However, in systems serving several floors, it may
be more effective to design a cascade, tapped-trunk
architecture. In this case, the secondary
distribution points will typically be located at a
central point on each floor. Some systems will, of
necessity, be most appropriately designed as a
combination of home run and cascade networks,
forming a "tree and branch" structure.
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The Contractor shall submit system calculations encompassing the losses and
gains for the various components of the system, including cable runs. The
Contractor shall establish the required signal strengths for each component
of the signal reception system and shall verify each with respect to signal
strength and quality. Interfaces shall be according to the following
tables:
TABLE IIa.
TELEVISION RECEIVER INPUT INTERFACE
75 ohms unbalanced
RF Video Carrier Level:
Minimum
3 dBmV
Maximum
12 dBmV
Relative RF Video
Carrier Level:
Within 3 dB to adjacent channel
All channels within 12 dB
Carrier Level
Stability:
Short-term (1 hour)
Within 0.5 dB maximum
Long-term (24 hours)
Within 2.0 dB maximum
Frequency range (MHz):
54-300 mHz
Peak to valleys for
system bandpass
Plus or minus 3 dB
Across any 6 MHz
Plus or minus 1 dB
channel referenced
to video carrier plus
200 kHz sideband
amplitude
Carrier to Noise
Ratio:
Greater than or equal to 45 dB
Cross Modulation
(NTCA Test Method):
Less than minus 50 dB
Carrier to Echo Ratio:
Greater than 40 dB
Composite Triple Beat:
Less than minus 53 dB
Second Order:
Less than minus 60 dB
SECTION 16785A
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