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CATV signal levels and how do you measure them?

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peterdb:
Wat are the recommended cable television signal levels for DVB-C and analog signal distribution and how do you measure them with a spectrum analyser?

I know they are described in the IEC 60728-1 international standard, but I don't have access to this document, and its not for free.

Can someone fill me in with the basic principals?

What’s the norm?
How much may the signals deviate from the norm?

Thanks in advance,

Peter

Nermash:
Of the top of my head, signal level of 60-70 dBuV, with SNR 35-40 dB. Installers use CATV analyzers/level meters for setup, most of them have simplified spectrum analyzer.

Not sure with how much lower level and SNR you can get away with, I think that 50-55 dBuV with 30 dB SNR should work.

You can choose a channel and measure it on any SA, providing you use impedance adapter 50 to 75 ohms. SNR is measured on the 8 MHz wide channel.

Bicurico:
Hi,

If you are looking for recommended measurement values for DVB-C, please look at this link: http://www.roverinstruments.com/upload/UserFiles/Articoli_Tecnici/SUGGESTED_MEASUREMENT_VALUES__AUTOMATIC_QUALITY_MEASUREMENT_ENG.pdf

Rover Instruments is a leading manufacturer of professional TV field meter.

In CATV you distinguish analog from digital transponders.

Analog transponders: you measure the signal LEVEL, Noise Margin and A/V-ratio.
Digital transponders: you measure the signal POWER. Also, looking at the constellation diagram provides important feedback regarding modulation problems. MER (Mean Error Ratio) and BER (Bit Error Rate) are important measurements, too.

Finally, on both you can and should measure TILT to adjust amplifiers in such a way that the whole CATV band provides an evenly amplified signal.

Regards

peterdb:
Thanks all,

looks like the numbers work out for me!  :-+

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