JP3834196B2 - High-speed handover PHS terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention constitutes a personal handy phone system (hereinafter referred to as PHS) and communicates with one of a plurality of base stations connected to a public network via a wireless line (hereinafter referred to as PHS). In particular, the present invention relates to a fast handover type PHS terminal.
[0002]
[Prior art]
Conventionally, as one of the typical service functions of PHS, in a PHS terminal communicating with a base station in a public network, it is sent from the base station based on detection of radio reception level deterioration or reception quality deterioration. A reconnection (handover) processing function for reconnecting from a currently communicating base station to another base station by receiving a predetermined control information signal is known.
An increasing number of PHS terminals are equipped with a high-speed handover processing function for performing this handover processing at high speed.
[0003]
In such a fast handover type PHS, as shown in FIG. 4, a PHS transmission / reception signal is composed of slots obtained by dividing 5 msec into 8 parts, and reception (RX) and transmission (TX) are 4 respectively. Each slot is assigned.
Then, four transmission slots TX1, TX2, TX3, TX4 and four reception slots RX1, RX2, RX3, RX4 are arranged sequentially in time.
Here, during a normal call, the first transmission slot TX1 and the first reception slot RX1 are used for the call.
[0004]
On the other hand, at the time of the fast handover operation, in the receiving slot, a search for neighboring base stations (hereinafter referred to as CS) is performed in the three slots RX2 to RX4 other than RX1 that is talking.
Here, the transition condition to the peripheral CS search operation is that the electric field level of the communication channel in the reception slot RX1 becomes a weak electric field of a certain value or less. And if it is judged that it is a weak electric field, peripheral CS is searched and it will shift to CS of the highest electric field level.
[0005]
The channel indicates a frequency. The frequency given to the call, that is, the call channel (local frequency f1-1 from the first oscillation unit), and the frequency given to the peripheral CS search, that is, the control channel (second channel). The local frequencies f1-2) from the oscillators are different. In the illustrated case, the call channel is 50 ch, and the control channel is 70 ch.
[0006]
FIG. 5 shows a configuration example of a main local oscillation unit among the two-stage local oscillation units in the conventional PHS terminal.
In FIG. 5, a local oscillation unit 100 includes a first oscillation unit 102, a first attenuator 103, a first buffer amplifier 104, and a predetermined control channel. Second oscillation switch 105 that generates a signal of frequency f1-2, second attenuator 106, second buffer amplifier 107, and second change-over switch that switches between first buffer amplifier 104 and second buffer amplifier 107 108.
In the local oscillation unit 100, the buffer amplifiers 104 and 107 and the second changeover switch 108 are on / off controlled based on the control signals LOSW1 and LOSW2.
[0007]
For example, a PLL-IC is used for the first and second oscillation units 102 and 105 so that various channels can be received and transmitted.
The attenuators 103 and 106 are used to keep the output loads of the first and second oscillating units 102 and 105 constant and suppress the frequency fluctuations.
Thus, when the second changeover switch 108 is switched, the first and second oscillation units 102 and 105 are connected to the buffer amplifiers 104 and 107 via the attenuators 103 and 106, respectively. The maximum load is not suddenly applied from no load. Therefore, frequency fluctuations of the first and second oscillation units 102 and 105 are reduced.
[0008]
The PHS terminal including the local oscillation unit 100 having such a configuration operates as follows.
First, during a normal call, the entire operation of the PHS terminal performs transmission and reception on a communication channel (for example, 50 ch) in the transmission slot TX1 and the reception slot RX1, respectively.
In the case of transmission, the data to be transmitted is mixed with the local oscillation signal (frequency f1-1) from the local oscillation unit 100 and transmitted.
In the case of reception, the radio wave received by the antenna is mixed down with the local oscillation signal (frequency f1-1) from the local oscillation unit 100, data demodulated, and restored as sound.
[0009]
Here, during normal operation, as shown in FIG. 6, in the transmission slot TX1 and the reception slot RX1, the local control signal LOSW1 becomes H level, and the signal of the frequency f1-1 from the first oscillation unit 102 is detected. Is output.
