FR2535132A1 - AUTOMATICALLY ADJUSTABLE EQUALIZATION NETWORK - Google Patents

Abstract

THIS AUTOMATICALLY ADJUSTABLE EQUALIZING NETWORK, INCLUDING SEVERAL ADJUSTMENT NETWORKS MOUNTED IN SERIES I, IV, THAT CAN BE CONTROLLED BY THE SAME CONTINUOUS VOLTAGE DERIVED FROM A PEAK DETECTOR 6, IS CHARACTERIZED IN THAT EACH REGULATION NETWORK I, IV IS CONNECTED TO ANOTHER REFERENCE VOLTAGE SO AS TO BECOME ACTIVE AFTER THE PREVIOUS NETWORK HAS REACHED ITS EXTREME ADJUSTMENT POSITION. APPLICATION: CODED PULSE MODULATION TRANSMISSIONS.

Description

-1 - "Equalization network automatically adjustable"

  The invention relates to an automatic equalization network

  adjustable, with several adjustment networks mounted in

  which are controlled by the same adjustment voltage derived from a

orgte detector.

  These automatic equalization networks are used, for example for coded pulse modulation transmission systems. In such a transzmation system, the transmission characteristic of the transmission path, which is constituted by the cable in omb xcs, is a function of the distance between the second and the second, and the ambient temperature, as well as uniformly, and as closely as possible, n. fcaterlIlegalization _necessary for-; regeneration has been carried out in the country, where it is carried out in a

  the Asian standard of the transmission characteristic

  - where it is transmitted, of length, nominal at the temperature

  in an adjustable section 2 for the equalization

  In comparison with this characteristic feature, these values are caused by deviations in practice from the length of time.

  This is the nominal signal for the setting signal.

  It can be obtained by means of a cir-

  and the Iotatu of the flow connected to the outlet 121 and the output signal of the cedetals for the equalizing anorlizer to the ngueu d or to a value of -cîr and it is In other conditions, it may be that a scale of magnitude has been extended that an equalization resonates at the same time, as well as for a system of Iodlula 2-channel, M-bits on ubiquitous ubiquitous cottons.

  n = 6 d 'P 3 for> 42224 1-iz 2, ie half the frequency

  bit) Cc-tt 1 st extended range gamma is required, because of

  Geographical graphs, the lengths of sections

  the 1 can, elmetêrz strongly bribut areas of the di Japho-

-2-

  close in the symmetric cables For precision design

  tion, it is important to obtain the phase linearity of the equali-

  because in the case of switching between configurations

  in the case of data transmission, the non-linearity

  that instability in the clock frequency (instability of

  tation) To keep the phase linear throughout the entire range of

  equalization, the attenuation of the cable must also be

  practically up to the bit rate This implies that when an adjustment excursion of 56 d B is requested at half the

  bit frequency it takes a setting excursion of 79 d B

  te the bit frequency It is not possible to realize this range

  very wide tuning using a single simple equalization network.

  In this case, several equalization networks are mounted in series.

  their amplifications being established simultaneously with the aid of a

control circuit.

  The simultaneous establishment of several networks has the disadvantage that an addition of the adjustment errors occurs in

  the various networks in the upper part of the frequency band

this; which is undesirable.

  The invention aims to indicate a solution for the aforementioned problem and is characterized in that each regulator network is connected to another reference voltage so that each network

  regulator is only activated after the previous network has

dyes its extreme position.

  The following description, with reference to the drawings

  nexés, all given as a non-limitative example, will make a good

  take how the invention can be realized.

  Figure 1 shows an equalizing network according to the invention. Figure 2 illustrates a possible embodiment of the

  equalizing network according to Figure 1.

  Figure 3 represents a diagram illustrating the function

  of the equalizing network according to the invention.

  The equalizing network according to FIG. 1 comprises the series connection of the control networks I to IV. At the input 1 of the network I is fed the input signal to be equalized. The output signal of the network IV is supplied via a filter 7 at the output 8 of the network

2535 132

-3-

  equalizer Output 8 is connected via a

  6 to the control inputs 2, 3, 4 and 5 of the respective control networks I to IV The reference voltage inputs 16, 14, 12 and 10 of the respective control networks I, II, III and IV are

  each connected to a different point of the voltage divider con-

  by the resistors 17, 15, 13 and 11 Said voltage divider

  inserted between points 18 and 9, to which the

  supply voltage for the equalizing network In the resistors, 13 and 11 are generated the respective threshold voltages U1, U2 and U3. These threshold voltages cooperate with the control signals

  brought to inputs 2, 3, 4 and 5 so that a control network

  before the previous tuning network has been

  dyes its extreme setting position As will be explained below

  afterwards, this implies that the preceding adjustment network occupies its nominal position without error. This can be a maximum position

  or a minimum position, depending on the required equalization This implies

  that in equalizing networks according to the invention, only

  the setting error of the following setting network is of importance.

