DE2123806C - Clock generator for the electronic receiving circuits of a teletype machine - Google Patents

Description

35

The invention relates to a start-stop operation suitable teletypewriter with receiver formed from electronic circuits, wherein clock signals generated by a clock generator with the participation of several frequency dividers, whose The period duration to the step duration of the telex characters are in a predetermined ratio, both the scanning of the telex characters and the cycle time of the shift register Control the receiver.

The main patent relates to a teletypewriter of the type mentioned above, which by switching the clock frequency, which is derived from a clock generator via a chain of divider stages, to different Working speeds is adjustable. You can choose to change one or more levels or can be switched off.

The invention has for its object to provide a device with the help of which it is with little Effort, in particular without replacing the oscillating quartz, is possible, the receiver optionally not only at working speeds with whole multiples of 25 Bd, e.g. B. 50, 75, 100, 150 or 200 Bd, but also set to 110 Bd to be able to, i.e. a working speed that is not an integral multiple of 25 Bd.

According to the invention, this can be carried out in such a way that a clock generator is used to achieve switchability of the clock frequency in the ratio 10: 11: 15: 20, the frequency of which is selected so that it is suitable for telegraphing speeds 100, 150 and 200 Bd differs from the clock frequency by an integer multiple of 11, but for the telegram speed HOBd by an integer multiple of 10, and that a frequency divider is used, the Ki HK; 150 and 200 Bd a division ratio of 1:! ! at 1 K) Ba, however, a division ratio of 1:10 au; shows.

In a preferred embodiment of the Erti: v manure is apart from bistable multivibrators as frequency divider stages, which can be switched off in a known manner from a division ratio of 1: 3 to 1: 4, and around reverses, are switchable, one of several bistable,;. Flip-flops of existing complex counter building skis :. provided, which can be switched from a divider ratio of 1: 10 to 1:11 and vice versa by means of external gates is.

An embodiment of the invention is described below and shown in the drawing

Tig. 1 a block diagram of the clock frequency on » electronic telex receiver,

F i g. 2 a circuit of the switchable frequency divider assembly,

Fig. 3 to 6 timing diagrams for the umschali divider assemblies according to FIG. 2.

In an electronic telex receiver circuit arrangement of a type known per se, the teletype characters received bit-serially are converted into parallel form in a shift register. The shift clock T for the shift register is derived from a quartz generator TG via two multi-stage frequency dividers UT and FT. The frequency divider UT (transferable divider) consists of a series connection of switchable frequency divider assemblies (FIG. 2); the frequency divider FT (fixed divider) has a constant division ratio of 1:40.

The divider circuit UT is made up of six bistable flip-flops Kl ... K 6, a complex counter module B and various gates G 1 ... G 10. The flip-flops Kl, KA ... K6 are each connected as a 1: 2 divider, Kl and K 3 together optionally as a 1: 3 or 1: 4 divider and module B optionally as a 1:10 or 1:11 divider. The tilting stage Kl can optionally be switched on or off. The desired frequencies of the step cycles can be generated by the following combinations of the switchable individual division ratios if the frequency divider UT shown is followed by a further FT frequency divider with a division ratio of 1:40 and the generator frequency is 2.112 MHz.

Generator frequency 2.112 MHz, divided by 2-3-11 -2 -2 -2 -40 = - 100 Hz 2 3 10 2 2 2 40 = 110 Hz 1 4 11 2 2 2 40 150Hz

1 x 3 x 11 x 2 x 2 x 2 x 40-200 Hz

In principle, the flip-flops K4 ... K6 are also omitted if a generator frequency lower by a factor of 8 would be used, but once there is 2 _; il2 MHz in a very favorable manufacturing range for crystals and on the other hand, the output frequency of the frequency divider UT must have a symmetrical duty cycle. (There are asymmetrical clocks at the outputs of K 3 and B, respectively.)

The switchover from the division ratio 1: 1 to I: 2, and vice versa, in the area of the flip-flop K 1 is done with the help of gates G3, G4 and GS. With 1: 1 switch-on, Kl is statically deleted, the general local cycle is sent undivided to K 2 via G 4 and G 5. With 1: 2 switch-on, the static reset is not effective and the rerouting of the generator cycle via G 4 is blocked.

When the divider ratio 1: 4 is switched on for the flip-flop K 2 and / C 3, in contrast to the 1: 3 connection, the return of the flip-flop K 3 to the static reset input is ineffective. (See pulse diagram according to FIGS. 3 and 4 with indication of the (see pulse diagram ... "- · ·, pulse ratios in lines a, b, c.) Of the pulse ratios in

1 sheet of drawings

Claims (2)

Patent claims: 1. Clock generator for the electronic receiving circuits of a teletypewriter, weleher enables different working speeds by switching the clock frequency, which is derived from the clock generator via a chain of divider stages, of which either one or more stages can be switched or switched off, according to patent 1907 013, characterized in that, that to achieve a switchability of the clock frequency in relation K): 11: 15: 20 a clock generator to use arrives whose frequency is chosen so that it is suitable for the telegraph speeds 100, 150 and 200 Bd by an integer multiple of 1 i, but 110 Bd for the engraving speed differs by an integer multiple of 10 from the clock frequency, and that a rrequcnzleiler is used, which has a division ratio of 1: 11 at 100, 150 and 200 Bd, and 110 Bd but has a division ratio of 1:10. 2. Teletypewriter according to claim 1, characterized in that apart from bistable multivibrators as frequency divider stages which can be switched off in a known manner or from a division ratio I: 3 to 1: 4 and vice versa, a complex counter module consisting of several bistable multivibrators (B) is provided, which can be switched from a division ratio of 1:10 to 1:11 and vice versa by means of external gates.