At this time, the first oscillating unit 102 starts operation for one slot before stabilization, that is, operates at the reception slot RX4 and the transmission slot TX1 at the time of transmission, and at the time of reception, at the transmission slot TX4 and the reception slot. By operating in RX1, transmission or reception can be performed while the local frequency f1-1 is stable.
[0010]
On the other hand, the PHS terminal performs a fast handover operation when a weak electric field is generated in the reception slot RX1.
In this case, the overall operation of the PHS terminal is that transmission and reception are performed on the communication channel in the transmission slot TX1 and reception slot RX1, respectively, and peripheral CS search is performed on the control channel (for example, 70ch) in the reception slots RX2 to RX4. To do.
[0011]
In this case, the control signal LOSW1 is the same as that during a normal call, and the first oscillation unit 102 similarly starts to operate one slot before, and the local oscillation unit 1 uses the transmission slot TX1 and the reception slot RX1. The signal of the local frequency f1-1 is output.
Further, in this case, the control signal LOSW2 becomes H level in the reception slots RX2 to RX4, and the signal of the frequency f1-2 from the second oscillation unit 105 is output.
At that time, the second oscillating unit 105 starts operation for one slot before stabilization, that is, operates in the reception slots RX1 to RX4, so that the local frequency f1-2 is transmitted in a stable state. Reception can be performed.
In this way, by configuring the first oscillating unit 102 and the second oscillating unit 105 to output signals of the frequencies f1-1 and f1-2, respectively, each signal is output in a stable frequency state. Can be output.
[0012]
In this way, by mixing up or down the transmission signal or reception signal of the PHS terminal with the local oscillation signal from the local oscillation unit 1, for example, for the reception signal, the difference frequency is extracted by the mixdown and the frequency is extracted. The signal is converted to a lower frequency by conversion and processed into a signal that is easier to demodulate, and the transmission signal is converted into a higher frequency by mixing up to be processed into a signal that is easy to transmit.
[0013]
[Problems to be solved by the invention]
However, in the PHS terminal equipped with such a fast handover processing function, the local oscillation unit 100 attenuates the signals from the oscillation units 102 and 105 by about 20 dB by the attenuators 103 and 106, and then the buffer amplifiers 104 and 107 are used. Therefore, the current consumption increases, and the current consumption increases even during normal communication other than during fast handover.
For example, when the current consumption of the buffer amplifiers 104 and 107 is 20 mA during a normal call, the call current increases on average by 5 mA.
For this reason, the power of the rechargeable battery mounted on the PHS terminal is wasted, and the use time of the PHS terminal by the rechargeable battery is unnecessarily shortened.
[0014]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-speed handover PHS terminal that reduces current consumption during normal communication.
[0015]
[Means for Solving the Problems]
  To achieve this object, a PHS terminal according to claim 1 of the present invention includes an antenna, a receiving unit that processes a signal received by the antenna, a transmitting unit that processes a signal to be transmitted and outputs the signal to the antenna, A local oscillation unit for transmitting a local oscillation signal for mixdown or mixup of a processing signal to the reception unit and the transmission unit, wherein the local oscillation unit is a first local oscillation frequency for a communication channel; A first oscillating unit that outputs a first signal of the first and a second signal that outputs a second signal of a second local oscillation frequency for a control channel for searching for a peripheral CS (base station) during a fast handover operation Two oscillators,A first changeover switch that selectively outputs the first signal or the second signal, and a first output load regulator connected between the first oscillation unit and the first changeover switch And a first buffer amplifier, and a second output load regulator and a second buffer amplifier connected between the second oscillation unit and the first changeover switch,In a fast handover PHS terminal,The local oscillation unit isThe output of the first oscillatorAbove first output load regulator sideOr a second changeover switch that selectively connects to the downstream side of the first changeover switch, and the second changeover switch is not connected to the first changeover switch except during the fast handover operation. The configuration is switched to the downstream side.
