DE1063220B - Tonrufempfaenger or converter for tone selection or tone control purposes for radio systems with selective call systems, in particular for radio networks with mobile radio systems - Google Patents

Description

GERMAN

For the selective evaluation of tone calls, as is the case in radio systems with selective call systems, in particular Radiotelephone networks with mobile radio systems are required, LC resonance circuits are particularly suitable, which trigger switching processes through relays via rectifier arrangements. The ones used Relays need to vaporize the LC circuit as little as possible and therefore only a small amount of its bandwidth to enlarge, are dimensioned so that they can be operated with low power requirements. the Relays can consist of sensitive telegraph relays. However, such an arrangement has the disadvantage relatively large dimensions. In addition, the purchase price for such relays is relatively high.

Therefore ringer receivers have already become known (British Patent 487 488), in which the one tuned to the ringing frequency The voltage picked up from the resonant circuit is not sent directly to a sensitive relay, but via one Rectifier is fed to an electron tube, in the anode circuit of which a simple relay is then arranged can be.

It is also already known (German patent specification 585 882) to supply the control grid of a double grid tube with the resonance voltage of a parallel resonance circuit tuned to the ringing ^{frequency, but the other low-frequency voltage to the room drawer 1} grid of the tube, so that an increase in the presence of frequencies other than the ringing frequency of the space charge grid current takes place and thereby the flow of the anode current and consequently the response of the relay located in the anode circuit is prevented. The part of the circuit causing this effect is separated from the parallel resonance circuit which responds to the ringing frequency. Such arrangements are highly level-dependent in their function.

There are also circuits known (German Patent 497115) in which the resonance voltages two oscillating circuits matched to the ringing frequency are switched against each other after separate rectification and fed to the grating of a subsequent amplifier tube, in. whose Anode circuit the switching relay is located. A series resonant circuit is in series with a parallel resonant circuit and the. Internal resistance of a preamplifier tube. The resonance voltages are the Rectifiers across two. Transmitters supplied, the resistances of which are large compared to the circular resistances must be so that they do not significantly affect the circle quality and circle tuning. Even with one In such an arrangement, safe operation is more dependent on the present input level.

Ringer receivers or converters

for tone dialing or tone control purposes

for radio systems with selective call systems,

especially for radio networks

with mobile radio systems

Applicant:

South German telephone apparatus ^,

Cable and wire works A. G., TEKADE,

Nuremberg, Allersberger Str. 185

Karl-Heinz Schmall, Baden-Baden,
has been named as the inventor

Compared to the known arrangements, the subject matter of the invention is characterized in that the Total voltage arising on a series resonant circuit and that on a reactance of this The oscillating circuit voltage is connected in series against each other after separate rectification and the resulting total voltage (difference between the rectified voltage amounts) is one Transistor, in the collector circuit of which the switching relay is located, is fed so that the bias of the The transistor can be controlled according to the total voltage and when the ringing frequency is received sets the threshold value for the response of the switching relay.

The progressiveness of the subject of the invention is not due to the known advantages of the transistor compared to the electron tube in terms of space and power requirements. Due to the special Arrangement according to the invention is rather reliable response of the relay largely independent reached by fluctuations in the input level. The circuit arrangement according to the invention makes also from the mutual connection of two Tensions use.

909 607/258

In the arrangement according to the invention, the two are thus with one and the same resonant circuit voltages switched against one another are generated. Since the voltages to be switched against each other according to the Rectification is smoothed by filter elements, becomes a phase dependence of the total voltage largely prevented.

Both voltages connected in opposite directions depend essentially on the input voltage in terms of their size which is due to the circuit. While in addition, in the case of resonance, the voltage drop across a Reactive resistance of the series resonant circuit derived; Tension prevails, wild. at. Lack of the The frequency causing the resonance of the content of the input signal exceeds that of the voltage drop at Total resonant circuit derived DC voltage determine the operating point of the transistor. At high The input level is also a due to the corresponding shift of the operating point of the transistor higher voltage at the reactance of the series resonant circuit for modulating the transistor and thus necessary to respond to the switching relay, and vice versa. This results in a far-reaching one The circuit is independent of fluctuations in the input voltage.

