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FCC PART 15, SUBPART C, SEC. 15.247 - DIRECT SEQUENCE SPREAD SPECTRUM TRANSMITTERS
PCMCIA Wireless LAN Card, Model WL-211F
Calculation of Field Strength:
The field strength is calculated by adding the calibrated antenna factor and cable factor, and subtracting the Amplifier
gain (if any) from the measured reading. The basic equation with a sample calculation is as follows:
Where FS
RA
AF
CF
AG
Example:
If a receiver reading of 60.0 dBuV is obtained, the antenna factor of 7.0 dB/m and cable factor of 1.0 dB are
added, and the amplifier gain of 30 dB is subtracted. The actual field strength will be:.
Field Level = 60 + 7.0 + 1.0 - 30 = 38.0 dBuV/m.
Field Level = 10 (38/20) = 79.43 uV/m.
8.5.
TRANSMITTED POWER DENSITY OF A DSSS SYSTEM
•
The radio was connected to the measuring equipment via a suitable attenuator.
•
Locate and zoom in on emission peak(s) within the passband
•
The spectrum analyzer were used and set as follows:
-
Resolution BW: 3 kHz
-
Video BW:
-
Detector Mode: Normal
-
Averaging:
-
Span:
-
Amplitude:
-
Sweep Time:
•
Locate and zoom in on emission peak(s) within the passband. Set RBW = 3 KHz, VBW > RBW, Sweep = SPAN/3
KHz. For example, a span of 1.5 MHz, the sweep should be 1.6x10
must be no greater than +8 dBm.
•
For devices with spectrum line spacing greater than 3 KHz no change is required.
•
For devices with spectrum line spacing equal to or less than 3 KHz, the resolution bandwidth must be reduced below
3 KHz until the individual lines in the spectrum are resolved. The measurement data must then be normalized to 3
KHz by summing the power of all the individual spectral lines within 3 KHz band (in linear power units) to
determine compliance.
•
If the spectrum line spacing cannot be resolved on the available spectrum analyzer, the noise density function on
most modern conventional spectrum analyzer will directly measure the noise power density normalized to 1 Hz noise
power bandwidth. Add 30 dB for correction to 3 KHz.
•
Should all the above fail or any controversy develop regarding accuracy of measurement, the Laboratory will use HP
89440A Vector Signal Analyzer for final measurement unless a clear showing can be made for a further alternate.
ULTRATECH GROUP OF LABS
3000 Bristol Circle, Oakville, Ontario, Canada L6H 6G4
Tel. #: 905-829-1570, Fax. #: 905-829-8050, Email: vhk.ultratech@sympatico.ca, Website: http://www.ultratech-labs.com
•
Assessed by ITI (UK) Competent Body, NVLAP (USA) Accreditation Body & ACA/AUSTEL (Australia)
•
Accredited by Industry Canada (Canada) under ACC-LAB (Europe/Canada MRA)
•
Recognized/Listed by FCC (USA )
•
All test results contained in this engineering test report are traceable to National Institute of Standards and Technology (NIST)
FS = RA + AF + CF - AG
=
Field Strength
=
Receiver/Analyzer Reading
=
Antenna Factor
=
Cable Attenuation Factor
=
Amplifier Gain
same or greater
Off
3 MHz
Adjust for middle of the instrument's range
1000 seconds
6
3
/3.0x10
= 500 seconds. The measured peak level
Page 71
FCC ID: MXF-WL211F
File #: GTT-013FTX
March 17, 2000
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