[0016]
When the PHS terminal has such a configuration, at the time of high-speed handover operation, the first changeover switch is switched to the first oscillation unit side in the reception slot and transmission slot assigned to communication, and the second changeover switch is It is switched to the output adjustment loader side. As a result, the first signal from the first oscillating unit is output to the receiving unit and the transmitting unit via the output load regulator and the buffer amplifier, so that the output load of the first oscillating unit is constant. The reception unit and the transmission unit can mix down and mix up the processed signal using the first signal having a stable frequency.
[0017]
In addition, when searching for neighboring CSs in other reception slots during the fast handover operation, the first changeover switch is switched to the second oscillation unit side, and the second signal from the second oscillation unit Is output to the receiving unit via the output load regulator and the buffer amplifier, so that the output load of the second oscillating unit is kept constant, and the receiving unit uses the second signal with a stable frequency. The processing signal can be mixed down.
[0018]
On the other hand, during normal communication other than during the fast handover operation, the second changeover switch is switched to the downstream side of the first changeover switch, so the first signal from the first oscillation unit is output load The signal is output directly to the receiver and transmitter without going through the adjuster and buffer amplifier.
In this way, in the fast handover PHS terminal, during the fast handover operation, the first oscillation unit operates in the same manner as the conventional fast handover PHS terminal and during normal communication other than during the fast handover operation. Since the first signal from is directly output to the receiver and transmitter without using a buffer amplifier, the current consumption of the buffer amplifier can be reduced and the power consumption of the PHS terminal can be reduced. Can be realized.
[0019]
The PHS terminal according to claim 2 is configured such that the output load adjuster is an attenuator.
Moreover, the PHS terminal according to claim 3 is configured such that the output load adjuster is an isolator.
[0020]
When the PHS terminal has such a configuration, the output of the first oscillating unit is connected to an attenuator or isolator serving as an output load regulator, so that the output load is kept constant. One signal can be output.
[0021]
  The PHS terminal according to claim 4 is:The first buffer amplifier and the second buffer amplifierHowever, the configuration is in a non-operating state except during the fast handover operation.
  When the PHS terminal has such a configuration, the first signal from the first oscillation unit is directly output to the reception unit or the transmission unit during normal communication other than during the fast handover operation. By disabling the buffer amplifier that is not operated, the current consumption of the buffer amplifier can be reduced to zero, and the power consumption of the PHS terminal can be further reduced.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0025]
First, an embodiment of the PHS terminal of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing the overall configuration of a PHS terminal according to the present invention.
[0026]
In FIG. 1, the PHS terminal 10 includes an antenna 11, a reception unit 20, a transmission unit 30, a modulation / demodulation unit 40, a control unit 50, a first local oscillation unit 60, and a second local oscillation unit 70. , Is composed of.
[0027]
  The antenna 11 receives a radio wave from a PHS base station and transmits a radio wave to the base station. Through the first bandpass filter 12,Transmission / reception selector switch13 is connected.
  thisTransmission / reception selector switch13 is for selectively connecting the antenna 11 to the receiving unit 20 and the transmitting unit 30, the common contact is connected to the antenna 11, and the two switching contacts are on the receiving unit 20 and transmitting unit 30 side, respectively. It is connected to the.
  AndTransmission / reception selector switch13 is controlled to be switched to the reception side in the reception slot and to the transmission side in the transmission slot based on a control signal (not shown).
[0028]
  The receiving unit 20 includes a first amplifier 21, a first mixing circuit 22, a second bandpass filter 23, a second mixing circuit 24, and a third bandpass filter 25.
  The input side of the first amplifier 21 is the aboveTransmission / reception selector switch13 is connected to a switching contact on the receiving side, and amplifies the received signal from the antenna 11.
[0029]
The first mixing circuit 22 mixes down the amplified signal from the first amplifier 21 and the local oscillation signal from the first local oscillation unit 60, that is, extracts both differential frequencies.
The second band pass filter 23 removes excess frequency components from the signal mixed down by the first mixing circuit 22 and transmits only a predetermined frequency width.
