"SJ" and "SD" radar - what does it stand for?

[Zayphod]

I hear the terms all the time, but what exactly does SJ and SD stand for?

[Quillan]

I'm not certain they stand for anything. I think they're probably just a code designation that has no meaning beyond model and series. S might for instance refer to all ship radar, with the D and J referring to specific models within the group.

[Raptor1]

I also believe that it does not stand for anything, I think surface ships' equivilant was called the SG Radar, and the model that succeded the SD Radar was called the SV Radar...

The S stood for S-Band while the other letter stood for the model as far as I know

[kylesplanet]

The SD radar got its name from the crew. Each time the radar picked up a plane the crew screamed SH*T! DIVE!!! Hence the acronym, SD.
:rotfl: :rotfl:

[V.C. Sniper]

^ I LUL'D!!1!1 :rotfl: :rotfl: :rotfl:

[Nisgeis]

There are two main groups of radar, search and fire control. Fire control radar is prefixed with an F and search radar is prefixed with an S. The second letter is usually the model of search radar, so the SJ radar is search radar, model J (model 10). Fire control radar used to be denoted by letters, but was standardised to be numbered instead, so what used to be called an FC or FD would subsequently be called just a Mark III or Mark IV.

Any number after the S<letter> system is a modification. So, SJ-1 is the first modification to the SJ radar set, which increased range.

[Able72]

Wow, some of you guys know more history about military equipment than a sane human being should ;)

[Raptor1]

Wow, some of you guys know more history about military equipment than a sane human being should ;)
Being a sane human must be boring then...

Anyway, Nisgeis, I think your right about the S standing for Search and the other letter standing for the model number, but the earliest type of US Shipborne Search Radar used in WWII was called the CXAM (Though I think the CXAM-1 was more widespread), which was introduced before the S models, What did that stand for?

[MonTana_Prussian]

Wow, some of you guys know more history about military equipment than a sane human being should ;)
Being a sane human must be boring then...

Anyway, Nisgeis, I think your right about the S standing for Search and the other letter standing for the model number, but the earliest type of US Shipborne Search Radar used in WWII was called the CXAM (Though I think the CXAM-1 was more widespread), which was introduced before the S models, What did that stand for?


Actually it was XCAM,and I don't know what it meant. I do know that USS Enterprise had it early on.

[LukeFF]

Any number after the S<letter> system is a modification. So, SJ-1 is the first modification to the SJ radar set, which increased range.

Kind of. Any number following the two-letter prefix denoted a factory modification. A lower-case letter denoted a field modification. In reference to WWII radar, SJ-a was a field-modified SJ radar set modified with a PPI screen, and likewise SD-a was an improved version of the original SD (what is known as "improved SD radar" in SH4).

[Raptor1]

Wow, some of you guys know more history about military equipment than a sane human being should ;)
Being a sane human must be boring then...

Anyway, Nisgeis, I think your right about the S standing for Search and the other letter standing for the model number, but the earliest type of US Shipborne Search Radar used in WWII was called the CXAM (Though I think the CXAM-1 was more widespread), which was introduced before the S models, What did that stand for?

Actually it was XCAM,and I don't know what it meant. I do know that USS Enterprise had it early on.
Nope, I'm 99% sure it was the CXAM, All the USN Pre-War Carriers had the CXAM-1 Radar (Including the Enterprise) and some of the BBs had it

[JetSnake]

There are two main groups of radar, search and fire control. Fire control radar is prefixed with an F and search radar is prefixed with an S. The second letter is usually the model of search radar, so the SJ radar is search radar, model J (model 10). Fire control radar used to be denoted by letters, but was standardised to be numbered instead, so what used to be called an FC or FD would subsequently be called just a Mark III or Mark IV.

Any number after the S<letter> system is a modification. So, SJ-1 is the first modification to the SJ radar set, which increased range.


[Austin Powers] Nerd Alert!!!! [Austin Powers]

:arrgh!:


Thanks for that explanation!

[Crosseye76]

Here is one from the Wiki on CXAM radar:

"
The CXAM radar system was the first production radar system deployed on US Navy ships. It followed several earlier prototype systems, such as the NRL radar installed in April, 1937 on the USS Leary (DD-158); its successor, the XAF, installed in December, 1938 on the USS New York (BB-34); and the first RCA-designed system, the CXZ, installed in December, 1938 or January, 1939 on the USS Texas (BB-35). Based on testing in January, 1939, where the XAF was more reliable, the US Navy ordered RCA to build six XAF-based units for deployment and then shortly thereafter ordered 14 more.
The first six units RCA produced (delivered in 1940) were denoted "CXAM" and were a fusion of XAF and CXZ technologies. These were installed on the USS California (BB-34), the USS Yorktown (CV-5) (in September, 1940), and four cruisers. The next 14 units RCA produced (also delivered in 1940) were denoted "CXAM-1" and were slight improvements over the CXAM design. These were installed on the the USS Texas (BB-35) (in October, 1941), USS Pennsylvania (BB-38), USS West Virginia (BB-48), USS North Carolina (BB-55), and USS Washington (BB-56); on the aircraft carriers USS Lexington (CV-2), USS Saratoga (CV-3), USS Ranger CV-4), USS Enterprise (CV-6), and USS Wasp (CV-7); on one heavy cruiser; on two light cruisers; and on the seaplane tender USS Curtiss (AV-4).
Radar detection range of aircraft depends on altitude, size, and number of aircraft. The CXAM is listed (in U.S. Radar, Operational Characteristics of Radar Classified by Tactical Application) as being able to detect single aircraft at 50 miles and to detect large ships at 14 miles. Other sources list CXAM detection range on aircraft out to 100 miles.
The US Army's first non-prototype radar system, the SCR 270 radar, was developed in parallel with the CXAM."


