A formula is derived enabling one to ascertain a group delay variation caused by poor amplifier VSWR in a broadband repeater line. Calculated examples are given whicn show that this periodic peak-to-peak variation of group delay is most severe in the low band VHF TV channels and can reach magnitudes of 100 nsec in present day coaxial cable repeater systems.

Group Delay Ripple in Broadband Repeater Line Caused by Amplifier Mismatch

A formulais derivedenablingonetoascertaina groupdelayvariation causedby pooramplifierVSWRin a broadbandrepeaterline. Calculated examplesaregivenwhicnshowthatthisperiodicpeak-to-peak variationof groupdelayismostseverein thelowbandVHFTV channelsandcanreach magnitudes of 100nsecin presentdaycoaxialcablerepeatersystems. ItiTRODUCTION

http://ieeexplore.ieee.org/iel5/4065009/4065082/04065087.pdf

Group Delay Ripple iBroadband Repeater Line Caused byAmplifier Mismatch

This paper deals with a build-up of television picture quality degradation in a TV rebroadcasting system. Performance parameters considered in the first part include intermodulation, visual-to-aural crossmodulation low frequency (luminance) nonlinearity, sync compression (expansion), differential gain, differential phase, incidental phase modulation, signal-to-noise ratio, and passband group delay and amplitude ripples due to poor VSWR. Closed form expressions presented in this report will help the system engineer in establishing performance specifications for individual TV stations. Also, the interrelationship between the RF intermodulation test and several baseband performance parameters will reduce the number of tests necessary to completely evaluate the system or individual station performance.

Degradation of Performance Parameters in a Television Relay System -I

The Volterra series approach is used to derive a simplified expression relating the single channel and multichannel cross modulation in a CATV amplifier The cross modulation from n unwanted carriers synchronously modulated is seen to be dependent upon the phase versus frequency variation of the third-order Volterra transfer function of an amplifier Only when the phase is constant for any frequency of interest is the increase in the magnitude of the cross-modulation vector given by 20 log n, n being the number of synchronously modulated carriers

A. Prochazka

Papers

Multichannel Cross Modulation in CATV Amplifier