Telecommunications – Receiver or analog modulated signal frequency converter – With particular receiver circuit
Reexamination Certificate
1998-12-15
2003-07-01
Chin, Vivan (Department: 2682)
Telecommunications
Receiver or analog modulated signal frequency converter
With particular receiver circuit
C455S574000, C455S161100
Reexamination Certificate
active
06587679
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an apparatus for scanning signals received by a wireless telephone, and further to a method of doing the same.
2. Description of the Related Art
FIG. 1
illustrates a conventional apparatus for scanning signals received by a wireless telephone. The illustrated apparatus is comprised of an antenna
11
, a first device
12
for transmitting and receiving radio signals, to which the antenna is connected, a second device
13
for judging a level of a received signal, a timer
14
, and a controller
15
.
The first device
12
receives and transmits radio signals through the antenna
11
. The second device
13
judges whether a radio signal received by the first device
12
has a level smaller than a threshold level. The controller
15
controls an operation of the first device
12
in accordance with output signals transmitted from the second device
13
and output signals transmitted from the timer
14
.
The apparatus illustrated in
FIG. 1
operates as follows.
With reference to
FIG. 2
, the timer
14
is reset to thereby be made to start in step C
1
.
Then, the first device
12
establishes an ordinary mode where an input signal is monitored at every period of time Tn, in step C
2
.
Then, the controller
15
judges whether an input signal received through the antenna
11
is monitored, in step C
3
. When an input signal is monitored in step C
3
, the second device
13
judges whether an electric field of the monitored input signal has a level smaller than a threshold level, in step C
4
.
If an electric field of the monitored input signal is judged not to have a level smaller than the threshold level, the ordinary mode is kept established in step C
2
. If an electric field of the monitored input signal is judged to have a level smaller than the threshold level, the controller
15
judges whether a period of time Tt longer than the period of time Tn (Tt>Tn) has passed or not in accordance with output signals transmitted from the timer
14
, in step C
5
.
When the period of time Tt has not passed yet, step C
2
and the subsequent steps are carried out again. When an input signal received through the antenna
11
is not monitored in step C
3
, step C
4
is skipped, and step C
5
is carried out.
When the period of time Tt has passed, the first device
12
has established a power-saving mode where an input signal is monitored at every period of time Ts (Ts>Tn), in step C
6
.
Then, the controller
15
judges whether an input signal received through the antenna
11
is monitored or not, in step C
7
. If an input signal is not monitored in step C
7
, the power-saving mode is kept established in step C
6
.
When an input signal is monitored in step C
7
, the second device
13
judges whether the an electric field of monitored input signal has a level equal to or smaller than a threshold level, in step C
8
.
If an electric field of the monitored input signal is judged in step C
8
to have a level equal to or smaller than the threshold level, the power-saving mode is kept established in step C
6
. If an electric field of the monitored input signal is judged in step C
8
not to have a level equal to or smaller than the threshold level, step C
1
is carried out again, and then, the power-saving mode is changed into the ordinary mode in step C
2
.
Hereinbelow is explained an operation of the conventional apparatus for scanning signals received by a wireless telephone, illustrated in FIG.
1
.
As illustrated in
FIG. 3
, an input signal is first scanned in the ordinary mode where a signal is scanned at every period of time Tn which is set to be 10 seconds. Even if an input signal is monitored, when a period of time Tt which is set to be 30 seconds has passed, the ordinary mode is switched into the power-saving mode where a signal is scanned at every period of time Ts which is set to be 10 minutes, if an electric field of the monitored input signal has a level equal to or smaller than a threshold level which is set to be 26 dB &mgr;V.
In the above-mentioned conventional apparatus for scanning signals received by a wireless telephone, if a predetermined period of time during which an electric field of a monitored input signal has a level equal to or smaller than a threshold level has passed, the ordinary mode having a shorter interval between scanning is changed into the power-saving mode having a longer interval between scanning. Hence, there is paused a problem that it would take much time for receiving an input signal, because the ordinary mode is changed into the power-saving mode even in a case that an input signal has to be shortly received.
The above-mentioned conventional apparatus for scanning signals received by a wireless telephone is accompanied with another problem that it would take much time for receiving an input signal due to a long interval between scanning, even if the apparatus moves to a location where an input signal can be received, after the power-saving mode has been once established.
Japanese Unexamined Patent Publication No. 4-241528 having been published on Aug. 28, 1992 has suggested a mobile communication terminal comprising a judgement circuit for measuring an intensity of an electric field of signals received from a radio base station, and judging whether the intensity of an electric field is going to increase or decrease, based on the measurement results, and a control circuit for varying an interval by which signals are intermittently received, in accordance with the result of judgement of the judgement circuit. The intensity of an electric field of the received signals is smaller than a threshold value and is going to decrease, an interval by which signals are intermittently received is made shorter. The intensity of an electric field of the received signals is greater than a threshold value and is going to increase, an interval by which signals are intermittently received is made longer.
Japanese Unexamined Patent Publication No. 6-338838 having been published on Dec. 6, 1994 has suggested a digitally modulated, codeless telephone having a parent phone and a child phone. The suggested telephone is comprised of a first timer for measuring time until a receiving section of the child phone becomes stable after the receiving section is turned on for intermittently receiving signals, a data width detector for judging whether a width of received data is effective or not, a second timer for measuring time necessary for judging received data is transmitted from the parent phone, and an identifier for identifying whether received data is transmitted from the parent phone while the second timer measures the time.
Japanese Unexamined Patent Publication No. 7-254872 having been published on Oct. 3, 1995 has suggested a controller for controlling a main power source of a digital mobile terminal. The controller is comprised of a timer for turning off a main power source when the mobile terminal stays by a certain period of time in an area where the mobile terminal cannot make communication with a base station, a back-up device for allowing the timer to measure time by a certain period of time after the power source has been turned off, and a second power source. When the timer has measured time by a certain period of time, the second power source transmits a signal to the main power source to thereby turn the main power source on.
Japanese Unexamined Patent Publication No. 8-19041 having been published on Jan. 19, 1996 has suggested a codeless telephone including a parent phone and a child phone. The child phone is comprised of a control channel detector for detecting a timing at which a control channel is transmitted from the parent phone, a timing generator for determining a timing at which a control signal is received and a response signal is transmitted, based on the timing at which a control channel is transmitted from the parent phone, and a controller for controlling a power source which supplies power to a signal transmitter and a signal receiver.
Japanese Unexamined Patent Publicat
Chin Vivan
NEC Corporation
Ramos-Feliciano Eliseo
Scully Scott Murphy & Presser
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