Satellite Guided Munitions.

[tjhkkr]

I am curious... and I admit I do more stuff with earlier time frames...
BUT
Back in the Harpoon II days, I saw there was a lot of munitions being delivered via Satellite, and that there was a diplomatic issue of some kind because Iraq had Satellite Jammers.
Has CMANO done much with Satellite Guided Munitions?
I know it was the rage for a while in governments because it was cheaper than laser guided kits. But the folly of it was shown in Iraq.
Are Satellite jammers modeled if it is being used?

[AlphaSierra]

I have not seen anything relating to sat guided munitions,

I doubt the validity of a report from anyone saying they can jam a satellite other than their own.
The platform necessary to radiate enough power on enough frequencies to disable it even slightly, would be immense and obviously easily targeted the second it illuminates.

I suspect the above "reasons" is why shooting down a satellite is a more viable option than jamming.

[jtoatoktoe]

GPS Jammers are pretty common in the real world.....modern weapons also have defenses for gps jammers. The U.S. and Russia have both been able to shut down GPS in areas before when testing systems. But yeah shooting down the satellite is probably;y easier.

[Primarchx]

Most modern GPS-guided weapons have an inertial guidance backup.

[Dysta]

And even more modern devices like SAR imaging, and drone-based datalink.

[Sharana]

ORIGINAL: AlphaSierra

I doubt the validity of a report from anyone saying they can jam a satellite other than their own.
The platform necessary to radiate enough power on enough frequencies to disable it even slightly, would be immense and obviously easily targeted the second it illuminates.

I suspect the above "reasons" is why shooting down a satellite is a more viable option than jamming.

We are speaing about GPS here, not comm sats. Them you can't jam obviously, but shutting down the GPS signal in area of 20-40km (arround SAM site for example) is very easy and totally possible. It's a serious problem to consider and that's why new munitions no longer rely on 1 guidenance methode alone. JDAM and Paveway are becomming both laser + GPS. SDB II gets Radars+IR+GPS compared to GPS only SDB. The SPICE family of bombs is EO/IR + GPS where it can visutally aquire target even if you jam the datalink controlling it which is also very possible.

ORIGINAL: Primarchx

Most modern GPS-guided weapons have an inertial guidance backup.

INS can't provide that accuracy. JDAM with INS only (GPS jammed) isn't really more accurate then dumb bombs dropped from modern fighters (CEP in the area of ~40m usually). Also INS accuracy drops with range, so SDB on top of having small warhead (needs direct hit, can't realy on close impact 10m away from the target) will be totally useless with it's big gliding range.


So yeah it would be cool to have GPS jammers in CMANO as that would provide for more interesting gameplay, but there is lots of stuff on the do to list and there are more important things to add first

[Primarchx]

ORIGINAL: Sharana

...
So yeah it would be cool to have GPS jammers in CMANO as that would provide for more interesting gameplay, but there is lots of stuff on the do to list and there are more important things to add first

Oh, I agree completely.

[SeaQueen]

So yeah it would be cool to have GPS jammers in CMANO as that would provide for more interesting gameplay, but there is lots of stuff on the do to list and there are more important things to add first

I love the idea, but if satellite jamming was modeled, then does that mean that if I use GPS guided ordinance then I need to include compatible satellites in the scenario? If that's the case, then what about other anti-satellite capabilities? It seems to me that satellite jamming is the gateway drug to space warfare in the simulation. How many anti-satellite weapons systems do we actually have hard data on?

[TXTBOOK]

ORIGINAL: Sharana

ORIGINAL: AlphaSierra

I doubt the validity of a report from anyone saying they can jam a satellite other than their own.
The platform necessary to radiate enough power on enough frequencies to disable it even slightly, would be immense and obviously easily targeted the second it illuminates.

I suspect the above "reasons" is why shooting down a satellite is a more viable option than jamming.

