RU2124810C1 - Method and system for ensuring intercommunication of two radio-relay stations - Google Patents

Abstract

FIELD: communications engineering. SUBSTANCE: method provides for communication between two radio-relay stations each one radiating microwave information-transfer signal to adjacent station and receiving it from the latter at same carrier frequency with time shared radiation and reception of signal at given station by time-division multiplexed channels. Provision is made at first station for time shift of initiation of received-signal sampling period relative to that of radiated signal which is a multiple of channel interval length. This is attained by measuring delay t_з1.2 of signal radiated by first station, received and re-radiated by second station towards first station, and by changing sampling period T $\genfrac{}{}{0ex}{}{\text{o}}{\text{g}}$ of signal radiated by first station to T_g1 so as to make it satisfy one of conditions

or

, where n is number of channel intervals in sampling period and usually n = 2^l; l = 5 through 9; k is integer number of channel intervals in remainder

; m = 2 through 4; is integer part of quotient. t_з1.2 can be found a priori by any known method, including that used in radio engineering. We propose measuring t_з1.2 prior to starting communications while radiating during certain period single channel interval frame sync signal within every four sampling periods using known method of pulsed range finding. System implementing this method is built up of two radio-relay stations each incorporating series-connected multiplexing equipment, AND gate, separating band filter, transmitter, TRANSMIT-RECEIVE switch with TR tube, and antenna; inserted between antenna output and input of multiplexing equipment synchronizing unit are series-connected second separating band filter and receiver. Series-connected modulating pulse shaper whose second input is connected to output of multiplexing equipment synchronizing unit and inverter whose input is combined with second input of AND gate are inserted between sync pulse generator output of multiplexing equipment and control input of TRANSMIT-RECEIVE switch with TR tube. In addition, series- connected sync pulse selector, delay measuring device whose second input is combined with input of modulating pulse shaper, and sampling period control device are inserted between receiver output and second input of multiplexing equipment synchronizing unit in first station. Second output of delay measuring device is connected to second input of modulating pulse shaper. EFFECT: reduced difference in carrier frequencies of simultaneously received adjacent symbols, simplified design of microwave receiving equipment, improved suppression of radiated signal at microwave receiver input. 4 cl, 2 dwg

Description

 The present invention relates to the field of radio engineering, namely, methods of radio communication between stationary objects. There are known methods of radio communication in which during the transmission of the channel interval the carrier frequency is abruptly changed several times (see, for example, Klimenko N.N., Kisel V.V., Zamarin A.I. "Signals with spreading of the spectrum in information transmission systems", Zarubezhna radio electronics N 11, 19, 80, Moscow, Radio communications, p. 50) or simultaneously emit in the same direction (or omnidirectionally) the same information signal at 2 carrier frequencies.

A device that implements this method is described in the book "Communication Systems and Relay Lines", ed. N.I. Kalashnikova, Communications, M, 1977, p. 108 and contains on one radio relay station (RRS) a series-connected first transmitter operating at a carrier frequency f ₁ , a first band-pass filter that transmits a signal at frequencies f ₁ and f ₂ and an antenna emitting both of these frequencies, as well as a series-connected second transmitter operating at a carrier frequency f ₂ and combined at the input to the first transmitter, and a second band-pass filter transmitting a signal at a frequency f ₂ , the output of which is connected to the second input of the first band-pass filter.

 There is another known, adopted as a prototype, a method of providing duplex communication between two adjacent radio relay stations, for example, a terminal radio relay station (ORS) and a basic radio relay station (BRS), or between ORS and an intermediate radio relay station (ORS), which consists in the fact that each of they are continuously emitted in the direction of each other by a microwave signal, including with temporary channel multiplexing, and the carrier frequencies of these emitted signals are significantly and necessarily different, and each of them continuously receives a signal the cash emitted by the neighboring RRS and weakens upon reception the signal emitted by its own RRS and the signals emitted by other RRS not adjacent to it.

