JPH06325283A - Flow rate measuring equipment - Google Patents

Abstract

PURPOSE:To easily register an identifying sign (ID) at a job site by providing an external connecting means transmitting/receiving a signal with an external part and an identifying signal storage means storing an identifying signal inputted from the external connecting means. CONSTITUTION:An external input means 6 stores ID from the signal output means of a setting equipment in the identifying signal storage means 5 and a signal receiving means 7 amplifies the receiving signal of a 400MHz band from a signal transmitting means 4, restores a transmitting signal by demodulation and transmits the receiving signal to a signal comparing means 13. The signal comparing means 13 collates ID in the received signal with ID previously stored in the identifying signal storage means 5 at a reception side. Only at the time of the coincidence of IDs, the signal comparing means 13 starts T-NCU 10 with an interface means 9 based on meter-inspection data and transmits meter-inspection data to a telephone line 11. Therefore, even when the number of a meter terminal becomes plural, etc., ID is easily registered at the job site by registering ID from the setting equipment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring device used in an automatic meter reading system such as a gas meter using a telephone line.

[0002]

2. Description of the Related Art In recent years, a so-called automatic meter reading system has been introduced which absorbs an integrated value measured by a meter from a remote place using a telephone line or the like. Further, it is often attempted to connect the telephone line and the meter by a wireless line such as a small electric power. 5 and 6 are block diagrams of a conventional flow rate measuring device and an automatic meter reading system using the flow rate measuring device. Reference numeral 1 is a gas pipe connected to a home, and 2 is a gas flow meter provided in the middle of the gas pipe 1 for measuring the amount of gas used in the target home (so-called gas meter)
Is. Reference numeral 3 is a storage means, 4 is a signal transmission means, and 5 is an identification signal storage means. Reference numeral 7 is a signal receiving means. Reference numeral 11 is a public telephone line, 10 is a no-ringing network control means (hereinafter T-NCU: Terminal-Net) connected to the public telephone line 11.
Work control unit), 9 is an interface means. Here, the interface means 9 and T-NC
Data collection means 8 for a series of telephone line connection parts including U10
Call.

5 and 6, the flow meter 2 measures the flow rate of gas flowing through the gas pipe 1 and electronically stores the integrated value in the storage means 3. The storage unit 3 outputs the stored integrated value to the signal transmission unit 4. The identification signal storage means 5 stores a 63-bit identification code (hereinafter referred to as ID) given by the Minister of Posts and Telecommunications in a system that uses a low power radio (400 MHz band) at the time of factory shipment. The signal transmission means 4 creates a transmission format in which the meter reading data from the storage means 3 is added with the ID stored in the identification signal storage means 5, frequency-modulates the oscillation signal with the transmission data, and then amplifies the signal. It radiates from the antenna as a radio wave into the space. The signal receiving means 7 receives the signal from the signal transmitting means 4 40
The transmission signal is restored by amplifying and demodulating the reception signal in the 0 MHz band, and the signal is sent to the signal comparison means 13.
The signal comparison unit 13 collates the calling signal in the received signal with the calling code previously stored in the identification signal storage unit 5 on the receiving side. Then, the signal comparison means 13 activates the T-NCU 10 via the interface means 9 based on the meter reading data only when the calling codes match, and the telephone line 1
The meter reading data is sent to 1.

In FIGS. 5 and 6, the meter side (flow meter 2
The operation was described centering on the transmission of the meter-reading data from the meter terminal side including T.) to the T-NCU side (telephone line side including the data collecting unit 8).
-A management device that provides the signal transmission means 4 on the NCU side and manages the meter reading data connected to the telephone line 11 (FIGS. 5 and 6).
(Not shown in the figure) via the telephone line 11 to the T-NCU1.
It may be configured to call 0 and request the meter side to transmit the meter reading data.

[0005]

However, in the above conventional configuration, both the meter side and the T-NCU side must be managed. That is, the ID is stored at the time of factory shipment. There is also a problem when the number of meter terminals increases. That is, since the ID has to be stored in the identification signal storage means 5 in advance, when the number of meter terminals for one T-NCU increases after the product is shipped, or when the meter reading of one meter terminal is performed. When transmitting data to a plurality of T-NCUs, it becomes difficult to input a call signal to each meter terminal or T-NCU at the installation site. When sending meter-reading data to a telephone line like T-NCU, it is necessary that the ID be the same in one system, which makes it more difficult to register the ID on site.

