Binary phase shift keying modulation system

• US 5,119,396 A
• Filed: 08/27/1990
• Issued: 06/02/1992
• Est. Priority Date: 08/27/1990
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated, M&FC Holding, LLC
• Original Assignee: Axonn LLC (Globalstar Incorporated)
• Inventors: Snderford, H. Britton Jr.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): CAIN, DAVID C
• Application Number:
  US07/572,468
• Time in Patent Office: 645 Days
• Field of Search: 375/1, 375/67, 375/56, 375/83, 332/103
• US Class Current: 375/130
• CPC Class Codes: H03C 1/545 using bipolar transistors
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04L 27/2057 with a separate carrier for each phase state
• CPC Class Codes: H04L 27/206 using a pair of orthogonal carriers, e.g. quadrature carriers

Abstract

A low cost spread spectrum modulator for BPSK, or Binary Phase Shift Keying capable of outputting the high modulation rate and suppressed carrier output needed in spread spectrum systems. The present invention provides high quality BPSK modulation without the double balance mixers as required in the prior art, thereby dispensing with the necessity of complex transistor/potonciometer or diode/transformer arrangements. The present invention provides BPSK modulation utilizing only one transformer, which can be adjusted for carrier suppression and two transistors, allowing the present system to be driven from low power CMOS logic levels, yet producing eight db of gain.

Claims

1. A BPSK Modulator circuit, comprising:

a transformer, said transformer further comprising first induction means having a carrier input leg and a grounded output leg, second induction means having first and second leg outputs, and a grounded center tap leg juxtaposed said first and second induction means, said transformer configured such that said first and second leg outputs of said second induction means modulates at opposite phases of 180 and 0 degrees, forming "MOD+" and "MOD-", respectively, relative a carrier signal supplied to said carrier input of said first induction means;

first and second phase selection means configured to modulate via input of said of said first and second outputs of said second induction means, said first and second phase selection means further comprising first and second load bipolar transistors or their equivalent, respectively, each having an emitter, a grounded collector, and a base or the equivalent, said base of said first transistor in circuit with said first output of said second inductor, receiving said "MOD+", said base of said second transistor in circuit with said second output of said second inductor, receiving said "MOD-".

2. A BPSK Modulator circuit having a tunable slug or core to adjust carrier suppression in a spread spectrum system, comprising:

a transformer, said transformer further comprising first induction means having a carrier input leg and a grounded output leg, second induction means having first and second leg outputs, and a tunable slug or core juxtaposed said first and second induction means, said transformer configured such that said first and second leg outputs of said second induction means modulates at opposite phases of 180 and 0 degrees, forming "MOD+" and "MOD-", respectively, relative a carrier signal supplied to said carrier input of said first induction means;

first and second phase selection means configured to modulate via input of said first and second leg outputs of said second induction means, said first and second phase selection means further comprising first and second load bipolar transistors, respectively, each having an emitter, a grounded collector, and a base, said base of said first transistor in circuit with said first output leg of said second inductor, receiving said "MOD+", said base of said second transistor in circuit with said second output leg of said second inductor, receiving said "MOD-".

3. A BPSK Modulator circuit utilizing a loosely coupled transformer to adjust carrier suppression in a spread spectrum system, comprising:

a transformer, said transformer further comprising first induction means having a carrier input leg and a grounded output leg, second induction means loosely coupled with said first induction means, said second induction means having first and second leg output, said transformer configured such that said first and second leg outputs of said second induction means modulates at opposite phases of 180 and 0 degrees, forming "MOD+" and "MOD-", respectively, relative a carrier signal supplied to said carrier input of said first induction means;

first and second capacitors, said first capacitor in parallel circuit with said carrier input leg and grounded output leg of said first induction means, said second capacitor in parallel circuit with said first and second leg outputs of said second induction means,

first and second phase selection means configured to modulate via input of said first and second outputs of said second induction means, said first and second phase selection means further comprising first and second load bipolar transistors, respectively, each having an emitter, a grounded collector, and a base, said base of said first transistor in serial circuit with said first leg output of said second inductor, receiving said "MOD+", said base of said second transistor in serial circuit with said second leg output of said second inductor, receiving said "MOD-".

4. The BPSK Modulation System of claim 3 wherein there is further included a tunable slug or core is juxtaposed said first and second inductors.

5. The BPSK Modulation System of claim 4, wherein there is further included resonator capacitor means in parallel circuit with said first and said second leg outputs of said second induction means, said resonator capacitor transformer coupling means configured to provide band pass filtering for previous stage harmonic suppression.

6. A BPSK Modulator circuit having a tightly coupled transformer having no center tap and a single parallel resonate capacitor on the secondary to provide BPSK modulation, comprising:

a transformer, said transformer further comprising first induction means having a carrier input leg and a grounded output leg, second induction means tightly coupled to said first induction means, said second induction means having first and second leg outputs, said transformer configured such that said first and second leg outputs of said second induction means modulates at opposite phases of 180 and 0 degrees, forming "MOD+" and "MOD-", respectively, relative a carrier signal supplied to said carrier input of said first induction means;

band pass filter means for filtering harmonic suppression from said transformer, said band pass filter means further comprising a resonate capacitor in parallel circuit with said first and second leg outputs of said second induction means;

first and second phase selection means configured to modulate via input of said first and second outputs of said second induction means, said first and second phase selection means further comprising first and second load bipolar transistors, respectively, each having an emitter, a grounded collector, and a base, said base of said first transistor in circuit with said first leg output of said second inductor, receiving said "MOD+", said base of said second transistor in circuit with said second output of said second inductor, receiving said "MOD-".

7. The BPSK Modulation System of claim 6, wherein said system further comprises adjustment means for adjusting carrier suppression, said adjustment means further comprising a tunable slug or core juxtaposed said first and second induction means.

8. The BPSK Modulation System of claim 6, wherein there is further included resonator capacitor means in parallel circuit with said first and said second leg outputs of said second induction means, said resonator capacitor means configured to provide band pass filtering for previous stage harmonic suppression.