[0030]
The second mixing circuit 24 mixes down the signal from the second bandpass filter 23 and the local oscillation signal from the second local oscillation unit 70.
The third band pass filter 25 transmits only a predetermined frequency width of the signal mixed down by the second mixing circuit 24.
[0031]
On the other hand, the transmitter 30 includes a third mixing circuit 31, a fourth mixing circuit 32, an adder 33, a fourth bandpass filter 34, a fifth mixing circuit 35, and a fifth bandpass filter. 36 and a second amplifier 37.
[0032]
The third mixing circuit 31 and the fourth mixing circuit 32 mix up the I signal and the Q signal of the transmission signal modulated by the modulation / demodulation circuit 40 with the local oscillation signal from the second local oscillation unit 70, respectively. That is, the frequency obtained by adding both signals is extracted.
[0033]
The adder 33 synthesizes the output signals of the third mixing circuit 31 and the fourth mixing circuit 32.
The fourth band pass filter 34 transmits only a predetermined frequency width of the signal synthesized by the adder 33.
[0034]
  The fifth mixing circuit 35 mixes the signal from the fourth bandpass filter 34 and the local oscillation signal from the first local oscillation unit 60.upTo do.
  The fifth band pass filter 36 is mixed by the fifth mixing circuit 35.upOf the received signals, only a predetermined frequency width is transmitted.
[0035]
  The second amplifier 37 amplifies the output signal from the fifth bandpass filter 36, andTransmission / reception selector switch13 is sent to the switching contact on the transmission side.
[0036]
The second local oscillator 70 generates a signal having a predetermined frequency f2 and sends it to the two mixing circuits 31 and 32.
[0037]
  On the other hand, as shown in FIG. 2, the first local oscillating unit 60 includes a first oscillating unit 61, a first attenuator 62, and a first attenuating unit 61 that generate a signal having a predetermined frequency f1-1 for the communication channel. Buffer amplifier 63, a second oscillation unit 64 that generates a signal of a predetermined frequency f1-2 for the control channel, a second attenuator 65, a second buffer amplifier 66, a first buffer amplifier 63, and a second buffer amplifier 63. Switch the buffer amplifier 661st changeover switch67, and further, the first oscillating unit 61 is replaced with the first attenuator 62 or1st changeover switchSwitch to the downstream side of 67Second changeover switch68.
[0038]
  In the first local oscillation unit 60, the buffer amplifiers 63, 66 and1st changeover switchOn / off control or switching control 67 is controlled based on the control signals LOSW1 and LOSW2.
  Also,Second changeover switch68 is controlled to be switched based on the control signals LOSW3 and LOSW4.
[0039]
For example, a PLL-IC is used for the first and second oscillators 61 and 64 so that various channels can be received and transmitted.
The attenuators 62 and 65 are used to keep the output loads of the first and second oscillating units 61 and 64 constant and suppress the frequency fluctuations thereof.
[0040]
  This1st changeover switchWhen the switching of 67 is performed, the first and second oscillating units 61 and 64 are connected to the buffer amplifiers 63 and 66 via the attenuators 62 and 65, so that the maximum load is suddenly applied from no load. There is no such thing. Therefore, frequency fluctuations of the first and second oscillation units 61 and 64 are reduced.
  Instead of the attenuators 62 and 65, for example, an isolator or the like may be provided as long as the output loads of the first and second oscillation units 61 and 64 are constant.
[0041]
  Also,1st changeover switchWhen the switching of 67 is performed, the first oscillating unit 61 is output via the attenuator 62 and the buffer amplifier 63, or directly output.
[0042]
The modulation / demodulation unit 40 demodulates the signal from the reception unit 20 and sends the data to the control unit 50, and also modulates the signal from the control unit 50 and sends it to the transmission unit 30.
The control unit 50 restores audio from the signal demodulated by the modem unit 40, converts the audio to be transmitted into an audio signal, and sends the audio signal to the modem unit 40.
