CN85107392B - Channel switching system for use in a radio digital transmission system - Google Patents

Abstract

The present invention relates to a technique of a channel switching device applied to a radio digital sending system. The present invention is characterized in that when the electrical property of a main sending channel for transmitting a digital signal turns bad, the transmitted digital signal can be automatically switched to a spare channel so as to ensure the quality of signal transmission. The detection of the signal phase difference on the main and the spare channels and a compensation technique are adopted so as to ensure the efficient channel switching and eliminate the bad result of asynchronism (out of control) generated in the system frame synchronization after the channel switching, and the bad result is caused by the phase difference problems of the original technique.

Description

The channel switching means that is used for digital radio transmission system

The present invention relates to be applied to the channel switching system of digital radio transmission system.

Usually, this class channel switching system is the reliability that is used for improving digital transmission system.This system is included as each main channel N(〉=1,2,3,) and an alternate channel of preparation, and the device of monitoring the fault of the performance quality of each channel or equipment, to ensure when breaking down, can finish by the switching of main channel to alternate channel or alternate channel to main channel.

The phase relation between the signal on main channel and the alternate channel is not considered in this in the past channel switch work.If, the same each other phase time of the signal on two channels, its conversion can't go wrong.But different relative when the two, the conversion of its channel will be omitted some digital signal.And the frame synchronization that causes level after the system thus becomes bad (asynchronous), consequently makes the reliability of digital transmission system become very poor.

The object of the present invention is to provide a kind of effective channel switching system that is applied to the radiodigital transmission system.This converting system has been eliminated above-mentioned defective.

One of characteristics of channel switching system of the present invention are: when two channels all do not have equipment fault, even the performance quality of the current main channel of just using can not meet the demands, as long as main channel with the signal out-phase on the alternate channel, does not just carry out being transformed into alternate channel from main channel.Another characteristics are: when equipment fault occurring on the main channel, just be transformed into alternate channel from main channel, and no matter whether have phase difference and channel quality to degenerate between the signal on two channels.

The channel switching system that is used for radiodigital transmission system (digital signal is wherein transmitted) on main channel and alternate channel of the present invention comprises: a channel quality observation circuit that is used to monitor the performance quality of described main channel and alternate channel; An equipment fault testing circuit that is used to detect equipment fault on the described alternate channel of advocating peace; Respond the output of described channel quality observation circuit and equipment fault testing circuit, so that the control circuit of first and second control signals to be provided respectively; And the change-over circuit of described first and second control signals of response to carry out changing between described main channel and the alternate channel; Its feature is: described change-over circuit comprises that also a receiving terminal that is used at described main channel and alternate channel detects the phase difference between two channel signals, and the phase difference observation circuit of the 3rd control signal is provided; And one in response to described first, second and the 3rd control signal, during equipment fault on detecting described main channel, carry out channel switch from described main channel to described alternate channel, and no matter whether there is the described first and the 3rd control signal to exist, and in the equipment fault that does not detect on described main channel and the alternate channel, and when having described phase difference,, and stop the gate circuit of channel switch then no matter the debase of described main channel.

Figure 1 shows that the prior art N that is used for the radiodigital transmission system: the functional-block diagram of 1 master-alternate channel converting system.

Figure 2 shows that N(=1 in the prior art): 1 master-alternate channel system, or the block diagram of so-called stand-by heat (hot standby) system.

Figure 3 shows that the functional-block diagram of the channel switching system of most preferred embodiment of the present invention.

Below with reference to accompanying drawings the present invention is done a detailed explanation.

As shown in Figure 1, be a N: 1 master-alternate channel converting system: first main channel comprises: 1011, one transmitter sections 1022 of a branch circuit; A receiver section 1032; Channel quality observation circuit 1042 and equipment fault testing circuit 1052.The N main channel comprises: a branch circuit 1012; A transmitter section 1023; A receiver section 1033; A channel quality observation circuit 1043 and an equipment fault testing circuit 1053.An alternate channel comprises: a transmitter section 1021; A receiver section 1031; A channel quality observation circuit 1041 and an equipment fault testing circuit 1051.Each transmitter section all comprises: bipolar (B) one pole (U) transducer; A data processing unit (DPU) and a modulator (MOD) (hereinafter also will mention).Each receiver section all comprises: a demodulator (DEMOD); A data processing unit (DPU); An one pole (U) bipolar (B) transducer and a vertical sync circuit.

To narrate the operation principle of this device below:

At first, when first when the N main channel is in operate as normal, a bipolar signal (signal B), by branch circuit 1011(1012) offer transmitter section 1022(1023), carry out the B/U conversion there, after adding a frame synchronizing signal and parity signal,, launch simultaneously by antenna as a for example phase shift keying (PSK) carrier wave.This PSK carrier wave is by receiver section 1032(1033) demodulation, carry out U/B conversion after, deliver to receiving terminal change-over circuit 1061(1062).Meanwhile, on alternate channel, a pilot signal that produces by pilot signal generation circuit 112, deliver to transmitter section 1021 by transmitting terminal change-over circuit 1112 and 1111, again through being similar to the processing procedure that occurs on the main channel, process receiver section 1031 and receiving terminal change-over circuit 1061 and 1062, arrival pilot detection circuit 1131, to detect its pilot signal, its result delivers to conversion control circuit 1071.At the observation circuit 1041,1042 or 1043 of receiver section 1031,1032 or 1033, the result offers conversion control circuit 1071 with its parity check.Testing circuit 1051,1052 or 1053(will be as further specifying below) to conversion control circuit 1071 provide the frame synchronization of a representative frame synchronous circuit destroyed, the pulse signal of DPU no pulse output and the output of U/B transducer no signal.

