Carrier to Noise Calculations (C/N)

Single Amplifier Carrier/Noise - CN₀=Output-(-59+NF+G), CN₁=Input-(-59+NF)
To Sum Identical C/N CN_S=CN_O-10log₁₀(N)
To Sum Different C/N ratios CN_S=-10log₁₀[10(-CN₁/10)+10(-CN₂/10)+10(-CN_N/10)]
C/N_S = System Carrier / Noise Ratio
N = Number of Amplifiers in Cascade
NF = Noise Figure
G = Gain
-59 dBmv = Thermal Noise in 4 MHz Bandwidth
NOTE: For every increase in input signal level, the C/N improves by 1 dB and Cross modulation worsens by 2 dB.

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Carrier to Cross Modulation (C/XM)
[Composite Triple Beat calculation: replace XM with CTB]

To sum Identical Cross Modulation Ratios XM_S=XM-20log₁₀(N)
To sum different Cross Modulation Ratios XM_S=20log₁₀[10(-XM₁/20)+10(-XM₂/20)+10(-XM_N/20)]
XMOD of One Amplifier at Operating Level XM=XM_REF+2(Output Level-Reference Level)
XM_S = System Cross Modulation
XM = Cross Modulation Distortion

NOTE: For every double number of amplifiers with identical crossmod there is a 6 dB degradation total crossmod. For every 1 dB reduction in amplifier output level, the XM improves 2dB.

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2nd Order Distortions

To Sum Identical 2nd Order SO_S=SO_O-10log₁₀(N)
To Sum Different SO_S=-10log₁₀[10(-SO₁/10)+10(-SO₂/10)+10(-SO_N/10)]
SO_S = System 2nd Order Distortions
N = Number of Amplifiers in Cascade

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System Frequency vs. dB Loss - L_F2 = L_F1(sqRt[F₂/F₁])

L_F2 = Unknown Cable Loss at a desired frequency (dB)
L_F1 = Cable Loss at a Known Frequency (dB)
F₂ = Desired Frequency (MHZ)
F₁ = Known Frequency (MHZ)

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Tilt and Equalizer Calculations

TILT = (1-F_R^(1/2)) x cable
Cable = Electrical cable length in dB at design frequency.
F_R^(1/2) = cable loss ratio ~ sqRt [f1/f2]

TILT = Difference in loss vs. frequency.
Example: Calculate the tilt provided by 20 dB of 0.750 cable from 54 MHz to 450 MHz.
TILT = (1-F_R^(1/2)) x cable = (1-0.3330) x 20 = 13.4 dB

Equalizer Value = TILT(dB)/(1-F_R^(1/2))
Example: Calculate the value of the equalizer to compensate for 12 dB of slope between 54 and 450 MHz.
Equalizer Value = TILT/(1-F_R^(1/2)) = 12/(1-0.3330) = 17.9 dB

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Field Intensity vs. Dipole Level - V(dBmv)=20log₁₀E(microvolts/m / 0.021 x f (MHZ) / 1000

Maximum Leakage Levels - Determine the maximum leakage levels by using the following equation: L=20log₁₀(E/21f)
L = Maximum leakage level (dBmv)
E = Voltage (microvolts/m)
f = Visual carrier frequency (MHZ)

Cumulative leakage index -
10log₁₀I 3000 is than or equal to -7 (Method 1)
10log₁₀I infinity is less than or equal to 64 (Method 2)

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Equations for dB and dBmv For Equal impedance: Z1=Z2

Power Gain can be expressed as follows:
dB=10log₁₀(P₁/P₂)
dB=10log₁₀(V₁/V₂)² = 20log₁₀(V₁/V₂)
dB=10log₁₀(I₁/I₂)² = 20log₁₀(I₁/I₂)

dB's for CATV
0dBmV = 1mV across 75  = 1,000 microvolts across 75

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Distance to the Horizon

Optical D = 1.23(sqRt[H])
Radio D = 1.41(sqRt[H])
Assume smooth earth
D = Distance statute miles
H = Height, Feet