Method of testing transceiver and transceiver including testing apparatus
AssigneeNissan Motor Co., Ltd.
InventorAkira Matsumura
Life of this patent
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Abstract
An ultra high frequency transceiver which transmits a modulated carrier wave and mixes a received signal with a locally generated signal to produce an intermediate frequency signal is tested by using the same transmitter as used during normal transceiver operation and by modulating the carrier with a wave having sudden transitions. A portion of the transmitted wave is reflected back to a receiver segment of the transmitter to produce an i.f. signal that is detected by a demodulator. Each transition causes the demodulator to detect a pulse signal. In response to the pulse signal being detected and not being detected during a testing interval, indications are derived to signal that the transceiver is and is not operating properly, respectively.
Claims17
An apparatus for transmitting and receiving an ultra high frequency signal, which comprises:
- (a) a circuit for transmitting a pulse modulated signal, a portion of the energy in the transmitted pulse modulated signal being reflected due to an internal configuration or spurious resonant circulation of the transmitting circuit;
- (b) a circuit mixing the reflected pulse modulated signal with a locally generated signal to produce an intermediate frequency signal having pulses that are a replica of pulses of the pulse modulated signal, the intermediate frequency signal pulses having leading and trailing edges;
- (c) a circuit for demodulating the intermediate frequency signal derived from said mixing circuit to produce short duration pulse signals occurring in response to the leading and trailing edges of the intermediate frequency signal;
- and
- (d) another circuit for deriving a clock pulse, said transmitting circuit responding to the clock pulse to derive the pulse modulated signal, said another circuit detecting whether the short pulse signal at the output of said demodulating circuit is present or absent to ensure that the apparatus is functioning normally, said another circuit including:
- a clock signal generator for deriving the clock pulse for said transmitting circuit, first and second simultaneously closed switches, the first switch being connected to said clock signal generator, the second switch being connected to a bias supply, an AND gate having first and second input terminals respectively connected to an output terminal of said demodulating circuit and the second switch for passing the output signal of said demodulating circuit while said first and second switches are closed, an OR gate having an input terminal connected to said clock signal generator via said first switch, a differentiator for differentiating the bias supply voltage in response to said second switch being closed, a flip-flop having reset and set terminals respectively connected to said differentiator and to said AND gate, said flip-flop having Q and Q output terminals on which are respectively derived a high-level voltage representing the occurrence of a short pulse signal at the output of said demodulating circuit and a high-level voltage representing the lack of a short pulse signal at the output of said demodulating circuit, and a display circuit for optically displaying first and second mutually exclusive indications in response to the high-level voltage signal from the Q and Q output terminals of said flip-flop.
A method of testing a transceiver without employing auxiliary transmitter circuitry, the transceiver, during normal, non-testing operation, deriving a carrier and transmitting a modulated carrier and mixing a received carrier, a portion of the energy of the transmitted modulated carrier being reflected back to a receiver segment of the transceiver, the testing method comprising suddenly increasing and decreasing the amount of modulation of the transmitted carrier, the carrier energy reflected back to the receiver being modified to include the sudden increases and decreases in the amount of modulation of the transmitted carrier, the mixing of the reflected received carrier energy including the sudden increases and decreases and resulting in a pulse each time the amount of modulation is increased and decreased, detecting the pulses, activating a first indicator for signalling that the transceiver is operating normally in response to the derivation of the detected pulse, and activating a second indicator for signalling that the transceiver is not operating normally in response to no detected pulse being derived during testing.
A transceiver comprising a source of carrier waves, means for modulating the carrier waves to derive a modulated carrier wave, a portion of the modulated carrier wave energy being reflected back to the transceiver, said modulating means including means for selectively suddenly increasing and decreasing the amount of modulation on the carrier during an interval while the transceiver is being tested, whereby the modulated carrier wave and the reflected carrier wave include sudden increases and decreases in the amount of modulation on the carriers thereof during the testing interval, the carrier waves from the same source that is modulated during testing being modulated during normal, nontesting transmitter operation of the transceiver, means for mixing the reflected carrier wave, said means for mixing being operative during normal non-testing operation and during the testing interval to derive a pulse each time the amount of carrier modulation is suddenly increased and decreased during testing and to derive a replica of wave energy received by the transceiver during normal operation, means for detecting the pulses, and indicator means responsive to the detected pulses only during the testing interval for indicating that the transceiver is or is not properly operating in response to the pulses being or not being detected during the testing interval.
Dependencies are inferred from the claim text.