Frustrated

[J0313]

Originally Posted by Redmane

Ultimately, you are not wrong in asserting that a US Fleet Type boat could both transmit and receive at radar depth. The only provisos are that they would have to have a VHF rig, and the communication would be limited to the capabilities of that gear. In other words, Fleet units close enough to receive the signal could do so, but by no means would it be possible for the boat to contact a ground station on this gear unless in range, not blocked by any interference, and the ground station would also need to have the appropriate gear. Additionally, I make this observation: I have been at radar depth on approach to a target in high sea states, had the periscope raised just enough to clear the housing, and had it be regularly washed by the wave action. So there also would be that factor of limitiation on the VHF.

Check this out. http://books.google.com/books?id=7qz...ntenna&f=false.

Look at page 165 and 166. Bottom right of 165. Upper left of 166 and tell me what you read there.

[J0313]

Originally Posted by Sailor Steve

Okay, you're still trying to make a fight out of this and blame someone else. This kind of behavior is not allowed here.

.

No I'm not. Just stating a fact.

[BigWalleye]

J0313, Steve is trying to tell you something important. If a policeman pulls you over and says that you need to slow down, it is prudent to take his advice. There is nothing to be gained by arguing yourself into a ticket.

[Redmane]

Originally Posted by J0313

Check this out. http://books.google.com/books?id=7qz...ntenna&f=false.

Look at page 165 and 166. Bottom right of 165. Upper left of 166 and tell me what you read there.

I read that the boat could transmit via radio at periscope depth, provided they could get the antenna clear of the water. What I don't read is that this arrangement was still in place on the Fleet type boats used during the war.

[CaptBones]

Well, since I was a Navy Communications Officer and Electronic Systems Engineer for nearly the first decade of my career...and I do have first person experience with submarine radio communications in GUPPY-converted Fleet Boats... I suppose I could make a couple of points here.

The discussion is, to some degree, mixing apples and oranges. In WWII, receiving broadcast messages and sending Contact Reports to HQ (which is the game "issue" that started this discussion), dealt with HF CW ("Morse code") radio communications. Tactical communications with other ships and aircraft was done with VHF and UHF voice radio as well as voice/CW at the low-HF/high-MF frequencies.

The primary Fleet Broadcast in the 60s and 70s was still the "Fox" broadcast, even though by then it was a machine-encrypted radio-teletype system and in WWII it was a Morse code, manually encrypted system (yeah, we had "Enigma" machines too). Yes, there were early TTY communication links being used during the war, but they were almost exclusively land-line (including transatlantic cable). Towards the end of the war, such technology was starting to be implemented in the forces afloat, but the equipment wasn't yet suitable for submarines.

There's a world of difference between transmitting and receiving equipment used in WWII and now-days. But, back when I started out, we were still using the WWII equipment and systems on the shore-side of long-haul communications. The long-haul system, both send and receive, was high frequency (the "HF" part of HFDF) 3-30MHz. HF is also commonly known as "short-wave" radio; the wavelength is 100-10m (higher freq = shorter wavelength). The full-wave transmitting towers at NAVCOMSTAs Washington D.C. (Annapolis), Wahiawa (Lualaulei), HI and Stockton (Dixon), CA were landmarks that I remember well.

I can assure you that an HF radio signal, of as little as 500W at the transmitter, can be received via sky-wave refraction, at a distance of some 6000 miles or more and at a receiving antenna depth (not keel depth!) of 33 ft (10m) or more. You're not pushing a signal through the water, you're bouncing it off an ionospheric scattering layer. The trick is that the receiving antenna is a bare long-wire, or two or three in parallel, insulated from ground and connected to an ungrounded receiver, the earth is the ground plane for the signal transmitter at the radio communication shore station. The signal strength that can be detected by a full-wave or half-wave wire antenna is incredibly small; a few milliwatts will generate a very solid signal voltage. Remember, you're picking up a radio wave that is between 10 and 100m long...it will definitely penetrate the water to a depth equal to the wave-length. We routinely had to practice establishing long-haul duplex terminations across the Pacific, between Japan, Guam, Hawaii, and California, with 100W transmitters (the really good operators could do it with 10W!).

