Transceiver with auto frequency sense

• US 4,649,569 A
• Filed: 05/31/1984
• Issued: 03/10/1987
• Est. Priority Date: 05/31/1984
• Status: Expired due to Fees

• Current Assignee: ABB Power T&D Co Inc (ABB Limited)
• Original Assignee: Westinghouse Electric Corporation (Paramount Global (f/k/a ViacomCBS Inc.))
• Inventors: Faulkner, James V. Jr., Kennon, Jerry M., York, Theodore H.
• Primary Examiner(s): Ng, Jin F.
• Assistant Examiner(s): KUNTZ, CURTIS A
• Application Number:
  US06/615,867
• Time in Patent Office: 1,013 Days
• Field of Search: 455/24, 455/115, 455/67, 455/77, 455/185, 455/186, 455/73, 324/79 D, 324/79 R, 324/78 D, 340/310 A, 364/484
• US Class Current: 455/67.11
• CPC Class Codes: G01R 23/02 Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
• CPC Class Codes: H04B 1/40 Circuits

Abstract

A transceiver is provided with a means for determining its own prescribed frequency upon the occurrence of an adverse transient condition, such as lightning, or upon initial installation after manufacture. Since it can safely be assumed that a transceiver'"'"'s prescribe reception frequency is the same as its transmission frequency, the present invention measures the period of its transmission frequency in order to determine the frequency of its reception frequency. The exact frequency of incoming demodulated messages must be known in order for the transceiver'"'"'s digital demodulator to properly demodulate the incoming signals. A high frequency signal, such as 1 mHz, is used to increment a pulse counter and the values of this pulse counter are stored upon the occurrence of two successive negative edges of the carrier signal. The present invention also provides means for directing its carrier signal to an input port of its microprocessor during power-up sequence in order for the period of the carrier signal to be easily measured.

Claims

1. A transceiver, comprising:

means for transmitting a modulated signal, said modulated signal being a carrier signal having a first frequency modulated with a base band data message;

first means for generating said carrier signal, said first generating means being connected in signal communication with said transmitting means;

a microprocessor having an input connected to an output of said first generating means comprising second means for generating an input signal upon the occurrence of a preselected edge of said carrier signal, said second generating means being connected in signal communication with said first generating means;

said microprocessor further comprising means for logging elapsed time, said logging means being responsive to a second frequency, said second frequency being higher than said first frequency, said logging means comprising a means for counting pulses of said second frequency and storing a representation of an accumulated value of said pulses, each of said pulses being representative of a preselected period of time;

said microprocessor further comprising means for comparing two values of said accumulated value representation of said elapsed time to determine an interval between two of said occurrences of said preselected edge of said carrier signal, said comparing means being connected in signal communication with said logging means; and

means for storing said interval.

2. The transceiver of claim 1, wherein:

said microprocessor further comprises means for comparing said interval to a table of exemplary interval values corresponding to a plurality of possible carrier frequencies.

3. The transceiver of claim 2, wherein:

said table comprises eight of said exemplary internal values.

4. A method of determining a carrier signal frequency, comprising:

generating said carrier signal;

generating a periodic signal having a frequency higher than said carrier signal frequency;

counting sequential pulses of said periodic signal;

storing a first instantaneous pulse count value of said counting step upon a first occurence of a preselected edge of said carrier signal;

storing a second instantaneous pulse count value of said counting step upon a second occurrence of said preselected edge of said carrier signal;

comparing said first and second instantaneous pulse count values to determine an elapsed time between said first and second occurrences of said preselected edge of said carrier signal; and

comparing said elapsed time to a table of time values for a preselected number of exemplary frequencies.