If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#21
|
|||
|
|||
matt weber wrote in message ... On Sat, 26 Jul 2003 20:37:19 +1000, "RT" wrote: matt weber wrote in message ... On Fri, 25 Jul 2003 22:44:02 +1000, "RT" wrote: The Raven wrote in message ... My only concern is that the Aerosonde UAVs will be over hyped to the point people will get the wrong impression of what they are and what they are capable of. Yair. Well. Not helped by the hype on the Aerosonde web site rabbiting on about its radar disruptive capabilities - shortly after saying the total power available is 30 watts or similar. It's not my field but I have a severe problem believing 30 W in a UAV will disable your average anti-aircraft/G-A missile radar...... 30 watts RMS is more than enought to disrupt most airborne radars. remember the radar duty cycles are very very short, typically less then .1%, so the ERP from 30 watts rms could easily be in the tens of kilowatts. Ground based fire control radars are another story. Those things often have ERP's of several hundred megawatts. They are designed to burn through almost any kind of intereference. Erm... I DID say..:- "I have a severe problem believing 30 W in a UAV will disable your average anti-aircraft/G-A missile radar......" Are you suggesting anti-aircraft/G-A missile radars are airborne? Or do you think they might be "Ground based fire control radars" which "are another story"? Depends whose it is. The Russian and American Fire Control radars are awesome beasts, however as you move to more locally manufactured product, they start to look more and more like the capabilities of airborne radars. AFCS - what sort of a cop out is that? Are you suggesting the Solomons have a home groan radar industry? Sheeeeesh.......... Mattt, you stuffed up - admit it and let's go on with something else..... |
#22
|
|||
|
|||
On Wed, 30 Jul 2003 22:55:58 +1000, "RT" wrote:
matt weber wrote in message ... On Sat, 26 Jul 2003 20:37:19 +1000, "RT" wrote: matt weber wrote in message ... On Fri, 25 Jul 2003 22:44:02 +1000, "RT" wrote: The Raven wrote in message ... My only concern is that the Aerosonde UAVs will be over hyped to the point people will get the wrong impression of what they are and what they are capable of. Yair. Well. Not helped by the hype on the Aerosonde web site rabbiting on about its radar disruptive capabilities - shortly after saying the total power available is 30 watts or similar. It's not my field but I have a severe problem believing 30 W in a UAV will disable your average anti-aircraft/G-A missile radar...... 30 watts RMS is more than enought to disrupt most airborne radars. remember the radar duty cycles are very very short, typically less then .1%, so the ERP from 30 watts rms could easily be in the tens of kilowatts. Ground based fire control radars are another story. Those things often have ERP's of several hundred megawatts. They are designed to burn through almost any kind of intereference. Erm... I DID say..:- "I have a severe problem believing 30 W in a UAV will disable your average anti-aircraft/G-A missile radar......" Are you suggesting anti-aircraft/G-A missile radars are airborne? Or do you think they might be "Ground based fire control radars" which "are another story"? Depends whose it is. The Russian and American Fire Control radars are awesome beasts, however as you move to more locally manufactured product, they start to look more and more like the capabilities of airborne radars. AFCS - what sort of a cop out is that? Are you suggesting the Solomons have a home groan radar industry? You never know who has been trading what with who. You can often be surprised at how good indigenous engineering is as well. NEVER UNDERESTIMATE the resources or persistence of a highly motivated enemy. If you asked someone what the odds were that an F117 could be shot down by a soviet SAM 5 years ago, everyone would have laughed at you, but a combination of smart indigenous engineering in Kosovo, and a dumb USAF resulted in just that. The US did indeed try fitting an airborne radar onto a AA gun, it was called the Divad. It was a spectacular failure, and was cancelled long before it ever got into volume production. The really good Russian and US stuff is hard to get on the black market, the not quite so sophisticated Indian, Chinese, French, North Korean stuff is a whole lot easier (and cheaper) to get, and a whole lot less capable. |
#23
|
|||
|
|||
On Fri, 25 Jul 2003 22:44:02 +1000, RT wrote:
The Raven wrote in message ... My only concern is that the Aerosonde UAVs will be over hyped to the point people will get the wrong impression of what they are and what they are capable of. Yair. Well. Not helped by the hype on the Aerosonde web site rabbiting on about its radar disruptive capabilities - shortly after saying the total power available is 30 watts or similar. It's not my field but I have a severe problem believing 30 W in a UAV will disable your average anti-aircraft/G-A missile radar...... Why? Couldn't the UAV check for radar emissions, and then broadcast a signal on the same frequency the radar is using? wouldn't that disrupt the radar? -- A: top posting Q: what's the most annoying thing about Usenet? |
#24
|
|||
|
|||
|
#25
|
|||
|
|||
