Bruce in alaska wrote in
:

In article ,
Wayne.B wrote:

The key difference is that they operate in two completely different
frequency ranges, much like the difference between VHF and UHF
television. X-band is from is from 7 to 12.5 GHz, S-band is at a
lower frequency (longer wavelength) between 2 and 4 GHz.

Because of the shorter wavelength, X band radar can resolve between
smaller objects but usually has less range because of increased
signal attenuation. S band typically has greater range but requires
much larger antennas, too large for the average small to mid size
pleasure boat.

Add to the above, that Marine S-Band Radars are 2.9 - 3.2 Ghz and
Marine X-Band Radar are 9.3 - 9.5 Ghz. S-Band Radars are much more
likely to be blinded by Snow and Heavy Rain that X-Band Radars. S-Band
Radars require Antennas that are MUCH Larger than X-Band Radars due to
the Frequencies involved. S-Band Radars predate X-Band Radars in
production because Magnetrons were easier to build, for the Lower
Frequencies. Most Marine WWII Radars were S-Band, including the
venerable SO Radar fitted to the PT Boats, who's antenna looks like an
upside down R2D2 on a Mast.

So am I correct in stating that the S-band radar is typically used for long
distance and X-band for shorter distance? Is it also valid to assume that
if a ship has S-band that it will also have X-band?

-- Geoff
www.GeoffSchultz.org

On Wed, 07 Jan 2009 06:48:33 -0600, Geoff Schultz
wrote:

So am I correct in stating that the S-band radar is typically used for long
distance and X-band for shorter distance? Is it also valid to assume that
if a ship has S-band that it will also have X-band?

Basically correct. The National Weather Service uses S Band radar for
weather tracking out to 200 miles or so using high power and large
antennas.

I'm not sure that it is safe to assume that large ships will always be
using an X Band radar if that is what you are driving at.

Wayne.B wrote in
news
On Wed, 07 Jan 2009 06:48:33 -0600, Geoff Schultz
wrote:

So am I correct in stating that the S-band radar is typically used for
long distance and X-band for shorter distance? Is it also valid to
assume that if a ship has S-band that it will also have X-band?

Basically correct. The National Weather Service uses S Band radar for
weather tracking out to 200 miles or so using high power and large
antennas.

I'm not sure that it is safe to assume that large ships will always be
using an X Band radar if that is what you are driving at.

What are the radar requirements for ships up to 300 tons and over 300 tons?

-- Geoff
www.GeoffSchultz.org

In article ,
Geoff Schultz wrote:

Bruce in alaska wrote in
:

In article ,
Wayne.B wrote:

The key difference is that they operate in two completely different
frequency ranges, much like the difference between VHF and UHF
television. X-band is from is from 7 to 12.5 GHz, S-band is at a
lower frequency (longer wavelength) between 2 and 4 GHz.

Because of the shorter wavelength, X band radar can resolve between
smaller objects but usually has less range because of increased
signal attenuation. S band typically has greater range but requires
much larger antennas, too large for the average small to mid size
pleasure boat.

Add to the above, that Marine S-Band Radars are 2.9 - 3.2 Ghz and
Marine X-Band Radar are 9.3 - 9.5 Ghz. S-Band Radars are much more
likely to be blinded by Snow and Heavy Rain that X-Band Radars. S-Band
Radars require Antennas that are MUCH Larger than X-Band Radars due to
the Frequencies involved. S-Band Radars predate X-Band Radars in
production because Magnetrons were easier to build, for the Lower
Frequencies. Most Marine WWII Radars were S-Band, including the
venerable SO Radar fitted to the PT Boats, who's antenna looks like an
upside down R2D2 on a Mast.

So am I correct in stating that the S-band radar is typically used for long
distance and X-band for shorter distance? Is it also valid to assume that
if a ship has S-band that it will also have X-band?

-- Geoff
www.GeoffSchultz.org

Range is relative in the Radar Biz. Radar Horizon is determined by LOS,
AND Horizon Lensing and Refracting Issues, but normally these are minor.
S-Band does get a bit more Refraction than X-Band but the difference is
minor. S Band usually has Higher TX Power. Just about ANY Vessel that
has a S-Band Radar fitted, will also have an X-Band Radar fitted as well.
The really BIG difference between the two, are Target Resolution, and
Water Vapor Reflectiveness.

--
Bruce in alaska
add path after fast to reply

On Jan 6, 7:23*pm, Geoff Schultz wrote:
In an attempt to discuss something related to cruising, can someone explain
the differences between X-band and S-band radar systems? *From what I know,
S-band is used on large ships and X-band is used on vessels less than 300
tons.

-- Geoffwww.GeoffSchultz.org

Geoff - X band is mandatory on all solas vessels - for the purpose of
search and rescue. Sarts been now mandatory. Most commercial
vessels will have two radars one x and one s but in many cases, older
vessels will have two x band radars. One radar must have a
arpa facility if the vessel is over 1600tons. In my part of the world
Southern Africa - X band is pretty useless in tropical storms with the
S band giving better target discrimination.(10cm wavelength against
3cm wavelength)
S band radars also generally have 12ft antennas against the 4/6 or 9
foot x band scanners.

Rgds
Mike