Re: Additional SBX-1 factoids [and not]


Andrew Robert Breen wrote:
In article <1147266671.509700.237640@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
Jack Linthicum <jacklinthicum@xxxxxxxxxxxxx> wrote:

Allen Thomson wrote:
http://www.kodiakdailymirror.com/?pid=19&id=3077
Once in Adak, the radar will be able to move anywhere in the Pacific
Rim. But like all radar [sic], the X-band radars will not be able to
see over the curvature of the earth, known as the radar horizon. Its
ability to detect incoming missiles and to discriminate between
warheads and decoys depends on where the radar is located in relation
to the incoming missile.

I realize the Kodiak Daily Mirror isn't exactly the IEEE on reporting
but can't the SBX see "over the horizon"? Front scatter anyway but the
last I heard you could work X band off one or more of the ionospheric
layers. BTW why does the military persist in using the old letter

You're not going to get radio "reflection" off the ionosphere at
X-band: going by the old rule-of-thumb that the frequency for
a direct return from an ionosonde goes as sqrt(81.5 Ne), where Ne is
the density at the level you're getting reflection from, then for
a typical daytime F2-region peak (the highest electron density in
the ionosphere, at about 300 km - space station height!) you'd get
reflection if you transmitted at around 6.3 MHz. Any of the bands
listed below will go[1] straight out of the ionosphere and keep going.

At HF (say, 8-20 MHz) you can get backscatter from ionospheric
irregularities which does give an over-the-horizon view, if you
know what your scatterers are doing - not easy in the auroral
zone!

http://ion.le.ac.uk/cutlass/SuperDARN.html

has details.

At VHF and UHF you can get backscatter from electrons in the ionosphere,
but the backscattered power is low:

http://www.eiscat.se

least 30 years since DoD published a directive telling the writers of
specs to cease and desist. I used to have a chart on my FCC computer
that listed all of the variations on letter bands.

Previous Band Designations and Frequencies
VHF: 100-300 MHz
UHF: 300 MHz-1 GHz
L: 1-2 GHz
S: 2-4 GHz
C: 4-8 GHz
X: 8-13 GHz
Ku: 13-19 GHz
K: 19-25 GHz
Ka: 25-40 GHz
Millimeter: 40-100 GHz

All the places I've worked use these designations, insofar as they
use anything. Jodrell Bank and other radio observatories certainly
refer to "L band", "C band" and so on. We were running on L-band
on monday, for example..

But "which" L Band? From Wikipedia L Band

"L band (20-cm radar long-band) is a portion of the microwave band of
the electromagnetic spectrum ranging roughly from 0.39 to 1.55 GHz. It
is used by some communications satellites, and by terrestrial Eureka
147 digital audio broadcasting (DAB). In the United States, the L band
is held by the military for telemetry, thereby forcing digital radio to
in-band on-channel (IBOC) solutions. DAB is typically done in the
1452-1492-MHz range as in Canada, but other countries also use VHF
and UHF bands.

The Global Positioning System carriers are in the L band, centered at
1176.45 MHz (L5), 1227.60 MHz (L2), 1381.05 MHz (L3), and 1575.42 MHz
(L1) frequencies.

WorldSpace satellite radio broadcasts in the 1467-1492 MHz L
sub-band.

Mobile phones operate at frequencies between 800 and 1900 MHz.

The different NATO L band is defined as frequency band between 40-60
GHz (5-7.5 mm)."



Current Band Designations and Frequencies
A: 100-250 MHz (UHF)
B: 250-500 MHz (Upper UHF and lower to mid VHF.)
C: 500 MHz-1 GHz (Mid to high VHF)
D: 1-2 GHz
E: 2-3 GHz
F: 3-4 GHz
G: 4-6 GHz
H: 6-8 GHz
I: 8-10 GHz
J: 10-20 GHz
K: 20-40 GHz
L: 40-60 GHz
M: 60-100 GHz

Those are all new to me.

http://www.everything2.com/index.pl?node_id=785251

source, taken from Source:
Sikorsky SH-60B/F Seahawk Basic Avionics Maintenance Review Course;
class materials, 1995

[1] Mostly..



Everytime I try to find a source I know exists on the 'net I run into
the need for subscription. I realize these are mainly tropo propagation
and I may have misspoke on the ionosphere. I have seen front scatter
from another transmitter illuminating a target between the transmitter
and receiver.

[PDF] X-band transhorizon measurements of CW transmissions over the sea
....
File Format: PDF/Adobe Acrobat
viability of an X-band transhorizon communications link ... duration of
fades in tropospheric scatter transmission," IRE Trans. Antenna
Propagat., vol. ...
ieeexplore.ieee.org/iel4/8/6682/00267348.pdf?arnumber=267348 - Similar
pages

X-band tropospheric transhorizon propagation under differing
meteorological conditions C. Spillard, M. Roorick, M. Juy and E. Vilar
(International Conference on Antennas and Propagation, Warwick, April
1989)

The classification of meteorological conditions influencing
transhorizon X-band propagation C. Spillard (Asia-Pacific Microwave
Conference, Tokyo, September 1990)


I did find as source for the ITU bands

Band ITU Frequency Waveform
Name Band Range Name
---- ---- -------------- ---------------
VLF 4 3 - 30 KHz Myriametric
LF 5 30 - 300 KHz Kilometric
MF 6 300 - 3000 KHz Hectometric
HF 7 3 - 30 MHz Decametric
VHF 8 30 - 300 MHz Metric
UHF 9 300 - 3000 MHz Decimetric
SHF 10 3 - 30 GHz Centimetric
EHF 11 30 - 300 GHz Millimetric
(IR) 12 300 - 3000 GHz Decimillimetric

I hope you see my problem, actually not my problem anymore but I'm sure
the lawyers are as confused today as they were when I could take them
aside and show them all the letter designators.

http://www.tiab2b.com/glossary/index.cfm?term='%234__SR%23HJ%20%23L%0A
C-band

Colloquially, a frequency band between 4 GHz and 6 GHz used in
satellite communications. Note 1: For procurement purposes, the radio
frequency band(s) must be specified using the upper and lower limits of
the band, per 47 CFR 300. Note 2: Letter designators of radio frequency
bands are imprecise, deprecated, and legally obsolete.

CFR 47 is the section of the Code of Federal Regulations dedicated to
the FCC. There is another cite for DTIC the Defense Technical
Information Center

.

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