The present invention has been made to solve the above problems, and an object of the present invention is to allow an identification code (ID) to be easily registered on-site in a flow rate measuring device.

[0007]

In order to achieve the above object, the present invention has a meter terminal for measuring a flow rate value with a flow meter and a data collecting section for collecting the measured data, and has a meter terminal and a data collecting section. In a flow rate measuring device that collects measurement data with a meter only when the identification signals of the above are coincident with each other, an external connection means for transmitting and receiving a signal to the outside and an identification signal storage means for storing the identification signal input from the external connection means It has a meter terminal equipped with.

Further, it has a meter terminal for measuring a flow rate value with a flow meter and a data collecting section for collecting the measured data,
In a flow rate measurement device that collects measurement data with a meter only when the identification signals of the meter terminal and the data collection unit match, the external connection means for transmitting and receiving signals to and from the external connection means and the identification signal input from the external connection means It has a data collecting section provided with an identification signal storage means for storing

Further, it has a meter terminal for measuring a flow rate value with a flow meter and a data collecting section for collecting the measured data,
A message creating means for creating a message, which is connected to a flow rate measuring device that collects measurement data by the meter only when the identification signals of the meter terminal and the data collecting part match, and a message creating means for creating a message. There is provided an initial setting device constituted by a signal output means for outputting the electronic message created in step 1 to the external connection means of the flow rate measuring device.

[0010]

According to the present invention, the above construction facilitates ID registration and reduces malfunctions of the apparatus.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to the block diagrams of FIGS. 1 to 4, 1 is a gas pipe connected to a home, and 2 is a gas flow meter (so-called gas meter) provided in the middle of the gas pipe 1 for measuring the amount of gas used in the target home. . Reference numeral 3 is a storage means. Reference numeral 4 is a signal transmitting means. Reference numeral 5 is an identification signal storage means. Reference numeral 6 is an external input means. Reference numeral 7 is a signal receiving means. Reference numeral 8 is a data collecting means. 9 is an interface means. Reference numeral 11 is a public telephone line, and 10 is a no-ringing network control means (hereinafter referred to as T
-NCU: called Terminal-Network Control Unit). Reference numeral 12 is a start signal storage means, and 13 is a signal comparison means. Reference numeral 14 is a keyboard, 15 is a display, 16 is a message creating means, and 17 is a signal output means. 18 is a switching means,
Reference numeral 19 is a signal determination means.

In FIG. 1, FIG. 2 and FIG. 4, initially, the radio unit of the flow rate measuring device is not activated. Therefore, various methods for activating the wireless unit are possible. For example, means such as short-circuiting a part of the external terminals, providing a switch to activate the external terminal, or activating when a signal is input to the external input means 6 can be considered.

