JP2811028B2 - RF band data communication device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RF band data communication apparatus using a coaxial transmission line such as a CATV.

[0002]

2. Description of the Related Art Conventionally, in this type of data communication apparatus, data transmission is required for a call termination procedure, and a carrier disconnection detection level for call termination detection is determined by a unique threshold level. I was

[0003]

For this reason, in the above-mentioned conventional data communication apparatus, not only data transmission is required for a call termination procedure, but also IM noise generated on a transmission path to a partner carrier at the time of call termination. However, there is a problem that the carrier disconnection detection level does not become lower than the threshold level, and the end-of-call detection cannot be performed reliably.

The present invention solves such a conventional problem. The present invention can simplify a call termination procedure, prevent the influence of IM noise generated on a transmission line, and use the level of a partner carrier as a reference. It is an object of the present invention to provide an excellent RF band data communication device capable of setting a threshold.

[0005]

According to the present invention, in order to achieve the above object, a stable carrier level can be obtained when performing data communication using an RF band on a transmission line using a coaxial cable such as CATV. By taking advantage of this, a level obtained by subtracting a certain value from the received partner carrier level is used as a carrier disconnection level to detect the end of call.

[0006]

Therefore, according to the present invention, the level of the partner carrier is monitored, and when the level is reduced by a certain value or more, the call is terminated.
This has the effect of preventing the influence of IM noise on the transmission path and improving the reliability of the data communication device.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of one embodiment of the present invention. In FIG. 1, 11 is a coaxial line, 12 is an RF circuit, 13 is a carrier detection circuit, 14 is an analog-to-digital conversion circuit, and 15 is a microprocessor. A is a carrier detection analog signal, and b is an RF control signal.

FIG. 2 is a characteristic diagram showing the mutual relationship between the carrier level of the communication partner and the setting of the threshold level. 101 is the carrier level of A when communicating with the partner A, 102 is the carrier level of B when communicating with the partner B, 103 is the carrier level of the partner A 10
The threshold level 104 for 1 is the threshold level for the carrier level 102 of the partner B. Reference numeral 105 denotes a threshold level when a carrier of a communication partner is detected, reference numeral 106 denotes an IM level when the carrier of the partner A is loaded with IM noise, and reference numeral 107 denotes an IM level when the carrier of the partner B is loaded with IM noise.

Next, the operation of the above embodiment will be described.
When the RF circuit 12 receives the data of the other party through the coaxial line 11, the carrier detection circuit 13 detects a carrier from the received data and outputs a carrier detection analog signal a. This signal a is converted into a digital signal through the analog-to-digital conversion circuit 14 and input to the microprocessor 14 as a carrier level. If the carrier level at this time is equal to or higher than the threshold level 105 shown in FIG. 2, the RF control signal b is sent to the RF circuit 12 to start communication.

On the other hand, the microprocessor 14 performs an operation of subtracting a constant value from the received partner carrier level, and sets the value of the operation result as the threshold level 103 of the partner A or the threshold level 104 of the partner B. Then, when the partner carrier level falls below this level, the RF control signal b is transmitted to the RF circuit 12 to terminate the communication.

When A is taken as an example of a communication partner, when the IM level 106 is on the carrier level 101 of the partner A, even if the C / N (carrier / noise) ratio is within the standard, the conventional C / N ratio is within the standard. In the method, the threshold level 1
Since the IM level 106 is higher than the carrier level 05, the carrier disconnection cannot be detected even if the carrier level 101 of the partner A drops, but the threshold level 103 is set based on the carrier level 101 of the partner A. , It is possible to easily detect the carrier disconnection at the carrier level 101 of the partner A, simplify the call termination procedure, and prevent the influence of IM noise on the transmission path.

As described above, according to the above-described embodiment, the procedure for terminating the data communication can be simplified, the influence of the IM noise on the transmission line is prevented, and the reliability of the data communication device is improved. be able to.

[0013]

As is apparent from the above embodiment, the present invention can simplify the call termination procedure in data communication, and can prevent the influence of IM noise on the transmission line beforehand. Since the threshold level can be set based on the carrier level of the communication partner, there is an effect that the reliability of the data communication device can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an RF band data communication device according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram showing a correlation between automatic setting of a carrier disconnection level in one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 Coaxial line 12 RF circuit 13 Carrier detection circuit 14 Analog-to-digital conversion circuit 15 Microprocessor a Carrier detection analog signal b RF control signal

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H04B 3/00-3/18 H04B 7/005 JICST file (JOIS)

Claims (1)

(57) [Claims] An RF circuit for receiving data on the other side through a coaxial transmission line, a carrier detection circuit for detecting a carrier from the received data, an analog-to-digital conversion circuit for converting the detected carrier from analog to digital, and a converted digital signal. An RF band data communication device comprising: a microprocessor which inputs a signal and calculates and sets a carrier disconnection level from a partner carrier level.