Back in the day, when people used modems with a LED that blinked
when transmissions were occurring, someone aimed a telescope at
the LED and was able to intercept the modem's transmission since
the LED was operated from the output data stream. When people
started experimenting, data rates of
Perhaps. But when I was doing spook tech in the early 1980’s, modern western
nations were already using encrypted digital modes. Encryption was strong
enough that tactical intelligence focused on non-content approaches. 35 years
later, I would expect that tech to be widespread. Some of what we
Hi Walter,
Your doubts have no basis in reality. Many nations -- but not modern
western nations -- still use Morse for military communications,
especially tactical comms.
73
Frank
W3LPL
- Original Message -
From: "Walter Underwood"
To: "Elecraft"
About training intercept operators … I doubt that Morse is used very often by
the opposition, even with good code books. But if we stopped training people to
read it, that would be a vulnerability.
wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)
> On Nov 21,
Fred, it's called LiFi and uses the ability of LED light sources to handle high
frequency modulation to send data securely since one has to intercept the
actual beam to even get the data, much less decode the information. Apparently
pretty high data rates are possible with the system.
Here's
Yes, 1st IF normally feeds a P3 at around 8 MHz thru a short length of
RG-58.
Yes, the BW at the 1st IF is quite wide, limited only by the front end
BPF. After down conversion to baseband [or something close, 15 KHz
comes to mind [:-)] it would need bandlimiting before the ADC. That's
not
Please carefully read everything that follows to avoid repetition of the steps
followed. What I have summarized here is the result of MANY hours of work and
extensive troubleshooting time via email with 2 incredibly helpful and patient
hams.
I have an RPi 3 with FLDIGI and WSJT-X installed.
A relatively new ham asked for a copy or diagram of my portable antenna
design. Here's my response.
Welcome on being a new ham. As to the antenna design..well
there is no such thing in existence.
We usually camp in National parks and State parks. There's
I tested the endfed from myantennas at 1 kw. The transformer was only warm
so no significant losses there. The feeder was RF hot so a toroid choke was
added. Cable no longer hot and toroid cold. SWR low on many bands. So the
only significant losses could have been through the ground.
This is
Erik,
About all you can conclude from the WSPR readings is the relative
difference between antennas. If you want to compare two horizontal
antennas, place them end to end. The radiation at the end is at a
minimum and the antenna will not interact.
As for comparing a vertical with a
I hope my interest in WSPRLite antenna comparisons doesn't lead this thread too
far off topic, but I have further thoughts on how to orient the two antennas
being compared.
Frank, who is much more experienced with this comparison system, suggested that
two horizontally polarized antennas
Ignacy,
For an end-fed wire, I would see the possibility of power losses not only in
the feed feeder, but also in the tuner, the transformer, and the effective
counterpoise path. For low counterpoise losses, small counterpoise current
is desirable, which means a high antenna impedance. When a
Antenna performance does not depend on how it is fed (if feeder losses are
low) but on height and ground type. For KX3 with AT, any special length
makes little sense, especially in portable conditions. KX3 matches most
random wires, and KX3 with 4:1 balun matches any wires. Lack of balance is
not
How much noise from "warts" enters the antenna depends on the antenna. Close
and low antenna will pick up more and high and far will pick up less or
nothing. Also, balanced or with a good balun will pick up less than
unbalanced or where KX3 is a counterpoise.
Ignacy, NO9E
--
Sent from:
International Morse
Sent from my iPhone
> On Nov 20, 2017, at 8:02 PM, elecraft-requ...@mailman.qth.net wrote:
>
> Send Elecraft mailing list submissions to
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>
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I've added regulators and (when needed) rectifiers to wallwarts. I just
put the components on a piece of perfboard, cut the wire, hook it up and
tape the board to the wart. Presto, a regulated linear wallwart.
73,
Victor, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
On 21
Two years ago, I embarked on a "wallwart-ectomy" in my shack, removing
all wall warts and replacing them with DC power cords that connected to
fused dc power strips, connected to a single shack linear supply. Band
decoder, PC speakers, SDR Rx, wavenode wattmeter... none of those items
have
I"m not sure what bw you are requiring for IP, but I assume you are
talking about the 1st IF of the K3 or K3s.
You do realize that its very wideband at that point. Roofing filters
follow the 1st IF to feed the 2nd IF and DSP ckts. I run two LP-Pan
from the IF of both my main and subRx on
On 11/20/2017 5:50 PM, Brian Hunt wrote:
Be careful using the non-regulated linear wall warts. The open circuit voltage
can be more than 16 VDC and could be harmful to gear not rated that high.
Yes and no. The vast majority of linear wall warts are UN-regulated,
but the current drawn by the
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