Specifications for the XPR
1. X-Band magnetron transmitter peak power:
25 kW peak (nominal).
2. Polarization:
Horizontal (it’s an Andrew HP6-102-P3A microwave antenna, single
polarization).
3. Pulse duration range:
User can select between 1.0, 0.38, or 0.19 µs.
4. Range to first gate:
The Gamic system starts taking data right after sending the transmit pulse, so
the first sample comes from the 0 to 50 m range (assuming 50 m range gate
spacing). Second gate would come from the 50 to 100 m range, and so on.
5. Range gate spacing (selectable) values:
Set to 50 m by default. It could be set to larger values in 50 m increments,
e.g., 100 m, 150 m, etc.
6. Pulse repetition frequency (range):
Set to 500 Hz (1.0 µs PW), 1,250 Hz (0.38 µs PW), and 2,000 Hz (0.19 µs
PW).
7. Antenna diameter:
1.8 m.
8. Beam width:
1.2 degrees according to the Andrew HP6-102-P3A specifications, but we
have redesigned the antenna feed. Antenna pattern calculations are currently
being carried out.
9. Transmit frequency:
9.410 GHz.
10. Noise floor (dBm):
We will make measurements later on.
11. Number of range gates:
number of range gates = (maximum range) / (range spacing)
= 10 km / 50 m = 200
4,096 is the maximum number of range gates. If the number exceeds 4,096
the Gamic software will automatically adjust the maximum range (or slant
range as it is called in the Gamic software).
12. Number of points in the Doppler spectrum:
Set to 50. Doppler spectrum is calculated using the DFT algorithm. User can
change this value along with the data processing algorithm (DFT, FFT, or
PPP).
13. Recorded parameters:
Corrected and uncorrected reflectivity.
Mean velocity.
Spectral width.
In-phase and quadrature (I and Q ) time series.
If I and Q and processed, Doppler spectra can be calculated.
14. Dwell times (minimum, maximum):
I usually associate dwell times with the time the antenna is pointing in one
direction and this antenna is fixed in the vertical direction. Instead I will
calculate the times taken to get one estimate of the velocity:
dwell time = (number of time samples) / PRF (maximum samples is 255)
PRF = 500 Hz
:
dwell time = 0.51 s (samples = 255)
PRF = 1,250 Hz :
dwell time = 0.204 s (samples = 255)
PRF = 2,000 Hz :
dwell time = 0.1275 s (samples = 255)