> Tony KT2Q wrote > > Bonnie, > > Not sure if it's been said before, but the > 14100.5khz ALE data channel seems awfully close > the NCDXF beacon frequency on 14100.0. >
Hi Tony, Yes, it is has been covered before in HFLINK group, and via direct communication with IARU Region frequency coordination. I will gladly cover it again for the benefit of new ALE operators and the digitalradio group. This ALE channel has been in use for a long time and there have been no complaints or problems. The 14100.5 kHz USB ALE channel has been frequency coordinated with the IARU Regions, including IARU Region 1, which has the widest beacon guardband (+/-1 kHz) for the IARU-NCDXF beacon at 14100.0 kHz CW. IARU Region 2 and IARU Region 3 both have lesser (+/-500Hz) guardbands for the IARU-NCDXF beacon CW channel. The ALE channel conforms to the more strict IARU Region 1 requirements. All amateur radio ALE channels are based upon accurate calibration within +/-20Hz and standard fixed audio frequencies. The ALE system inherently fails to operate if these rigid standards are not followed. All ALE operators are admonished to operate with the highest technical standards. The lowest tone of the 8FSK ALE signal is exactly 750Hz and the highest tone is exactly 2500Hz. For the 14100.5 kHz USB channel, it translates to RF frequencies: 1. Lowest tone = 14101.25 kHz 2. Highest tone = 14103.00 kHz The 1750Hz "bandwidth" for the 8FSK signal has a spectrum that is widened slightly (+/-200Hz) by the transition of the shifting of the 8 FSK tones at the 125 baud (symbol) rate. The -23dBc bandwidth of the RF spectrum of the 8FSK ALE signal is 2150Hz and the low end is equivalent to an audio frequency of 550Hz. 14100.5 kHz + 550Hz = 14101.05 kHz Beacon guardband clearance bandwidth: Top edge of IARU Region 1 beacon guardband = 14101.00 kHz Bottom edge of 14100.5 kHz USB ALE Channel = 14101.05 kHz Channel Edge to Beacon Guardband Edge Clearance = 50Hz. Maximum allowed calibration frequency error = 20 Hz. Total clearance including calibration error = 30 Hz. The ALE channel meets the strictest IARU Region 1 recommended guardband by 30 Hz and meets the less strict IARU Region 2 and IARU Region 3 by 530 Hz. 73---Bonnie KQ6XA .
