PURPOSE: To provide a heterodyne dual band radio communication equipment which is used in common in two bands like 800MHz band and 1.5GHz band of a digital land mobile radiotelephone.
CONSTITUTION: A reception intermediate frequency fIFR is made equal to a transmission/reception frequency difference ΔTR1 or ΔTR2 between first and second radio frequency bands, and a frequency fIFT is set to two-fold frequency 2ΔTR1 or 2ΔTR2 of the transmission/reception frequency difference, and a first local oscillation signal 01 which converts a reception signal fR1 of the first radio frequency band into the reception intermediate frequency signal fIFR, a second local oscillation signal 02 which converts a reception signal fR2 of the second radio frequency band into the reception intermediate frequency signal fIFR, a switch 04 which performs switching between first and second local oscillation signals to output them to a reception mixer 06, and a switch 05 which performs switching between the first or second local oscillation signal and a third local oscillation signal 03 are provided. The output of the switch 05 is inputted to the transmission mixer 07 and is multiplied by the transmission intermediate frequency signal fIFT to output a transmission signal fT1 having a prescribed frequency band of the first radio frequency band and a transmission signal fT2 having a prescribed frequency band of the second radio frequency band.
NAKAGAWA HIROYASU
HAYASAKA KATSUNORI
KURODA OSAMU
SAKATA MINORU
CHIBA KOJI
TAKEDA SOJI
NIPPON TELEGRAPH & TELEPHONE