Receiver and transmitter-receiver

Details Receiver and transmitter-receiver Receiver and transmitter-receiver

1998-08-28

2001-07-10

Vo, Nguyen T. (Department: 2682)

Telecommunications

Transmitter and receiver at same station

C455S077000, C455S314000, C455S182300, C455S076000

Reexamination Certificate

active

06259895

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention principally relates to a radio that performs transmission of data between equipment, and, more particularly, to a receiver and transmitter-receiver well suited for applications, such as a pager, a cordless remote control, a cordless telephone and a telemeter, that involve repeating intermittent reception or switching of receiving channels.
2. Description of the Related Art
In recent years, communication data transmission using a radio of the type that performs intermittent reception and transmission or frequently repeats switching of transmitting and receiving channels for effective use of both limited radio wave resources and power sources is largely used in, for example, a pager, a cordless remote control, a cordless telephone and a telemeter.
Such a conventional transmitter-receiver of the type that performs intermittent reception or frequently repeats switching of several receiving channels will be described by means of the drawings.
FIG. 5
is a block diagram showing the configuration of a conventional transmitter-receiver. An antenna
100
to which a radio-frequency signal is input is coupled to the common contact
102
a
of a switch
102
, and a receiving contact
102
b
of the switch
102
is coupled through a radio-frequency filter
104
composed of a band-pass filter such as an SAW or LC filter for rejecting signals in an unnecessary band to a receiving radio-frequency amplifier
106
. The output of the receiving radio-frequency amplifier
106
is coupled to a frequency converter
108
, to which the output of a PLL synthesizer
110
is also coupled. The output of the frequency converter
108
is coupled through an intermediate frequency filter
122
that rejects signals in an unnecessary band as in the radio-frequency filter
104
and a demodulation circuit
124
to a demodulation data output terminal
126
.
In a PLL synthesizer
110
, the output of a voltage control oscillator (VCO)
116
is input to a variable frequency divider
118
. The variable frequency divider
118
divides a frequency of an input signal by N for output. A frequency division ratio is then preset to a predetermined value. The output of the variable frequency divider
118
is input to a phase comparator
112
that performs phase comparison with the output of a reference signal source
120
and outputs a signal depending on the magnitude of the phase difference, wherein the output of the phase comparator
112
is input through a low-pass filter
114
that rejects radio-frequency components to a control terminal of the voltage control oscillator
116
. If a frequency of the reference signal source
120
is selected as a channel interval frequency, a frequency of the voltage control oscillator
116
may be varied by one channel each time a frequency division number of the variable frequency divider
118
is varied by 1. Thus setting a frequency division number respectively may output a frequency corresponding to any channel frequency. A crystal oscillator may be used as a reference signal source
120
or a frequency divided signal of the output of a crystal oscillator may be used for radio-frequency stability.
A modulation data input terminal
128
to which modulation data is input is coupled through a modulation signal generator
130
to the PLL synthesizer
110
, and the output of a modulation signal generator
130
is also coupled through the reference signal source
120
to the PLL synthesizer
110
. The output of the PLL synthesizer
110
is coupled through a transmission radio-frequency amplifier
132
to the transmission contact
102
c
of the switch
102
.
Operation of the transmitter-receiver thus configured during reception will now be described. A radio-frequency signal input to the antenna
100
passes from the common contact
102
a
of the switch
102
through receiving contact
102
b
to a radio-frequency filter
104
where signals in an unnecessary band are rejected and amplified by the receiving radio-frequency amplifier
106
to input to the frequency converter
108
. On the other hand, the output frequency of the PLL synthesizer
110
is set to a somewhat higher or lower frequency with respect to a radio-frequency signal to be received. The output of the PLL synthesizer
110
is input to the frequency converter
108
where it is mixed to output an intermediate frequency signal which is a difference between the frequencies, signals in an unnecessary band are rejected by an intermediate frequency filter
122
before demodulation is performed by demodulation circuit
124
, demodulation data is output from the demodulation data output terminal
126
.
Operation during transmission will now be described. The modulation data input to the modulation data input terminal
128
is input to the modulation signal generator
130
where the PLL synthesizer
110
is modulated according to the modulation data, and a signal is generated for modulating a frequency of the PLL synthesizer
110
through the reference signal source
120
. The modulation output of the PLL synthesizer
110
thus modulated is amplified by the transmission radio-frequency amplifier
132
and passed through the common contact
102
a
of the switch
102
that is switched to the transmission contact
102
c
to be output from the antenna
100
.
However, a problem with such a conventional receiver using a PLL synthesizer
110
is that the use of a feedback loop for control to obtain a predetermined frequency requires some time for boot-up operation of powering and frequency switching. Boot-up time and switching time of frequency are characterized by a natural angular frequency of the feedback loop of the PLL. Setting a large natural angular frequency may reduce time required in boot-up operation of powering and frequency switching. However, due to the constraints of setting a signal at a channel interval corresponding to each channel and that of C/N or spurious characteristics, it is difficult to have a sufficiently large natural angular frequency. Therefore, the comparison frequency of the phase comparator must be equal to the channel frequency interval or less due to the constraint of setting a signal at a channel interval corresponding to each channel, large loop gain may not be obtained. For this reason, a conventional receiver using a PLL synthesizer has limits to reduce boot-up operation time and frequency switching time and sufficient characteristics may not be obtained to meet these demands.
Since a pager, a cordless remote control, a cordless telephone and a telemeter often involve repeating intermittent transmission and reception or switching of transmitting and receiving channels and employ a battery as a power source, however, boot-up time of frequency switching will become longer, leading to reduced battery life and lowered commercial value.
SUMMARY OF THE INVENTION
The present invention is to solve such a conventional problem as described above and aimed to provide a receiver and transmitter-receiver that achieves boot-up operation during powering and frequency switching in a short time.
The first invention of the present invention is a receiver that performs reception by selecting any of a plurality of equally set channels, comprising an oscillation means for oscillating a signal at a certain frequency; a first frequency conversion means for getting a received radio-frequency signal an output signal of said oscillation means to convert the received radio-frequency signal to a first intermediate frequency signal; a frequency division means for dividing the signal frequency of said oscillation means by a factor of N; a second frequency conversion means for getting said first intermediate frequency signal and the output signal of said frequency division means to output a second intermediate frequency signal; and a demodulation means for demodulating said second intermediate frequency signal; wherein the frequency division number N of said frequency division means and the frequency of the output signal of said oscillation means are predeterm

Affiliated with

Also associated with

Rating

Receiver and transmitter-receiver does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Receiver and transmitter-receiver, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Receiver and transmitter-receiver will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2476136