sam.gov
Looks like they're utilizing 12 September 2023 except they use traunches of misleading language in this, as per usual.
They keep referring to it as a "filter" but it is nothing quite so simple. AESA, which is a 20+ year old technology, has been improved over the years and works by emitting RADAR signals on a rotating modulations and listening only on certain frequencies at certain times and ignoring all other signals. The ability to jam such a system is predicated upon creating high amplitude signals which are rotated at a rate that is substantially greater than the AESA rotational rate. If signals are transmitted on all possible frequencies, rotation is not necessary to support jamming.
I've come up with a few different possible solutions to this problem of the jamming, one of which is to use layered metamaterials to act as a physical gating mechanism (although I feel as though filtering according to angular momentum is a cleaner approach and I have explained exactly how we can do this.) As for the metamaterial gating approach, the concept is actually to both block and permit EM through shielded and unshielded areas of a receiver, respectively.
It is much easier to suss out the content of an authentic signal in a high-noise environment when one knows in advance exactly
when a signal will be received. If a receiver is programmed in advance to expect signals on a certain schedule (and they are transmitted on a schedule) an adversary would eventually adapt and focus their jamming during those windows (millisecond or less) during when signals are sent e.g. telling a drone to make a turn or fire a missile.
The use of tailored metamaterial layers of up to dozens or perhaps hundreds of layers of thickness in which each layer has unique properties enables only specific, complex signal patterns to make it through the shielded portions of a receiver. Only when a signal authenticity "tag" is sent will actual data be sent to a drone or other platform. False "tag" codes would be sent continually except when actual data is to be sent. When an authentic tag code is sent, authentic data is transmitted to the platform in the RF-denied environment. The noise-mitigation software onboard the platform (entirely automated) would use this information concerning the expected timing of the authentic signal in order to "focus in" on that window of time. Repeated signals would be sent (also tagged) and after a series of re-transmissions in which the platform can know, beyond a doubt, that a valid instruction is being sent during those timeframes, the ability to analyze repeated "noisy" versions of authentic signals greatly enhances the ability of automated software-based noise reduction to be effective.
Is it a filter? No. It is a kind of a cue or prompt that enables the software-based noise reduction software to work more effectively. It is also being used without my consent as I have never sent this information to them, sold it, or any other such thing.
It is remarkable the number of specific concepts which have been flat-out stolen in recent months. What do the Ph.D.s who work for them do all day? Do they have no ideas of their own?