gambit
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SPECTRA does sample. But not in-flight and under EM threat. The sampling was done in what is called the 'offline' testing mode.
If you are in combat, you are online. Whatever happens that could affect an undesirable outcome, you have to adjust on the fly. In being 'stealthy', that undesirable outcome is you being detected AND tracked.
The three main modes of radar detection:
- Detection
- Tracking
- Targeting
Even civilian systems operates that way. It sounds 'military' but it is actually not. Air traffic controls usually do not focus or 'target' a specific flight except for emergencies.
Mr. Random gave the clue on how SPECTRA works back on page 344 post 5156 with this explanation...
"Every single time you add a payload on the Rafale, the aircraft undergoes rigorous RCS testing."
That does not mean the Raffle entered measurement before every sortie. That would be prohibitively expensive to operate the jet. What he meant -- as in whoever told him -- was the TYPE or external load that would be on the Raffle.
For example...
If the Raffle was RCS measured for a 500 lbs (230 kg) external fuel tank, that is all the Raffle will be allowed to fly in combat. SPECTRA performed the necessary signal sampling OFFLINE, meaning in that EM anechoic chamber, a tightly controlled environment, and SPECTRA generate a countermeasure signal based upon that tightly controlled testing environment. That RCS value and its associated countermeasure signal is stored.
If aerodynamically a 600 lbs (275 kg) is available and passed all testings, the Raffle will still not be allowed to fly with the new fuel tank because the Raffle's baseline RCS plus the larger fuel tank is not in SPECTRA's countermeasure library. Any threat radar would immediately detect and track the jet with the new and larger fuel tank.
If a current bomb is modified with larger stabilizer fins, this modified bomb would not be allowed on the Raffle because now the larger fins would create new EM radiation patterns. The jet with the modified bomb would have to be measured, SPECTRA would generate a countermeasure signal, and the new baseline RCS plus modified bomb pair would be stored in SPECTRA's library.
Everything above is strictly dependent upon KNOWN signals fed to SPECTRA. In flight -- the online mode -- if SPECTRA detects a threat signal that is in its threat library, SPECTRA then search for the associated RCS value for that threat signal, then calls up the matching countermeasure signal.
For a frame of reference, see Perl hash table or Python dictionary.
So SPECTRA as a countermeasure capability is no different than other systems in that it does uses signal sampling, just in a different time and place. The weakness and flaw is when SPECTRA encounters a threat signal NOT in its threat library or not in that hash/dictionary table.
Mr. Randsom's lack of experience in the radar field is why he could not deduce how SPECTRA works. SPECTRA cannot violate the laws of nature or the laws of common sense, in this case it is statistical sampling. Common sense tells you that you must know even a slight bit of whatever it is you are facing before you can formulate a response mechanism. So all Mr. Random can say is "SPECTRA does not use sampling", which is nonsensical. SPECTRA does use sampling, just at a different time in that chain of response formula.
The aircraft is generally above most seeking radar, so structurally, a bottom mounted large antenna will do the job %99.999 of the time. The Raffle probably does have smaller antennas at other locations on the jet. Am just not going to spend a lot of time on it.
Right now, AESA is still fairly new in deployment. In theory, an AESA system WILL defeat the active cancellation method used by SPECTRA, but in practice, it is COMPLETELY dependent on the software running the AESA system. If the threat signals generated by the AESA system are within certain parameters of known threat signals that SPECTRA knows, then SPECTRA wins.
