CN101414883B

CN101414883B - Receiver independent from carrier frequency

Info

Publication number: CN101414883B
Application number: CN2007101625240A
Authority: CN
Inventors: 维克多·伏拉斯; 麦可·善姆; 利昂尼德·榭密斯
Original assignee: Winbond Electronics Corp
Current assignee: Winbond Electronics Corp
Priority date: 2007-10-16
Filing date: 2007-10-16
Publication date: 2012-03-28
Anticipated expiration: 2027-10-16
Also published as: CN101414883A

Abstract

The invention provides a method for generating signal envelope by demodulating received signals. The received signals comprise the characteristics of transmitting with a carrier frequency, modulating pulse series of data symbol with a given baud rate according to the preset communication protocol, and defining the modulated signals by the preset communication protocol. The method includes: measuring the duration of time of selected characteristics in the signal envelope defined by the communication protocol. Without pulse counting of the received signals, the baud rate of signals is estimated based on the measured duration of time. The signal envelope is processed in respond to the estimated baud rate so as to transcode the data symbol.

Description

Be independent of the receiver of carrier frequency

Technical field

The invention relates to data communication, and the digit receiver of saying so more specifically and can be independent of frequency of carrier signal and operate about a kind of.

Background technology

The consumer electronics device uses infrared ray (IR) remote control to receive the input from the user usually.The infrared signal through modulation of remote controller emission carrying predetermined codes, predetermined codes indication electronic installation is carried out desired function.Device is separated modulation, sampling and decoded signal so that carry out desired function.In use have many different agreements, and different manufacturer uses usually different agreement and different pieces of information speed to launch.Shared agreement comprises RC-5 and RC-6 agreement (by the Philips research and development) and NEC agreement (by Nippon Electric Corporation research and development).

Patent application is announced No. 2004/0208182 and is described the consumption-orientation IR transceiver that is independent of form.Transceiver through to IR step-by-step counting confirm the carrier frequency that IR imports.The applicant points out that typical IR carrier frequency can make that being used for the directly sampling of this signal of definite carrier frequency need carry out with about 1MHz or higher frequency up to 455kHz or higher.Can be relatively costly with the sampling equipment of this sample at rates; Therefore the applicant proposes a kind of method to the hardware counter sampling; The pulse number counting of hardware counter to containing in the IR signal, and then carry out the algorithm of confirming carrier frequency from the number of pulse of counting and sample.

Summary of the invention

Embodiments of the invention are confirmed by need not step-by-step counting or the directly method and the device of definite pulse train carrier frequency through the baud rate of process the encoded signals of the pulse train carrying of modulation.Truth does, receiving system is confirmed baud rate (baud rate) through the duration of the special symbol estimating to be defined by the associated transport agreement after separating the modulation pulse train.Therefore receiving system can confirm the sample time through the symbol sampling that contains in the encoded signals.This machine-processed convenient receiving system uses low frequency sample clock cheaply.

Below described embodiment be particularly useful for decoding consumer electronics infrared ray (consumer electronic infrared; CEIR) signal, but it also can be used for the limited running length of other data transmission applications like continuous time slot that low and/or high levels are provided.

Therefore; According to embodiments of the invention; The method of the signal envelope that a kind of processing produces through the signal of separating modulation and receiving is provided; The signal that is received comprises that predefined communication protocol defines the characteristic through the signal of modulation with the carrier frequency transmission and according to the pulse train of predefined communication protocol with given Baud rate regulation data symbol, and method comprises:

The duration of the selected characteristic in the signal envelope that measurement is defined by communication protocol;

Based on the baud rate of measured duration estimated signal and need not to the step-by-step counting in the signal that is received; And

Through coming the processing signals envelope and the decoding data symbol in response to estimated baud rate.

In the embodiment that is disclosed, signal comprises infrared ray (IR) signal, and it is according to consumer electronics infrared ray (CEIR) agreement modulation, and wherein the CEIR agreement comprises in RC-5 agreement, RC-6 agreement and the NEC agreement.

In certain embodiments; Separate modulating signal and cause that envelope stretches (temporal stretch) with respect to the time of the transmission cycle of pulse train and forms through the selected characteristic in the signal of modulation, and estimate that baud rate comprises from measured deduction time duration stretching, extension so that estimate baud rate.In some cases, the time stretches and to look the amplitude of the signal that is received and decide, and the deduction time stretch the mean value that comprises that time of confirming on the amplitude range of signal stretches, and deduct mean value from the measured duration.

