Dual frequency radio apparatus for data transmission and direction finding

Claim 2

A radio-signalling system comprising: a. a transmitter station including means for simultaneously transmitting a modulated fundamental signal and a beacon signal which is a harmonic of said fundamental signal, b. a receiving station including a data receiver adapted to receive said fundamental signal for utilization of the information represented by said modulation, said data having a pass band wide enough to accommodate said modulation, c. said receiving station further including a beacon receiver adapted to receive said beacon signal, said beacon receiver including a mixer and I-F amplifier having a pass band substantially narrower than that of said data receiver, and d. frequency changing means responsive to the signal received by said data receiver to produce a heterodyne reference signal for the mixer of said beacon receiver.

Claim 3

A radio direction-finding system for use in the location of transmitter stations which transmit data on a frequency that is lower than optimum for accurate direction finding, comprising: a. a radio beacon device adapted to be placed at a transmitter station and including pickup means for absorbing a portion of the relatively low-frequency transmitter output, b. said beacon device further including a frequency changer device connected to said pickup means and energized solely by the power absorbed thereby to produce output of a higher frequency more suitable for radio direction finding, and means for radiating said higher frequency output, c. a receiving station including a data receiver for receiving the relatively low-frequency data transmission, d. said receiving station further including a direction-finding receiver for receiving said relatively higher frequency beacon transmission, said direction finding receiver including a mixer and a narrow band I-F ampLifier, and e. means responsive to the signal received by said data receiver for producing a heterodyne reference signal for the mixer of said direction-finding receiver.

Claim 4

A radio direction-finding system for use in the location of transmitter stations which transmit data on a frequency that is lower than optimum for accurate direction finding, comprising: a. a radio beacon device adapted to be placed at a transmitter station and including pickup means for absorbing a portion of the relatively low-frequency transmitter output, b. said beacon device further including a frequency changer device connected to said pickup means and energized solely by the power absorbed thereby to produce output of a higher frequency more suitable for radio direction finding, and means for radiating said higher frequency output, c. a receiving station including a data receiver for receiving the relatively low-frequency data transmission, d. said receiving station further including a direction-finding receiver for receiving said relatively higher frequency beacon transmission, said direction finding receiver including a mixer and a narrow band I-F ampLifier, and e. means responsive to the signal received by said data receiver for producing a heterodyne reference signal for the mixer of said direction-finding receiver.

Claim 5

A radio receiver system for use with a transmitter system that simultaneously transmits a fundamental signal subject to frequency variations and a harmonic of said signal, comprising: a. a receiver adapted to receive said fundamental signal, said fundamental receiver having a pass band wide enough to accommodate said frequency variations, b. a receiver adapted to receive said harmonic, said harmonic receiver including a frequency converter and a narrow band I-F amplifier, and c. frequency changing means responsive to the signal received by said fundamental receiver to produce a heterodyne reference signal for the frequency converter of said harmonic receiver, said heterodyne reference signal carrying the same frequency variations as said harmonic, whereby the output of said I-F amplifier of said harmonic receiver is an essentially constant frequency continuous wave signal suitable for narrow band processing and utilization.

Claim 6

A radio receiver system for use with a transmitter system that simultaneously transmits a fundamental signal subject to frequency variations and a harmonic of said signal, comprising: a. a receiver adapted to receive said fundamental signal, said fundamental receiver having a pass band wide enough to accommodate said frequency variations, b. a receiver adapted to receive said harmonic, said harmonic receiver including a frequency converter and a narrow band I-F amplifier, and c. frequency changing means responsive to the signal received by said fundamental receiver to produce a heterodyne reference signal for the frequency converter of said harmonic receiver, said heterodyne reference signal carrying the same frequency variations as said harmonic, whereby the output of said I-F amplifier of said harmonic receiver is an essentially constant frequency continuous wave signal suitable for narrow band processing and utilization.

Claim 7

A radio direction finding receiver system for use with a transmitter system that simultaneously transmits a frequency-modulated fundamental signal and a harmonic of said signal, comprising: a. a data receiver adapted to receive said fundamental signal for utilization of the information represented by said modulation, said data receiver having a pass band wide enough to accommodate said frequency modulation, b. a direction finder including a directional antenna and a receiver adapted to receive said harmonic, said direction finder receiver including a frequency converter and an I-F amplifier having a pass band substantially narrower than that of said data receiver, and c. frequency-changing means responsive to the signal received by said data receiver to produce a heterodyne reference signal for the frequency converter of said direction finder receiver, said heterodyne reference signal carrying the same frequency modulation as said harmonic, whereby the output of said I-F amplifier of said direction finder receiver is an essentially constant frequency continuous wave signal suitable for narrow band processing and utilization.

Claim 8

A radio direction finding receiver system for use with a transmitter system that simultaneously transmits a frequency-modulated fundamental signal and a harmonic of said signal, comprising: a. a data receiver adapted to receive said fundamental signal for utilization of the information represented by said modulation, said data receiver having a pass band wide enough to accommodate said frequency modulation, b. a direction finder including a directional antenna and a receiver adapted to receive said harmonic, said direction finder receiver including a frequency converter and an I-F amplifier having a pass band substantially narrower than that of said data receiver, and c. frequency-changing means responsive to the signal received by said data receiver to produce a heterodyne reference signal for the frequency converter of said direction finder receiver, said heterodyne reference signal carrying the same frequency modulation as said harmonic, whereby the output of said I-F amplifier of said direction finder receiver is an essentially constant frequency continuous wave signal suitable for narrow band processing and utilization.

Claim 9

The invention set forth in claim 4, wherein said data receiver is of the superheterodyne type including an adjustable frequency local oscillator and an I-F amplifier, and said last-mentioned frequency changing means includes a stable fixed frequency oscillator, a first mixer connected to receive the output of said I-F amplifier and that of said fixed frequency oscillator, a second mixer connected to receive the output of said first mixer and that of said local oscillator, and a frequency multiplier for producing a harmonic of the output of said second mixer.

Claim 10

The invention set forth in claim 4, wherein said last-mentioned frequency-changing means includes a stable oscillator and a mixer for producing a signal like said received data signal but offset in frequency therefrom by a fixed amount, and a frequency multiplier for producing a harmonic of said frequency-offset signal.