We are speaing about GPS here, not comm sats. Them you can't jam obviously, but shutting down the GPS signal in area of 20-40km (arround SAM site for example) is very easy and totally possible. It's a serious problem to consider and that's why new munitions no longer rely on 1 guidenance methode alone. JDAM and Paveway are becomming both laser + GPS. SDB II gets Radars+IR+GPS compared to GPS only SDB. The SPICE family of bombs is EO/IR + GPS where it can visutally aquire target even if you jam the datalink controlling it which is also very possible.

ORIGINAL: Primarchx

Most modern GPS-guided weapons have an inertial guidance backup.

INS can't provide that accuracy. JDAM with INS only (GPS jammed) isn't really more accurate then dumb bombs dropped from modern fighters (CEP in the area of ~40m usually). Also INS accuracy drops with range, so SDB on top of having small warhead (needs direct hit, can't realy on close impact 10m away from the target) will be totally useless with it's big gliding range.


So yeah it would be cool to have GPS jammers in CMANO as that would provide for more interesting gameplay, but there is lots of stuff on the do to list and there are more important things to add first

I question the following and would be interested in source data/backup so that I can better understand/learn:

-"Comm sats" can't be jammed
-INS can't provide the accuracy needed for munitions
-JDAM with INS only (GPS jammed) isn't more accurate than dumb bombs
-SDB would be useless at its gliding range with INS only

[AlphaSierra]

Agreed I think you could throw up enough noise in a small area to throw off a GPS device.

That said I recall testing cruise missiles that had digital imaging etc.. before GPS was a thing...they worked pretty well [;)]

[TXTBOOK]

ORIGINAL: AlphaSierra

Agreed I think you could throw up enough noise in a small area to throw off a GPS device.

That said I recall testing cruise missiles that had digital imaging etc.. before GPS was a thing...they worked pretty well [;)]

GPS jamming is fairly widespread in current conflict areas. The L-band signal is relatively weak and even handheld jammers on eBay, etc can cause problems (much less proper EW systems jamming L1/L2 GPS). In the US, we often see NOTAMs alerting of GPS jamming for testing.

[Sharana]

ORIGINAL: TXTBOOK
I question the following and would be interested in source data/backup so that I can better understand/learn:

-"Comm sats" can't be jammed

How do you imagine "jamming a sattelite", because AlphaSierra said "I doubt the validity of a report from anyone saying they can jam a satellite other than their own". With "Them you can't jam obviously" I mean satellites. Because while you can jam the communication frequencies in some specific area closer to the ground (and to the jammer itself), you can't "jam" the satellite itself. Also it will be extremely hard to jam UAV datalink for example with big directed antenna flying high using ground jammer (as in most cases).

INS can't provide the accuracy needed for munitions

What do you understand under "accuracy needed for munitions"? INS can't provide the optical/laser/GPS level of accuracy that allows pin-point shots against hardened targets, specific buildings, specific vehicles and so on. It's of course a lot better to have INS compared to not having any guidance (freefall bomb), but at the same time you simply can't assume the same success rate when you know GPS arround the target area is probably jammed - you will have to assign more bombs to the target due to the lower CEP to assure it's destruction. Meaning it's NOT "the same" with or without GPS signal and it has to be taken into account.

JDAM with INS only (GPS jammed) isn't more accurate than dumb bombs

Speaking about "accuracy" only pretty much, but I said with modern fighters that have the latest achievments in computer assisted bombing. The MK 80 series of bombs is low drag and using the same bomb the CEP was decreasing with each generation of avionics. At the beginning of the Vietnam war the CEP of MK.84 bomb was ~120m with ~100m at the end. During Desert Storm F-16s achieved ~50-60m with the same bombs. After 1991 I haven't seen official statements, only that CCIP on the F-16 can get up to 30m CEP in ideal circumstances. In memoir books from USAF pilots I've seen figures like "reliably" and "30-40 meters" for the period 1997-2004 for the same Mk 80 series (the exact book I don't have the time or desire atm to track in my archive sorry). Yes that's up to medium attitude, stable flight profile and so on, but we are speaking about possible accuracy and not convenience.