In the embodiment that is disclosed, the measurement duration is included in continuous rising and the drop edge counting of the duration of selected characteristic to clock signal.

Usually, measuring the duration comprises and uses the clock signal that is independent of carrier frequency to measure the duration.

In the embodiment that is disclosed, communication protocol defines the initial symbol with transmission when each information begins, and selected characteristic comprises at least a portion of initial symbol.Usually; Communication protocol defines the binary cell (binary cell) with unit duration; In the data symbol each comprises two or more in the unit; And communication protocol doubly defines the duration of selected characteristic according to the predetermined number of unit duration, and estimate baud rate comprise measured duration through will selecting characteristic divided by predetermined number the estimation unit duration.In certain embodiments, the decoding digital data symbol comprises the sample time selected in response to estimated baud rate signal envelope is taken a sample so that to each sampling in the unit.

According to embodiments of the invention, also be provided for the equipment of communicating by letter, it comprises:

Demodulator receives signal and separates the said signal of modulation to produce signal envelope, and signal comprises that predefined communication protocol defines the characteristic through the signal of modulation with the carrier frequency transmission and according to the pulse train of predefined communication protocol with given Baud rate regulation data symbol;

Synchronizer couples measuring the duration of the selected characteristic in the signal envelope that is defined by communication protocol, and need not the step-by-step counting in the signal that is received based on the baud rate of measured duration estimated signal;

Sampler couples in response to estimated baud rate signal envelope is taken a sample, so that produce the sequence of output sample; And

Decoder couples to handle output sample so that the decoding data symbol.

Description of drawings

Fig. 1 is for use the schematic icon explanation of the multimedia system of CEIR remote control according to an embodiment of the invention.

Fig. 2 is for schematically showing the calcspar of the details of CEIR receiver according to an embodiment of the invention.

Fig. 3 for schematically show according to an embodiment of the invention through the pulse train of modulation with and through the signal timing diagram of the envelope of separating modulation.

Fig. 4, Fig. 5, Fig. 6 are the signal timing diagram of a kind of according to an embodiment of the invention measurement of schematically explanation corresponding to the method for the baud rate of the signal envelope of different CEIR agreements.

Fig. 7 A and Fig. 7 B are for schematically explaining the signal timing diagram of the baud rate measurement that is applied to the RC-5 signal envelope according to an embodiment of the invention.

Fig. 8, Fig. 9 A and Fig. 9 B are the signal timing diagram of the method for a kind of according to an embodiment of the invention sample of signal of the process that is applied to unlike signal envelope pattern being separated modulation of explanation schematically.

Drawing reference numeral:

20: multimedia system 22: the multimedia platform

24:IR remote control 26:IR reflector

28:IR receiver 30:IR transducer

32: amplifier 34: demodulator

36: sampler 38: synchronizer

40: edge detector 42: clock counter

46: clock 48: decoder

50: signal 52: pulse train

54: the cycle 56 of not having transmission: envelope

58: rectangular wave 70:RC-5 protocol information

72: high levels unit 74: the low level unit

76: stop or end message symbol 80:NEC protocol information

85:RC-6 protocol information 90: signal

92: signal 94: signal

B0: be worth 0 B1: value 1

G: gap L: leading

M: duration R: heavily loaded point

S: begin symbol SA: sampling point

ST: signal transition STR: stretching, extension time

T: tail position

Embodiment

Fig. 1 explains the schematic icon explanation of multimedia system 20 according to an embodiment of the invention.The user of system use IR remote control 24 control multimedia platforms 22 (such as, suitably computer or electronic game machine).This device comprises IR reflector 26, and it sends the IR signal that comprises through the TR pulse train of modulation in response to the user's of remote controller actuating.IR receiver 28 induction, separate modulation and decipher the IR signal so that instruction is provided to platform 22 according to user's order.

The IR pulse that (such as, above-mentioned RC-5, RC-6 or NEC CEIR agreement) comes modulation to be sent by reflector 26 according to predetermined protocol.These agreements allow reflectors to be chosen in the arbitrary carrier frequency in 30kHz to the 56kHz scope (having the scope of being higher or lower than up to 10% extra tolerance).