In FIG. 1, after starting, the flow meter 2 measures the flow rate of the gas flowing through the gas pipe 1 and electronically stores the integrated value in the storage means 3. The storage unit 3 outputs the stored integrated value to the signal transmission unit 4. On the other hand, the external input means 6
An identification code called an ID is input to the external setting device. This is a 63-bit identification code given by the Minister of Posts and Telecommunications in a system using low power radio (400 MHz band). Here, the block diagram of the setting device (Fig. 3)
The operation of will be described. When the ID of the flow rate measuring device is input from the keyboard 14, the ID is displayed on the display unit 15. The input person confirms on the display whether or not the ID input by himself / herself is correct, and if it is correct, inputs the fact from the keyboard. Upon receiving the signal, the electronic message creating means 16 converts the ID input from the keyboard 14 into an electronic message of a predetermined format, and outputs the signal.
Send to. The signal output means 17 outputs the electronic message to the flow rate measuring device. Therefore, the signal output means 1 of the setting device is used for that purpose.
7 is connected to the external input means 6 of the flow rate measuring device. Specifically, the external input means 6 has an external terminal, and the signal output means 17 of the setting device is connected to this external terminal. here,
The communication between the signal output means 17 and the external input means 6 may be wireless communication. In that case, the signal output means 17 frequency-modulates the oscillation signal by the electronic message signal of the ID, and then amplifies the signal and radiates it as a radio wave into the space from the antenna.
The external input means 6 receives the signal from the signal output means 17 from the antenna, amplifies and demodulates the received signal to identify the ID.
Restore the message. Next, returning to the explanation of the block diagram of FIG. 1, the external input means 6 stores in the identification signal storage means 5 the ID sent from the signal output means 17 of the setting device by wire or wirelessly. The signal transmission means 4 creates a transmission format in which the calling code stored in the identification signal storage means 5 is added to the meter reading data from the storage means 3, frequency-modulates the oscillation signal with the transmission data, and then amplifies the signal. The antenna radiates it as a radio wave into the space. The signal receiving means 7 restores the transmission signal by amplifying and demodulating the 400 MHz band received signal from the signal transmitting means 4, and sends the received signal to the signal comparing means 13. The signal comparison unit 13 collates the ID in the received signal with the ID stored in the identification signal storage unit 5 on the reception side in advance. Then, only when the IDs match, the signal comparing unit 13 activates the T-NCU 10 via the interface unit 9 based on the meter reading data, and sends the meter reading data to the telephone line 11. With the above configuration, even when the number of meter terminals is increased, the ID can be easily registered on-site by performing the ID registration from the setting device.

Further, in order to prevent a malfunction of the device or a mischief, the following structure may be adopted. That is, in the configuration of FIG. 1, an input error or the like may occur even when the ID is directly input from the setting device and the display device 15 confirms the ID. Therefore, the configuration shown in FIG. 2 can also be adopted. In FIG. 2, the flow meter 2 measures the flow rate of the gas flowing through the gas pipe 1 and electronically stores the integrated value in the storage means 3. The storage unit 3 outputs the stored integrated value to the signal transmission unit 4. On the other hand, an ID and a start signal specific to each flow rate measuring device are input to the external input means 6 from an external setting device. Here, the block diagram of the setting device (Fig. 3)
The operation of will be described. When the activation signal and ID of the flow rate measuring device are input from the keyboard 14, the activation signal and I
D is displayed on the display unit 15. The activation signal here is a signal such as a pseudo-random code. The input person confirms on the display whether or not the activation signal and the ID input by himself / herself are correct, and if so, inputs the fact from the keyboard. When receiving the signal, the electronic message creating means 16 converts the activation signal and the ID input from the keyboard 14 into an electronic message of a predetermined format and outputs the signal.
Send to 7. The signal output means 17 outputs the electronic message to the flow rate measuring device. For that purpose, the signal output means 17 of the setting device is connected to the external input means 6 of the flow rate measuring device. Specifically, the external input means 6 has an external terminal, and the signal output means 17 of the setting device is connected to this external terminal. Here, the communication between the signal output means 17 and the external input means 6 may be wireless communication. In that case, the signal output means 1
Reference numeral 7 frequency-modulates an oscillation signal by a telegram signal of ID, amplifies the signal, and radiates it as a radio wave from an antenna into space. The external input means 6 receives the signal from the signal output means 17 from the antenna and amplifies and demodulates the received signal to restore the activation signal and the telegram of the ID. Next, returning to the explanation of the block diagram of FIG. 2, the external input means 6 receives the input ID.
Is stored in the identification signal storage means 5. Further, the input activation signal is sent to the signal comparison means 13. Starting signal storage means 1
In 2, a starting signal unique to each flow rate measuring device is stored in advance. Since this activation signal is unique to each flow rate measuring device, there is no problem even if it is input at a factory or the like when the device is manufactured. The signal comparison means 13 compares the activation signal input to the external input means 6 with the activation signal stored in advance in the activation signal storage means 12, and outputs a signal to that effect to the signal transmission means 4 only when they match. To do. When the signal transmitting means 4 receives the signal indicating that the activation signals match from the signal comparing means 13, it creates a transmission format in which the meter reading data from the storing means 3 is added with the ID stored in the identification signal storing means 5, After the oscillation signal is frequency-modulated by the transmission data, the signal is amplified and radiated as a radio wave into the space from the antenna. The signal receiving means 7 amplifies the received signal in the 400 MHz band from the signal transmitting means 4,
The transmission signal is restored by demodulation, and the reception signal is sent to the signal comparison means 13. The signal comparing means 13 preliminarily receives the ID in the received signal and the receiving side identification signal storing means 5
The ID stored in is collated. Then, only when the IDs match, the signal comparing unit 13 activates the T-NCU 10 via the interface unit 9 based on the meter reading data, and sends the meter reading data to the telephone line 11. In this configuration, the device does not start the operation unless the activation signals match, so that malfunctions can be reduced.

