🚀 go-pugleaf

In article <909@occrsh.ATT.COM> qac@occrsh.ATT.COM (Quentin_Conner) writes:
   >
   >Speaking of video questions:
   >
   >How would one test out some arbitrary television transmission facility,
   >for instance a cable company's video distribution system or a broadcast
   >transmitter/receiver pair.  Would you perform a frequency response check
   >and then measure the received power of some known complex signal?  Does
   >any automated equipment exist that a technician could use in the field?
   >
   >Thanks in advance,
   >
   >Quentin Conner
   >--------------
There are many paramaters and thus may test that can be performed, of which
the main tests are:
	signal to noise
	differential gain		(change of gain with luminance)
	differential phase		(change of phase with luminance)
	frequence response
	group delay			(time delay) (should be equal for
							all frequencies)
	bounce test			(for low frequency response)

+ many more (especially when your testing digital vieao components!)

Many stations (facilities) transmit a Vertical interval test signal "VITS",
which may have stairstep (with subcarrier modulation) & 2T pulse + bar.
Many tests can be performed with very crude test equipment (an oscilloscope
and a line selector (used to trigger the cro on the vits line).

There are automatic boxes (from Tektronix, Marconi, Anritsu and others) that
read and interpret vits but they are VERY expensive!

Marconi publishes "Video Measurements" by Weaver of the BBC
		which is the "bible"
and the European Broadcasting Unit also has a very good publication on the
subject.

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Michael Katzmann
Broadcast Sports Technology.
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