ANSI/SCTE 16 2001R2007

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Hum Modulation Test Setup Signal Generator Isolation Transformer Step (Optional) DC-<strong>16</strong> (RF Test Point) Attenuator 10dB Pad RF Power Inserter (AC Blocking) RF+AC DUT RF+AC RF Power Inserter (AC Blocking) 10dB Pad Step Attenuator RF Amp AC Power Analyzer AC AC Load Bank. SLM AM Detector Power Supply AC Calibration Jumper Isolation Transformer (Optional) Volt Meter LPF GFCI AC Isolation Transformer Oscilloscope Pre- Amplifier (Optional) Figure 1 10
Appendix 1 – Hum Modulation Derivation The equation for a TV sinewave amplitude modulated carrier is: y(t) = B[1 − (k / 2)(1 + cosω m t)]cosω c t (A -1) where B is the peak amplitude of the RF carrier and k is the modulation factor which is equal to: M pk−pk k = , k ≤ 1 B and k is related to the conventional AM modulation index by the equation: (A - 2) k = 2m ( 1+ m) where m is the conventional AM modulation index. If the peak-to-peak amplitude variation in time is kB, and this amplitude variation is considered to be hum modulation, hum is defined as. AM Mod(dB) = 20Log = B ( kB ) 20Log( k) (A Hum modulation is simply a measurement of k, which is the ratio of the peak-to-peak hum on the carrier to the peak of the RF carrier (B). - 3) k = Hum B pk−pk (A - 4) Figure 2 shows a graphical representation of hum modulation using a continuous wave (CW) carrier as an example. Hum pk-pk V peak (Peak Voltage of RF Carrier) Carrier Voltage Time Figure 2 11
Page 1 and 2: ENGINEERING COMMITTEE Interface Pra
Page 3 and 4: Table of Contents 1.0 Scope 1 2.0 D
Page 5 and 6: 4.0 EQUIPMENT 4.1. The general equi
Page 7 and 8: 5.3. Set the oscilloscope to the fo
Page 9 and 10: Note: The mV p-p value must be divi
Page 11: 7.7 Set the oscilloscope to the fol
Page 15 and 16: Appendix 3 - Conversion of Hum Modu
Page 17 and 18: Appendix 4 - Time domain vs. Freque
Page 19 and 20: The relationship of the peak to pea
Page 21: Appendix 7 - Special Test Condition

ANSI/SCTE 16 2001R2007

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