JP3166669B2 - Received input level detection value correction circuit, correction method, and wireless transmission / reception device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio transmission / reception apparatus for transmitting and receiving radio waves and a reception level detection circuit thereof, and more particularly to a reception input level detection value correction circuit and a correction method for correcting variations in the detection values of the reception input level. And a wireless transmitting and receiving device.

[0002]

2. Description of the Related Art Conventionally, as this kind of radio transmitting / receiving apparatus,
There is a mobile radio device such as a PHS specified in the 2nd generation cordless telephone system standard, second edition (RCR STD-28) issued on December 26, 1995. This mobile radio device checks the level of the received radio wave of the channel used for transmitting the radio wave, and if the reception input level detection value of the received radio wave is equal to or less than the specified level, it determines that the channel is empty, and according to the channel, It is prescribed to transmit radio waves.

In this case, a reception level detection circuit for detecting a reception input level usually has an RSSI (Receive Signal) indicating a detection value proportional to the reception input level.
A strength indication signal is generated, and it is determined whether or not the level of the RSSI signal is equal to or lower than a specified level to determine whether the channel is empty.

[0004] However, the RSSI signal level changes due to variations in the characteristics of the receiving circuit device for receiving radio waves and the detection circuit. As a result, the result of the comparison with the specified level becomes erroneous. In order to prevent this, conventionally, an offset adjustment circuit is provided in the reception level detection circuit to adjust a change due to variation.

For example, Japanese Unexamined Patent Application Publication No. 7-212261 discloses an RS signal for correcting an offset amount.
An S level corresponding to the SI signal is detected, a difference from the standard S level is obtained as a correction amount, stored in a memory, and a value obtained by adding the correction amount to the S level when a received radio wave is input from an antenna is received. It is disclosed to use as a detection value of.

However, this conventional technique cannot correct for variations in gain. In a conventional reception level detection circuit, when performing both offset adjustment and gain adjustment, a standard signal generator is connected to the antenna input side, and the reception input levels of many standard signals from the standard signal generator are detected. It is necessary to adjust a variable resistor and a variable capacitance element for adjusting the offset and the gain so that the detected values of the plurality of detected values become target values.

[0007]

In the above-mentioned conventional reception level detection circuit, offset adjustment and gain adjustment must be performed for a large number of input levels, and any input level must be adjusted to fall within a specified value. However, there is a problem that the adjustment takes time and is very troublesome.

It is a first object of the present invention to provide a reception input level detection value correction circuit and a radio transmission / reception apparatus which do not have any offset adjustment and gain adjustment using a variable resistor or a variable capacitance element.

A second object of the present invention is to reduce the adjustment time by calculating a plurality of correction values corresponding to a plurality of detection values of the reception input level using a small number of standard input levels. An object of the present invention is to provide a circuit, a correction method, and a wireless transmission / reception device.

[0010]

SUMMARY OF THE INVENTION A reception input level detection value correction circuit according to the present invention (3, 4, 5, or 3, 5 in FIG. 1).
Is for correcting a detection value from a detection circuit (1 in FIG. 1) for detecting a reception input level of a radio wave, and a target based on a detection value detected by the detection circuit and a target reception input level-detection value characteristic. A target detection value for the detection value is calculated according to an arithmetic expression representing a relationship with the detection value, and the calculated target detection value is used as a corrected detection value.

With this configuration, it is not necessary to adjust a variable resistor or a variable capacitance element for correcting variations in offset and gain characteristics of a radio wave receiving circuit and a detecting circuit, and a correction value can be easily obtained.

In the present invention, when a radio wave is received, a target correction value may be generated using an arithmetic expression, and transmission control may be performed based on the target correction value.

In the present invention, a plurality of target detection values for a plurality of detection values may be obtained by an arithmetic expression before receiving a radio wave, and may be stored in a storage means in advance as a correction table.

