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||{{attachment:SSPSmag.png||height=300}}||This is the noise from a magnetron. Not sure how to interpret this - if we assume a 1 MHz bandwidth and extrapolate to -70 dBc/Hz at 2.7 GHz, how much noise power is that assuming a 15 mW carrier hitting the 5x3 meter antenna?|| ||{{attachment:SSPSmag.png||height=300}}||This is the noise from a [[ attachment:Kyoto2004MagnetronA.pdf | magnetron]]. Not sure how to interpret this - if we assume a 1 MHz bandwidth and extrapolate to -70 dBc/Hz at 2.7 GHz, how much noise power is that assuming a 15 mW carrier hitting the 5x3 meter antenna?||

SSPS Interference with Airport Radar


ARSR-4: Air Route Surveillance Phased array Radar

ASR-11: Airport Surveillance Radar, Terminal Area

( AN/GPN-30 )

PSR Probability of Detection: The PSR shall be capable of detecting a 1.0 m2 Radar Cross Section (RCS), Swerling 1 target to a range of 55 nmi in the clear and at the nose of the beam with a single scan Pd of 0.8 and a Probability of False Alann (PFA) of 10-6 •

Operational Subclutter Visibility: Operational SCV shall be 42 dB minimum at all ranges for nonfluctuating targets.

ARSR-4

ASR-11

Band

L Band

S Band

Peak Power

60 kW

25 kW

Average Power

2.1 kW

Wavelength cm

21.4-24.7

10.3-11.1

Frequency GHz

1.21-1.39

2.7-2.9

Max interference

?

-117

dBm/MHz!! assumed EIRP

LNA bandwidth

?

?

IF bandwidth

?

1 MHz

Table D2 pg 107 13-490

Polarization

Linear

Linear

Circular

Circular

Beam width

1.41°

1.41°

Beam Elevation

2.2°

4.8°

Antenna Gain

34dB

Antenna Size

9 x 7 m

5 x 3 m

Pulse width

1μs

80μs

Coverage nm

250 nm

60 nm

Coverage km

463 km

111 km

Scan period

12 sec

12 sec

Weather map

36 sec

# deployed

43

213

NWS Supplemental Product Generator (SPG)for the ARSR-4 and ASR-11 Radars Product Specification & Interface Control Document

13-490 Effects of Wimax on airport radar and weather radar.


Guessing about radar

If the antenna gain is 34dB, and the peak pulse power is 25 kW, that suggests that the EIRP is 63 MW. A 1 m2 target at a range of 111 km gets 400 microwatts of illumination. If that radiates back with a 1 steradian spread, it delivers 83 pW to the antenna, -70 dBm ?


ArndtSlideV4.png

Sidelobe graph, Cleaned up from Arndt 1978

Note - This is the theoretical, average power without atmospheric scattering (rain, dust, etc.). Assume 1mW/m2, depositing 15 mW of carrier on a 5x3 meter antenna.

SSPSmag.png

This is the noise from a magnetron. Not sure how to interpret this - if we assume a 1 MHz bandwidth and extrapolate to -70 dBc/Hz at 2.7 GHz, how much noise power is that assuming a 15 mW carrier hitting the 5x3 meter antenna?

Of course, the SSPS is not pointed at a radar, but it does create 100's of megawatts of sidelobe power lighting up the whole earth. THe radar dish does not point at SSPS overhead, but if there are 100 in orbit, some will be near the horizon within the 360 degree antenna horizontal and 40 degree vertical scan. A radar will see any SSPS that appears near the horizon, and at low elevation there will be significant atmospheric and terrain scattering.

SspsRadar (last edited 2016-09-25 05:42:02 by KeithLofstrom)