A device that implements this method is given in the book "Communication Systems and Relay Lines", ed. N.I. Kalashnikova, Communications, M, 1977 p. 80. It contains, in particular, terminal radio relay stations (RRS), each of which consists of sealing equipment (AU), the output of which is connected to a series-connected transmitter (P), a band-pass filter (RPF) and a transmitting antenna (A) emitting a signal at a frequency f ₁ , while a receiving antenna (A) receiving a signal at a frequency f _{2 is} connected in series, a second band-pass filter (RPF) and a receiver (PR) are connected to the AU input .

This method, adopted as a prototype, has several disadvantages, the main of which are:
- the need to use two carrier frequencies;
- the need for significant diversity of these carrier frequencies, amounting to several hundred and even thousands of megahertz (see the above literature p. 217), which greatly reduces the speed of information transfer or the number of radio channels (or both) in the selected frequency range;
- the need for serious complication of the equipment to ensure deep attenuation of the reception of interfering signals, primarily radiated by its own RRS, due to the large range between the power of the emitted signal and the sensitivity of the receiver;
- repeated complication of the situation with an increase in the number of trunks (or simultaneously emitted by this RRS in one direction of operating frequencies).

 The proposed method is to some extent free from all these disadvantages.

The essence of the invention lies in the fact that in this RRS emit a signal with temporary channel compaction in the direction of the neighboring RRS and receive a signal from the latter not continuously, but with time separation (i.e., quasi-continuously with duty cycle
Q ≈ 2,
Where
Q = T _d / T _rad .
T _d - the sampling period of the emitted signal,
T _rad - total time spent on radiation for the sampling period).

 In addition, during radiation, reception at this RRS is stopped (blocked) and is carried out after the radiation of the transmitted signal ceases.

 To implement such alternating transmission and reception alternation on both adjacent RRSs, a time shift is immediately provided on each RRS between the beginning of the sampling period of the emitted signal and the beginning of the sampling period of the received signal multiple of the length of the channel interval.

 In turn, in order to achieve a multiple of the shift of the sampling period of the received signal relative to the sampling period of the emitted signal on the first RRS of the channel signal duration, the delay time is measured when the signal propagates from the first RRS to another and is reradiated back and received by the first RRS (or, which is the same thing, range between the first and second RRS) by any known method, including radio engineering.

где
T_д1 - новое значение периода дискретизации;
n - общее число канальных интервалов за период дискретизации (обычно n = 2^l, где l = 5,6...L);
к - число канальных интервалов, составляющих дробную часть частного от деления измеренной задержки t_з1.2 на период дискретизации, к = 1,2,3...(n-1);
m - целая часть от деления измеренной задержки t_з1.2 на период дискретизации.The present invention proposes a measurement of the delay and, consequently, the distance during the propagation of the signal from its radiation from the first RRS towards another RRS return from it and reception on the first RRS. To do this, at the very beginning of work from the first RRS for 18 ... 40 ms once in several (for the current state, four are sufficient, which corresponds to a delay of 600 μs (180 km) when propagating in one direction or about 90 km when propagating there and back) sampling periods (cycles) equal to T $\genfrac{}{}{0ex}{}{\text{o}}{\text{d}}$ = 125 μs, only cyclic synchronization pulses emit. According to the second RRS, they receive this signal, separate it and re-emit the clock signal in the direction of the first RRS (see G.I. Kolesnichenko, V.S.Speransky "Radio-technical systems for transmitting information, study guide, Ministry of Communications of the USSR Moscow Institute of Communications, M ., 1991, p. 23). If the measured delay of the range of the channel interval is not repeated, the sampling period is changed so that it meets the condition

Where
T _d1 - the new value of the sampling period;
n is the total number of channel intervals for the sampling period (usually n = 2 ^l , where l = 5,6 ... L);
k is the number of channel intervals that make up the fractional part of the quotient of the measured delay t _z1.2 by the sampling period, k = 1,2,3 ... (n-1);
m is the integer part of dividing the measured delay t s _1.2 by the sampling period.