[0043]
  Then, as shown in FIG. 2, the local control signal LOSW1 or LOSW21st changeover switchSwitching of 67 and on / off of the buffer amplifiers 63 and 66 are controlled. For example, if the local control signal LOSW1 is at H level and LOSW2 is at L level, the buffer amplifier 63 ison, Buffer amplifier 66off, Changeover switch 67 is a buffer amplifier63Switched to the side.
  If the local control signal LOSW1 is at L level and LOSW2 is at H level, the buffer amplifier 63 isoff, Buffer amplifier 66on, Changeover switch 67 is a buffer amplifier66Switched to the side.
[0044]
If the local control signal LOSW1 is H level and the LOSW2 is H level logically, and if the local control signal LOSW1 is L level and LOSW2 is L level, both buffer amplifiers 63 and 66 are turned off, and the first The local oscillator 60 does not operate.
Thus, by performing local switching by the changeover switch 67, the communication channel is used in RX1 among the reception slots, and the control channel is used in RX2 to RX3.
[0045]
  Further, as shown in FIG. 2, by the local control signal LOSW3 or LOSW4,Second changeover switch68 is controlled. For example, if the local control signal LOSW3 is H level and LOSW4 is L level,Second changeover switch68 isBIf the local control signal LOSW3 is at L level and LOSW4 is at H level,Second changeover switch68 isASwitched to the side.
  In this waySecond changeover switchBy performing the switching control of 68, the signal of the frequency f1-1 from the first oscillation unit 61 is output as the first local oscillation signal via the attenuator 62 and the buffer amplifier 63 or directly. .
[0046]
The first oscillating unit 61 and the second oscillating unit 64 each take about several hundreds of microseconds until the frequency becomes stable. Therefore, it is preferable that one slot (that is, 5 msec / s) of the slot to be transmitted or received is preferably used. 8 = 625 μsec), the drive control is performed so that transmission or reception is started in a state where the oscillation frequency is stable.
Thus, the high-speed headover type PHS terminal 10 can perform a peripheral CS search during a call.
[0047]
Next, the operation of the PHS terminal 10 according to the present embodiment will be described.
First, the operation of the PHS terminal 10 during a normal call will be described with reference to FIG.
The overall operation of the PHS terminal 10 performs transmission and reception on the communication channel 50ch in the transmission slot TX1 and the reception slot RX1, respectively.
In the case of transmission, data to be transmitted is input from the control unit 50 to the modem unit 40 and is modulated by the modem unit 40. Then, the data-modulated I signal and Q signal are input to mixing circuits 31 and 32, respectively.
[0048]
Here, in the third mixing circuit 31, the local oscillation signal from the second local oscillation unit 70 is mixed with the I signal from the modulation / demodulation unit 40, and in the fourth mixing circuit 32, the modulation / demodulation unit The local oscillation signal from the second local oscillation unit 70 is mixed up with the Q signal from 40.
Then, the signals mixed up by the mixing circuits 31 and 32 are combined by the adder 33 and thereby modulated at the frequency f2 of the signal from the second local oscillation unit 70.
[0049]
  Next, the excess frequency component is removed from the signal from the adder 33 by the fourth band pass filter 34, and the local oscillation signal (frequency) from the first local oscillation unit 60 is obtained by the fifth mixing circuit 35. f1-1) is mixed up, and an extra frequency component is further removed by the fifth band-pass filter 36, which is input to the second amplifier 37.
  The signal amplified by the second amplifier 37 isTransmission / reception selector switch13 and the first band pass filter 12 are transmitted from the antenna 11 to the base station.
[0050]
  Further, in the case of reception, the radio wave received by the antenna 11 has an excess frequency component removed by the first band pass filter 12,Transmission / reception selector switch13 is input to the receiving unit 20.
  Then, the signal input to the receiving unit 20 is amplified by the first amplifier 21 and mixed with the local oscillation signal (frequency f1-1) from the first local oscillation unit 60 by the first mixing circuit 22. Further, an extra frequency component is removed by the second band pass filter 23 and input to the second mixing circuit 24.