In this case, the reception input level detection value correction circuit calculates the detection value according to an arithmetic expression representing a relationship between the detection value detected by the detection circuit and a target detection value based on the target reception input level-detection value characteristic. Calculating means (3 in FIG. 1) for calculating a target detection value for the target; storage means (4 in FIG. 1) for storing a plurality of target detection values calculated by the calculating means in correspondence with the detection values; Means (3 in FIG. 1) for reading out from the storage means a target detection value corresponding to the detection value detected by the detection circuit (1 in FIG. 1) when received.

As a specific example of the calculation formula in the calculation means (3 in FIG. 1), when two standard levels are used as the reception input levels, the detection values for the target reception input level-detection value characteristics are V1, V2, Assuming that the detection value for the reception input level versus detection value characteristic of V1 ′ is V1 ′, V2 ′, and the detection value between V1 ′ and V2 ′ is Vin, the calculated target detection value is expressed by the following equation: Vout = ((V2− V1) / (V2'-V1 ')) ×
(Vin−V1 ′) + V1, and a plurality of Vouts may be calculated for a plurality of Vins according to the above-described formula.

A method for correcting a reception input level detection value according to the present invention generates detection values for reception inputs of at least two standard levels in advance, and detects a target based on the generated detection value and a target reception input level-detection value characteristic. According to a predetermined arithmetic expression representing a relationship with a value, a plurality of target detection values for a plurality of detection values are calculated and stored in the storage means for each detection value, and the detection value detected from the detection circuit at the time of subsequent radio wave reception is used as the detection value. It is to convert to the target detection value stored in the storage means.

With this configuration, it is possible to correct the detection value of the reception input level only by generating the detection values of the reception input level with respect to at least two standard levels, so that the correction value can be obtained in a short time. is there.

The radio transmitting / receiving apparatus according to the present invention includes a transmitting / receiving means (1 in FIG. 1) for transmitting / receiving a radio wave and a detecting means (FIG. 1 in FIG. 1) for detecting a reception input level of a radio wave and generating a detection value (RSSI signal). 1) calculating the target detection value with respect to the detection value in accordance with an arithmetic expression representing a relationship between the detection value detected by the detection means and a target detection value based on a target reception input level-detection value characteristic; Reception input level detection value correction means (3, 4, 5, or 3, 5 in FIG. 1) that uses the calculated target detection value as a corrected detection value, and a target detection value from the reception input level detection value correction means. And a means (3 in FIG. 1) for instructing the transmission / reception means to transmit a radio wave if the target detection value is equal to or less than the specified level and the target detection value is equal to or less than the specified level.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, a wireless transmission / reception apparatus according to an embodiment of the present invention checks the level of a received radio wave and transmits a radio wave (data signal) when the level of the received radio wave is equal to or lower than a specified level. As an example of such a wireless transmission / reception device, the wireless transmission / reception device of FIG.
2nd generation cordless telephone system standard issued by Japan, second
Wireless communication specified in the edition (RCR STD-28) shall be executed.

In FIG. 1, a radio transmitting / receiving device is connected to an antenna input / output terminal 7 connected to an antenna for transmitting and receiving radio waves, detects signal transmission / reception and reception input levels, and detects RSSI (RF level estimation value) signals. Unit 1 for generating a signal, and RSSI from the RF unit 1
An A / D converter 2 for A / D converting a signal;
The microprocessor 3 is connected to the bus 6 and a microprocessor 3 for controlling the level of the received radio wave based on the D-converted RSSI signal and controlling transmission of the radio wave (data signal) when the level of the received radio wave is equal to or lower than a specified level. It has a RAM 5, a programmable ROM 4, and a modem 9.

The microprocessor 3 stores the A / D conversion output at two or more specified levels in the RAM 5 in addition to the radio wave transmission control, and uses the stored data to perform a predetermined operation to detect the reception input value ( That is, control for creating a correction table for correcting the value of the RSSI signal) is also executed. RSS created by microprocessor 3
The correction table of the I signal is stored in the programmable ROM 4, and the contents thereof are RS detection values of the reception input level.
It is used as a correction value of the SI signal at the time of radio wave transmission control.