Fig. 2 is for schematically showing the calcspar of the details of receiver 28 according to an embodiment of the invention.IR transducer 30 (such as, photodiode) produces electricity output in response to the IR pulse of being sent by reflector 26, and pulse is amplified by amplifier 32.The envelope of demodulator 34 acquisition pulse trains (like hereinafter shown in Fig. 3).A kind of exemplary methods and circuit that is used for the envelope acquisition is described in the patent application that is entitled as " Low-Power Digital Demodulator " that applies on the same day, and its assignee and its disclosure of being amortized to present application for patent is incorporated herein by reference.Perhaps, can use known additive method and circuit in like this technology.

Be the symbol from the IR signal acquisition process coding that is received, sampler 36 was taken a sample to the amplitude of envelope with the times of being confirmed by synchronizer 38.Synchronizer use method that hereinafter describes in detail based on as confirm these sample times by the time edge that becomes in the envelope of edge detector 40 indications.Synchronizer uses the time between the clock counter 42 measurement particular edge, and therefore estimates the baud rate of IR signal.Clock counter is driven by local clock (local clock) 46, and local clock 46 is independent of the clock that uses in the reflector 26.

For minimizing cost, clock 46 can be provided by the existing clock source in the platform 22.Low frequency clock source is desirable so that reduce power consumption.For satisfying these purposes, might (for example) use with as the clock source of the frequencies operations of available about 32kHz in personal computer and battery power supply system usually.This clock is independent of the carrier frequency of being used by IR reflector 26.For clock rate is doubled, clock can use existing clock signal rising edge and drop edge both.Use error to be introduced into estimated baud rate to this of low frequency clock with specified quantitative.Synchronizer 38 is considered this potential error (explaining like hereinafter) when confirming to treat the sample time of being used by sampler 36.

Decoder 48 is handled by the sequence of the sample of sampler 36 outputs so that produce corresponding to the bit sequence through the order of coding by device 24 emissions.Before exporting bit sequence or order to platform 22, decoder can at first send wake-up signal, and indicator console is from the resting state power supply so that in response to user's order.Decoder 48 can comprise and be used for the holding position sequence and supplied power and prepare to receive the buffer of data until platform 22.

The assembly of the receiver 28 shown in Fig. 2 can the electronic hardware circuit except that transducer 30 and amplifier 32 or is realized with the software that on suitable processor, turns round, or with the combination realization of hardware and component software.Though for the purpose of clear concept is shown as stand-alone assembly with the mac function of receiver, these blocks can be realized by single electronic integrated circuit in practice.Think all these various being implemented in the category of the present invention.

Fig. 3 is for schematically explaining the signal timing diagram of the operation of demodulator 34 according to an embodiment of the invention.The signal 50 through modulation (and similarly, inputing to the signal through modulation of demodulator 34) by reflector 26 emissions comprises the pulse train 52 with the special carrier frequency transmission.As noted above, for CEIR RC-5, RC-6 and NEC agreement, carrier frequency can be any one in 30kHz to the 56kHz scope (± 10%).

The binary on-off modulation is applied to pulse train, and pulse train comprises the cycle (left side of signal 50) of transmission IR pulse and the cycle 54 of not having transmission.The cycle prior art of IR transmission is called " unit 1 ", and the cycle of not having a transmission is called " unit 0 ".The symbol that is transmitted is made up of the predetermined sequence of two types unit.Usually, two types unit has the identical duration, and it equals fixed number of cycles purpose IR carrier wave.(therefore, unit duration and carrier frequency are inversely proportional to and change.)

Demodulator 34 acquisitions are through the envelope 56 of the signal 50 of modulation.Envelope has corresponding to the form at the rectangular wave 58 of each pulse train 52 of unit in 1 cycle.Usually; Demodulator 34 comprises simulation low-pass filter or Digital Logic (as describing in the patent application case of mentioning at preceding text that is entitled as " Digital Demodulator "), and it makes pulse smoothly and also add specific " stretching, extension " (STR) after last pulse in each unit 1 before unit 0.This stretching, extension makes the sequential of envelope with respect to the distortion of actual symbol clock.Distortion during the baud rate (as described in greater detail below) of the signal that synchronizer 38 is estimated to be transmitted.

Existing referring to Fig. 4 to Fig. 6, it is for schematically explaining the signal timing diagram of the information format that is used for different CEIR agreements.The all figure of mark are used so that measure the method for the baud rate of the signal that is received by synchronizer 38 according to embodiments of the invention with explanation.Measurement is based on the signal envelope by demodulator 34 outputs.Fig. 4 shows RC-5 protocol information 70; Fig. 5 shows NEC protocol information 80; And Fig. 6 shows RC-6 protocol information 85.

