Tuesday, January 3, 2023

Digital mode hotspots and bad choice of operating frequency

 I was having a look at the VK-DMR and Brandmeister network dashboards today, seeing what new repeaters are active and what hotspots are running to gauge usage on DMR (as it seems rather quiet lately) and I noticed again, that there are still plenty of STUPID people running their digital hotspots on the most inappropriate frequencies, I have trouble trying to fathom how people with "supposedly" technical background and license (ham radio license) can make such stupid blunders, with 20MHz bandwidth to play with on the 70cm band, that they can't find a simplex without interferring with other services, especially the amateur satellite segment on 70cm, why would someone setup their hotspot in the amateur satellite segment when there are lots of amateur satellites constantly circling the globe operating across many frequencies ? People can't seem to grasp that you don't need lots of watts to work a satellite travelling overhead. That's why you can work ISS with a small handheld. Your little hotspot running milliwatts can interfere with amateur satellites passing overhead.

Likewise, why would someone setup their hotspot on the same frequency as the input of a analogue voice rptr that's less than 100km away ? Same for the output frequency.  The hotspot may only run milliwatts, but given some enhanced propagation, that tiny signal can go a long way.  I run three hotspots, for P25, VK-DMR and BM and I try to run them with as minimal impact on each other and maximum isolation between each hotspot and other services, i.e. power output turned down and use internal antennas, I was surprised how far away I can hear my hotspots when out walking with my P25 and DMR handhelds, a couple milliwatts, cct bd antenna and located downstairs in the garage and I can hear them almost a kilometre away. Weak signal experimenters will agree, small signals can go a long way under the right conditions.

If you see a friend operating a hotspot on an inappropriate frequency, can you politely ask them to think about a more appropriate simplex. Also if you running a low pwr hotspot you don't need a repeater frequency pair. Repeater frequency pairs are for high powered repeaters providing a large coverage area and as such, are licensed as repeaters. And if you running a hotspot whilst mobile all over the countryside, the choice of frequency for your hotspot is more important it needs to be on a simplex frequency, not on the allocated voice repeater allocations.

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