В некоторых случаях может оказаться желательным или необходимым, чтобы выходной сигнал имел период дискретизации T $\genfrac{}{}{0ex}{}{\text{°}}{\text{д}}$ = 125 мкс. В этом случае новый период дискретизации должен отвечать условию

где символ E [ ] означает целую часть от частного,
n - число канальных интервалов в периоде дискретизации,
к - 1,2...n.It is obvious that the discrete change in the sampling period ΔT _d should be noticeably less than the duration of one bit of a digital word. For digital microwave links, an 8-bit code is used (see N.P. Markin, "Principles for the Construction of Digital Switching Fields," study guide, Ministry of Communications of the USSR, Moscow Institute of Communications, M, 1991, p. 3), therefore, it is sufficient so that the discretization of the change in the sampling period meets the conditions

In some cases, it may be desirable or necessary for the output to have a sampling period T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ = 125 μs. In this case, the new sampling period must meet the condition

where the symbol E [] means the integer part of the quotient,
n is the number of channel intervals in the sampling period,
k - 1.2 ... n.

Такой выбор T_д1 всегда обеспечивает условие T_д1>T $\genfrac{}{}{0ex}{}{\text{°}}{\text{д}}$ .
Следовательно, в АУ всегда можно выполнить преобразование коммутации в пространстве и времени с частотой дискретизации T $\genfrac{}{}{0ex}{}{\text{°}}{\text{д}}$ = 125 мкс, применив схему пространственно-временного коммутатора, приведенную в литературе (Н. П. Маркин "Принцип построения цифровых коммутационных АТС", стр. 9, 10) путем передачи на управляющую память (УП) сигнала с частотой считывания

Предлагаемый способ дуплексной связи имеет следующие преимущества:
1. Использование для дуплексной связи лишь одной несущей частоты. Это достигается за счет синхронизированного разделения во времени излучения канальных сигналов в направлении соседней РРС попеременно с приемом ее канальных сигналов.The discrete change in the repetition period, as in the previous case, meets the condition

This choice of T _d1 always provides the condition T _d1 > T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ .
Therefore, in AU, it is always possible to carry out the transformation of switching in space and time with a sampling frequency T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ = 125 μs, using the space-time switch circuit shown in the literature (N. P. Markin, “The Principle of Digital Switching ATS Construction,” pp. 9, 10) by transmitting a signal with a readout frequency to the control memory (UP)

The proposed duplex method has the following advantages:
1. Use for duplex communication only one carrier frequency. This is achieved due to the synchronized time separation of the radiation of channel signals in the direction of the adjacent RRS alternately with the reception of its channel signals.

 2. The ability to provide more trunks. This is achieved by the fact that all channel signals of each trunk are emitted simultaneously, as well as all channel signals of all trunks are received simultaneously.

 When a signal is emitted at a single carrier frequency, measures are taken to protect the receiving device, such as blocking the input of the receiver under the influence of the incident power of the penetrating signal of the transmitter, nonreciprocal attenuation of the signal in the receiving path depending on the direction of the power input or polarization of the incoming signal, and introducing controlled deterministic attenuation into reception path. These operations are implemented by devices such as arresters, circulators, polarizing filters and ferrite or diode protection devices, or attenuators.

 The latter ones make it possible to attenuate the incident power of the emitted microwave signal by 100 ... 120 and 60 ... 80 dB HF signal with a switching time of 30 ... 100 ns. If the insertion loss is reduced, the switching time can be obtained even shorter.

 3. Invariance in the number of trunks used is achieved due to the fact that attenuation, even without taking other measures into account, is sufficient so that there is no noticeable effect of the emitted signal on the receiver. Even ten simultaneously emitting transmitters of equal power will not have a noticeable effect on the receiver or receivers without additional measures to attenuate the incident power of the emitted signals.

 4. The possibility of a significant increase in operating frequencies in the selected range. It is achieved due to the fact that the spacing of the carrier frequencies can be very small and is mainly determined by the effect on the receiver (s) of the received signals from an adjacent and more remote RRS. Since for digital transmission methods it is practically possible to neglect any interfering signal with a level lower than the level of the useful signal by 20 dB or more (see the aforementioned book Communication Systems and Radio Relay Lines, page 247), and only significantly weaker signals act on the receiver input, than the signals emitted by its own RRS, it is enough to weaken the out-of-band signals emitted by the neighboring and possibly more distant RRS by 20 ... 30 dB in order to solve the problem of noise immunity of a given barrel from the effects of signals from other barrel ov with significantly less detuning (10 ... 30 times) than in the prototype. This is several times greater than the reduction ≈ twice the number of transmitted channel signals per cycle, characteristic of the proposed method.