The subject matter of the invention is explained in more detail below with reference to the circuit arrangement shown schematically in the drawing. In the exemplary embodiment shown, the arrangement essentially contains a series resonant circuit made up of an inductance L and a capacitance C as well as a transistor K and the switching relay R. In the case of resonance, the total voltage on the LC circuit is small compared to the voltage on the inductance L. The transistor K becomes preferably formed by a planar transistor, for example of the pnp type, the electrodes of which are denoted by B, C and E. The required control power is below 100 μW. In this case, the transistor is connected in an emitter-base circuit. The switching relay R with a pick-up excitation of about 50AW is connected to the collector C of the transistor K. The operating point of the transistor K is at rest so positioned that via the variable resistor R ₂ and the input resistance R _e (parallel to W \ + W _'2 + W' _s) as a voltage divider to the base B of the transistor K is a negative bias of approximately 300 mV. The negative voltage of the base B causes a relatively high negative current in the collector circuit: That ^; Relay R is picked up.

When an audio frequency signal is received, the frequency of which corresponds to the resonance frequency of the LC circuit, an increased voltage is generated at the secondary winding of L. On the other hand, the voltage drops at the secondary winding of the transformer Tr connected in parallel to the series resonant circuit. Both voltages are rectified by means of rectifiers Gl 1, Gl 2 and connected to one another as DC voltages (in series). Their total voltage, which can become positive, is located via a filter element at the base B of the transistor K and there removes the negative bias. The working characteristic Ic —file) ⁼ f ( ¹ ^ b) of the transistor i? subsequently the collector current I ₀ drops steeply and becomes almost zero. The relay R drops out. .Sein ': Switching criterion'serves', for example, to control the selective call converter. •. The counter-voltage, which comes from the secondary winding of the transformer Tr and which is rectified by durßh.-GII , should not only participate in the switching process via the base circuit of the transistor K. Above all, it also serves to stabilize the mode of operation of the arrangement when the input level fluctuates. This voltage follows, regardless of the frequency, the amplitude at the low-frequency input (parallel to the series resonant circuit). At a high input level, it shifts the operating point of transistor K further into the negative via the counter voltage, so that the voltage, which is also increased at L in this case, if there is no resonance, cannot influence the transistor circuit.

With a suitable dimensioning of the links, the entire Arrangement (above a certain minimum level) largely independent of level fluctuations.

The variable resistor P ₁ is used to adjust the size of the counter voltage. Eq 3 is intended to limit the positive voltage at base B to a maximum value so that the transistor is protected from overload.

ao protects. The bandwidth of the input circuit can be set by means of the variable resistor R _1.

The capacitors C ₁ to C ₃ screen the partial voltages and the total voltage and are dimensioned in such a way that speech protection is guaranteed. ■

It is also possible to combine the base control voltage of the transistor from several partial voltages, which are taken from different audio frequency circuits. Then the operating point of the transistor is set by means of R ₂ so that the relay R can only drop when all positive partial voltages are present. A tone combination of two or more tone frequencies can thus be evaluated.

Claims (4)

Patent claims: 1. Tone call receiver or converter for tone dialing or tone control purposes for radio systems with selective call systems, in particular for radio networks with mobile radio systems, in which a voltage taken from a series resonant circuit tuned to the tone call frequency is fed via a rectifier to an amplifier arrangement with a switching relay connected downstream, characterized in that that the total voltage that arises at the series resonant circuit (L, C) and the voltage that arises across a reactance (L or C) of this resonant circuit are connected to each other in series after separate rectification (Gl 1, GlI) and the resulting total voltage (difference of rectified voltage amounts) is fed to a transistor (K), in whose collector circuit the switching relay (R) is located, so that the bias voltage of the transistor can be controlled according to the total voltage and the threshold value for the response of the switching relay is adjusted when the ringing frequency is received ellt. 2. Ringing receiver or converter according to claim 1, characterized in that the transistor (K) works in an emitter-base circuit with a fixed negative base bias, - the switching relay (R) is attracted in the idle state and the fixed base bias by a voltage divider, consisting of an adjustable resistor (R ₂ ) and the input resistance (R _e ) of the transistor, is adjustable. 3. tone call receiver or converter according to claim 2, characterized in that the sum voltage is connected in parallel to the fixed base bias of the transistor (K). 4. tone call receiver or converter according to claim 1 or one of the following, characterized in that for evaluating several tone call frequencies several tone frequency circuits each with a series resonant circuit and two rectifiers jointly control the transistor (K) . Considered publications: German Patent Specifications Nos. 497115, 585 882; British Patent No. 487,488; "Frequency", 1948, pp. 309 to 311. 1 sheet of drawings