  Next, the signal input to the second mixing circuit 24 is mixed down with the local oscillation signal (frequency f 2) from the second local oscillation unit 70, and an extra frequency component is further filtered by the third band pass filter 25. Is removed and input to the modem unit 40.
  The signal input to the modulation / demodulation unit 40 is data demodulated and restored as sound by the control unit 50.
[0051]
  Here, at the time of normal operation, as indicated by a symbol Y in FIG.Second changeover switchSince 68 is switched to the B side, the signal of the frequency f <b> 1-1 from the first oscillating unit 61 is output to the first mixing circuit 22 and the fifth mixing circuit 35.
  At that time, the first oscillating unit 61 starts operation for one slot before stabilization, that is, operates at the reception slot RX4 and the transmission slot TX1 at the time of transmission, and at the time of reception, at the transmission slot TX4 and the reception slot. By operating in RX1, transmission or reception can be performed while the local frequency f1-1 is stable.
[0052]
Further, the local oscillation signal from the first oscillating unit 61 is directly output to the first mixing circuit 22 and the fifth mixing circuit 35 without passing through the first attenuator 62 and the first buffer amplifier 63. The
Accordingly, since it is not necessary to operate the buffer amplifier 63 during a normal call, the local control signal LOSW1 is held at the L level, and the current consumption can be reduced by the amount corresponding to the buffer amplifier 63.
[0053]
  On the other hand, in the case of the conventional PHS terminal, as indicated by a symbol X in FIG. 3, the local oscillation signal from the first oscillation unit 102 is output via the attenuator 103 and the buffer amplifier 104. As a result, current is consumed by the operation of the buffer amplifier 104.
  In this case, the load of the first mixing circuit 22 and the fifth mixing circuit 35 varies somewhat depending on the power on / off, but the power of the mixing circuits 22 and 35 is turned on sufficiently before the reception slot or the transmission slot. Therefore, the load fluctuation does not affect the operation of the mixing circuits 22 and 35. further,First and second selector switchNo current flows through 67 and 68.
[0054]
In contrast, when the PHS terminal 10 becomes a weak electric field in the reception slot RX1, the PHS terminal 10 performs a fast handover operation as in the case of the conventional PHS terminal shown in FIG.
In the overall operation of the PHS terminal 10, transmission and reception are performed on the communication channel 50ch in the transmission slot TX1 and reception slot RX1, respectively, and peripheral CS search is performed on the control channel 70ch in the reception slots RX2 to RX4.
In this case, the control signal LOSW1 is the same as that during the normal call, and the first oscillation unit 61 similarly starts operating from one slot before, and the first local oscillation unit 60 includes the transmission slot TX1 and the reception slot. In RX1, a signal having the local frequency f1-1 is output.
[0055]
Further, in this case, the control signal LOSW2 becomes H level in the reception slots RX2 to RX4, and the signal of the frequency f1-2 from the second oscillating unit 64 is supplied to the first mixing circuit 22 and the fifth It is output to the mixing circuit 35.
At this time, the second oscillating unit 64 starts operation for one slot before stabilization, that is, operates in the reception slots RX1 to RX4, so that the local frequency f1-2 is transmitted in a stable state. Reception can be performed.
[0056]
In addition, by configuring the first oscillating unit 61 and the second oscillating unit 64 to output signals of frequencies f1-1 and f1-2, respectively, each signal is output in a stable frequency state. Can do.
Further, during the fast handover operation, local oscillation signals from the first oscillating unit 61 and the second oscillating unit 64 are output via the attenuators 62 and 65 and the buffer amplifiers 63 and 66, respectively. The fluctuation is suppressed, and a stable frequency signal can be output.
[0057]
Thus, in the present embodiment, in a PHS terminal equipped with a fast handover processing function, during a normal call other than during the fast handover operation, the frequency f1-1 for the call channel in the first local oscillation unit 60 Since the local oscillation signal from the first oscillation unit 61 that outputs the above signal is directly output to the mixing circuits 22 and 35 without passing through the attenuator 62 and the buffer amplifier 63, it is necessary to operate the buffer amplifier 63. Absent.