 5. Simplification of the receiving equipment and, possibly, the antenna.

 It is achieved because the required attenuation outside the reception band at a given barrel operating frequency is small enough to be implemented with simple filters or with direct conversion receivers.

 6. One transceiver antenna with a circulator (receive-transmit switch) separating the transmitter and antenna paths can easily be dispensed with.

In FIG. 1 is a timing chart explaining the method for the number of channel pulses n = 4, the duration of the sampling period T _d = 8τ _ki , where τ _{ki is the} duration of the channel interval.

t_з1.2= T_д1+τ_ки (m=1;к=1).
Ц.С. - цикловый синхросигнал
С.С. - канал служебной связи
К.С. - канальный сигнал
На фиг. 2 представлена блок-схема устройства, реализующего предлагаемый способ.FIG. 1a - delay of the beginning of the sampling period of the received signal relative to the beginning of the sampling period, equal t t _1.2 = T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ + 3τ _ki (m = 1, k = 3)
FIG. 1b - t _s1.2 = T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ + 2τ _ki (m = 1, k = 2)
FIG. 1c - t _s1.2 = T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ + 1.45τ _ki (m = 1, k = 1.45);

t _z1.2 = T _d1 + τ _ki (m = 1; k = 1).
C.S. - cyclic clock
S.S. - communication channel
K.S. - channel signal
In FIG. 2 presents a block diagram of a device that implements the proposed method.

The device consists of:
1. Sealing equipment (AU)
2. Devices AND (logical adder)
3. The transmitter.

4. The first separation-band filter (RPF)
5. The "transmit-receive" switch with a receiver protection device (RFP with SPD)
6. Antennas
7. Inverter
8. Pulse modulator
9. Receiver
10. The second separation-band filter (RPF)
11. The clock selector (SSI)
12. Delay measurement devices (UIZ)
13. Devices for controlling the period of sampling (UPDD)
The method is implemented as follows (the description implies the use of digital PPC). In the first PPC, digital signals are compressed in time in the compaction apparatus 1 and fed through a logical adder (circuit I) 2 to a transmitter 3, from the output of which a microwave signal with a frequency of f ₁ with pulse-code modulation through a series-connected dividing-band-pass filter 4 and the “receive” switch -transmission "(RFP) with a receiver protection device (SPD) 5 is fed to the antenna 6 and, through it, is radiated in the direction of the second RRS with a duty cycle of ≈ 2. At the moments of emission of the channel signal, the signal received from the second RRS is blocked, Which would be the carrier frequency, he did not. This is ensured by supplying to the second input of the circuit And 2 a meander with a duty cycle of 2 and its inversion, which is obtained using an inverter 7, to the control input of the SPD with USP 5. The square wave is formed by the modulation pulse generating device 8. After the radiation is finished, reception is blocked from the SPP with USP 5 and receive the signal from the second PPC using the receiver 9, pre-filtering it using the second band-pass filter 10. The received signal enters the compaction apparatus 1, including the one located in it lock synchronization (BS) (content compaction equipment 1 disclosed, for example, in the aforementioned book "Communication systems and radio links", p. 38).

