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Building a Digital Mobile Radio Repeater Part 2: Radios, Enclosure, Raspberry Pi and Power

Andrew Back
Open source (hardware and software!) advocate, Treasurer and Director of the Free and Open Source Silicon Foundation, organiser of Wuthering Bytes technology festival and founder of the Open Source Hardware User Group.


April 23, 2018 09:50

Hi Andrew
bear in mind duty cycle with mobiles are now as good as dedicated base station
also the front-ends on Motorola or any other mobile tend to have very wide front ends.The system may require a High-Q filter on the RX port (in addition of the duplex er) if locating this repeater on a commercial site thats has a lot of radio equipment on board radio tower.
Built something similar for commercial use a long time ago and it suffered this problem with front end overload,just something to bear in mind.WE ended up using a very Hi-Q notch filter inline on RX port,this cured our problem on a heavy traffic,busy radio UHF and VHF site.Just thought id mention this when deploying the base station.Enjoyed article very good Rob

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April 30, 2018 11:20

@ro_comms Hi Rob, thanks for the tips! The site is a church tower and I'm fairly sure there's no commercial equipment on there, but good point to raise and will obviously bear this in mind if that turns out not to be the case.


April 17, 2018 08:21

How do you make it work - dmr on 2 analog radios, and with the motorola crypting?

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