Further, with the configuration shown in FIG. 4, the ID can be registered on the T-NCU side by simply connecting the setting device to the meter side. Explaining the block diagram of FIG. 4, after the wireless unit is activated, the flow rate measuring device is set to a mode called a registration mode. This is a mode for registering an ID. The setting of the registration mode is performed by the switching means 18. As a switching method, switching by a switch or the like can be considered. That is, the registration mode is set for a certain period of time after pressing a certain switch. In this registration mode, the external input device 6 receives an identification code called an ID from an external setting device. This is a 63-bit identification code given by the Minister of Posts and Telecommunications in a system using low power radio (400 MHz band). Here, the operation of the block diagram (FIG. 3) of the setting device will be described. When the ID of the flow rate measuring device is input from the keyboard 14, the ID is displayed on the display unit 15. The input person confirms on the display whether the ID entered is correct,
If it is correct, enter that fact from the keyboard. Upon receiving the signal, the electronic message creating means 16 converts the ID input from the keyboard 14 into an electronic message of a predetermined format and sends it to the signal output means 17. Signal output means 1
7 outputs the message to the flow rate measuring device, for which purpose the signal output means 17 of the setting device is connected to the external input means 6 of the flow rate measuring device. Specifically, the external input means 6 has an external terminal, and the signal output means 17 of the setting device is connected to this external terminal. Here, the communication between the signal output means 17 and the external input means 6 may be wireless communication.
In that case, the signal output means 17 frequency-modulates the oscillation signal by the electronic message signal of the ID, and then amplifies the signal and radiates it as a radio wave into the space from the antenna. The external input means 6 receives the signal from the signal output means 17 from the antenna and amplifies and demodulates the received signal to restore the ID message. Next, returning to the description of the block diagram of FIG. 4, the external input means 6 outputs the ID input from the setting device to the identification signal storage means 5. The identification signal storage means 5 stores the ID itself and outputs it to the switching means 18. Since the switching means 18 is in the registration mode by a switch or the like, it outputs the ID from the identification signal storage means 5 to the signal transmission means 4. The signal transmitting means 4 frequency-modulates the oscillation signal with the ID signal, amplifies the signal, and radiates it as a radio wave into the space from the antenna. The signal receiving means 7 is 400M from the signal transmitting means 4.
The transmission signal is restored by amplifying and demodulating the reception signal in the Hz band and sent to the signal determination means 19. Signal determination means 19
Analyzes the received signal and when the signal is an ID,
The ID is sent to the identification signal storage means 5. The identification signal storage means 5 stores the ID. On the other hand, after a lapse of a certain time after switching the switching means 18 to the registration mode, the device returns to the normal mode for exchanging meter reading data. Then, the flow meter 2 measures the flow rate of the gas flowing through the gas pipe 1 and electronically stores the integrated value in the storage means 3. The storage unit 3 outputs the stored integrated value to the switching unit 18. Since the switching means 18 is in the normal mode, the meter reading data from the storage means 3 and the ID stored in the identification signal storage means 5 are sent to the signal transmission means 4. The signal transmission means 4 creates a transmission format in which the calling code stored in the identification signal storage means 5 is added to the meter reading data from the storage means 3, frequency-modulates the oscillation signal with the transmission data, and then amplifies the signal. The antenna radiates it as a radio wave into the space. The signal receiving means 7 amplifies and demodulates the received signal in the 400 MHz band from the signal transmitting means 4, restores the transmitting signal, and outputs it to the signal determining means 19. The signal judging means 19 analyzes the received signal and outputs the received signal to the signal comparing means 13 when it confirms that the received signal includes the meter reading data. The signal comparison means 13 collates the ID in the received signal with the ID stored in the identification signal storage means 5 on the receiving side. Then, only when the IDs match, the signal comparison means 13 receives TN through the interface means 9 based on the meter reading data.
The CU 10 is activated and the meter reading data is sent to the telephone line 11. With such a configuration, it is possible to register the ID even on the side to which the setting device is not connected (in this case, the T-NCU side).

