20425 - CAI Feedback Sep2019 COMPLETE v1 lowres

bit) At the low frequency end there is some roll- off too, but channel 10 could be switched on to avoid this; unfortunately there is no channel 13 However, the roll-off of the highest frequency multiplex shouldn’t significantly affect receiver performance FM Radio The FM band has its own separate input, and this behaves more like a conventional amplifier in that there is no ALC or tunable filtering It can be turned on or off by the ASuite software, and the gain tracks the setting of the TV channel target level and the equaliser setting The software does indicate a level, but this is not the actual level of the signals, it is the recommended maximum signal level It is up to the installer to ensure that input levels to the AvantX are suitable Strong signal handling It should go without saying that with increasing use of the 800 MHz and 700 MHz bands for mobile base stations, the ability of an amplifier to operate in the presence of strong signals is highly important To simulate an 800 MHz band base station, a DTT signal on channel 61 (794 MHz) was added to the off-air signals shown in Figure 3 The added signal’s level was 94 dBµV, 24 dB higher than the most powerful wanted multiplex No change could be seen at the AvantX output, indicating that effective filtering is in place Then the added signal was moved to channel 48 (690 MHz) After running the “Adjust” function in the ASuite software, the MERs of the six wanted multiplexes were checked with and without the added signal, and the maximum degradation recorded was 0 7 dB This shows that the AvantX is capable of performing well in the presence of a high-level unwanted signal on a nearby channel Conclusions Mandercom’s tests have shown the AvantX to be a flexible device that is easy to use and also provides a high level of performance, both in terms of filtering wanted signals and its ability to maintain minimal signal degradation in the presence of high levels of adjacent mobile signals 209 216 223 230 237 50 60 70 80 90 100 110 120 Frequency (MHz) Signal level (dBµV) Figure 5: DAB output in channels 11 and 12 78 CAI Feedback Autumn 2019