DE1172319B - Method for setting orthogonal equalizers for multi-channel carrier frequency transmission systems - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Kl .: H 04 ra

German class: 21 a2- 36/13

Number: 1172 319

File number: T 24259 VIII a / 21 a2

Filing date: July 10, 1963

Opening day: June 18, 1964

The main patent relates to a method for adjusting orthogonal equalizers for attenuation and Runtime equalization, especially of cosine equalizers, for multi-channel carrier frequency transmission systems, in which the acquisition of the setting criterion through transmission of constantly sent Pilot voltages takes place, the frequencies of which are distributed over the frequency range of the transmission system are evaluated and their level at the receiving end and used to set the orthogonal equalizer will. The setting of the individual equalizer elements is done automatically one after the other by means of in particular, purely electronic adjustment devices carried out step by step.

In the exemplary embodiment of the main patent, the individual pilot voltages are each received on the receiving side Sieved out via a filter and a chain switch which, according to claim 8 of the main patent, is a fully electronic device with bistable flip-flops and diode ports can be supplied, which the pilot voltages successively from the lowest to highest frequency and vice versa in the rhythm of a low-frequency repetition or clock frequency (ζ. B. 400 Hz) periodically to a common high-frequency amplifier with a downstream rectifier switches. The time constant of the rectification is chosen so that at the output of the rectifier the low frequency envelope of the sampled pilot voltages, d. H. the repetition or clock frequency and their harmonics appear. This envelope curve represents a periodic voltage curve over time which simulates the attenuation curve of the transmission path to be equalized and whose spectral amplitudes correspond to the amplitudes of a number of orthogonal functions, in particular one Cosine series. This low-frequency voltage is applied to the inputs of six bandpass filters which sift out the first six components of the low frequency spectrum. The sifted out Low-frequency components are used to adjust six equalizer elements that control the the first six harmonics of the envelope are used.

In multichannel carrier frequency systems, the constantly transmitted pilot voltages are now frequency-wise housed in gaps between the various supergroups of the entire carrier frequency band. For various reasons, these have gaps and thus also the pilot frequencies sent no equal distances from each other. To achieve that the low-frequency envelope of the sampled pilot voltages the method to be equalized for setting orthogonal equalizers for multi-channel carrier frequency transmission systems

Addendum to the patent: 1143 236

Applicant:
Telefunken

Patentverwertungsgesellschaft mb H.,
Ulm / Danube, Elisabethenstr. 3

Named as inventor:

Dipl.-Ing. Joel Korn, Backnang (Württ.)

Faithfully simulating the attenuation curve, the switching times, i.e. H. the time intervals in which the individual pilot frequencies through the chain switch to the common high-frequency amplifier be switched, be correspondingly different. It is necessary that the switching times the individual pilot voltages kept constant as independently of temperature fluctuations as possible so that the effort required for the bandpass filter, which is the components of the low frequency spectrum sieve, can be kept particularly small.

It is known (German Auslegeschrift 1146 124) to build the chain switch from a number of monostable multivibrators, which stimulate each other in a certain sequence with differentiated pulses, the possibly different switching times of the individual pilot voltages being determined by the possibly correspondingly different dimensioning of the monostable multivibrators. Since the resistors and capacitors of the individual multivibrators that determine the switching times have relatively large and widely scattering temperature coefficients, it is difficult to ensure the desired constancy of the switching times over a larger ambient temperature range with such a chain switch.
This disadvantage can be avoided in a chain switch with bistable flip-flops and diode gates according to claim 8 of the main patent in that, according to the invention, a single astable multivariable

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brator with particularly good temperature compensation serves as a central clock generator and a reversible one Counter (digital counter or shift register) from a corresponding number of bistable multivibrators controls and that the individual bistable multivibrators of the counter or switching transistors controlled by the counter in each case according to the time of their response via appropriately designed voltage dividers change the discharge voltage of the capacitors belonging to the astable multivibrator so that the switching times of the chain switch for the associated pilot voltages the desired values own.

Each bistable multivibrator switches an electronic one in a known manner after it has responded Switch by connecting one of the pilot filter outputs to the input of the common high-frequency amplifier connects.

An embodiment of the chain switch according to the invention is shown below with reference to the figure explained.

The astable, symmetrical multivibrator AM comprises two identical transistors Ts ₁ and Ts. ₂ , two identical feedback capacitors C, two identical base series resistors R and two identical collector resistors R '. The latter are connected to the operating voltage U ₁₁ , while the resistors R are connected to the discharge voltage U ₀ , which is controlled by the reversible counter. The period of such a symmetrical astable multivibrator is known

T = 2RCIn (I + U _B / U ₀ ).