The RF unit 1 has an antenna input / output terminal 7
And a function to convert the received radio signal from the antenna 9 into an intermediate frequency signal and output it to the modem 9, and to convert the intermediate frequency signal from the modem 9 into a transmitted radio signal. And a reception level detection function of generating an RSSI signal. The RSSI signal is
A voltage signal obtained by detecting and converting a received radio wave from an antenna into a direct current, and the voltage signal changes in proportion to the reception input level of the radio wave.

FIG. 2 shows a signal frame of a radio signal specified by RCR STD-28. As shown in FIG.
The radio signal of 8 slots is used for the frame.
The slots are transmission slots (1, 2, 3, 4), and the latter four slots are reception slots (1 ', 2', 3 ',.
4 '). Slots 1 and 1 'are the same channel. Slots 2 and 2 ', slots 3 and 3', and slots 4 and 4 'are the same channel. RF unit 1
Is RSSI indicating the reception input level of each reception slot.
Generate a signal. The RSSI signal of each receiving slot is
Output to A / D converter 2.

On the other hand, the modem 9 demodulates the intermediate frequency signal from the RF unit 1 and outputs demodulated data to the data input / output terminal 8, modulates the data signal from the data input / output terminal 8, and outputs the demodulated data to the RF unit 1. Supply.

Transmission of a signal from the modem 9, that is, FIG.
In transmitting a radio wave in the transmission slot, the microprocessor 3 checks the reception input level of the channel to be used based on the RSSI signal from the RF unit 1 and switches to the radio transmission state when the reception input level exceeds the specified level. Control is performed to set the radio wave transmission state when the level is equal to or lower than the specified level without shifting.

More specifically, the microprocessor 3 searches for an empty channel by performing carrier sense for determining whether the RSSI signal of the receiving slot of the channel to be used has exceeded a prescribed level (carrier sense level), The data signal from the data input / output terminal 8 (the intermediate frequency signal from the modem 9) is set to be transmitted to the transmission slot of the vacant channel. In this case, R of the receiving slot of the channel to be used (for example, receiving slot 1 'in FIG. 2)
When the state in which the SSI signal is lower than the specified level continues for four or more frames, it is determined that the channel is empty. Thus, the RF unit 1 transmits a signal from the modem 9 through the transmission slot 1 in FIG.
Carrier sensing is performed by switching channels until a free channel is found.

Microprocessor 3, RAM 5 and R
OM4 is a reception input level detection value correction circuit that generates a correction table for correcting a variation in the detection value from the RF unit 1 with respect to the target detection value, that is, a variation in the RSSI signal so that accurate carrier sensing can be performed. .

Next, the operation for correcting the reception input level will be described. First, a standard signal generator (not shown) is connected to the antenna input / output terminal 7. At this time, the microprocessor 3 controls the RF unit 1 to be in a receiving state. The output level of the standard signal generator is RCR STD-
At least two standard levels are used, with the standard levels defined at 28. For example, when the RF unit 1 has a characteristic (RSSI characteristic) that linearly changes the RSSI signal with respect to the reception input level, the standard level is RSSS
A level of two points on the I characteristic is sufficient. In this embodiment, the upper limit and the lower limit of the dynamic range of the reception input level are set to two standard levels. In this case, the values of the two standard levels are 16 dB microV and 60 dB
Micro V.

When the RSSI characteristic is not a straight line but a curve, two or more standard levels are used. In this case, the curve is regarded as a characteristic approximated by a plurality of straight lines, and the level at both ends of each straight line is set as a standard level. The following description will be made on the assumption that the RSSI characteristic is simply a straight line.