For JDAM the official figures are:

Once released, the bomb's INS/GPS will take over and guide the bomb to its target regardless of weather. Guidance is accomplished via the tight coupling of an accurate Global Positioning System (GPS) with a 3-axis Inertial Navigation System (INS). The Guidance Control Unit (GCU) provides accurate guidance in both GPS-aided INS modes of operation (13 meter (m) Circular Error Probable (CEP)) and INS-only modes of operation (30 m CEP). INS only is defined as GPS quality hand-off from the aircraft with GPS unavailable to the weapon (e.g. GPS jammed). In the event JDAM is unable to receive GPS signals after launch for any reason, jamming or otherwise, the INS will provide rate and acceleration measurements which the weapon software will develop into a navigation solution. The Guidance Control Unit provides accurate guidance in both GPS-aided INS modes of operation and INS-only modes of operation. This inherent JDAM capability will counter the threat from near-term technological advances in GPS jamming.

In Air Force magazine from June 2017 you can see the following for JDAM:
- Performance: Range up to 15 miles, CEP with GPS 16.4 ft, CEP with INS only 98 ft.
http://secure.afa.org/joinafa/AFMag2017 ... ge124.html

The difference between ~30m CEP (INS only) and ~40m CEP ("dumb" on F-16 models after Desert Storm) isn't that big, is it compared to CEP of ~3m that EO/IR or laser can provide or 5-7m for GPS? The russians with their SVP-24 score ~40m CEP usually with their FAB-500s too (some claims like 10-20m are pure propaganda obviously). And as we can see that's far from "enough" for hardened targets or urban warfare where you need specific buildings. After all PGMs were made in order to hit targets like that:



because the alternative is using lots of ammo with larger CEP till you finally hit what you are trying to hit. And INS only as you see from the CEP can't provide for that and that's why most new ammo types add laser, optics or radar on top of the GPS/INS as GPS jammers will be getting more common.

SDB would be useless at its gliding range with INS only

First of all SDB's warhead has 16kg of explosive. Compared to 89kg explosive on Mk.82, 202kg on Mk.83 and 429kg on Mk.84 you obviously need direct impact or really close miss. For reference tge 429kg of explosives on the Mk.84 can destroy vehicles withing 30m ... so how close should the 16kg on SDB "miss" in order to get the job done?
They have small warhead, because they are supposed to be really accurate and hit hardened targets, JDAM can't really do that:



There are no figures about the "INS only" accuracy on SDB out there, only the GPS. But we saw the what kind of degrade there is on the JDAM:

In its most accurate mode, the JDAM system will provide a weapon circular error probable of 5 meters or less during free flight when GPS data is available. If GPS data is denied, the JDAM will achieve a 30-meter CEP or less for free flight times up to 100 seconds with a GPS quality handoff from the aircraft.

Notice the up to 100 seconds part. INS accuracy degrades over time, the good ones degrade at rate of 8-9m per minute (60 seconds) without GPS correction to reset the error building up over time. As you can see from the values listed for the JDAM you don't put the most accurate (=expensive) INS on cheap bomb, so the accuracy degrades faster then 8-9m per minute. If the JDAM ends up gliding more then 100sec the CEP will be larger and as we know SDB has a lot bigger gliding range, so more gliding time and more error building up in the INS. So yes SDB really looks useless with INS only as the CEP will be above 30m while the tiny warhead needs to land with way higher accuracy to do it's job. For that reason SDB II has millimeter wave radar for active radar homing and IR camera for infrared homing that will provide the terminal guidance while the GPS/INS is only supposed to bring it to the general area where the target is which it will clearly do no matter how hard you try to jam it.

[TXTBOOK]

Sharana, thanks for taking the time to put that together. Lots of interesting stuff and i had not considered many of the points.

[AlphaSierra]

Nailed it!

Few things to remember about Jamming


Never let an enemy know their jamming is working
Long range munitions will use gps to "update" its position (it doesn't need many)
If you are trying to jam something you can see...it may be too late.