ISED Basic flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Wavelength formula
- Wavelength in metres equals 300 divided by frequency in megahertz. This approximation applies to free space and is the basis for antenna dimension calculations.
- Free-space path loss
- FSPL in dB equals 32.45 plus 20 log of frequency in MHz plus 20 log of distance in km. Loss increases 6 dB when distance or frequency doubles.
- EIRP definition
- Equivalent isotropically radiated power is transmitter power plus antenna gain minus feedline loss, expressed in dBm or watts relative to an isotropic radiator.
- ERP versus EIRP
- ERP is referenced to a half-wave dipole and is 2.15 dB lower than EIRP. Converting: EIRP equals ERP plus 2.15 dB.
- Decibel power ratios
- A 3 dB change is roughly a factor of two in power, 10 dB is a factor of ten, and 20 dB is a factor of one hundred.
- Necessary bandwidth
- The minimum emission bandwidth needed to transmit information at the required rate and quality under the specified emission class.
- Occupied bandwidth
- The frequency width containing 99 percent of the mean radiated power of an emission, measured with the resolution bandwidth specified by the standard.
- Certification requirement
- Radiocommunication apparatus must be certified against the applicable technical standard before sale, lease, import, or offer for sale in the jurisdiction.
- Test report contents
- A compliance test report identifies the standard and version, test methods, instrument calibration, measured values, limits, and the tested equipment configuration.
- Certificate holder duty
- The certificate holder is responsible for ensuring every unit produced or imported matches the certified design and bears the required label and certificate number.
- Variation to certification
- Changes to RF circuitry, firmware affecting emissions, or antenna type may require a new certificate or an approved variation before the modified product is marketed.
- Mutual recognition arrangement
- An agreement allowing test data from a recognized foreign laboratory to be accepted in support of a domestic certification application.
- Emission designator
- A coded string describing necessary bandwidth, modulation type, nature of signal, and additional characteristics, required in licence and certification records.
- Conducted versus radiated emissions
- Conducted emissions travel along cables and are measured on power and signal leads, typically from 150 kHz to 30 MHz. Radiated emissions leave the enclosure through the air.
- Immunity meaning
- The ability of equipment to operate without degradation in the presence of electromagnetic disturbance such as radio fields, transients, or electrostatic discharge.
- Common-mode current
- Current flowing in the same direction on all conductors of a cable, often the dominant cause of radiated emissions. Ferrites and shielding suppress it.
- Intermodulation products
- Spurious signals generated when two or more frequencies mix in a nonlinear stage, appearing at sums and differences such as 2f1 minus f2.
- Harmonic emission
- Radiation at integer multiples of the transmitter fundamental, suppressed by low-pass or band-pass filtering to meet spurious emission limits.
- Shielding aperture rule
- Apertures and seams larger than about one-twentieth of a wavelength allow significant leakage, reducing shielding effectiveness at higher frequencies.
- Half-wave dipole length
- Length in metres is approximately 143 divided by frequency in MHz, with a practical shortening factor of about 0.95 for conductor thickness and end effects.
- VSWR formula
- VSWR equals one plus the reflection coefficient magnitude divided by one minus that magnitude. A value of 1.5 to 1 reflects about four percent of power.
- Return loss
- Return loss in dB equals minus 20 log of the reflection coefficient magnitude. A return loss of about 14 dB corresponds to VSWR near 1.5 to 1.
- Antenna gain reference
- Gain in dBi compares to an isotropic radiator; gain in dBd compares to a half-wave dipole, and dBi equals dBd plus 2.15.
- Feedline loss effect
- Cable attenuation in dB reduces transmit power and received signal equally. Minimizing cable length and using low-loss cable improves both links.
- Antenna substitution rule
- Only antennas permitted by the certification may be used. Higher-gain antennas can raise EIRP beyond limits and breach compliance.
- Resolution bandwidth
- The spectrum analyzer filter width that determines frequency resolution. It must be narrow enough to resolve the emission and set as the standard requires.
- Quasi-peak detector
- A detector weighting signals by pulse repetition rate, giving readings between peak and average. It is specified for many disturbance measurements.
- Antenna factor
- Field strength in dB microvolts per metre equals the received voltage in dB microvolts plus the antenna factor in dB per metre.
- Measurement uncertainty
- The quantified range of doubt in a measurement from instrument, setup, and environmental contributions. It must be calculated and applied per the standard.
- Calibration traceability
- Instrument and antenna calibrations must be current and traceable to national standards, with certificates available for inspection during compliance testing.
- RF exposure limit
- Frequency-dependent limits on power density or specific absorption rate protect people from heating. Exclusion zones are calculated from EIRP and antenna pattern.
- Lockout tagout
- A procedure isolating and marking energy sources before servicing antennas or transmitters, preventing accidental energization during work.