The received synchronization pulse, which indicates the beginning of the sampling period in the signal received from the second PPC, is isolated in the clock selector 11 and fed to a delay measurement device (UIZ) 12, the second input of which is supplied with a clock from a synchronization pulse generator (GIS), also contained in the compaction equipment 1. The delay measurement device can be performed by any known method and device, for example, described in the book "Radar Reference", ed. M. Skolnik, vol. 4, M, Sov. Radio, 1978, p. 55. The delay measuring device determines the delay value of the beginning of the sampling period T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ , received from the second PPC signal relative to the beginning of the sampling period T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ in the radiated first PPC signal, as well as its multiplicity of the duration of the channel interval (in Fig. 1 it is T _d / 8). If the multiplicity is integer and odd, then at the output of the pulse shaper modulation 8 form a meander with a pulse duration equal to τ _ki and a repetition period of 2 τ _ky (see Fig. 1a). Thus the output 12 to the input of D & C shaper modulation pulses supplied logical 0. If the delay is integer and odd multiplicity (in this case the output 12 is fed Weese logic 1), then outputs a modulation pulse shaper 8 square wave with a pulse width equal to 2τ _ki, and a period of 4τ _ki (see Fig. 1b). If the delay factor is not integer and exceeds an odd number (see Fig. 1c), then from the output of the UIZ 12 to the pulse shaper modulation 8 serves a logical 0 (zero), and from the other output a control signal that is not equal to zero is sent to the input of the control device the sampling period (UPDD) 13, which is, for example, an integrator with memory. The control signal from the output of the SPD 12 leads to the appearance of a signal at the output of the UPDF 13 that goes to the input of the synchronization unit in the compaction apparatus 1 and causes an increase in the sampling period T _d1 until the delay on becomes an odd integer value dτ _ki1 , where d = 1 , 3 ... n-1 (see Fig. 1c). In this case, the control signal from the output of the UIZ 12 will become equal to zero, the pulse width of the meander is equal to τ _ki1 , and the repetition period of 2τ _ki1 . If the delay factor is non-integer and exceeds an even number h, then from the output of the UIZ 12 to the modulation pulse shaper 8, the corresponding command (logical 1) is sent, and from the other output a control signal is supplied that is not equal to zero, to the input of the DAC 13, under the influence of which the output receives a control signal. This signal is fed to the input of the compaction equipment 1 (to the synchronization unit contained in it), as a result of which the sampling period is increased to a value of T _d1 , at which the delay becomes an integer multiple of the duration of the channel interval hτ _ki1 , where h = 2.4 ... n . In this case, the control signal from the output of the UPDD 13 becomes equal to zero. Accordingly, the meander pulse duration will be 2τ _ki1 , and the repetition period will be 4τ _{ki1 /} .

где обозначение E [ ] означает целую часть от частного.The microwave signal emitted by the first RRS (for example, a sync group) at a frequency f ₁ on the second RRS is selected in space using an antenna 6 and transmitted through the receive-transmit switch with the receiver protection device 4 to the input of the band-pass filter 10, in which it is filtered and fed to the input of the receiver 9. The received clock signal is fed to the BS synchronization block contained in the compaction apparatus 1, for phasing and equalizing the duration of the sampling period on the second RRS with a sampling period on the first RRS, which the beginning of work should be equal to T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ = 125 μs. After an interval of duration τ _{ki, the} meander pulse from the output of the modulation pulse shaper 8 will change polarity and thereby open the input of transmitter 3 for supplying a channel signal from the output of the compaction equipment 1 through the And circuit and simultaneously block the reception of signals in receiver 9. This is achieved by applying a switch to the control input "transmit-receive" with the protection device of the receiver 5 inverted in the inverter 7 of the meander pulse. The microwave signal from the output of the transmitter 3 with a frequency of f ₁ (one or two channel intervals, depending on the multiplicity of the delay measured on the first RRS t _{t1.2 the} duration of the channel interval τ _ki ) is filtered out in a band-pass filter 4, transmitted through the receive-transmit switch with the protection device of the receiver 5 to the antenna 6 and emit in the direction of the first RRS. Thus, each of the RRS blocks the reception of signals during transmission and radiation on a given RRS and synchronizes its work with the other, the first acting as the active side and the other as passive, adapting to the reception parameters specified by the first - radiation and T _d values. It should be noted that in the case of a discrete change in jΔT _{d, the} quantity T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ sampling period from T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ up to T _d1 , then the value of ΔT _d should not exceed the value of T _d / 64n, since the capacity of the transmitted code is 8. The delay t t _1.2 (or range corresponding to it) can be determined by any known method, including radio engineering, and must be entered in the delay measurement unit. At the same time, using the available equipment described above, it is possible to measure the value of t _З1.2 directly or as the remaining fractional part of dividing the value of t _З1.2 by the standard sampling period T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ = 125 μs, i.e.

where the notation E [] means the integer part of the quotient.