It doesn't work in reverse, the transmitting antenna has to be high-and-dry, or at least not immersed in good old salt-water; that will definitely attenuate the outgoing signal, totally. You need to be well above the water's surface to use it as the antenna's ground plane. As I noted, the shore station transmitting antennas were 350ft tall full-wave towers. Typically, the shipboard HF transmitting antennas were both long-wire (10-50m or so) and base-loaded 8ft and 16ft whip antennas. In the case of WWII US submarines, the whips were retractable, but not nearly capable of being extended sufficiently above the water when at periscope depth or radar depth to keep from being grounded by passing waves (US subs also had rod antennas incorporated in the SD radar supports). Early-on, US subs also had retractable, vertical wire antennas, consisting of a mast with a cross-head that supported two or more wires per side.

Most of the 1/4 wave and dipole VHF and UHF tactical radio antennas were small and could certainly be attached to or incorporated into a periscope, radar antenna mast, the shears, or a snorkel mast. Those you could use while the boat was submerged at either periscope or radar depth; I can guarantee they don't work underwater though.

Although it's too late to make this long story short...getting back to the topic...for both US and German WWII submariners, receiving HF "broadcast" messages at shallow depths was possible and done routinely, but transmissions to HQ had to be done on the surface.

[J0313]

Originally Posted by CaptBones

Well, since I was a Navy Communications Officer and Electronic Systems Engineer for nearly the first decade of my career...and I do have first person experience with submarine radio communications in GUPPY-converted Fleet Boats... I suppose I could make a couple of points here.

The discussion is, to some degree, mixing apples and oranges. In WWII, receiving broadcast messages and sending Contact Reports to HQ (which is the game "issue" that started this discussion), dealt with HF CW ("Morse code") radio communications. Tactical communications with other ships and aircraft was done with VHF and UHF voice radio as well as voice/CW at the low-HF/high-MF frequencies.

The primary Fleet Broadcast in the 60s and 70s was still the "Fox" broadcast, even though by then it was a machine-encrypted radio-teletype system and in WWII it was a Morse code, manually encrypted system (yeah, we had "Enigma" machines too). Yes, there were early TTY communication links being used during the war, but they were almost exclusively land-line (including transatlantic cable). Towards the end of the war, such technology was starting to be implemented in the forces afloat, but the equipment wasn't yet suitable for submarines.

There's a world of difference between transmitting and receiving equipment used in WWII and now-days. But, back when I started out, we were still using the WWII equipment and systems on the shore-side of long-haul communications. The long-haul system, both send and receive, was high frequency (the "HF" part of HFDF) 3-30MHz. HF is also commonly known as "short-wave" radio; the wavelength is 100-10m (higher freq = shorter wavelength). The full-wave transmitting towers at NAVCOMSTAs Washington D.C. (Annapolis), Wahiawa (Lualaulei), HI and Stockton (Dixon), CA were landmarks that I remember well.

I can assure you that an HF radio signal, of as little as 500W at the transmitter, can be received via sky-wave refraction, at a distance of some 6000 miles or more and at a receiving antenna depth (not keel depth!) of 33 ft (10m) or more. You're not pushing a signal through the water, you're bouncing it off an ionospheric scattering layer. The trick is that the receiving antenna is a bare long-wire, or two or three in parallel, insulated from ground and connected to an ungrounded receiver, the earth is the ground plane for the signal transmitter at the radio communication shore station. The signal strength that can be detected by a full-wave or half-wave wire antenna is incredibly small; a few milliwatts will generate a very solid signal voltage. Remember, you're picking up a radio wave that is between 10 and 100m long...it will definitely penetrate the water to a depth equal to the wave-length. We routinely had to practice establishing long-haul duplex terminations across the Pacific, between Japan, Guam, Hawaii, and California, with 100W transmitters (the really good operators could do it with 10W!).

It doesn't work in reverse, the transmitting antenna has to be high-and-dry, or at least not immersed in good old salt-water; that will definitely attenuate the outgoing signal, totally. You need to be well above the water's surface to use it as the antenna's ground plane. As I noted, the shore station transmitting antennas were 350ft tall full-wave towers. Typically, the shipboard HF transmitting antennas were both long-wire (10-50m or so) and base-loaded 8ft and 16ft whip antennas. In the case of WWII US submarines, the whips were retractable, but not nearly capable of being extended sufficiently above the water when at periscope depth or radar depth to keep from being grounded by passing waves (US subs also had rod antennas incorporated in the SD radar supports). Early-on, US subs also had retractable, vertical wire antennas, consisting of a mast with a cross-head that supported two or more wires per side.

Most of the 1/4 wave and dipole VHF and UHF tactical radio antennas were small and could certainly be attached to or incorporated into a periscope, radar antenna mast, the shears, or a snorkel mast. Those you could use while the boat was submerged at either periscope or radar depth; I can guarantee they don't work underwater though.

