FYI, Daniel, K9NPX, has a good article on using MMDVMCAL to get more exact RXOffset (and TXOffset) settings for a DMR radio:
http://www.k9npx.com/2019/02/hotspot-of ... n.html?m=1
RXOffset on a JumboSpot/ChinaSpot
Re: RXOffset on a JumboSpot/ChinaSpot
73, Toshen, KE0FHS
Playing with Pi-Star (unofficial notes about setting up and using Pi-Star):
https://amateurradionotes.com/pi-star.htm
Playing with Pi-Star (unofficial notes about setting up and using Pi-Star):
https://amateurradionotes.com/pi-star.htm
Re: RXOffset on a JumboSpot/ChinaSpot
Be picky about the vendor you're acquiring a Chinese made JumboSpot MMDVM HS Hat from (either simplex or duplex versions).
Be sure that they are using a quality, and preferably US made reference oscillator chip. These tend to be more temperature stable. Look for boards that properly manufactured to comply with the opensource standard board.
Use a consistent packaging, preferably something metal that can passively dissipate heat. I have the tiny Raspberry Pi Zero-W board running both simplex and duplex style MMDVM HS Hat boards in compact metal cases.
I have several of these running, and they all have slightly different MMDVMCAL tested offset frequencies.
Be sure that they are using a quality, and preferably US made reference oscillator chip. These tend to be more temperature stable. Look for boards that properly manufactured to comply with the opensource standard board.
Use a consistent packaging, preferably something metal that can passively dissipate heat. I have the tiny Raspberry Pi Zero-W board running both simplex and duplex style MMDVM HS Hat boards in compact metal cases.
I have several of these running, and they all have slightly different MMDVMCAL tested offset frequencies.