In FIGS. 1, 2 and 4, mainly the transmission of meter reading data from the meter side (meter terminal side including the flow meter 2) to the T-NCU side (telephone line side including the data collecting means 8). Although the operation has been described as above, the signal receiving means 7 is provided on the meter side, the signal transmitting means 4 and the external input means 6 are provided on the T-NCU side, and the setting device is connected to the T-NCU side and connected to the telephone line 11. Management device that manages the meter reading data (Fig. 1,
(Not shown in FIGS. 2 and 4) via a telephone line 11
The NCU 10 may be called to request the meter side to transmit the meter reading data. Further, a system in which the method of FIG. 4 is combined with the method of collating the activation signal of FIG. 2 may be used.

[0017]

As described above, the flow rate measuring device provided with the initial setting device of the present invention uses the radio by easily registering the ID at the site and by minimizing the malfunction of the device due to a registration error or the like. This has the effect of increasing the popularity of automatic meter reading systems.

[Brief description of drawings]

FIG. 1 is a block diagram of a flow rate measuring device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a flow rate measuring device according to another embodiment of the present invention.

FIG. 3 is a block diagram of an initialization device according to an embodiment of the present invention.

FIG. 4 is a block diagram of a flow rate measuring device according to another embodiment of the present invention.

FIG. 5 is a block diagram of a conventional flow rate measuring device.

FIG. 6 is a block diagram of a conventional flow rate measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas piping 2 Flowmeter 3 Storage means 4 Signal transmission means 5 Identification signal storage means 6 External input means 7 Signal reception means 8 Data collection means 9 Interface means 10 T-NCU 11 Telephone line 12 Startup signal storage means 13 Signal comparison means 14 Keyboard 15 Display 16 Message creating means 17 Signal outputting means 18 Switching means 19 Signal judging means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H04Q 9/00 311 H 7170-5K (72) Inventor Shinichi Nakane 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Denki Sangyo Co., Ltd.

Claims (18)