The RSSI signals corresponding to the two standard levels are converted into digital signals by the A / D converter 2, input to the microprocessor 3, and stored in the RAM 5. Therefore, the digital signal (data) stored in the RAM 5 includes variations due to devices in the RF unit 1.

Next, the microprocessor 3 creates a correction table for correcting the variation of the RSSI characteristic of the RF unit 1 from the data stored in the RAM 5 and stores the correction table in the programmable ROM 4.

FIG. 3 shows the reception input level of the RF unit 1,
A / D conversion output of A / D converter 2 and corrected A
FIG. 9 is a diagram showing a relationship between / D conversion correction output (ie, target detection value). In FIG. 3, the graph on the right side shows the RSSI characteristics of the RF unit 1, the horizontal axis is the reception input level, and the vertical axis is the A / D conversion output. The graph on the left side shows the correction characteristics by the microprocessor 3, the vertical axis shows the A / D conversion output (correction input data), and the horizontal axis shows the A / D conversion correction output (target detection value).

The solid line AB represents the RSSI characteristic of the target RF unit 1. Target RF unit 1 RS
The SI characteristics need not always be the standard of the RF unit 1. A broken line A'-B 'is an example of the RSSI characteristic of the RF unit 1 at the time of the actual measurement (when the standard level is detected from the standard signal generator). In the case of the target RSSI characteristic of the RF unit 1, the correction characteristic has the same input and output as shown by the solid line CD, which is equivalent to the case where no correction is performed.

In FIG. 3, when the two standard levels are the reception input levels, the A / D conversion outputs for the target RSSI characteristics are V1 and V2,
A / D conversion output at the time of actual measurement for SSI characteristics is V1 ',
V2 ', a plurality of input points between V1' and V2 '
Assuming that in, the microprocessor 3 calculates the following equation for the RSSI characteristic of the RF unit 1 as follows: Vout = ((V2−V1) / (V2′−V1 ′)) ×
A table in which the target detection value Vout for each input point Vin between the lines A 'and B' is calculated from (Vin-V1 ') + V1 is stored in the programmable ROM 4.

A broken line C'-D 'is obtained as a correction characteristic from the table stored in the programmable ROM 4.
The A / D conversion output with respect to the standard level becomes V1 'and V2' due to the difference in the RSSI characteristics of the RF unit 1, and does not become the target A / D conversion values V1 and V2. By performing the correction indicated by the characteristic line C'-D ', the A / D conversion corrected output becomes V1 and V2 regardless of the difference in the RSSI characteristic, and the difference in the detection level (the level of the RSSI signal) due to the difference in the RSSI characteristic is eliminated. .

FIG. 4 is a flowchart showing a process of creating a correction table when the number of standard levels is two. After setting the output level of the standard signal generator to the first standard level (16 dB micro V), the level of the RSSI signal is measured (1
0-1). The microprocessor 3 checks whether the measured value is within a predetermined range (10-
2). If it is not within the range, it is regarded as defective and an abnormal display is performed (10-7), and the processing is terminated. If it is within the range, the output level of the standard signal generator is set to the second standard level (60 dB microV), and then the level of the RSSI signal is measured (10-3). Again, the microprocessor 3 checks whether the measured value is within a predetermined range (10-4). If it is not within the range, it is regarded as defective and an error is displayed (10-7).
finish. If the value falls within the range, the microprocessor 3 creates a correction table based on the above-mentioned formula (10-5). After the completion of the correction table creation, the correction table is written into the programmable ROM 4 (10-
6) After writing is completed, the process ends.

Next, a case where an antenna (not shown) is connected to the antenna connection input / output terminal 7 will be described. The microprocessor 3 controls the RF unit 1 to be in a receiving state. When a radio wave of any level is received, A / D
An A / D conversion output VX 'is obtained at the output of the converter 2. The A / D conversion output VX 'of the RF unit 1 is read by the microprocessor 3 and the correction table stored in the programmable ROM 4 (the correction characteristic is indicated by line C'-
By performing the correction according to D ′), an A / D conversion correction output corresponding to the target RF unit 1 is obtained.

