DE2030292C

DE2030292C - Circuit arrangement for a radio receiver with an electronic automatic station search

Info

Publication number: DE2030292C
Application number: DE19702030292
Authority: DE
Inventors: Kurt 3200 Hildesheim Wiedemann
Original assignee: Blaupunkt Werke GmbH, 3200 Hildes heim
Filing date: 1970-06-19
Publication date: 1973-02-15

Description

beitsweise der bisher beschriebenen Schaltung kann Widerstand 19 sowie der Emitter-Kollektor-StreckeBy way of the circuit described so far, resistor 19 and the emitter-collector path can be used

im einzelnen als bekannt vorausgesetzt werden, wo- des Transistors 18, die Zeitkonstante des- Auflade-in detail are assumed to be known, including transistor 18, the time constant of the charging

durch sich eine detaillierte Beschreibung erübrigt. Vorganges verändert. Die Zeitkonstante wird so vera detailed description is unnecessary. Process changed. The time constant is so ver

In dieser bekannten Schaltung (1,2) ist eine Schalt- ändert, daß die Frequenzzunahme pro Zeiteinheit stufe 4 vorgesehen, die dem Widerstand 15 parallel 5 konstant ist, d. h., die Abstimmspannung steigt nicht geschaltet ist Die Schaltstufe 4 besteht aus einem mehr linear an. Statt dessen folgt sie einer Kurve, die Transistor 18, einem im Kollektorzweig liegenden zu Beginn der Abstimmzeit langsam und zum BeWiderstand 19 sowie den beiden Widerständen 20 reichsende hin stetig schneller ansteigt (s. Fig; 2).
und 21, wobei der Widerstand 20 den Emitter mit Die in Fig. 2 dargestellten Kurven zeigen:
der Basis des Transistors 18 verbindet, während der io „ „ , , „„„„„,, _f _ _f _%.
Widerstand 21 die Basis des Transistors 18 mit dem ^Kurve ^a: Empfangsfrequenz f_e - ^u_x)
Punkt 17 verbindet. Die Emitter-Kollektor-Strecke Kurbe b- Diodenkapazität C₀ = f_iUlt)
des Transistors 18 sowie der Widerstand 19 liegen . .
also parallel zu dem Widerstand 15, der ein mitbe- wobei U_R die Abstimmspannung ist, die linear gestimmendes Glied für die Zeitkonstante der Auf- 15 maß Kurve c ansteigt,
ladung des Kondensators 12 ist. Steigt die Abstimmspannung ^r,₍ gemäß den vor-In this known circuit (1, 2) there is a switching change that the frequency increase per time unit stage 4 is provided which is constant 5 parallel to the resistor 15, ie the tuning voltage does not rise. The switching stage 4 consists of a more linear one . Instead, it follows a curve that transistor 18, one located in the collector branch at the beginning of the tuning time, increases slowly and steadily faster towards the resistor 19 and the two resistors 20 (see FIG. 2).
and 21, the resistor 20 showing the emitter with the curves shown in Fig. 2:
the base of the transistor 18 connects, while the io "", """"",, _f _ _f _% .
Resistor 21 the base of transistor 18 with ^curve ^a: receiving frequency f _e - ^ u _x )
Point 17 connects. The emitter-collector path Kurbe b- diode capacitance C ₀ = f _iUlt )
of the transistor 18 and the resistor 19 lie. .
that is, parallel to the resistor 15, which is a co-determinant, U _{R being} the tuning voltage, the linearly tuning member for the time constant of the measurement curve c increases,
charge of the capacitor 12 is. If the tuning voltage ^{r increases} ₍ according to the

Während des Suchlaufs steigt nun die Spannung hergehenden Ausführungen an, so ergibt sich eineDuring the search run, the voltage of the previous versions rises, this results in a

am Punkt 17 an und der Transistor 18 wird über die ähnliche Kurve, wie sie α und b zeigen, so daß dieat point 17 and the transistor 18 is over the similar curve as they show α and b , so that the

beiden Widerstände 20 und 21, die als Spannungs- Kurve/_e =/_(£;_Ä)eine linear ansteigende Gerade wird,both resistors 20 and 21, which becomes a linearly rising straight line _{as a voltage curve / e} = / _(£ ; _Ä),

teiler wirken, derart gesteuert, daß die Parallelschal- 20 Somit ist durch die erfindungsgemäße Schaltungs-divider act, controlled in such a way that the parallel circuit 20 is thus by the circuit according to the invention

tung, bestehend aus dem Widerstand 15 und dem anordnung eine konstante Abstimmsteilheit erreicht.device, consisting of the resistor 15 and the arrangement achieved a constant tuning slope.