Even though the Wiki calls them 'production' sets, I think they were still pretty much prototype sets or low-rate production test sets to try them out in the field, and the designation seems to reflect that. When the first real production line sets were made in large quantities, they were given the standard designations.

[Raptor1]

"Production" might be misleading, I think the proper term would be "Operational"...

[Nisgeis]

"Production" might be misleading, I think the proper term would be "Operational"...

Two books that I checked in call the CXAM a pre-production set. CXAM-1 was an enhancement to existing sets and then it was enhanced further and called SC, which was then mass produced and termed a production set (500 ordered).

I haven't been able to find out what CXAM stood for though, as none of the sources mention it. I did however find out what the SCR- in army sets meant. The only thing they say is that CXAM was based on the XAF set, which proved sturdy in testing. The set RCA designed and was keen to produce did not perform well during testing and only wikipedia seems to think that the RCA set was incorporated into the design

There is mention of other experimental radars all beginning XA-letter, so it seems reasonable to assume the X or XA stood for experimental, the rest though, I have no idea. All the sources that mention CXAM seem to say almost exactly the same thing and are very brief, suggesting they are all based on the same source.

[Nisgeis]

Any number following the two-letter prefix denoted a factory modification. A lower-case letter denoted a field modification. In reference to WWII radar, SJ-a was a field-modified SJ radar set modified with a PPI screen, and likewise SD-a was an improved version of the original SD (what is known as "improved SD radar" in SH4).

I typed out the thing about field mods and then deleted it, because I can't remember the source I got that from and I'm not actually sure I ever did see one. Do you happen to know of a source for that field mod convention?

[Raptor1]

I know that USS North Carolina and USS Washington we're refitted with SG Radar in 1942, But does anyone know if the pre-war Carriers retained the CXAM-1 or we're they also refitted with a more advanced set (And if so, when)?

[LukeFF]

I typed out the thing about field mods and then deleted it, because I can't remember the source I got that from and I'm not actually sure I ever did see one. Do you happen to know of a source for that field mod convention?

Norman Friedman talks about it in his book for both SD and SJ radars, in the footnotes for his chapter on WWII.

[Crosseye76]

I know that USS North Carolina and USS Washington we're refitted with SG Radar in 1942, But does anyone know if the pre-war Carriers retained the CXAM-1 or we're they also refitted with a more advanced set (And if so, when)?

They were refitted also.

In Norman Friedmans book "U.S. aircraft Carriers" There are a couple great pics:

On page 10, there is one of the Saratoga in May, 1942 showing her with the CXAM.

On page 11, it shows the Saragota in August 1944, and she now has the standard later radar fit of 2 air search, and SK and a backup SC-2, along with an SM height finder for fighter direction.

On page 95, there is a picture of the Yorktown in Pearl Harbor in undergoing hasty repair right before heading to her destiny at Midway, and she has a CXAM radar fitted.

Radar and other electronic fits for U.S. ships could be VERY complex and confusing as these installations / upgrades were carried out whenever and wherever they could be done.

On page 144 of the same book there is a line at the start describing Essex radar arrangements:

" The Essex-class radar arrangements were both complex and individualistic, the latter so much so that ships can often be identified in photographs by their radars. "

The text follwoing this line lists a number of radars, and different types of masts or places where the antennas were fitted, and it really seems it was like fingerprints, no two ships had exactly the same fit.

[Zayphod]

I typed out the thing about field mods and then deleted it, because I can't remember the source I got that from and I'm not actually sure I ever did see one. Do you happen to know of a source for that field mod convention?

Norman Friedman talks about it in his book for both SD and SJ radars, in the footnotes for his chapter on WWII.

He he, it's just odd that I cannot find out what the SJ and SD stood for. I know the military loves to make acronyms out of just about anything they get their hands on. My guess was that, as someone said earlier, the "S" probably stood for the "s-band", but what the "J" and "D" part was for, well, I guess that's one of those military secrets that'll never be released. ;)

[Crosseye76]

I think Zayphod, that the first two posts kind of hit on the head. the SD and SJ and SC and SV and SX were not acronyms, there were just designations applied to a radar set.