[0058]
  Therefore, the PHS terminal 10 according to the present embodiment can operate with substantially the same power consumption as that of a normal call of a PHS terminal that does not have a high-speed handover processing function. Is output to the mixing circuits 22 and 35 via the attenuators 62 and 65 and the buffer amplifiers 63 and 66, respectively.1st changeover switchEven during the switching control by 67, the output load is kept constant by the attenuators 62 and 65, so that a signal with a stable frequency can be output.
[0059]
In the embodiment described above, the case of a call by the PHS terminal 10 has been described. However, the present invention is not limited to this, and the same effect can be obtained also in the case of data communication.
[0060]
【The invention's effect】
As described above, according to the present invention, the fast handover PHS terminal operates in the same manner as the conventional fast handover PHS terminal during the fast handover operation, and during normal communication other than during the fast handover operation. Since the first signal from the first oscillating unit is directly output to the receiving unit and the transmitting unit without using the buffer amplifier, the current consumption of the buffer amplifier can be reduced, and the PHS Low power consumption of the terminal can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a PHS terminal of the present invention.
FIG. 2 is a block diagram of a first local oscillation unit in the PHS terminal of FIG.
FIG. 3 is a time chart showing an operation during a fast handover operation in the PHS terminal of FIG. 1 and a conventional PHS terminal.
FIG. 4 is a time chart showing the basic operation of the PHS terminal.
FIG. 5 is a block diagram illustrating a configuration example of a local oscillation unit in a conventional PHS terminal.
6 is a time chart showing operations during normal call and fast handover operation of the PHS terminal of FIG. 5. FIG.
[Explanation of symbols]
  10 PHS terminal
  11 Antenna
  12 First bandpass filter
  13Transmission / reception selector switch
  20 Receiver
  21 First amplifier
  22 First mixing circuit
  23 Second bandpass filter
  24 Second mixing circuit
  25 Third bandpass filter
  30 Transmitter
  31 Third mixing circuit
  32 Fourth mixing circuit
  33 Adder
  34 Fourth bandpass filter
  35 Fifth mixing circuit
  36 Fifth bandpass filter
  40 modem
  50 Control unit
  60 First local oscillator
  61 First oscillator
  62 First attenuator
  63 First buffer amplifier
  64 Second oscillator
  65 Second attenuator
  66 Second buffer amplifier
  671st changeover switch
  68Second changeover switch
70 Second local oscillator

Claims (4)

An antenna, a reception unit that processes a signal received by the antenna, a transmission unit that processes a signal to be transmitted and outputs the signal to the antenna, and a mixdown or mixup of the processing signal to the reception unit and the transmission unit A local oscillation unit for sending a local oscillation signal for
The local oscillation unit outputs a first signal of a first local oscillation frequency for a communication channel, and a second control channel for a search for neighboring base stations during a fast handover operation. A second oscillation unit that outputs a second signal of the local oscillation frequency, a first changeover switch that selectively outputs the first signal or the second signal, the first oscillation unit, and A first output load regulator and a first buffer amplifier connected between the first changeover switch and a second output connected between the second oscillation unit and the first changeover switch; In a fast handover PHS terminal having a load regulator and a second buffer amplifier,
The local oscillation unit further includes a second changeover switch that selectively connects the output of the first oscillation unit to the first output load regulator side or the downstream side of the first changeover switch;
The high-speed handover PHS terminal, wherein the second switch is switched to the downstream side of the first switch except during a high-speed handover operation.   The fast handover PHS terminal according to claim 1, wherein the output load adjuster is an attenuator.   The fast handover PHS terminal according to claim 1, wherein the output load adjuster is an isolator. The fast handover PHS according to any one of claims 1 to 3, wherein the first buffer amplifier and the second buffer amplifier are in an inactive state except during a fast handover operation. Terminal.

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