JPH0123976B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a full break-in keying circuit that improves the problem in which the acoustic output between characters and space sections of a transmitted code is mixed with the self-transmitted sidetone output and is difficult to hear. .

break-in keying
keying) In wireless telecommunications, the manual operation for switching between transmitting and receiving states is omitted, and when the telephone key is pressed down, the receiving state is automatically switched to the transmitting state, and radio waves are emitted while the telephone key is held down. , refers to a form of communication in which communication is performed using Morse code, etc. by operating a telephone key, and automatically returns to the receiving state once the key operation is completed, and is further classified into full break-in method and semi-break-in method.

In full break-in keying, the dots and dashes that form the code (called marks) are transmitted at the same time as the key is pressed, and the reception status is transmitted in the middle of the dots and dashes and in the space between characters. It is something to keep.

On the other hand, in semi-break-in keying, the first press of the key enters a transmission state with a holding time constant, and the code is transmitted according to the operation of the key, but no radio waves are emitted during the space period, but the transmission state is maintained, and the receiving circuit is stopped. A holding time constant of, for example, 0.5 seconds is required from the end of transmission (key operation) to the reception state. Therefore, there is a risk of missing the beginning of the transmission from the other party, but it is relatively easy to provide a holding time constant for switching between transmission and reception.
Because it can be used in common with the VOX (voice control) circuit for telephone transmission and reception, it is often used in relatively inexpensive equipment.

With full break-in keying, the signal is in the reception state except when the key is pressed down to mark, so reception can be performed at the same time as the key operation is completed, and there is no worry that the beginning will be cut off. Furthermore, since the space period is also received, even if the content of the communication is unknown, it is possible to know that some signal is coming, so by stopping the telephone key and checking,
This is advantageous in that it can also handle urgent interrupt communications. However, in order to perform such a full break-in operation, the receiving circuit must remain in operation at all times, and switching between transmission and reception depends on the operation of the antenna relay. Advanced technology is required to prevent wraparound and to prevent circuit transients when switching between transmitting and receiving, and the antenna relay uses high-priced products such as high-frequency coaxial relays that can withstand transmission power at high speeds that can handle key operations. Therefore, the full break-in keying method is used in communication equipment that requires high performance.

Even the full break-in method, which is excellent in this way, may have some disadvantages depending on the application. In other words, in commercial wireless communication, the reliability of communication is important, so it is assumed to be used with sufficient electric field strength, and the signal-to-noise ratio during reception is good, so there is no problem, but as in amateur communication, signals at the audible limit During communication with the other station, strong reception noise is generated during the transmission interval, and the transmission signal of the own station may be mixed with the sidetone for monitoring, making it extremely difficult to hear.

The present invention has been made to address the above-mentioned problems, and the present invention has been made in a wireless telegraph transmitter/receiver with full break-in keying operation. It is a full break-in keying circuit that features a visual indication of the presence of a signal.

FIG. 1 shows an example of a circuit implementing the present invention, and FIG. 2 shows its operation timing diagram, and details will be explained below.

In FIG. 1, a transmitting/receiving switching relay 1 connects an antenna to a receiving circuit 10 and a transmitting circuit 3 through a switching contact 1a.
0, and at the same time, the receiving circuit input section is grounded during transmission by the contact 1b interlocked with this, thereby preventing transmission power from flowing into the receiving circuit. The operation of this relay 1 is controlled by a control voltage generated by a break-in control circuit 3 controlled by an electric key 2. The relay 1 normally connects the antenna to the receiving side, but when the telephone key 2 is pressed down, the control circuit 3 switches the relay 1 to the transmitting side, simultaneously activating the transmitting circuit and emitting radio waves from the antenna.
It also generates sidetones for the purpose of monitoring communication transmission codes. For that, sidetone transmitter 11
may be controlled directly, but in order to avoid delays in the rise of oscillation and changes in tone, the buffer amplifier
2 is normally controlled. Tone outputs often share the speaker 13 of the receiver.

The visual indicator 14 is suitably a small LED (light emitting diode), which is small, consumes little power, has high brightness, and is quick-acting.The detection output of the receiving circuit 10 is supplied through the buffer 15, and if there is a detection output, it is displayed. Vessel 1
4 emits light to indicate the presence of an output.
If the buffer 15 or the display 14 itself has a threshold characteristic for light emitting operation, it is possible to emit light only in response to an input signal without emitting light due to noise.

In order to prevent the reception sound from being generated during the space period of transmission, in FIG.
In addition to the time constant circuit of 8, the voltage across it is passed through the stabilizing resistor 19 to the base B of the control transistor 20.
In addition, when this voltage E _B exceeds the initial bias of the transistor (usually about 0.6 V), the internal resistance between the collector C and the emitter E rapidly decreases. Miyut. When the switch 21 of this circuit is opened, the mute operation is stopped and normal full break-in keying is performed. The diode 16 has the effect of rapidly charging the time constant capacitor 17 during the transmission mark signal, improving the rise of the mute control voltage E _B , preventing backflow during discharge, and keeping the discharge time constant large. The recovery time of the mute operation may be set appropriately according to the keying speed by making the time constant resistor 18 variable. Incidentally, the mute circuit 22 can also be used in common with a reception squelch circuit if it is provided.

FIG. 2 shows the timing relationship of the above-mentioned operations, and shows the operation waveform of the electronic key 2 in which - (represents "I" in Japanese and "A" in English) is transmitted.

is the waveform of the transmission control voltage associated with the key operation, which is H when marking a transmission and L when space.

Along with this, the transmitted radio waves change as follows.

is the sidetone acoustic output that self-indicates the transmitted code.

is the detection output (noise) when there is no input signal.

is a mute signal waveform for muting the received acoustic output during transmission with full break-in keying, with a steep rise and a gentle fall. By adjusting the time constant resistor 18 so that the drop in signal level during space does not exceed the threshold level, acoustic output such as noise is muted during transmission, and sidetones without noise are output from the speaker. will be output.

is a waveform when there is an incoming signal such as an interrupt communication. The detection output becomes a waveform in which a part of the incoming signal is added to the noise waveform, and only the part where the noise output is separated by the threshold level is displayed by emitting light to warn that there is an incoming signal.

If keying is then stopped, audio reception can be performed automatically.

As described above, in the present invention, the received acoustic output during the space period of the telephone key is muted in the full break-in keying operation.
The speaker outputs only sidetone without noise, making it easy to hear.The full break-in keying system also has a luminous display that allows you to visually confirm the detection of incoming signals during transmission. Since the feature of full break-in keying is not lost, it is possible to return to normal full break-in keying by simply opening the switch 21 if necessary. Therefore, it is convenient because it can be used depending on the purpose and situation.

[Brief explanation of drawings]

FIG. 1 shows an example of a circuit according to the present invention, and FIG. 2 shows operation timing waveforms of each part in FIG. 1 ...Transmission/reception switching relay, 2...Electronic key, 3...
Transmission control circuit, 10...Receiving circuit, 11...Sidetone transmitter, 12, 15, 22...Buffer amplifier, 13...Speaker, 30...Transmission circuit.

Claims (1)

[Claims] 1. Full break-in keying in a wireless telegraph transmitter/receiver capable of full break-in keying operation, which is characterized by muting the received acoustic output of the intercharacter and space sections of the transmitted code and visually indicating the presence of the received signal. circuit.