См. вышеупомянутую книгу "Системы связи и радиорелейные линии", стр. 80) только синхроимпульсы в течение отрезка времени 18...40 мс и измеряют задержку t_з1.2 и ее кратность величине τ_ки посредством УИЗ 12. Данные о нечетности или четности кратности t_з1.2 величине τ_ки передают из первой РРС на вторую РРС по каналу служебной связи.For this, before starting the normal operation, they radiate once for four sampling periods T $\genfrac{}{}{0ex}{}{\text{°}}{\text{d}}$ (this is quite enough, since the distance between radio relay stations R _1.2 does not exceed 70 km, i.e.

See the aforementioned book “Communication Systems and Relay Lines”, p. 80) only clock pulses for a period of 18 ... 40 ms and measure the delay t _z1.2 and its multiplicity to the value of τ _ki by means of UI 12. Data about oddness or parity multiplicity t _{z1.2 the} value of τ _{ki is} transmitted from the first RRS to the second RRS through the communication channel.

Claims (4)

1. A method of providing communication between two radio relay stations (RRS), which consists in the fact that each of them radiates a microwave signal carrier information in the direction of each other and each receives a radiated adjacent RRS microwave signal, characterized in that each RRS radiates in the direction of the neighboring RRS and receives from it a microwave signal at the same carrier frequency with time separation of radiation and reception on a given RRS signal with temporary channel multiplexing and provide on the first RRS a time shift of the beginning of the sampling period emogo signal relative to the sampling period of the signal emitted by multiple slot duration, wherein the measured signal delay _z1.2 t, PPC emitted first received PPC and reradiated in the second direction of the first and changed RRS signal sampling period T $\genfrac{}{}{0ex}{}{\text{0}}{\text{g}}$ on T _g1 emitted by the first PPC, so that it meets the condition
t _z1.2 = T _g1 (m + k / n),
Where

symbol E | | means the integer part of the quotient, usually n = 2 ^l , l = 5 ... 9;
k is the integer number of channel intervals located in the remainder t _s1.2 - m T _g1 , k = 1, 2, 3, ..., (n - 1). 2. The method according to claim 1, characterized in that after measuring the delay of the signal increase the sampling period so that it meets the condition

where n is the number of channel intervals in the sampling period;
k is the integer number of channel intervals located in the remainder t _z1.2 - m • 125 • 10 ^-6 , while the dimension t _z1.2 is a second. 3. The method according to p. 1 or 2, characterized in that initially, before normal operation, they include several times a single channel interval of cyclic synchronization for four or more adjacent synchronization periods, in total exceeding the maximum delay value t _{z 1.2} , and measure it, after which, in the case of a multiple of the measured delay t _{z1.2 the} duration of the channel interval τ _ki , measure the value of T $\genfrac{}{}{0ex}{}{\text{o}}{\text{g}}$ with a discrete ΔT _g satisfying the condition ΔT _g <T0 / 64n until the delay becomes an odd integer d • τ _ki , where d = 1, 3, 5, ..., n - 1.  4. A digital radio communication system of two radio relay stations (RRS), each of which consists of an antenna, a series-connected transmitter and a band-pass filter, and also a series-connected second band-pass filter, receiver and compaction equipment, characterized in that in each RRS the first output of the sealing equipment is connected through the And element to the transmitter, and the output of the dividing-band filter through the receive - transmit switch with the receiver protection device to the antenna, the output is formed For modulation pulses, the corresponding inputs of which are connected to the outputs of the synchronization pulse generator of the compaction equipment and the synchronization unit of the compaction equipment, is connected directly to the And element and through the inverter to the control input of the switch is receiving - transmitting with a receiver protection device, the output of which is connected to the input of the second dividing-band filter, in addition, in the first RRS additionally introduced sequentially connected clock selector, delay measurement device and device of your control of the sampling period and are connected between the output of the receiver and the corresponding input of the synchronization unit of the compaction equipment, the second input of the delay measuring device is combined with the input of the modulation pulse shaper connected to the synchronization pulse generator, and the third input of the modulation pulse shaper is connected to the second output of the delay measuring device.

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