Alpha Sigma Delta Radio Society – W5TC

Amateur Radio at the University of Oklahoma

Repeaters, repeaters, repeaters

Operating “on the ultra-highs” is a popular part of amateur radio though by all means not the only part.  Bouncing signals off the ionosphere is a popular part, too, and requires no infrastructure beyond your station’s antenna.  But people love to talk to other people on their small (and getting cheaper) handi-talkies.

The OU club is blessed with a generous alumnus — local attorney Micheal Salem, N5MS — who likes to build the infrastructure part and let us use it (Law degree, sure, but he was an EE as an undergrad!).  The club has been the beneficiary of the 146.8800 MHz FM analog (20K0F3E) repeater for some 30 years now.  It had been off the air in recent years, for a variety of reasons, but since mid-August, it has been back on the air continuously.  If you have a receiver (or transceiver) for VHF and have the frequency plugged in, you’ve no doubt heard the increased traffic.

As of last night, there is a new repeater on the air on 443.8250 MHz (7K60FXE) but it is neither FM nor analog.  This repeater is a DMR, or Digital Mobile Radio, repeater and requires DMR equipment to use.   I won’t go into technical details other than “TDMA” and “4FSK”.   Motorola Solutions calls their implementation of DMR “MOTOTRBO™“.  I will, however, give you some breadcrumbs:

Digital Mobile Radio via Wikipedia

The DMR-MARC Worldwide Network

RTL-SDR Tutorial: Decoding Digital Voice (P25, DMR, NXDN, D-STAR) with DSD


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