This paper presented the implementation and design of narrowband wireless MODEM for packet transmission. The MODEM consists of transmitter, receiver, and the control unit. The BPSK modulation with narrowband filtering is used. The receiver consists of functional modules such as carrier recovery, bit synchronization, lock detector, etc. We evaluated the performance of packet transmission with three MODEM sets implemented in distributed packet radio network. We confirmed the transmission of packetized data through RS232C port of PC. Also, we presented results of experimental data by using measuring instruments. The implemented MODEM in this paper is expected to be useful for the design of wireless LAN system.