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### System Operating Margin:

SOM = RX Signal Level - RX Sensitivity

RX Signal Level = TX Power - TX Cable Loss + TX Antenna Gain - FSL + RX Antenna                             Gain - RX Cable Loss

Enter the Frequency in MHz

Enter the Distance between sites in miles

Enter the Transmit Power in dBm

Enter the Transmit Cable Loss in dB

Enter the Transmit Antenna Gain in dB

Enter the Receive Antenna Gain in dB

Enter the Receive Cable Loss in dB

Enter the Receive Sensitivity in dBm and

The Free Space Loss is dB.

Your Theoretical System Operating Margin is dB.

However, the only way to be absolutely certain is to use a YDI Attenuator Kit.

NOTE: These calculations are based on clear Fresnel Zones. If the antennas themselves have clear line of sight (LOS) but the Fresnel Zone is encroached, the actual received signal strength could be 10 dB or more lower than the calculated received signal strength.

### Watts to dBm:

dBm = (10Log10(Power Watts)) + 30

Enter power in Watts: Watts and

= dBm.

### dBm to Watts:

Watts = 10((dBm - 30)/10)
MilliWatts = 10(dBm/10)

Enter power in dBm: dBm and

= Watts.
= MilliWatts.

### Parabolic Antenna Tilt in Degrees:

Tilt = 57.2957795[((hB - hR)/(5280*DistMi)) - (DistMi/7920)]

Enter height above sea level of the Base Antenna in feet: feet above sea level
Enter height above sea level of the Remote Antenna in feet: feet above sea level

Enter Distance in miles: miles and

Base downtilt is Degrees.

### Free Space Loss (isotropic):

Free Space Loss (isotropic):FSL (isotropic) = 20Log10(Frequency in MHz) + 20Log10 (Distance in Miles) + 36.6

Enter Frequency in MHz: MHz
Enter Distance in miles: miles and

FSL(isotropic) = dB.

### Fresnel Zone Clearance:

Fresnel Zone = 72.1 * SqrRoot(dist1Mi * dist2Mi / FreqGHz * DistanceMi)

Enter Distance 1(d1) in miles : miles
Enter Distance 2(d2) in miles : miles

Enter Frequency in GHz: GHz and

The 1st Fresnel Zone is feet across to radius.

60% of the 1st Fresnel Zone is feet across to radius.

### Inverse Position (Azimuth and Distance):

 Latitude A: Deg. Min. Sec. Longitude A: Deg. Min. Sec. Latitude B: Deg. Min. Sec. Longitude B: Deg. Min. Sec.

Azimuth from A to B: Degrees
Azimuth from B to A: Degrees

The Distance from A to B is Miles.
The Distance from A to B is Kilometers.