A group two-way radio system for providing temporarily emergently expanding communication range as a portable dispatch system with no available signal repeater involved, where a group of utilizing two-way radios to communicate in a task when moving frequently from one place to another place and needing to expand the communication range emergently under a condition of no repeater or the repeater being damaged is capable of designating one of the two-way radios from a request of a group commander, according to locations of users of the group, to function as a signal repeater through manual control or an over-the-air programming (OTAP) command so as to expand the communication range for the two-way radios of the group when needs to move the groups for carrying out duties;
- and wherein the group two-way radio system is performed by steps comprising:
- a. the group commander designating at least one of the two-way radios at a most appropriate location for relaying, according to a global positioning system (GPS) location of each user of the group displayed on a screen of the radio of the group commander;
- b. the group commander requesting the at least one of the two-way radios to switch from a direct call mode to the one channel repeater mode through manual control or the OTAP command so as to function as the signal repeater which is then to retransmit signals through time division multiple access (TDMA) communication protocol over a same channel at different time slots;
- c. the designating two-way radio then transmitting a notice or OTAP command in an all call manner to all of the two-way radios on the same channel to request to switch to the one channel repeater mode;
- d. the other two-way radios received the notice of communicating in TDMA communication protocol being manually or automatically switched from the direct call mode to the one channel repeater mode for receiving and transmitting signals in TDMA communication protocol over the same channel at different time slots;
- and
- e. the other two-way radios after switching to the one channel repeater mode automatically transmitting an acknowledgement (Ack) message of already in one channel repeater mode to the signal repeater or/and the two-way radio of the group commander.