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Nawaii Preliminary Technical Assessment lCTAP-HUHA-PREASSESS-00/-RO bands using a single radio. It would not, however, help users migrating onto the County of Hawaii's system if they do not operate in the same frequency band. 2.1.1 VHF, 700 and 800 MHz Frequency Licensing Frequency licensing for the VHF, 700 MHz and 800 MHz bands are different. Four aspects of those differences are discussed below: spectrum efficiency, analog versus digital modulation, band reconfiguration and channel spacing. Spectrum efficiency: In the 800 MHz band, the spectrum efficiency required by the FCC is one voice path per 25 kHz. In the VHF and 700 MHz band the required efficiency is currently one voice path per 12.5 kHz with a FCC mandate to transition to one voice path per 6.25 kHz. In the 700 MHz band, new systems going in service after December 31, 2014 must use 6.25 kHz efficiency. All 700 MHz systems, including pre-existing systems, must be converted by December 31, 2017. It is uncertain if 700 MHz equipment procured today, intended to operate using 12.5 kHz voice paths, will be capable of operating at 6.25 kHz without upgrades, modifications or even replacements. ICTAP recommends inquiring about this from any potential manufacturer to address long term operation of the equipment. The FCC has not set a date for when VHF systems must operate with 6.25 kHz efficiency but have stated they will designate a date. From the spectrum efficiency aspect, the 800 MHz band is generally the preferred band in areas which have a sufficient number of available 800 MHz channels because the system operator is not facing a mandatory change in the system's operation. Many areas do not have the luxury of sufficient channels as the 800 MHz band is highly congested. In the future, the FCC may dictate better spectrum efficiency (more voice paths in less kHz) for the 800 MHz band. If they do, their historical record indicates that they will allow ample time for system operators to use their present system to obsolescence before they have to migrate. Analog versus digital modulation: In the VHF and 800 MHz bands, either analog or digital voice modulation is permitted. The interoperability channels must use analog voice. In the 700 MHz band, digital voice is the primary mode with analog allowed only on a secondary basis. The interoperability channels of the 700 MHz band are specified to use Project 25 voice, that is, digital voice modulation. Recently the quality and intelligibility of digital voice has been found lacking for some extreme conditions such as fire ground operations with high background noise. Some public safety entities have opted to continue to use analog or, at least, have an analog option available for extreme circumstances. This issue is being addressed by a P25 standards development working group and other interested organizations. Some enhancements have been made to the P25 vocoder (the device that converts voice between digital and analog) that has improved the voice quality but more needs to be done. To determine a solution the P25 working group is looking at all aspects of the voice system including improved types and locations of microphones and speakers. Band configuration: The 800 MHz band is undergoing a comprehensive reconfiguration (rebanding) to reduce the interference due to cellular type systems. The only part of the band that is not changing frequency is the so-called interleaved portion, that is, base transmitter frequencies in the range from 854.75 to 860 MHz. The 700 MHz band is also being reconfigured. However, since there are very few users in this band and since only half the band is being reconfigured, this affects a much smaller number of users. The VHF band lacks configuration; there are not separate, FCC-defined bands for base receive and base transmit, with a separation between the bands for isolation. This lack of configuration complicates VHF system design because extra care has to be taken when choosing frequencies to avoid self-interference. In addition, the VHF band generally has fewer frequencies available for public safety. Despite these problems several state-wide VHF systems (Virginia, Montana, Wisconsin and Wyoming) have been either deployed or are in the process of being deployed. Several of these systems were able to obtain sufficient frequencies by augmenting the public safety frequencies from October 2008