Frequency hopping communication device with simple structure

• US 20040005866A1
• Filed: 03/11/2003
• Published: 01/08/2004
• Est. Priority Date: 03/11/2002
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Igarashi, Katsuhito
• Granted Patent: US 7,269,200 B2
• Time in Patent Office: Days
• US Class Current: 455/78
• CPC Class Codes: H03C 3/0958 applying frequency modulation by varying the characteristics of the voltage controlled oscillator
• CPC Class Codes: H03C 3/0991 including calibration means or calibration methods

Abstract

A frequency hopping communication device has a memory memorizing modulation coefficients related to hopping frequencies of a carrier wave. Whenever a following hopping frequency is decided, a CPU reads out one of the modulation coefficients on the basis of the following hopping frequency from the memory and supplies it to a Gaussian filter. The Gaussian filter stores the read out modulation coefficient in a register and multiplies transmission data signal supplied thereto by the read out modulation coefficient stored in the register to produce a modulation signal. Thus, the modulation signal has voltage amplitude depending on the carrier frequency. A voltage controlled oscillator modulates the carrier wave having the following hopping frequency by the use of the modulation signal from the Gaussian filter and produces a transmission signal. Therefore, the transmission signal has an approximately uniform frequency deviation regardless of the carrier frequency.

Claims

1. A frequency hopping communication device including a voltage controlled oscillator for producing a modulated signal that a carrier wave is modulated by a modulation signal, said carrier wave having a carrier frequency changed into any one of hopping frequencies at regular intervals, said frequency hopping communication device comprising:

a memory for memorizing a plurality of modulation coefficients related to the hopping frequencies;

a control unit connected to said memory for reading out one of the modulation coefficients as a read out modulation coefficient on the basis of a following hopping frequency from said memory when the following hopping frequency is decided; and

an adjusting portion connected to said control unit and said voltage controlled oscillator for adjusting voltage amplitude of the modulation signal by the use of the read out modulation coefficient to restrict frequency deviation of the modulated signal within a predetermined range regardless of the carrier frequency.

2. A frequency hopping communication device as claimed in claim 1, the modulation signal being made from transmission data signal, wherein said adjusting portion comprises a multiplier for multiplying the transmission data signal by the read out modulation coefficient.

3. A frequency hopping communication device as claimed in claim 2 further comprising a Gaussian filter for supplying the modulation signal to said voltage controlled oscillator, wherein said multiplier provided in said Gaussian filter.

4. A frequency hopping communication device as claimed in claim 3, wherein said Gaussian filter comprises:

a digital filter for limiting a band of the transmission data signal to supply band-limited transmission data signal to said multiplier;

a digital analog converter connected to said digital filter through said multiplier for converting the band-limited transmission data signal multiplied by the read out modulation signal from said multiplier into an analog data signal; and

a low pass filter connected to said digital analog converter for filtering the analog data signal to supply filtered analog data signal to the voltage controlled oscillator as the modulation signal.

5. A frequency hopping communication device as claimed in claim 1, wherein said modulation coefficients are obtained by the means of linear interpolation using measuring results of measurement of frequency deviation regarding at least two of the hopping frequencies.

6. A method for restricting frequency deviation of a transmission signal transmitted from a frequency hopping communication device within a predetermined range regardless of hopping frequencies, said frequency hopping communication device including a voltage controlled oscillator for producing a modulated signal that a carrier wave is modulated by a modulation signal, said carrier wave having a carrier frequency changed into any one of hopping frequencies at regular intervals, said method comprising the steps of:

memorizing a plurality of modulation coefficients related to the hopping frequencies;

reading out one of the modulation coefficients as a read out modulation coefficient on the basis of a following hopping frequency from said memory when the following hopping frequency is decided; and

adjusting voltage amplitude of the modulation signal by the use of the read out modulation coefficient to restrict frequency deviation of the modulated signal within a predetermined range regardless of the carrier frequency.

7. A method as claimed in claim 6, the modulation signal being made from transmission data signal, wherein said adjusting step comprises a step of:

multiplying the transmission data signal by the read out modulation coefficient.

8. A method as claimed in claim 7 further comprises the steps of:

limiting a band of the transmission data signal to supply band-limited transmission data signal to said multiplier;

converting the band-limited transmission data signal multiplied by the read out modulation coefficient from said multiplier into an analog data signal; and

filtering the analog data signal to supply filtered analog data signal to the voltage controlled oscillator as the modulation signal.

9. A method as claimed in claim 6 further comprises a step of:

obtaining said modulation coefficients by the means of linear interpolation using measuring results of measurement of frequency deviation regarding at least two of the hopping frequencies.

10. A method for finding modulation coefficients related to hopping frequencies, said modulation coefficients used for restricting frequency deviation of a transmission signal transmitted from a frequency hopping communication device within a predetermined range regardless of a carrier frequency, said frequency hopping communication device including a voltage controlled oscillator for producing a modulated signal that a carrier wave with the carrier frequency is modulated by a modulation signal, the carrier frequency changed into any one of hopping frequencies at regular intervals, said method comprising the steps of:

connecting a measuring computer and a frequency deviation measuring unit with said frequency hopping communication device;

directing, from said computer, said frequency hopping communication device to maintain one of the hopping frequencies as a first carrier frequency;

transmitting, from said frequency hopping communication device to said frequency deviation measuring unit, a first transmission signal that the first carrier frequency is modulated by the use of a predetermined pattern signal;

measuring, at said frequency deviation measuring unit, frequency deviation of the first transmission signal to obtain a first result;

directing, from said computer, said frequency hopping communication device to maintain another one of the hopping frequencies as a second carrier frequency;

transmitting, from said frequency hopping communication device to said frequency deviation measuring unit, a second transmission signal that the second carrier frequency is modulated by the use of the predetermined pattern signal;

measuring, at said frequency deviation measuring unit, frequency deviation of the second transmission signal to obtain a second result; and

calculating the modulation coefficients by the use of linear interpolation using the first carrier frequency, the first result, the second carrier frequency and the second result.

11. A method claimed in claim 10 comprises a step of writing the modulation coefficients into a nonvolatile memory in a lump.