Hierzu 1 Blatt Zeichnungen1 sheet of drawings

Claims

1 2 change, since the change in capacitance of the capacitance claims: diodes is not proportional to the change in voltage, d. that is, with a constant increase in voltage, the

1. Circuit arrangement for a radio capacity decrease with increasing voltage always receiver with an electronic transmitter search 5 is lower and consequently the automatic frequency feed, which would take a voltage generator, also decreases. The ratio of the frequency that is required to sweep a tuning range change to the voltage change over an entire receiving range changes by about the factor that is generated when tuning to a transmitter on gate 6. As a result, the pulse duration should also be at its instantaneous value is held and when the search is continued, depending on the position of the station selected by a pulse of constant duration within the frequency band, is continued to be keyed, thereby being marked with changed, since the search during the net that eineta the temporal course the down pulse is already running and not stopped who tuning (üß) Tiit-determining resistance (15) can. This measure would be required ^v to a switching stage (i. Is connected in parallel to prevent their 15 that a transmitter is skipped effective resistance is so adjustable by the Abstimmspan- or the auto scan to the previously introduced alternate voltage (U _R), that the group consisting of The th transmitter slips back. It is therefore necessary to connect the resistor (15) in parallel and to generate a search start pulse, the resistance resulting from the unabrnn switching stage (4) is one gig of the age of the triggering process, the timing of the tuning voltage (U _R ) 20 is mostly triggered by hand. For this purpose, it results in a constant frequency change an electronic pulse generator, which corresponds to pulses per unit of time, delivers constant duration

2. Circuit arrangement according to claim 1, there- frequency change for voltage change with linearly characterized in that the tuning voltage increasing the search run time is not constant, co-determining resistor (15), which in the charging 35 it would be necessary e ^; NEN pulse generator to the circuit of the capacitor (12) of the voltage genes, the pulses of different duration is entsprerators (2), the emitter-Kol'iktor-path according to the ratio of the frequency change to a transistor (18), in the ^c en collector branch voltage change supplies. Such a pulse is present in resistor (19), in parallel with g. ; is switched on, encoder would be expensive and only with a relatively large amount of effort to implement a control line to the base of the transit.

stors (18) bridges the capacitor (12). The invention therefore describes a solution that

3. Circuit arrangement according to one of the on both easy to create, and effective is Proverbs 1 or 2, characterized in that and the deficiency described eliminated in which the base of the transistor (18) of the switching stage (4) the time course the tuning voltage with one hand through a resistor (20) with the 35 tuning resistor a switching stage is switched in parallel geKollektor and on the other hand through another, the effective resistance of which is adjustable through the resistor (21) with an output (17) of the tuning voltage so that the off Voltage generator (2), which generates the tuning span parallel connection of the resistor and the voltage (U _R ). Switching stage resulting resistance a temporal

40 shows the course of the tuning voltage, which corresponds to a constant frequency change per unit of time.

The invention provides a constant

, Tuning steepness reached. This has the consequence that

the automatic station search good start and catch

45 properties for the transmitter.

The invention relates to a circuit arrangement. A drawing is an example of one

for a radio receiver with an electronic station search automatic according to the invention closer

see automatic station search that explains a span. It shows

contains voltage generator, which for sweeping over a Fig. 1 is a circuit diagram of a station search auto tuning range a changing tuning range 50 and

generated voltage that when tuned to a transmitter F i g. 2 the associated diagrams,
is kept at its momentary value fct and at The automatic station search consists of a known station change by means of a pulse of constant duration from a differential amplifier 1 and a further keyed. Voltage generator 2, which is designed as a sawtooth generator It is an electronic transmitter search automatic 55. The differential amplifier 1 is known, bid controls a sawtooth generator used to generate a changing known by a discriminator 3 such ge tuning voltage that the station search is on when tuning. This sawtooth generator delivers a linearly a transmitter is stopped, that is, the steadily changing voltage which is fed to the variable capacitance diodes serving as tuning elements of the sawtooth generator 2. Before 60 held constant. The sawtooth generator 2 preferably consists of a Miller integrator as a sawtooth generator, which is used as an integrator, since with its help it is possible for the Darlington-connected transistor to charge or drain a capacitor 10 and 11 and Load the capacitor 12 built up that oinc is linearly changing tuning span. During the search, the capacitor 12 voltage arises on the capacitor. 65 across the resistors 13, 14, 15 and the diode 16, as is known, changes during the tuning process, charged so that a linearly increasing tuning process; the frequency change can be fed to the voltage capacitance diodes. The ar-