  When setting the next controller network, all other networks

  are in the nominal position without error and do not

  therefore do not interfere with the total adjustment error of the equalizing network

  that the control networks themselves also present the

  DC plenum for the control voltage

  The difference between two successive reference voltages does not necessarily exceed 0.2 V, a non-critical value. To be absolutely sure that the control networks are successively actuated, the said slightly greater difference is chosen, for example at least 0.3 V.

  The high amplification in the control loop ensures

  automatic adjustment of the following control network in the case where one of the control networks has reached its extreme position and thus avoids

the formation of hiatus.

  In the exemplary embodiment of the equalizing grating according to FIG. 2, the control network I comprises transistors 20 to 25,

  the amplifier 29, the resistors 26, 27 and 28, as well as the

  40, 41, 42, 43 and 44 The various control voltages are formed by the voltage divider constituted by the series connection

  resistors 13 and 17 -; this voltage divider is inserted in

  -4- be the points 12 and 18 of the equalizing network The input signal to

  V (i) is fed to the input terminal 1 of an impedance network

  This impedance network is coupled to the two regulatory networks I and II. The output of the impedance network is fed to a filter 7 having the prescribed transmission characteristic, for example a Nyquist filter; to the output

  8, the output signal is taken and from this signal a

  The control signal is generated by means of the peak detector 6 for the control of the amplification of the two regulator networks I and II. The regulator network I comprises an amplifier 29 which has a

  amplification equal to or greater than unity, the output of which is

  connected to the point of connection of impedances 44 and 45 and whose input

  is connected to the connection points of the collectors of the two tran-

  sistors 20 and 22 Said connection point is also connected to point 12 via a resistor 26

  transistors 20 and 21 are connected together at point 18 through

  intermediary of the serial connection of the collector-transmitter path of the tran-

  sistor 24 and resistor 26 The base of transistor 24 is con-

  connected to the point of connection of the impedances 40 and 41 The emitters of the two transistors 22 and 23 are connected together at the point 18 via the series connection of the collector-emitter path of the transistor 25 and the resistor 28 The base of the transistor 25 is connected to the point of connection of the impedances 43 and 44 The point of

  connection of impedances 41 and 43 is connected to point 18 by the

  The basis of the two transistors 21, 22

  are connected together at the connection point 16 of the two resis-

  these 15 and 17 of the voltage divider; this connection point constitutes the reference voltage input of the regulator network I. The bases of the two transistors 20 and 23 are connected to the control input 2 of the regulator network I.

  The regulator network II comprises a pre-amplifier 39

  feeling amplification greater than or equal to unity; the exit

  of this amplifier 39 is connected to the connection point of the

  and impedance 49 and the input of the filter 7 while its input, is con-

  connected to the connection point of the collectors of the two transistors 30 and 32 to the latter connection point is also connected the resistor 36 connected to point 12 the emitters of the transistors 30 -5-

  and 31 are connected together at point 18 via the

  The base of the transistor 34 is connected to the point of connection of the impedances 45 and 46 The emitters of the two transistors 32 and 33 are connected together to the point 18 via the intermediate channel of the collector-emitter path of the transistor 34 and the resistor 37. of the series connection of the collector-emitter path of the transistor 35 and the resistor 38 The base of the transistor 35 is connected to the

  connection of impedances 48 and 49, the point of connection of the impedances

  these 46 and 48 is connected to point 18 via the

  The bases of the two transistors 31, 32 are connected together.

  i at the connection point 14 of the two resistors 13 and 15 of the

  This point of connection is the gateway to tension.

  The bases of the two transistors 30 and 32 are connected to the control unit 3 of the respective control networks and 11 and via the

  A (peak 6 at output 8 of the equalizing network

  Transistors 31 and 33 are connected together at point 12.

  When it is assumed that the adjusting voltage of the peak detector 6 is such that the potential at the bases of the transistors 20 and 23 3 S Cit negative with respect to the potential at the bases of the transistors 21, 22, the transistors 20 and 23 are blocked and the transistors 21 and

  The input signal present at input 1 is applied

  that at C transistors 25 and 22 at the input of the amplifier 29 by means of the basic lines 40, 41, 42 and 43. In this case, the input of the dots at inexon 50 impedances 43 and 44 constitutes 1 input of

  -: insl proe rme t of the amplifying part of the network of re-

  The total allowance is the sum of the amplifications of the

  In this case, the requirement

  dance is inserted between the exit and the entrance of the anplifica-

  The input signal V (i) arrives from the

  9 was held by I intermediate imlpédances> 04, 41, 42 and 43 at the entree of 50 proper signal of the amplifying portion of the network ie IT adjustment while only the impedance 44 is present in

  reaction eounlage of the instructing party of the network of re-

  In the case in question, the maximum attenuation

  compared to the nominal rating, see Figure 3a.

  When it is assumed that the adjustment voltage of the peak detector 6 is such that the base potential of the transistors 20 and 23 is positive with respect to the potential at the base of the transistors 21, 22, the transistors 20 and 23 are conductive and the transistors 21, 22

  are blocked The input signal presented at input 1 is also pre-

  at the input of the amplifier 29 via the

  dance 40 and transistors 24 and 20 In this case, the point of con-

  connection 51 of the impedances 40 and 41 constitutes the signal input

  of the amplifying part of the control network I.

