JPH03280739A - Reception timing phase setting system in digital signal transmission and reception circuit - Google Patents

Abstract

PURPOSE:To reduce the test time of a transmission reception circuit required for loopback and introduction of test by adjusting a phase so as to start training in an optimum reception timing retarded by a prescribed phase from a transmis sion timing. CONSTITUTION:In the case of 2-way communication by master and slave trans mission reception circuits 101, 102, when a transmission timing of the circuit 101 is set to tauMT=0, the reception timing phase tauSR of the circuit 102 depends on the phase tauSR=T1+taud, being the sum of the delay phase T1 of the optimum reception timing and the transmission line delay taud with respect to a pulse waveform sent at tauMT=0. Moreover, the transmission timing phase tauST of the circuit 102 is expressed as tauST=taud. Then the reception timing phase of the circuit 101 is expressed as tauMR=T1+2taud. Thus, when the training is started in the optimum reception timing delayed by a prescribed phase from the trans mission timing at loopback, the training time is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reception timing phase setting method in a digital signal transmission/reception circuit.

[Conventional technology]

Conventionally, when performing bidirectional digital communication between two transmitter/receiver circuits, in order to absorb fluctuations in transmission path delay, there is a transmission timing at which the transmission waveform is sent out, and a reception timing at which the reception signal is punched out to restore the reception symbols. Often independent.

In addition, when operating two communicating transmitter/receiver circuits in slave synchronization, one is set as the master and the other is the slave, and the reception timing on the slave side matches the optimal phase of the signal in the master-slave direction, which is determined by the transmission timing on the master side. For slave synchronization, the transmission timing on the slave side is the same as the reception timing on the slave side, and the reception timing on the master side is set to match the optimum phase of the signal in the master direction. It is common to remove slave synchronization, '5.

, 2, etc., are performed in the stage before the step f3, which is called ``total 1 training''.

FIG. 3 is a diagram showing the phase relationship of transmission and reception timing in normal digital communication. Master side transmitting/receiving circuit〕
Assuming that the transmission timing phase τ of 10 is 70, the reception tie of the transmission/reception circuit 200 on the slave side, the mink phase τ,
0 is determined by -rMT=O and the phase τ, which is the sum of the delay phase T1 of the optimal reception timing for the sender=pulse waveform and the transmission path delay τ(d), . Sl/
- Transmission timing of the transmitter/receiver circuit 200 on the side and phase τs
1 is τS T ”τ5I. Similarly, the reception timing phase τ of the transmitter/receiver circuit 11.0 on the master side is !-
Therefore, τMR=2(T,+τ(d)).

[Problem to be solved by the invention]

In recent years, the f-1/·-=〉·g time for tie and mink phase adjustment has increased from several seconds to several -4 seconds in the Echo Gyan-type transmission equipment for ISDN basic access. There is. L statement 1. Conventional technology involves the operation of connecting the transmitter/receiver circuit to the transmitter/receiver circuit, especially when testing the transmitter/receiver circuit, and the operation of returning the signal from the transmitter circuit to the own receiver circuit via line 5. When a loopback operation is performed in a system including a large number of circuits, the loopback operation is sequentially performed line by line, which has the disadvantage that the total test time becomes enormous.

[Means to solve the problem]

The receiving timing phase setting method in the digital signal transmitting/receiving circuit of the present invention includes two digital signal transmitting/receiving circuits including a transmitting circuit that sends out a transmitted waveform according to the transmitting timing, and a receiving circuit that punches out the received signal and restores the received symbol according to the receiving timing. One side is the master side and the other side is the slave side, and when two-way communication is performed through a line between these two digital signal transmitting/receiving circuits, the digital signal transmitting/receiving circuit operating on the slave side has its reception timing set to the transmit timing. The digital signal transmitting/receiving circuit, which is configured to be delayed by a certain phase from the timing, and which operates on the master side, also starts training from a phase that is a certain amount mutually different from the transmission timing. The optimal reception timing is obtained during the loopback type test I, which loops back the signal to the receiving circuit through the line (-), and the propagation delay of the digital signal through the line does not delay the phase of the reception timing. A feature is that when performing two-way communication under short-distance conditions, the optimum reception timing on the master side is matched.

r Example] Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram of a transmitting/receiving circuit showing an embodiment of the present invention;
FIG. 2 is a diagram showing the phase relationship of transmission and reception timing in an embodiment of the present invention.

