Revision to SERA Coordination Policy for Digital Repeaters Due to the wide variety of formats, modes and bandwidths for digital repeaters, coordination of digital and mixed mode (digital and analog operating on same frequency pair) presents unique challenges for repeater coordination. As new digital and mixed modes are developed, changes in coordination guidelines should be adopted to ensure best use of spectrum and minimize impact to existing repeater operators. In all cases, standard co-channel and adjacent channel parameters apply. New Repeater Coordination Requests • D-STAR and NXDN operating in digital only mode may be coordinated in the 2m band on one of the 8 pairs designated for narrowband digital repeaters (144.920 – 145.08 outputs) or one of the 10 KHz splinter pairs in the 144-145 sub-band (i.e. 145.12, 145.140, etc.). In the 70cm band, coordination on one of the 18 pairs between 440.5125 and 440.7250 or one of the 12.5 KHz splinter pairs between the standard 25 KHz pairs. If none of these pairs are available, one of the standard repeater pairs in the 2m or 70cm band may be used, but should only be used as a final choice to avoid mixing digital and analog repeaters. • DMR (MotoTRBO), P25 (APCO25) operating in either digital only or mixed mode coordination requests should first be attempted in the 70 cm band using one of the 12.5 KHz splinter pairs. If this cannot be accommodated on a 70cm pair, one of the standard 2m or 70cm repeater pairs may be used as a final choice. • System Fusion repeaters operating in digital only mode coordination requests should first be attempted in the 70 cm band using one of the 12.5 KHz splinter pairs. If this cannot be accommodated on a 70cm pair, one of the standard 2m or 70cm repeater pairs may be used as a final choice. • NXDN and System Fusion repeaters operating in mixed mode may be coordinated on standard repeater pairs in either 2m or 70cm bands. Change from Existing FM to Digital Repeater Coordination Requests • If an existing FM repeater owner operating on a standard repeater pair wishes to change to a digital repeater operating in digital only mode, a frequency change to one of the digital only pairs above should be suggested according to the digital mode to be used. If none of pairs are available for the specific digital only mode, the repeater may remain on the standard pair in the 2m or 70cm band. • If an existing FM repeater owner operating on a standard repeater pair wishes to change to a digital repeater operating in mixed digital and analog mode, it should remain on the standard repeater pair. • If an existing FM repeater was coordinated with a waiver due to short spacing or other conditions and is converted to a digital mode, a new waiver must be obtained to include notification of the conversion to digital.
Of particular note, some simplex frequencies listed in the ARRL Band Plan may, or may not, be repeater inputs in some areas as our coordinators make changes to better suit their area.
Another example is the different assignments of spectrum for FM Voice Simplex, and Packet/ Digital Simplex. Repeater users as well as packet/digital users are asked to honor these frequencies by utilizing the ones specifically assigned to the particular mode they are operating.
All coordination and spectrum management by coordinators is based on “gentlemen’s agreements” and usage by all hams whether they are operators using FM repeaters, simplex, or packet digital using duplex packet modes or simplex. For spectrum management to continue to work successfully around the nation, operators must take the responsibility of working only frequencies in the mode in which that frequency is assigned.
This prevents chaos and interference and arguments. All modes of amateur operations are well represented by frequency spectrum assignments on most all bands. Using only those frequencies assigned prevents unwanted problems.
Download Frequency Utilization Plans at SERA Forms Available for Download