The microprocessor 3 executes carrier sense according to the A / D conversion correction output. That is, A
It is determined whether or not the / D conversion correction output exceeds a prescribed level, and a vacant channel is searched as described above, and a signal from the modem 7 is transmitted through the transmission slot of that channel.

As described above, according to the embodiment of the present invention, when the detection value from the detection circuit (RF unit 1) for detecting the radio wave reception input level is corrected, the detection value (RSSI signal) detected by the detection circuit is corrected. ) And a target detection value for a detection value (RSSI signal) in accordance with the above-described arithmetic expression representing the relationship between a target reception input level and a target detection value based on a detection value characteristic, and calculating the calculated target detection value. It is characterized in that the detected value is a corrected detection value. Therefore, it is not necessary to adjust a variable resistor or a variable capacitance element for correcting variations in offset and gain characteristics of the RF unit 1, and a correction value can be easily obtained.

The microprocessor 3 is a calculating means for calculating a plurality of target detection values for a plurality of detection values.
Are at least two detection values (RSSI signals) detected by the detection circuit based on at least two levels of reception inputs.
And calculating a plurality of target detection values for the plurality of detection values in accordance with an arithmetic expression representing a relationship between the at least two reception inputs and at least two target detection values obtained in accordance with a target reception input level-detection value characteristic. Therefore, it is possible to correct the detection value of the reception input level only by generating the detection values of the reception input level for at least two standard levels, and there is an advantage that the correction value can be obtained in a short time.

The present invention is not limited to the embodiment described above. For example, the RF unit 1 has both a transmission / reception circuit for transmitting and receiving radio waves and a detection unit for detecting a reception input level, but the detection unit for detecting a reception level may be separated from the RF unit 1.

Further, the reception input level detection value correction circuit comprises:
The target detection value calculated by the arithmetic expression is stored in the storage unit (programmable ROM 4) as a correction table for each detection value, and is stored in the storage unit by an RSSI signal generated from the detection circuit (RF unit 1) at the time of actual radio wave reception. The microprocessor 3 reads out the detected target value,
It is output as a correction value. However, if the processing speed of the microprocessor 3 is high, the arithmetic by the above-described arithmetic expression may be executed in real time for receiving and inputting radio waves.
In this case, two detection values (RSS) detected by the detection circuit for the two-level reception input in the above-described arithmetic expression
I1), V1 'and V2', and target detection values V1 and V2 based on target reception input level-detection value characteristics.
Is stored in the RAM 5 in advance, and the target detection value Vout is obtained by using the above-described arithmetic expression with the detection value from the detection circuit as Vin at the time of radio wave reception. In this case, the programmable ROM 4 for storing the correction table becomes unnecessary.

In the embodiment of the present invention, the communication system of the radio transmitting / receiving device may be a system other than the RCR STD-28.

[0045]

As described above, according to the present invention, when the detection value from the detection circuit for detecting the radio wave reception input level is corrected, the detection value (RSSI signal) detected by the detection circuit is corrected.
The target detection value for the detection value (RSSI signal) is calculated in accordance with the above-described arithmetic expression representing the relationship between the target reception input level and the target detection value based on the detection value characteristic, and the calculated target detection value is corrected. Since the detected value is
It is not necessary to adjust a variable resistor or a variable capacitance element for correcting variations in offset and gain characteristics of the F unit 1, and a correction value can be easily obtained.

Further, according to the present invention, a correction table is prepared from data of at least two or more detected values at the time of standard level input, and the detected values are corrected by the correction table even when radio waves of an arbitrary level are received. , RF unit R
There is an effect that an A / D conversion correction output without an error due to the variation of the SSI characteristic can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a wireless transmission / reception device of the present invention.