A known slide register is used as the reversible counter which, for the sake of clarity, contains only four bistable multivibrators B ₁ , S, B _t and B _i , which are symbolically represented as two-part rectangles with a slash. The shift register is connected in a known manner via series circuits i? /, R. /, R ₃ ', i? ₄ 'of capacitors and resistors brought by a start pulse at one control terminal 1 of the shift register in the starting position in which the multivibrator B _{1 is} excited and the remaining three multivibrators B. ,, B ₃ and S ₄ are in the rest position. Another bistable multivibrator S ₅ , which determines the counting direction of the shift register, is also brought into the starting position by a pulse fed to one input E ₅ of multivibrator B ₅ from output A ₁ of multivibrator B ₁ via a capacitor C ₁ and a diode D ₁ brought, in which there is a low potential at one output A _{5 of} the multivibrator B ₅ and a high potential at the other output Λ _β. As a result, the individual bistable multivibrators connecting, each a diode, a resistor and a capacitor comprising diodes gates DT ₁ , DT ₂ , DT ^ DT ₁ , DT., DT ₆ controlled so that the via a capacitor C ₃ from the astable multivibrator AM pulses arriving at the other control terminal 2 of the shift register shift the excitation state of the multivibrators from left to right up to the last multivibrator B ₄ . As soon as this multivibrator is excited, the multivibrator B _{5 is brought} into the other position by a _{pulse fed through a capacitor C 2} and a diode D ₂ from the output A _{4 of} the multivibrator B _{4 to} the other input E _{6 of} the multivibrator B ₅ there is high potential at output ^ ₅ and low potential at output / I _6. As a result, the diode gates of the shift register are reversed so that the pulses emanating from the astable multivibrator Λ M shift the excitation state of the multivibrators of the shift register from right to left to multivibrator B ₁ . As soon as this multivibrator is excited, the multivibrator is brought into the starting position by a pulse it emits via the capacitor C ₁ and the diode D _{1, thus reversing the counting direction again.} This game repeats itself continuously until the cosine equalizers are set. As already mentioned, the multivibrators S _{1 to S 4,} when excited, cause associated electronic switches (not shown) to be switched through, e.g. B. diode gates, which in turn connect the corresponding pilot filter outputs to the input of the common high-frequency amplifier. This ensures that the pilot voltages are switched through one after the other from the lowest to the highest frequency and vice versa in the rhythm of the low-frequency repetition frequency determined by the astable multivibrator AM.

The outputs A ₁ , A. ,, A _a and A _{4 of} the bistable multivibrators B ₁ , B. ,, S ₃ and S ₄ are via appropriately selected resistors R ₁ , / ?.>, /?., And /? ₄ , each of which has a blocking diode D ₃ , Z) ₄ , D ₅ and D _{6 connected} in series, to terminal U ₀ , a further resistor R being connected between this terminal and terminal O.

As soon as one of the four bistable multivibrators S ₁ , S ₂ , S ₃ , S _{4 of} the shift register is excited, there is a high potential at its output A ₁ or A, or A ₃ or A ₁ , the blocking diodes D ₃ or D ₅ or D ₆ switches permeable, and the discharge voltage U ₀ for the next period of the astable multivibrator is determined by the voltage divider R ₁ ZR ₅ or RJR ₅ or R ₃ ZR ₅ or RJR _{5 fed by this output} . The voltage divider resistors, which are at outputs with a low potential, are decoupled by the associated, in this case high-resistance diodes, so that each bistable multivibrator determines its switching time entirely via the corresponding voltage divider.

If the temperature coefficients of all voltage divider resistors R ₁ , R 1, R ₃ , A ₄ and A _{6 are} chosen to be the same, their influence on the period is eliminated.

Claims (2)

Patent claims: 1. Procedure for setting orthogonal equalizers for attenuation and transit time equalization for multi-channel carrier frequency transmission systems, especially of cosine equalizers, in which the setting criterion is obtained by transmitting constantly sent pilot voltages takes place, the frequencies of which are distributed over the frequency range of the transmission system are evaluated and their level at the receiving end and for setting the orthogonal equalizer can be used in that the individual pilot voltages are screened out through a filter on the receiving side and a chain switch, which switches the pilot voltages one after the other from the lowest to the highest frequency and inverted in the rhythm of a low-frequency repetition frequency (e.g. 400 Hz) periodically switches to a common high-frequency amplifier with a downstream rectifier, the chain switch being a fully electronic device with bistable flip-flops and diode gates, according to claim 8 of patent 1143 236, characterized in that for the chain switch a single astable multivibrator (AM) with particularly good temperature compensation serves as a central clock and a reversible counter (digital counter or shift register) from a corresponding number of bistable multivibrators (B ₁ , B ₂ , Β _Ά , 5 ₄ ) controls and that the individual bistable multivibrators of the counter or switching transistors controlled by the counter, depending on the time of their response via appropriately designed voltage dividers (R ₁ ZR ,, R ₂ IR ₅ , RJR ₅ , RJR ₅ ) the discharge voltage (U ₀ ) of the capacitors (C ) so that the D The switching times of the chain switch for the associated pilot voltages have the desired values. 2. The method according to claim 1, characterized in that the temperature coefficients of all voltage divider resistors (R ₁ , R ₂ , /? ₃ , R _i and R ₅ ) are chosen to be the same. 1 sheet of drawings