Although it's too late to make this long story short...getting back to the topic...for both US and German WWII submariners, receiving HF "broadcast" messages at shallow depths was possible and done routinely, but transmissions to HQ had to be done on the surface.

Thank you for this info. I have a question. Could it be done in calm sea's?

[BigWalleye]

CaptBones, you've settled most of our questions. I still have just one. Most of the US accounts I've read describe receiving radio transmissions at shallow depth, as you say about 30ft antenna depth. But the German accounts routinely describe receiving messages at 30 meters. In your professional opinion, what was the reason for this difference?

EDIT: I regret that my terminology confused you. By "pushing the signal through the water", I did not mean to imply that the signal propagated through water all the way from the transmitter to the sub, only the last few meters. I recognize that it was primarily atmospheric propagation.

[Redmane]

Thanks Capn, your expertise and knowledgeable reply is appreciated.

[Sailor Steve]

Originally Posted by J0313

.

No I'm not. Just stating a fact.

You didn't bring it up again after my warning because it was a fact. You brought it up again because you wanted to show you were right. Otherwise it didn't need to be mentioned at all. This is your last warning.

[Sailor Steve]

Originally Posted by CaptBones

I can assure you that an HF radio signal, of as little as 500W at the transmitter, can be received via sky-wave refraction, at a distance of some 6000 miles or more and at a receiving antenna depth (not keel depth!) of 33 ft (10m) or more.

Thank you for that wealth of information. I was an apprentice radioman myself in 1969-70, so you would think I'd have some of that knowledge, but I wasn't in long enough to learn that much, or to retain it after I got out.

Originally Posted by BigWalleye

But the German accounts routinely describe receiving messages at 30 meters. In your professional opinion, what was the reason for this difference?

I might be able to help shed some light on that. It was my understanding that the mentioned depth was closer to 20 meters, but I haven't read the same accounts you have, so you may be right. Don't forget that whatever the depth was, it was measured at the keel. The Type VII u-boat is 9.4 meters from the keel to the top of the conning tower. If 20 meters is correct then the recieving antenna at that depth is only 10.6 meters beneath the waves, or about 35 feet, which is in line with what CaptBones gave for the US boats. If it was indeed 30 meters then the antenna depth would be closer to 70 feet, so that does invite questions.

[BigWalleye]

Originally Posted by Sailor Steve

Thank you for that wealth of information. I was an apprentice radioman myself in 1969-70, so you would think I'd have some of that knowledge, but I wasn't in long enough to learn that much, or to retain it after I got out.


I might be able to help shed some light on that. It was my understanding that the mentioned depth was closer to 20 meters, but I haven't read the same accounts you have, so you may be right. Don't forget that whatever the depth was, it was measured at the keel. The Type VII u-boat is 9.4 meters from the keel to the top of the conning tower. If 20 meters is correct then the recieving antenna at that depth is only 10.6 meters beneath the waves, or about 35 feet, which is in line with what CaptBones gave for the US boats. If it was indeed 30 meters then the antenna depth would be closer to 70 feet, so that does invite questions.

And a further point CaptBones makes is that the signal penetrates easily to a depth of "about one wavelength". Physically, the one wavelength criterion makes sense. Thats a minimum of 33ft for HF. Lower frequencies would penetrare further. My question could be restated as "Why didn't our subs receive messages at greater depths, like the German subs did?" Why were we more limited?

[Sailor Steve]

Answer 1: If the 20-25-meter depth is the correct one, then the recieving depths were about the same. If your 30-meter depth is indeed correct, see answer 2.

Answer 2: I don't know. I hope he does.

[CaptBones]

Originally Posted by J0313

Thank you for this info. I have a question. Could it be done in calm sea's?

Could what be done...tactical voice communications while at PD/RD, or HF transmissions?

A "qualified" yes for both, actually. As you have found, by late '43 there were tactical voice VHF and UHF antennas that were useable at periscope depth/radar depth. But calm, or at least "low" sea states were necessary (they can't transmit when under water, even just temporarily). Except for unusual circumstances (or unique designs today), VHF and UHF are USUALLY line-of-sight. For all practical purposes, you had to have the station you wanted to talk to in sight and the distance to the horizon for a sub at PD ain't very far...and it's not much farther when you're surfaced either! Although, before Secure Voice equipment became common in the '70s, the biggest COMINT security concern was people jabbering away on tactical circuits with the misperception that you absolutely couldn't be heard "over the horizon"...tain't so.

