ANSI SCTE 119-2018 pdf free download – Measurement Procedure for Noise Power Ratio.
This procedure defines a method of measurement for Noise Power Ratio (NPR) of active Cable Telecommunications equipment. It is intended for measurement of 75-ohm devices having type “F” or 5/8-24 KS connectors. See SCTE 96 2008 Cable Telecommunications Testing Guidelines for a discussion of proper testing techniques.
This procedure uses a spectrum analyzer to measure the noise power in a narrow frequency band. Other means of measurement such as a narrow band filter followed by a power meter may be used as long as the results can be shown to correlate to this method.
1.3. Benefits
A uniform procedure to measure the noise power ratio of active equipment
1.4. Intended Audience
Equipment manufacturers
1.5. Areas for Further Investigation or to be Added in Future Versions
None
2. Normative References
The following documents contain provisions, which, through reference in this text, constitute provisions of this document. At the time of Subcommittee approval, the editions indicated were valid. All documents are subject to revision; and while parties to any agreement based on this document are encouraged to investigate the possibility of applying the most recent editions of the documents listed below, they are reminded that newer editions of those documents might not be compatible with the referenced version.
2.1. SCTE References
• No normative references are applicable.
2.2. Standards from Other Organizations
• No normative references are applicable.
2.3. Published Materials
• No normative references are applicable.
3. Informative References
The following documents might provide valuable information to the reader but are not required when complying with this document.
3.1. SCTE References
• [SCTE 96] SCTE 96 2013, Cable Telecommunications Testing Guidelines
3.2. Standards from Other Organizations
• No informative references are applicable.
3.3. Published Materials
• No informative references are applicable.
6. Equipment
Only equipment specific to this procedure is described in detail here. SCTE 96 should be consulted for further information on all other equipment.
6.1. Required Equipment
• Additive White Gaussian Noise (AWGN) source with a bandwidth at least as wide as the passband to be tested
• “Signal Shaping” bandpass filter equal to the passband to be tested
• Bandstop (notch) filter centered at the specified frequency (generally in the middle of the passband) with a depth at least 10 dB deeper than the desired maximum NPR measurement
NOTE: As an alternative to the first three items, a synthesized source may be used, provided that the output waveform is Gaussian (i.e., not clipped or compressed) and the programmed bandstop region has sufficient depth. If the bandstop depth is not sufficient, a filter may be added to the output of the
synthesized source.
• 2 way signal splitter/combiner
• (2) Precision variable attenuators (0.5 or 1 dB step capable)
• Self terminating A/B switch
• RF power meter
• Spectrum analyzer with noise measurement mode (sometimes referred to as a noise marker or a noise normalization)
• Adapters, connectors, and cables as required
6.2. Optional Equipment
• Amplifier to obtain sufficient level at the DUT input
• Amplifier to obtain sufficient level at the spectrum analyzer input
• 1 dB step attenuator to adjust input level to spectrum analyzer
• Bandpass filter with a passband wider than the notch filter.
7. Setup
Following the equipment manufacturer’s recommendations, perform the appropriate warm-up and calibration procedures.ANSI SCTE 119 pdf download