In FIG. 1, the transmitter/receiver circuit 1. OO is a transmitting circuit] and
It includes a receiving circuit 2 and a delay circuit 3, and the delay circuit 3 delays the phase of the transmission timing ta by a delay phase T1.

Next, the operation of this embodiment will be explained using FIG. 2.

In FIG. 1, a transmitting circuit 1 converts an inputted transmitting symbol A into a transmitting signal B according to a transmitting timing taU and outputs the converted signal. On the other hand, the receiving circuit 2 transmits the received signal C received from the other party's transmitting/receiving circuit by the delay circuit 3 at the transmission timing t.
Delayed phase T1t, reception timing tb delayed by 5 orders of magnitude from a
The delay circuit 3 of the slave side transmitting/receiving circuit 1.02, which punches out the received symbol D and outputs it, always operates to delay by a fixed delay phase T1, but the master side transmitting/receiving circuit 101 The delay circuit 3 delays only the initial phase of ()-learning of the reception timing by a delay phase T1, and thereafter moves to bring in the optimum reception phase of the signal in the direction from slave to master.

As a result, the transmission/reception circuits 101 on the master and slave sides
．． The phase relationship of transmission and reception timing when bidirectional communication is performed between 102 is as shown in FIG. That is, in FIG. 2, if the transmission timing phase τMT of the master side transmitting/receiving circuit 101 is set to 0, then the slave side transmitting/receiving circuit 10
The reception timing phase τ5R of No. 2 is the delay phase T of the optimal reception timing with respect to the pulse waveform sent out when τMT=O.

and the phase of the sum of the transmission path delay τ(d) τ5R=T1+τ(d
). The transmission timing phase τ5T of the transmission/reception circuit 102 on the slave side is τST=τ(d). Similarly, the reception timing phase τMR of the transmitting/receiving circuit 101 on the master side becomes (d) with τMR=T 1+2.

For example, the optimum reception timing during loopback on the master side is the same as the optimum reception timing τSR on the slave side when the transmission distance d=o, and has a phase T. Therefore, if training is started from the initial phase T1 during loopback, the training time will be significantly shortened.

Furthermore, when communication is carried out between the master and slave side transmitter/receiver circuits 101 and 102 at a transmission distance d=o, the optimum reception timing on the master side is τMR''T from FIG. 2, so in such a case, the initial phase If training starts from T1, the training time will be significantly shortened.

〔Effect of the invention〕

As explained above, the present invention adjusts the phase so that training starts at the optimal reception timing that is delayed by a certain phase from the transmission timing, so the testing time of the transmission and reception circuits by loopback and test pull-in is significantly shorter than the conventional method. It has the effect of being able to.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a transmitting/receiving circuit showing an embodiment of the present invention;
FIG. 2 is a diagram showing the phase relationship between transmission and reception timings in an embodiment of the present invention, and FIG. 3 is a diagram showing the phase relationship between transmission and reception timings in normal digital communication. DESCRIPTION OF SYMBOLS 1... Transmission circuit, 2... Receiving circuit, 3... Delay circuit, 100.110,200... Transmitting/receiving circuit, A...
- Transmission symbol, B... Transmission signal, C... Reception signal, D... Reception symbol, TI... Delay phase, Ta.
...Transmission timing, tb...Reception timing.

Claims (1)

[Claims] Two digital signal transmitting/receiving circuits comprising a transmitting circuit that sends out a transmitted waveform according to the transmitting timing and a receiving circuit that punches out the received signal and restores the received symbol according to the receiving timing, one of which is a master side and the other is a slave side,
When bidirectional communication is performed between the two digital signal transmitting and receiving circuits through a line, the digital signal transmitting and receiving circuit operating on the slave side is configured so that its reception timing lags the transmission timing by a certain phase, and the digital signal transmitting and receiving circuit operating on the master side In the signal transmitting/receiving circuit, the receiving timing when training is started from a phase delayed by the fixed phase from the transmitting timing is determined during a loopback test in which the signal is looped back from the own transmitting circuit to the own receiving circuit through the line. When performing bidirectional communication under short-distance conditions where the propagation delay of the digital signal through the line does not delay the phase of the reception timing, the optimal reception timing is made to match the optimal reception timing on the master side. A receiving timing phase setting method in a digital signal transmitting/receiving circuit, characterized in that: