries to be compatible with Matlab. Matlab programs
can generally be ported to Octave with more or less work.

I noticed the signal was wide, so I used the 9.5Khz filter,
though clearly that isn't enough if the signal is 30Khz wide. BTW, it
has an interesting sound with FM demod.

I suppose if I had the ability to digitize at a higher bandwidth, I
could sample my 455Khz IF output and get the whole sweep.

Yeah, the IF is centered at 455 kHz and has a certain width.
30 kHz wouldn't surprise me.

the VCO around a bit and couldn't find a center of the signal.

The center is half way between the top and the bottom.
It is a sweep. So it doesn't have a central carrier.


I've been looking at various high speed digitizers for use as a
pan-adapter. This is the most interesting of the bunch:
http://www.universal-radio.com/catal...rxvr/0014.html

Wow, cool. I wish I had $1000 to spare.
One could do a lot of cool things with that.

--
rb

"Ron Baker, Pluralitas!" wrote in message
...

"Ron Baker, Pluralitas!" wrote in message
...
There are numerous radars running in the HF bands.
Some of them run continuously.

Frequencies heard in San Diego.
4407
4814
12180 to 12100
13370 to 13450
13500 to 13570
13920 to 13970
26340 to 26190

We can examine their echos too.
I recorded the one at 26190 (a while back) for 60
seconds and ran an autocorrelation.
A plot of it is posted in alt.binaries.alt.
We can see that it echos over great distances,
on the order of the circumferance of the Earth.
(The horizontal scale is time converted to distance
figuring the signal travels at the speed of light.)

Any chance of posting a .WAV file? Like to hear what they sound like.

HankG