Frequency modulation transmitter for voice or data
First Claim
1. A frequency shift keyed signal generator circuitcharacterized bya first variable modulus counter (302) for dividing a clock frequency by a particular first or second modulus (M or N), an applied input (A) being a binary zero or one data signal respectively, the output being a frequency shift keyed signal (B),a second variable modulus counter (303), responsive to the applied input signal (A) and the frequency shift keyed output signal (B) of the first variable modulus counter (302), for dividing the frequency shift keyed output signal by the predetermined second or first modulus (N or M), the output (C) being at the bit rate of the applied input signal (A), anda data bit counter (304), responsive to the output of the second variable modulus counter (303), for dividing the output of the second variable modulus counter by a particular binary quantity of data bits.
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Abstract
A portable frequency modulation transmitter (1) for voice or data is disclosed for operation at infrared frequencies. The transmitter comprises keyboard (200) or microphone (402) input capability and dual modes of use. In the data mode, carrier is generated when the keyboard is operated and is not generated when the keyboard is idle in order to conserve power. In the voice mode, either voice or data may be transmitted, data having priority over voice. A series connection of two variable modulus counters (302, 303) and other counters (304, 305, 306) provide a frequency shift keyed data signal, marker data signal, marker data frames between data frames, parity insertion and other features. In the event that the local battery power level falls below a particular level, a particular word is inserted in the applied binary data input.
11 Citations
9 Claims
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1. A frequency shift keyed signal generator circuit
characterized by a first variable modulus counter (302) for dividing a clock frequency by a particular first or second modulus (M or N), an applied input (A) being a binary zero or one data signal respectively, the output being a frequency shift keyed signal (B), a second variable modulus counter (303), responsive to the applied input signal (A) and the frequency shift keyed output signal (B) of the first variable modulus counter (302), for dividing the frequency shift keyed output signal by the predetermined second or first modulus (N or M), the output (C) being at the bit rate of the applied input signal (A), and a data bit counter (304), responsive to the output of the second variable modulus counter (303), for dividing the output of the second variable modulus counter by a particular binary quantity of data bits.
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2. A frequency shift keyed signal generator circuit
characterized by means (302) for dividing a clock frequency by a particular first or second modulus (M or N), an applied input (A) being a binary zero or one data signal respectively, the output being a frequency shift keyed signal (B), means (303), responsive to the applied input signal (A) and the frequency shift keyed signal (B), for dividing the frequency shift keyed signal by the predetermined second or first modulus (N or M), the output (C) being at the bit rate of the applied input signal (A), and means (304), responsive to the output (C) of the second variable modulus counter (303), for dividing the output of the second variable modulus counter by a particular binary quantity of data bits.
Specification