Protected Contours

Note:  * Single signal calculations – Each interferor will be evaluated individually against the protection ratio, or the presently authorized value.

Class A stations have been supplanted as long range skywave services by satellite radio.  The importance of skywave service by Class A stations is now negligible, as it was always subject to the vagaries of skywave propagation and fading.  Class A stations can not afford to have fees levied on them based upon vast populations that they only theoretically serve.  Eliminating the secondary service areas of class A stations will permit the establishment or  improvement of night service to many other stations.

Nearly all Class B stations have night interference free contours well above the 2.5 mV/m level, including expanded band stations, so any change to that value will have little effect.

Expanded band stations are presently allocated on a spacing table basis, which provides for 800 km spacing between 1 kW Stations.  Expanded band stations at 800 km spacing cause over 3.5 mV/m limits on co-channel stations.

Protection Criteria

note: GW – Groundwave; SW – Skywave; NS – Not Specified

Propagation Calculations

Under this proposal, calculation of the 50% Skywave field for  domestic purposes is no longer required, so Section 73.190 can be substantially simplified.  All 10% skywave fields should be calculated using John Wang’s propagation model as accepted by the ITU.  There would be no requirement for separate calculations for high latitude cases, as the Wang model properly incorporates corrections for high latitudes.

It is proposed that the “ratchet clause” in FCC Rules Section 73.182 Footnote 1 be deleted, a second proposal is to delete use of the 25% exclusion method, as it has not shown a significant benefit in interference reduction, and inhibits improved night service.  Calculation of the required protection for Class B standard band stations should use the 50% exclusion method.

In order to preserve the high quality night service for class A and Class B expanded band stations, it is proposed to utilize the single signal calculations for Co-channel allocations, and 50% exclusion method for first adjacent channel calculations.