Conversion control circuit 1071 is controlled receiving terminal change-over circuit 1061 and 1062 according to these results, and controls transmitting terminal change-over circuit 1111 and 1112 by control channel (not drawing on the figure).

When if first quality of channel degenerates, its phenomenon that degenerates will be identified by observation circuit 1042.And, detecting alternate channel when being in normal operating conditions at pilot detection circuit 1131, transmitting terminal change-over circuit 1111 will be energized, thereby at the signal B that transmits abreast on first main channel and the alternate channel on first main channel.This parallel transmission signal respectively by observation circuit 1041 and 1042 and testing circuit 1051 and 1052 monitor.If the transmission quality of alternate channel meets the demands, the change-over circuit 1061 of then controlling receiving terminal comes output signal on alternate channel selectively.

But, if detect main channel when there is no equipment fault equipment fault appears and on the alternate channel, will ignore the logical quality-monitoring result of letter and select main channel.

More than this related N: the technology of 1 a main alternate channel converting system, can be referring to the 4th, 442, No. 518 patents of the U.S. of delivering on April 10th, 1984, this patent has transferred the applicant.

Square frame is shown in Figure 2 to be the block diagram that is called as the stand-by heat converting system, and N=1 wherein is to help key-drawing 1.Below with reference to Fig. 2, the channel switching system of this prior art will be introduced in more detail.

Among Fig. 2, deliver to a bipolar signal B of 1 end, delivered to respectively in main channel and the alternate channel through branch circuit 1013, main channel comprises: a transmitter section 1025; A receiver section 1035; A channel quality observation circuit 1045 and an equipment fault testing circuit 1055; And alternate channel comprises: 1024 receiver sections 1034 of a transmitter section; A channel quality observation circuit 1044 and an equipment fault testing circuit 1054.Transmitter section 1024(1025) comprising: a transducer 401(411 B/U(bipolar-unipolar)); A DPU(data processing unit) 402(412) and a MOD(modulator) 403(413).Receiver section 1034(1035) comprising: a 404(414 DEMOD(demodulator)); A DPU(data processing unit) 405(415); U/B(one pole-bipolar) transducer 406(416) and a vertical sync circuit 407(417).

Signal B by branch circuit, offer the transmitter section 1025 of main channel, process B/U(bipolar-unipolar) after transducer 411 carries out the bipolar-unipolar conversion, by the DPU(data processing unit) 412 add a frame synchronizing signal and a check digit etc., convert for example PSK(phase shift keying to by MOD413 then) ripple, for launching.This phase shift keying ripple is by the demodulator in the receiver section 1035 (DEMOD) 414 demodulation, and carry out after data processing and U/B transducer 416 carry out one pole-bipolar conversion through DPU415, deliver to change-over circuit X(change-over circuit X and comprise a switch 201 and one or 211).And carry out frame synchronization by vertical sync circuit 417.Circuit 1024(401-403 in the alternate channel) with 1034(404-407) the course of work identical with above-mentioned main channel corresponding circuits, so no longer superfluous chatting.

Observation circuit 1045 comes the working condition of supervisory channel by check digit.And monitor signal 5 offered control circuit 1072.Situation (if the words that have) detection DPU415 and U/B transducer 416 that testing circuit 1055 detects frame synchronization destruction have no-output, and provide a detection signal 7 to control circuit 1072.In like manner, observation circuit 1044 and testing circuit 1054 also provide a monitor signal 4 and detection signal 6 to control circuit 1072 respectively.According to the signal 4-7 that sends here, control circuit 1072 produces control signal 8 and 9.If the service behaviour variation of main channel will produce control signal 8.But if equipment fault occurs, then control signal 9 will produce prior to signal 8.For example, in the time of main channel service behaviour variation, equipment fault has also appearred in the alternate channel that change, does not so just carry out being transformed into alternate channel from main channel.When two channels all do not have equipment fault, change-over circuit X will move according to the performance quality variation situation of any channel so.

In this channel switching system, from the alternate channel of advocating peace, select performance person the best in quality and do not consider between the two data phase relation.Therefore, if under the different situation of the data phase of two interchannels, result as channel switch control, some digital signal that is launched might be lost in the burst that outputs to end 10, cause frame synchronization destruction occurring in the back level of system, the result destroys and transmits or the correct data of regenerating.

Be that it will eliminate this defective according to change-over circuit y of the present invention as shown in Figure 3.