FIG. 2 is a diagram illustrating a signal frame of a radio signal of the wireless transmission / reception device of FIG. 1;

3 is a diagram showing a relationship between a reception input level of an RF unit of the wireless transmission / reception device of FIG. 1, an A / D conversion output of an A / D converter, and a corrected A / D conversion correction output (that is, a target detection value). .

FIG. 4 is a flowchart showing an operation up to creation of a correction table in the wireless transmission / reception device of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 RF unit 2 A / D converter 3 Microprocessor 4 Programmable ROM 5 RAM 6 Bus 7 Antenna input / output terminal 8 Data input / output terminal 9 Modem

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 1/16-1/26 H04B 7/26

Claims (6)

(57) [Claims] 1. A reception input level detection value correction circuit for correcting a detection value from a detection circuit for detecting a reception input level of a radio wave , comprising: a standard signal generator for generating a predetermined standard signal; The target detection value for the detection value according to an arithmetic expression representing a relationship between a detection value detected by the detection circuit when input to the detection circuit and a target reception input level versus a target detection value based on a detection value characteristic. Calculating means for calculating a plurality of target detection values calculated by the calculating means in correspondence with the detection values, and detecting by the detection circuit when a received radio signal is input to the detection circuit. Means for reading out the target detection value corresponding to the detected value from the storage means. 2. The apparatus according to claim 1, wherein the calculating unit detects at least two detection values detected by the detection circuit with respect to at least two levels of the reception input, and a target reception input level-detection value characteristic from the at least two reception inputs. 2. The reception input level detection value correction circuit according to claim 1, wherein a plurality of target detection values for a plurality of detection values are calculated in accordance with an arithmetic expression representing a relationship with at least two target detection values obtained according to the following equation. . 3. The arithmetic expression calculates two detection values detected by the detection circuit with respect to a two-level reception input as V
1 ′, V2 ′, target detection values based on target reception input level-detection value characteristics are V1 and V2, detection values are Vin, and target detection values to be calculated corresponding to the detection values Vin are Vout.
Then, Vout = ((V2−V1) / (V2′−V1 ′)) ×
3. The reception input level detection value correction circuit according to claim 2, wherein the reception input level detection value correction circuit is represented by (Vin-V1 ') + V1. 4. The reception input level detection value correction method for correcting the detected value from the detection circuit for detecting a reception input level of the radio wave to generate a target detected value, at least two outputs in advance signal generator A detection value is generated for two standard-level reception inputs, and a plurality of detection values are generated for a plurality of detection values in accordance with a predetermined arithmetic expression representing a relationship between the generated detection value and a target detection value based on a target reception input level-detection value characteristic. Calculating a target detection value for each detection value, storing the target detection value in the storage means for each detection value, and converting the detection value detected from the detection circuit at the time of subsequent radio wave reception to the target detection value stored in the storage means. A method for correcting the detected input level. 5. The method of calculating a plurality of target detection values, wherein at least two detection values detected by the detection circuit with respect to at least two levels of reception input, and the target reception input based on the at least two reception inputs. The reception input according to claim 4, wherein a plurality of target detection values for the plurality of detection values are calculated according to an arithmetic expression representing a relationship between at least two target detection values obtained according to a level-to-detection value characteristic. Level detection value correction method. 6. A transmitting and receiving means for transmitting and receiving radio waves ,
A standard signal generator that generates a standard signal, and a signal input level
Detecting means for detecting a signal and generating a detection value; and detecting the detection when the standard signal is input to the detecting means.
Between the detected value detected by the means and the target received input level
An arithmetic expression that expresses the relationship with the target detection value based on the detection value characteristics
Therefore, the target detection value for the detection value is calculated.
Means and a plurality of target detection values calculated by the calculation means.
Storage means for storing in response to the detected value, the detected upon inputs the received radio wave signal to said detection means
The target detection value corresponding to the detection value detected by the means
From the storage means, and from the storage means
If the read target detection value is below the specified level,
Means for instructing the transmitting / receiving means to transmit a radio wave .