When
controlling the Panther with the Panther
DataLogger™via PC, the
user may perform an incremental scan which steps one-by-one through
the channels of the entire band.
-------------------------------PANTHER
1 SECOND REPORT------------------------------- ITEM
/ DATE / GPS / MARKER / FREQ 1 / 512 MEASUREMENTS / FREQ 2 / 512 MEASUREMENTS
/ FREQ 3 / 512 MEASUREMENTS / FREQ 4 / 512 MEASUREMENTS Incremental
Scan (using PC software): steps one-by-one through entire band Table
Scan (using PC or Panther keypad): scans through a list of user-defined
channels (80 channels per Rx)
40
Lambda Averaging in Chameleon CW In some instances
it is desirable to reduce the effect of fading in the analysis of
transmitted signal propagation. The 40 Lambda averaging technique
is a known scheme for accomplishing this goal. Berkeley Varitronics
Systems, Inc. has support for this type of averaging in ChameleonCW™,
the universal data conversion tool, starting with version 1.53.
This tool converts data that has been collected using Berkeley's
CW line of receiver equipment. It has been concluded that
the sampling rate needed to suppress the Rayleigh fading of a propagated
signal is:
36-50 samples/ 40 wavelengths An explanation
of this theory can be found in the book titled "Mobile Cellular
Telecommunications Systems" by William C. Y. Lee. Therefore,
assuming that the sampling rate of the receiving equipment is greater
than the number of samples required by the 40 Lambda theory, the
samples maybe reduced to the needed number of samples per second
through averaging. Example: Signal
frequency = 800MHz.
Drive-study speed = 100KM/H.
l = Wavelength of signal
v = Velocity of signal
f = frequency of signal Therefore,
l=v/f. l=(300000000m/s)/(800000000/s). l = .375 meters
- Now,we will
take 40 samples per 40 wavelengths. Therefore, we need the time
duration for 1 wavelength.
T = time duration to drive 1 wavelength.
V = Velocity of vehicle. V = (100km/h)(1000m/km)/(3600s/h)
= 27.78 m/s
T = (l) / V = (.375m) / (27.78m/s)
T = .0135 seconds S = Sampling
rate needed. S = 1 / .0135
s = 74.08 samples / second
- Chameleon
CW 40 Lambda Conversion The BVS Chameleon
CW data conversion tool has an option for averaging based on the
40 Lambda theory. This option is available for data collected via
the BVS Panther 4-channel receiver.
- In the FAST
mode of each piece of equipment, 512 samples per second are taken.
The BVS Chameleon CW then reduces this data to the appropriate amount
of samples required by the 40 Lambda criteria. The user only has
to input the average drive speed of the vehicle.
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