Skyler Fennell asked:
Would anybody happen to have a figure here:
What is the typical natural environmental noise floor ( for standard 5KHz deviation FM bandwidth) for the 2 meter band vertically polarized 3dBi dipole antenna?
Assuming:
NO man made noise ( no powerlines nearby, no other electronics )
Room temperature: 75 degrees
VHF 2 meter band is used
Sunny day with no crazy storm weather
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Environmental noise is a complicated issue. ?
You can't rule out man made noise because it is a principle component of environmental noise, even in rural areas.
Numerous studies have been done with the results summarized in general guidance based on LULC (Land Use Land Cover).? Expect more noise in urban areas, less in rural areas.
Environmental noise at radio sites is highly variable, cannot be accurately predicted, and must be assessed either directly or indirectly.
Environmental noise tends to diminish with increasing frequency. Degradation of receiver effective sensitivity at radio sites will almost always be present at VHF but is seldom an issue above 400 MHz although you must always check effective sensitivity of any system because there can be degradation due to noise from other sources at or in in proximity to the site.
When proposing VHF systems, in the past, Motorola used 12.6 dB above kTB for determining the initial coverage predictions with the recommendation to the customer that the actual noise be evaluated at each proposed site.
Takeaway?? Expect some degradation of your 2 meter repeater receiver pretty much anywhere your site is located.