So, for submarines, the tactical communication sets were most handy for talking to aircraft; "line of sight" to an A/C at 20,000-30,000 ft or even 10,000 ft, is a lot farther than you can actually "see". The other welcome use of those tactical voice sets in US submarines came later in the war, when we started forming "Wolfpacks" in October '43. You should also note that the antennas you see in photos, most often mounted high on the shears or in a periscope/snorkel head are the ESM and IFF antennas, receiving units only...it's nice to know before you surface, if somebody up there is sweeping or has locked-on to you and whether or not it's a "friendly."

Also by late war, several types of whip antennas with tunable VSWR antenna couplers were developed for HF use in submarines. In some photos they can be seen at the aft end of the shears or on a stub mast on the cigarette deck, in both raised and lowered positions. They didn't retract vertically, they had motor operated geared trunnions to lower them to a horizontal "trailing" position when submerged. Again, the sea state would generally determine whether or not you could transmit (receiving is easier, the antenna isn't "hot", you're not trying to push electromagnetic energy out into the "ether", just trying to collect a few stray electrons here or there, riding their wave). Practicality would again dictate the purposes to which you would put that equipment. It wasn't usually suitable for the long-haul HF transmissions (especially at PD/RD), but was used for tactical medium range communications in the low-HF/high-MF band (frequencies assigned usually between 2200-2800KHZ). Again, good for keeping the "Wolfpack" spread out searching for targets and calling them together when one (target) is found.

I suppose that's some more of the "long way around" to an answer, but I hope it helps (and everybody can calm down again).

[J0313]

Originally Posted by CaptBones

Could what be done...tactical voice communications while at PD/RD, or HF transmissions?

A "qualified" yes for both, actually. As you have found, by late '43 there were tactical voice VHF and UHF antennas that were useable at periscope depth/radar depth. But calm, or at least "low" sea states were necessary (they can't transmit when under water, even just temporarily). Except for unusual circumstances (or unique designs today), VHF and UHF are USUALLY line-of-sight. For all practical purposes, you had to have the station you wanted to talk to in sight and the distance to the horizon for a sub at PD ain't very far...and it's not much farther when you're surfaced either! Although, before Secure Voice equipment became common in the '70s, the biggest COMINT security concern was people jabbering away on tactical circuits with the misperception that you absolutely couldn't be heard "over the horizon"...tain't so.

So, for submarines, the tactical communication sets were most handy for talking to aircraft; "line of sight" to an A/C at 20,000-30,000 ft or even 10,000 ft, is a lot farther than you can actually "see". The other welcome use of those tactical voice sets in US submarines came later in the war, when we started forming "Wolfpacks" in October '43. You should also note that the antennas you see in photos, most often mounted high on the shears or in a periscope/snorkel head are the ESM and IFF antennas, receiving units only...it's nice to know before you surface, if somebody up there is sweeping or has locked-on to you and whether or not it's a "friendly."

Also by late war, several types of whip antennas with tunable VSWR antenna couplers were developed for HF use in submarines. In some photos they can be seen at the aft end of the shears or on a stub mast on the cigarette deck, in both raised and lowered positions. They didn't retract vertically, they had motor operated geared trunnions to lower them to a horizontal "trailing" position when submerged. Again, the sea state would generally determine whether or not you could transmit (receiving is easier, the antenna isn't "hot", you're not trying to push electromagnetic energy out into the "ether", just trying to collect a few stray electrons here or there, riding their wave). Practicality would again dictate the purposes to which you would put that equipment. It wasn't usually suitable for the long-haul HF transmissions (especially at PD/RD), but was used for tactical medium range communications in the low-HF/high-MF band (frequencies assigned usually between 2200-2800KHZ). Again, good for keeping the "Wolfpack" spread out searching for targets and calling them together when one (target) is found.

I suppose that's some more of the "long way around" to an answer, but I hope it helps (and everybody can calm down again).

Thanks again for the educated information. I appreciate it. I knew that it could and was done in those days. Maybe not to the extent or purpose that I thought but its all good historical information to know. My Grandfather was a plank owner on the Grenadier. He was with her from the start to the end when they had to scuttle her. Then he got to be a guest of the Emperor for a few years. He raised me and I got to go to quite a few Sub Vets of WW2 conventions growing up. It was great. I wish he was still around so he could see stuff like the SH series games. He would get a kick out of them.

[Redmane]

Just a note regarding wolfpack comms during the period mentioned: I've read a couple of patrol reports from the USS Sea Cat (SS-399) which mention the fact that the boats involved also sometimes used radar to communicate, and while the reports don't mention the specific method it seems pretty obvious that it would involve pulsing the radar set on an off to send morse code type messages.