Optical to microwave converter using direct modulation phase shift keying

• US 6,741,139 B2
• Filed: 01/16/2002
• Issued: 05/25/2004
• Est. Priority Date: 05/22/2001
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: YDI Wireless Incorporated (Proxim Wireless Corporation)
• Inventors: Chandler, Joseph, Pleasant, Wayne E.
• Primary Examiner(s): MIS, DAVID C
• Application Number:
  US10/050,689
• Publication Number:
  US 20020175776A1
• Time in Patent Office: 860 Days
• Field of Search: 332/103-105, 375/308, 375/372
• US Class Current: 332/103
• CPC Class Codes: H04B 10/25752 Optical arrangements for wireless networks

Abstract

A point-to-point microwave radio link that operates in a Frequency Division Duplex (FDD) mode using direct digital modulation with a Continuous Phase Shift Keyed (PSK) scheme. The transmit signal is generated by a circuit that uses a Voltage-Control Oscillator (VCO) operating in a microwave radio band to obtain the modulated signal. The VCO output is fed to a phase modulator to obtain the modulated signal. The output of the VCO is then frequency multiplied by the predetermined factor to produce the modulated microwave output signal at the desired band.

Claims

1. A transport to microwave radio frequency adapter that accepts an input telecommunications transport signal on an input port and converts information in such signal to a desired microwave Radio Frequency (RF) carrier, the input transport signal carrying information at an input bit rate, the apparatus comprising:

a phase encoder, coupled to receive the transport signal, the phase encoder implementing a Phase Shift Keyed (PSK) encoding such that at least first phase is selected to indicate a first logical value for an input data bit in the transport signal and a second phase is selected to indicate a second logical value for an input data bit in the transport signal, the deviation between the two phases selected to be equal to a predetermined value;

a local reference oscillator, connected to provide a first microwave carrier;

a frequency multiplier, connected to receive the output of the local reference oscillator and to multiply the output thereof to a desired microwave RF carrier frequency; and

a phase modulator, connected to impart a direct phase modulation to the microwave RF carrier.

2. An apparatus as in claim 1 wherein the telecommunications transport signal is provided on an optical physical medium.

3. An apparatus as in claim 2 additionally comprising:

an optical-to-voltage transducer connected to receive the telecommunications signal and to provide a baseband electrical signal at an output.

4. An apparatus as in claim 1 wherein the frequency multiplier implements a multiplication factor.

5. An apparatus as in claim 4 wherein the frequency multiplier is implemented in a plurality of frequency multiplication stages.

6. An apparatus as in claim 1 wherein the phase modulator and frequency multiplier perform a direct phase conversion of the input transport signal to the microwave RF carrier.

7. An apparatus as in claim 6 wherein the direct conversion is performed without using the input transport signal to modulate an intermediate carrier signal.

8. An apparatus as in claim 1 additionally comprising:

a microwave bandpass filter connected to the output of the frequency multiplier to filter harmonics of the carrier frequency of the voltage-controlled oscillator.

9. An apparatus as in claim 1 additionally comprising:

a microwave RF to transport adapter, to convert a received microwave RF signal to a transport signal carrying an output telecommunications transport signal.

10. An apparatus as in claim 9 wherein the microwave RF to transport adapter further comprises:

an oscillator, operating at a carrier frequency which is a predetermined fraction of a desired direct down-conversion frequency;

a frequency multiplier, connected to receive the oscillator output, and to multiply the oscillator output up to the desired direct down-conversion frequency; and

a mixer, coupled to the frequency multiplier and the microwave RF signal, to provide a down-converted transport signal.

11. An apparatus as in claim 1 wherein the phase modulator implements a sub-phase deviation phase shift prior to the frequency multiplier.

12. An apparatus as in claim 11 wherein the sub-phase deviation phase shift is equal to an output desired phase shift divided by a frequency multiplier factor implemented by the frequency multiplier.

13. An apparatus as in claim 1 wherein the phase modulator implements a phase deviation after the frequency multiplier.

14. An apparatus as in claim 13 wherein the phase modulator imports a direct phase shift to the microwave RF carrier.