  Total amplification is the sum of the amplifications of the

  twisted 24 and 20 and the amplifier 29 In this case, the impedances

  41, 42, 43 and 44 are provided between the exit and the entrance of the

  amplifying part of the control network I The input signal V (i)

  can not be mitigated by means of the impedance 40 at the

  signal itself 51 of the amplifying part of the

  control bucket I, while the impedances 41, 42, 43 and 44 are present in the reaction coupling of the amplifying portion of the

  In the case in question, there is an am-

  maximum fold with respect to the nominal amplification, see

figure 3 b.

  In all other setting positions of the network,

  In this example, the input of the amplifier 29 is connected to another point of the series connection of the impedances 41 and 43 located between the points 50 and 51. The nominal amplification occurs when all the transistors 20 to 23 are conducting in the same direction. When the two impedances 41 and 43 have the same value, this implies that the input of the amplifier 29 is connected to the connection point 52

impedances 41 and 43.

  For an ideal equalization setting, the following relation is generally applied: F (w) = F 1 (w) + F 2 (w) F 3 (<> e) (1) expression in which F 1 (w) represents a constant weakening

  which depends on the frequency and which may already be pre-

  in the setting or can be obtained by a downstream

  upstream of separate fixed equalizing networks and / or amplifiers

  In the exemplary embodiment according to FIG. 2, F 1 (w) is produced for example by means of the Nyquist filter 7 F 2 (w) represents the requested adjustment characteristic and is realized using the

2535 1 32

  -7- Imnédances 40 to 49 F 3 (O <) is a function that is proportional to the set voltage or current supplied by the peak detector

  Figure 3c is a graph showing the characteristic of adjustment

  ge. The adjustment characteristic for Co≤ 1 corresponds to the adjustment position according to Figure 3b, the adjustment characteristic for C≤O corresponds to the adjustment position according to Figure 3a and the adjustment characteristic for Oc = 1 / 2 corresponds in the case where the input of the amplifier 29 is connected to the point 52 In all these three cases, it was made that the adjustment error is equal to O (three-point adjustment) For all the others values of it occurs a setting error i, as indicated

  for example in Figure 3 c for O C = 3/4 and C> = 1/4.

  This is due to the fact that in the case of

  of the transmission formula, it occurs in addition to the term

  f 2 (w) 3 F 3 (04) also a series of harmonic terms su

  odd-numbered peritons having the form F 2 (w) 3 F 3 (w) 3 + In the case of an intermediate position, for example O <= 3/4, the amplification at the higher frequencies decreases much more rapidly and not proportionally because of higher harmonic terms than in the case of lower frequencies, because the influence of these terms is noticeably lower.

  when several control networks are mounted a priori successively

  In this case, the adjustment errors of the separate control networks are adjusted, which can lead to a total adjustment error which

is no longer eligible.

  In the exemplary embodiment according to FIG. 2, the reference voltage input i 4 of the regulation network II is connected to a point of the voltage divider constituted by the resistors 13, 15 and

  17; this point is greater than that of the referenced voltage

  By means of the resistor 15 is generated the differential voltage required between the two arrays.

  setting I and II, this difference is such that the space of com-

  between points 13 and 16 of the control network II and the

  points 2 and 16 of the control network I do not have

  This implies that when one of the amplifiers

  setting I or II is set, the other adjustment amplifier

  -8- ge II or I is established in one of the final adjustment positions

  without error for C> = O or Q <> = 1, see Figure 3 c.

  Thus, only one adjustment network is set, so that the total adjustment error is always equal to the error

  setting this single network set.

  As we know, the noise factor of an equalized network

  is increased by an impedance network at the input by an amount equal to the attenuation of this impedance network In the case of large cable sections, that is to say a low level of entrance, he

  It is therefore important that the control network at the entrance of the equalized network

  In this case, the impedance network is inserted into the feedback coupling loop of the control network. This network can only operate after the cable length has become sufficiently short and that

  following control networks have reached their minimum ex-

  trane (c≤ 0) Thus, this adjustment principle is not only

  important to reduce the adjustment error but also the influence

  noise, the latter being also decisive for the order of

  succession of setting of cascaded control networks.

-9

Claims (1)

CLAIMS:   1 automatically adjustable equalization network, with several series-regulated control networks, which are controlled by   the same setting voltage derived from a peak detector,   in that each control network (I), (IV) is connected to   another reference voltage so as to enter into service only   the previous network has reached its ex- The reme.   Equalizing network automatically adjustable according to the   ieation 1 in which each control network is provided with a   reseed voltage (10, 12, 14, 16) characterized in that   the reference voltage input (10, 12, 14, 16) of the control networks   4, III, II, I) are connected to each other point of a voltage divider (11, 13, 15, 17) which is inserted between two feed points (9, 18) between which connected a voltage (3).