"matt weber" wrote
This is why ECM system are so complex. To defeat the other radar effectively, you have to figure out exactly what it is (and the USA and it's allies have a long history is doing things to 'excite' the air defenses of less than friendly countries so they can characterize the radar, and build a threat library. The big thing today, is to direction find (DF) the emitter and kill it. Not a whole lot of jamming anymore except for self-protection. The U.S. and British DF aircraft are very good at finding emitters, and then the UAV's can go in and get a visual, and the plan made for its destruction. The mobile stuff is not that hard to kill. Even the Patriot was blown-up when it targeted the HARM equipped aircraft in the recent war. Shoot first, and live. |
#26
|
|||
|
|||
On Thu, 31 Jul 2003 21:38:38 -0700, matt weber wrote:
On Thu, 31 Jul 2003 16:11:48 +0100, (phil hunt) wrote: On Fri, 25 Jul 2003 22:44:02 +1000, RT wrote: The Raven wrote in message ... My only concern is that the Aerosonde UAVs will be over hyped to the point people will get the wrong impression of what they are and what they are capable of. Yair. Well. Not helped by the hype on the Aerosonde web site rabbiting on about its radar disruptive capabilities - shortly after saying the total power available is 30 watts or similar. It's not my field but I have a severe problem believing 30 W in a UAV will disable your average anti-aircraft/G-A missile radar...... Why? Couldn't the UAV check for radar emissions, and then broadcast a signal on the same frequency the radar is using? wouldn't that disrupt the radar? Depends upon the type of radar. There is very little 'CW' radar in use anylonger. most is "chirp" frequency modulated, so if you don't appropriately modulate the signal, it is simply ignored. That makes sense. How easy would it be for the UAV to listen to thre incoming signal, and match its response to it? I would guess the radar uses a different "chirp" for each pulse it sends out; is that correct? (Think about why the AM radio hears the ignition noise on the cars as they go buy, I can't say I've ever noticed that effect, but I'll take your word for it. but an FM radio does not. Ignition noise is amplitude modulated, and FM detectors do not detect amplitude. Others are monopulse. they fire a single pulse. The next pulse they fire will be on another frequency. There are all sorts of modulation and transmission schemes to extract additional information from the target, and to make the radar more difficult to jam. EF-111's and EA6-B use the entire payload for Electronic counter measures. It seems to me the best way to counter a radar is to fire a missile that homes in on the radar's signals -- since a radar, to work, must emit signals. (Of course, an adversary could build lots of cheap boxes that give off signals that appear the same as a real radar, to soak up lots of anti-radiation missiles). This is why ECM system are so complex. To defeat the other radar effectively, you have to figure out exactly what it is (and the USA and it's allies have a long history is doing things to 'excite' the air defenses of less than friendly countries so they can characterize the radar, and build a threat library. How good are passive sensors compared to radar? I would imagine that visual light and infra-red would be quite good ways of detecting aircraft (and if you have 2 detectors some distance away you can use triangulation to get the exact position), at least when there are no clouds. -- A: top posting Q: what's the most annoying thing about Usenet? |
#28
|
|||
|
|||
"M.R." wrote in message
u Really interesting this evolution of UAV's and other weapons such as JDAM munitions. How do the JDAM munitions work? Is it and inertia launch then initial GPS guidance and an infra-red image for the last stage to home in on. If a UAV and JDAM weapon where combined that would have to be a fairly stealthy target? Current JDAMS are pure GPS -- no IR seeker. The weapon isn etirely passive and certainly could be stealthy. The problem is that even the 500-lb JDAM is really too big for current UAVs. Smaller bombs are in development, and we may well see UAVs armed with them in the not-too-distant future. -- Tom Schoene Replace "invalid" with "net" to e-mail "If brave men and women never died, there would be nothing special about bravery." -- Andy Rooney (attributed) |
#29
|
|||
|
|||
On Fri, 01 Aug 2003 20:34:07 -0700, matt weber wrote:
That makes sense. How easy would it be for the UAV to listen to thre incoming signal, and match its response to it? The Self Projection jammer pods often represent more than the available lift capacity of the UAV unless you are talking about something the size of a Predator or a Global Hawk... Why would it need to be so big? Is it the receiving equipment, the transmitting equipment, or the electronics in between that takes up the space? (Of course, an adversary could build lots of cheap boxes that give off signals that appear the same as a real radar, to soak up lots of anti-radiation missiles). While it could be done, it isn't all that cost effective, to build an emitter that would look enough like a real radar to be attacked would probably cost 15-20% of the price of the real thing. How much do