[Claims] 1. A meter terminal for measuring a flow rate value with a flow meter,
In a flow rate measuring device that has a data collection unit that collects the measurement data, and collects the measurement data with the meter only when the identification signals of the meter terminal and the data collection unit match,
A flow rate measuring device having a meter terminal equipped with an external connection means for transmitting and receiving a signal to and from the outside and an identification signal storage means for storing an identification signal input from the external connection means. 2. External connection means for transmitting and receiving signals to and from the outside, and input from the external connection means only when a start signal input from the external connection means and a start signal previously stored in the meter terminal match. The flow rate measuring device according to claim 1, further comprising a meter terminal having identification signal storage means for storing the identification signal. 3. The flow rate measuring device according to claim 1, further comprising a signal transmitting means for transmitting a signal on a carrier wave from an antenna and a signal receiving means for receiving a signal transmitted from the signal transmitting means from the antenna and demodulating the signal. 4. A meter terminal for measuring a flow rate value with a flow meter,
In a flow rate measuring device that has a data collection unit that collects the measurement data, and collects the measurement data with the meter only when the identification signals of the meter terminal and the data collection unit match,
A flow rate measuring device having a data collecting unit provided with external connection means for transmitting and receiving signals to and from the outside and identification signal storage means for storing the identification signal input from the external connection means. 5. An external connection means for transmitting and receiving a signal to and from the outside, and an input from the external connection means only when an activation signal input from the external connection means and an activation signal stored in advance in a data collecting unit match. The flow rate measuring device according to claim 4, further comprising a data collecting unit including an identification signal storage unit that stores the identified identification signal. 6. The flow rate measuring device according to claim 4, further comprising signal transmitting means for transmitting a signal on a carrier wave from an antenna and signal receiving means for receiving a signal transmitted from the signal transmitting means from the antenna and demodulating the signal. 7. A meter terminal for measuring a flow rate value with a flow meter,
In a flow rate measuring device that has a data collection unit that collects the measurement data, and collects the measurement data with the meter only when the identification signals of the meter terminal and the data collection unit match,
External connection means for transmitting and receiving signals to and from the outside, identification signal storage means for storing identification signals, and transmission of the signal stored in the identification signal storage means by the signal input from the external connection means A flow measuring device having a meter terminal provided with a signal transmitting means. 8. An external connection means for transmitting / receiving a signal to / from the outside, an identification signal storage means for storing an identification signal, a start signal input from the external connection means, and a start signal previously stored in the meter terminal. 8. The meter terminal is provided with a signal transmitting means for starting transmission of the signal stored in the identification signal storage means only when the two coincide with each other.
The flow measurement device described. 9. A meter terminal for measuring a flow rate value with a flow meter,
In a flow rate measuring device that has a data collection unit that collects the measurement data, and collects the measurement data with the meter only when the identification signals of the meter terminal and the data collection unit match,
External connection means for transmitting and receiving signals to and from the outside, identification signal storage means for storing identification signals, and transmission of the signal stored in the identification signal storage means by the signal input from the external connection means A flow rate measuring device having a data collecting section provided with a signal transmitting means. 10. An external connection means for transmitting and receiving a signal to and from the outside, an identification signal storage means for storing an identification signal, and an activation signal input from the external connection means and an activation prestored in a data collecting section. 10. The flow rate measuring device according to claim 9, further comprising a data collection unit including a signal transmission unit that starts transmission of the signal stored in the identification signal storage unit only when the signals match. 11. A meter terminal for measuring a flow rate value with a flow meter and a data collecting section for collecting the measured data, and the measured data by the meter can be measured only when the identification signals of the meter terminal and the data collecting section match. In the flow rate measuring device for collecting, a meter terminal equipped with an external connection means for transmitting / receiving a signal to / from the outside and a signal transmission means for transmitting an identification signal input from the external connection means, and a signal transmitted from the signal transmission means. A flow rate measuring device comprising a signal receiving means for receiving a signal and a data collecting section having an identification signal storage means for storing the identification signal received by the signal receiving means. 12. External connection means for transmitting and receiving signals to and from the outside, and input from the external connection means only when a start signal input from the external connection means and a start signal previously stored in the meter terminal match. The flow rate measuring device according to claim 11, further comprising a meter terminal equipped with signal transmitting means for transmitting the identification signal. 13. The flow rate measuring device according to claim 11, further comprising an external connection means for receiving a signal transmitted from a signal output means of the initialization device from an antenna and demodulating the signal. 14. A meter terminal for measuring a flow rate value by a flow meter, and a data collecting section for collecting the measured data, and the measured data by the meter can be measured only when the identification signals of the meter terminal and the data collecting section match. In the flow rate measuring device for collecting, a data collecting unit having an external connection means for transmitting and receiving a signal to and from the outside and a signal transmission means for transmitting an identification signal input from the external connection means, and a data transmission part transmitted from the signal transmission means. And a meter terminal having an identification signal storage means for storing the identification signal received by the signal reception means. 15. External connection means for transmitting / receiving a signal to / from the outside, and input from the external connection means only when a startup signal input from the external connection means and a startup signal stored in advance in the data collecting unit match. 15. The flow rate measurement device according to claim 14, further comprising a data collection unit including a signal transmission unit that transmits the generated identification signal. 16. An external connection means for receiving a signal transmitted from a signal output means from an antenna and demodulating the signal.
4. The flow rate measuring device according to 4. 17. A meter terminal for measuring a flow rate value by a flow meter, and a data collecting section for collecting the measured data, and the measured data by the meter can be measured only when the identification signals of the meter terminal and the data collecting section match. It is connected to the flow rate measuring device for collecting, has a display and a keyboard, and has a message creating means for creating a message, and a signal output means for outputting the message created by the message creating means to the external connecting means of the flow measuring device. Initial setting device for the configured flow rate measuring device. 18. The initial setting device for a flow rate measuring device according to claim 17, further comprising signal output means for transmitting a message generated by the message generating means on a carrier wave and transmitting it from an antenna.