Now consult Fig. 3, the phase shifter 2041 and 2042 of variable phase carries out the start-phase adjustment in advance, to guarantee that the phase place of the signal on the alternate channel of advocating peace 2 and signal 3 is consistent respectively.But,, then can remove initial adjustment from if signal 2 and signal 3 are with regard to same phase time at the beginning.Phase difference observation circuit 203(is comprising a gate circuit 101 and a phase difference detecting circuit 102) detect phase shifter 2041 and 2042 s' phase difference, and export a control signal 12.Gate circuit 212(comprising one with 103 and one at door or 104) come control switch 202 according to control signal 8,9 and 12.

May see Fig. 2 by control circuit 1072() output control signal 8 and 9 in, if showing the control signal 9 that equipment fault occurs really arrives, this change-over circuit y then, X(sees Fig. 2 as the prior art change-over circuit), will under the situation of the phase relation of not considering signal 2 and signal 3, carry out the conversion of channel by switch 202.

If channel performance degradation, perhaps radio transmission path 301 or 302(see Fig. 2) because of decay or suchlike former thereby when being disturbed occurring, then phase difference detecting circuit 102 will detect the phase difference between signal on main channel and the alternate channel 2 and signal 3 respectively, and provide a control signal 12 by gate circuit 101.Even owing to the channel performance quality becomes the bad signal 8 that produces, but this moment except that the phase place of digital signal of leaveing no choice but be converted 2 and digital signal 3 be homophase otherwise will forbid control signal 8 by gate circuit 101 with door 103.Switch 202 will be prevented from changing like this, protect the frame synchronization of level after the system, and it is avoided otherwise the adverse effect that is subjected to possibly.

If, signal 2 that will be converted and signal 3 homophases, then control signal 12 will be opened AND circuit 103, allow control signal 8 pass through, and supply with or door 104, and switching circuit 202 is changed.Subsidiary mentioning in stand-by heat system as shown in Figure 2, is input to the signal 11 of gate circuit 101, be placed in low level.Otherwise gate circuit 101 also can omit, and the output of phase difference detecting circuit 102 is delivered directly to and door 103 as control signal 12.

Gate circuit 101 is at the N that is applied to as change-over circuit y as shown in Figure 1: adopt in the time of on the change-over circuit 1061 and 1062 in the 1 master-alternate channel converting system.As shown in Figure 1, when primary, spare channel is in normal operating conditions, as discussed previously, at main channel transmitting data signal, upload transporting signal frequently at alternate channel, i.e. two of this two channel groups of signal out-phase, then control signal 11 rises to high level, to forbid that testing circuit 102(sees Fig. 3 this moment) output, to avoid the misoperation of change-over circuit y.

If main channel breaks down or performance quality becomes bad, data-signal is parallel transmission on the alternate channel of advocating peace, and then control signal 11 will be suppressed and presents low level.So the output of testing circuit 102 will be transported to and door 103.

If in system illustrated in figures 1 and 2, the possibility that wireless device fault or other cell failure occur is very little, then perhaps the equipment fault testing circuit can omit, and the conversion of only finishing (realization) channel according to the output of channel performance quality-monitoring circuit gets final product.In this case, have only control signal 9 as shown in Figure 3 to be maintained at low level.Like this, switch 202 will be controlled by control signal 8 and 12.

As mentioned above, channel switching system of the present invention, when the signal 2 and 3 that will be converted is in the out-phase state, even main channel performance quality variation, do not carry out channel switch yet, thereby make the vertical sync circuit of level after the system be unlikely to be adversely affected, thereby can realize effective channel switch.

Claims (3)

1, a kind of channel switching system that is used for the radiodigital transmission system, digital signal is wherein transmitted on main channel and alternate channel, and this converting system comprises: a channel quality observation circuit that is used to monitor the performance quality of described main channel and alternate channel; An equipment fault testing circuit that is used to detect equipment fault on the described alternate channel of advocating peace; Respond the output of described channel quality observation circuit and equipment fault testing circuit, so that the control circuit of first and second control signals to be provided respectively; And the change-over circuit of described first and second control signals of response to carry out changing between described main channel and the alternate channel; It is characterized in that: described change-over circuit comprises that also a receiving terminal that is used at described main channel and alternate channel detects the phase difference between two channel signals, and the phase difference observation circuit of the 3rd control signal is provided; And one in response to described first, second and the 3rd control signal, during equipment fault on detecting described main channel, carry out channel switch from described main channel to described alternate channel, and no matter whether there is the described first and the 3rd control signal to exist, and in the equipment fault that does not detect on described main channel and alternate channel, and when having described phase difference, stop channel switch, and ignore the gate circuit of the debase of described main channel.

2, channel switching system as claimed in claim 1, it is characterized in that described gate circuit comprises the OR-gate of response the described first and the 3rd control signal with AND gate that the 4th control signal is provided and response described second and the 4th control signal.

3, channel switching system as claimed in claim 1, it is characterized in that described phase difference observation circuit comprise one be used for when equipment fault and debase the two one of when on described main channel, occurring, and, described the 3rd control signal is offered the door of described gate circuit when data during in main channel and alternate channel parallel transmission.

Images