real radars cost? Certainly there are some radio transmitting equipments that are cheap -- for example mobile phones and wi-fi stations -- and I'd imagine that scaling up the transmitting powrer on such a device would be too expensive either. How good are passive sensors compared to radar? I would imagine that visual light and infra-red would be quite good ways of detecting aircraft (and if you have 2 detectors some distance away you can use triangulation to get the exact position), at least when there are no clouds. Depends upon what you are looking for. [...] If you are looking for an F4 or a B52, it won't be very hard, That's exactly the sort of thing I had in mind (or an F-16 or Tornado or F-22, etc, bascially any modern supersonic aircraft) -- A: top posting Q: what's the most annoying thing about Usenet? |
#30
|
|||
|
|||
Really interesting this evolution of UAV's and other weapons such as JDAM
munitions. How do the JDAM munitions work? Is it and inertia launch then initial GPS guidance and an infra-red image for the last stage to home in on. If a UAV and JDAM weapon where combined that would have to be a fairly stealthy target? Is it fairly easy to have a sensor that warns of overhead SAR from a UAV or such. Whats the difference between Synthetic Aperture Radar and just radar? Is there any such thing as active infra-red or is infra-red solely a passive means of detection. What's its range? What's the formula for roughly working out the horizon of a radar? Height in feet squared is the horizon in miles or something. This new Surface Wave Radar blows it all out of the water. "matt weber" wrote in message ... On Fri, 1 Aug 2003 14:54:31 +0100, (phil hunt) wrote: On Thu, 31 Jul 2003 21:38:38 -0700, matt weber wrote: On Thu, 31 Jul 2003 16:11:48 +0100, (phil hunt) wrote: On Fri, 25 Jul 2003 22:44:02 +1000, RT wrote: The Raven wrote in message ... My only concern is that the Aerosonde UAVs will be over hyped to the point people will get the wrong impression of what they are and what they are capable of. Yair. Well. Not helped by the hype on the Aerosonde web site rabbiting on about its radar disruptive capabilities - shortly after saying the total power available is 30 watts or similar. It's not my field but I have a severe problem believing 30 W in a UAV will disable your average anti-aircraft/G-A missile radar...... Why? Couldn't the UAV check for radar emissions, and then broadcast a signal on the same frequency the radar is using? wouldn't that disrupt the radar? Depends upon the type of radar. There is very little 'CW' radar in use anylonger. most is "chirp" frequency modulated, so if you don't appropriately modulate the signal, it is simply ignored. That makes sense. How easy would it be for the UAV to listen to thre incoming signal, and match its response to it? The Self Projection jammer pods often represent more than the available lift capacity of the UAV unless you are talking about something the size of a Predator or a Global Hawk... I would guess the radar uses a different "chirp" for each pulse it sends out; is that correct? It may, but more likely it is a mono pulse, same chirp, but broadcast on a different frequency each time... (Think about why the AM radio hears the ignition noise on the cars as they go buy, I can't say I've ever noticed that effect, but I'll take your word for it. (Of course, an adversary could build lots of cheap boxes that give off signals that appear the same as a real radar, to soak up lots of anti-radiation missiles). While it could be done, it isn't all that cost effective, to build an emitter that would look enough like a real radar to be attacked would probably cost 15-20% of the price of the real thing. That's a lot of money to spend on decoys! How good are passive sensors compared to radar? I would imagine that visual light and infra-red would be quite good ways of detecting aircraft (and if you have 2 detectors some distance away you can use triangulation to get the exact position), at least when there are no clouds. Depends upon what you are looking for. At fair amount of effort has gone into reducing both the RF and Visual 'cross section' of aircraft. A great deal of effort has also gone into reducing exhaust gas temperatures. You can actually hold your hand in the exhaust stream of an AH64 Apache while the engine is at idle. If you are looking for an F4 or a B52, it won't be very hard, it is big, noisy and smokey. If you are looking for a 100kg UAV at 5000 feet, or a Proteus at 70,000 feet... good luck... one of the reason sat links are preferred is they only radiate energy upward, so they don't provide much to listen for from the ground. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Boeing Boondoggle | Larry Dighera | Military Aviation | 77 | September 15th 04 02:39 AM |
U.S. Air Force award of four rocket launches this year is likely to be delayed | Larry Dighera | Military Aviation | 15 | May 14th 04 01:58 PM |
Who's At Fault in UAV/Part91 MAC? | Larry Dighera | Instrument Flight Rules | 24 | April 29th 04 03:08 PM |
RV-7a baggage area | David Smith | Home Built | 32 | December 15th 03 05:08 AM |
Air Force Academy Review Panel Sets Second Public Meeting | Otis Willie | Military Aviation | 0 | July 10th 03 02:39 AM |