Found a document detailing the capability downgrading and modification of the APY-10 going into the P-8I.
Modify APY-10 Radar for Export to India
- Modify Radar navigator to remove accumulated carrier phase and revert to earlier, less sophisticated navigator
This appears to be precision GPS that provides input to the radar computer to provide greater accuracy utilizing timing of RF pulses as they return to radar receiver. The situation display operator may therefore have better background map information, and more importantly perhaps better clutter filtering.
- Remove Precision Targeting capability
This is probably referring to radar target detection capability and modifying radar software to properly use the sensors in place for this version of the P-8.
- Remove UHR ISAR capability
- Remove 1 and 3 foot SAR capability
Both of these items are for limiting synthetic aperture radar capability. I find it amazing that Raytheon reveals that the P-8 radar for the USN is capable of 1 and 3 foot range gate capability, but of course they don't state the pulse repitition interval time and range.
- Limit performance to meet 30 meter SAR geo-location accuracy
This is means the radar is capable of 30 m range gate resolution, which is very good. For comparison civilian radar for ATC is capable of 100 m range gate resolution. Note I am not talking about target resolution. With a resolved 30 m range gate, the actual target pulse width is about 0.2 micro seconds which should provide good target resolution provided you can get at least several return pulses.
Add an Interleaved Weather Capability
This seems straight forward and primarily adding software capability.
Add an Air-to-Air Target Detection / Tracking Capability
Although this is limited by a 240 degree view, given the resolution of this radar, it's a good modification. I would probably bet its better than the Phalcon, but of course the P-8 doesn't have the radar range and full azimuthal and elevation coverage. Much will depend on the clutter filtering capability and software. Don't think for a minute Raytheon is going to give this away, not because it is India, but because this is their bread and butter. Even the USN is proababaly paying hundreds of dollars an hour for this type of support.
taken from here:Link