| 摘要 |
PURPOSE:To attain hopping with small sized transmitter over a wide range without making the transmitter complicated by using a changeover device to switch plural band pass filters in response to the frequency hopping or varying the tuning frequency of the tuning type band pass filter. CONSTITUTION:A modulation output signal from a modulator 1 is fed to a mixer 3. Another input to the mixer 3 is an output of a frequency synthesizer 2 and the output is a frequency hopping signal controlled by a digital output of a hopping pattern generator 4. Let the output at a time of the frequency synthesizer 2 be fL, the output of the mixer 3 is caused at upper side (fL+fm) and at lower side (fL-fm). A band pass filter 5 passes the lower frequencies of the output of the mixer 3 and a band pass filter 6 passes upper frequencies. A changeover device 7 selects any of the band pass filters 5, 6 in response to the hopping by the control of the hopping pattern generator 4. That is, two of (fL+fm) and (fL-fm) are selected as the transmission output with respect to one output fL of the frequency synthesizer 2. |