Each information to be beginning through the control character of appointment, and it can be begin symbol (S) or leading (L) of (G) succeeded by the gap.(RC-6 use leading and begin symbol both, and tail position (T), but this tail position characteristic of agreement is outside category of the present invention).Each more data bit (it can have value 1--and be labeled as B1, or is worth 0---be labeled as B0) is encoded to and corresponds respectively to unit 1 and one or more high levels unit 72 of unit 0 and the predetermined sequence of one or more low level unit 74 that preceding text are mentioned.The end of message is in stopping or end message symbol 76.

For precise sampling, need synchronizer 38 to trigger sampler 36 is separated modulation near the process the centre of each

unit

72 or 74 signal envelope sampling.Be to confirm sample time, under the situation of inaccuracy ground to the carrier pulse counting, synchronizer 38 is through measuring in duration of the control character that begins to locate of information and the unit sequential (it is equivalent to and estimates baud rate) of estimated signal.To embodiment illustrated in fig. 6, the duration that measures is labeled as " M " at Fig. 4.Perhaps, can measure other information characteristics.Though, have the knack of this art and will understand measuring technique easily and may extend to other agreements and other information characteristics, and think that it is in category of the present invention herein with reference to three specific these measuring techniques of CEIR protocol specification.

In the present embodiment, under each situation, measure following characteristic:

In RC-5 (Fig. 4), the duration of unit 1 part of synchronizer 38 measurement start bit S (yet, in this measures, possibly have ambiguity, such as hereinafter referring to Fig. 7 A, Fig. 7 B explanation).Each RC-5 unit contains 32 clock circulations.

In the NEC agreement (Fig. 5), the duration that synchronizer 38 is measured leading L.The agreement leading duration of regulation is 16 times of unit duration.Each unit contains 22 clock circulations.

In RC-6 (Fig. 6), agreement stipulates that the duration of leading L is 6 unit, and follow-up clearance G is two unit.Therefore, synchronizer 38 is measured the duration through making up of L and G, and it is contemplated to 8 times of unit duration.Each RC-6 unit contains 16 clock circulations.

As noted above, synchronizer carries out these measurements through number of cycles counting rising edge and the tail edge of clock signal (use usually both) that self-clock counter 42 receives the clock 46 of passing between the edges by edge detector 40 inductions.

Fig. 7 A and Fig. 7 B are for schematically explaining the signal timing diagram that is applied to the baud rate measurement of RC-5 signal envelope according to embodiments of the invention.In Fig. 7 A, start bit S is succeeded by B1, and wherein unit 0 (unit 74) therefore 1 (unit 72) and can clearly detect the edge between S and the B1 before in the unit.On the other hand, in Fig. 7 B, S is succeeded by B0, and wherein unit 1 (unit 72) therefore 0 (unit 74) and possibly not exist clearly between the unit 72 in S and B0 and describe before in the unit.Therefore, under unit 0 (unit 74) situation before, synchronizer 38 will be measured the duration of two sequential cells shown in mark " M " among Fig. 7 B in this kind unit 1 (unit 72).

For solving this potential ambiguity, synchronizer 38 is with respect to the unit duration M that measures that checks the RC-5 signal based on the programmable maximum of practical carrier frequency.If the value M that measures is greater than maximum, then the clock counter hypothesis has measured the duration of two sequential cells 72 shown in Fig. 7 B.In the case, with measurement result M divided by two so that confirm the unit duration.

For estimating the actual cell duration, synchronizer 38 is looked the expected duration (in the unit) of the characteristic that measures and is decided, when the expection measure error is used specific correction, with the suitable divisor of the characteristic duration that measures divided by each agreement.Such as preceding text referring to Fig. 3 explanation, by duration of the rectangular wave 58 of demodulator 34 output than long " stretching, extension " time STR of actual corresponding envelope through the signal of modulation.Therefore, in order to draw the actual duration of the pairing characteristic of value M that measures, synchronizer can deduct the STR value to confirm the unit duration from M before being divided by.If use the numerical digit demodulator, then can know the STR value exactly.Otherwise, when demodulator is used the simulation smoothing circuit, the intensity of the visual IR signal that receives of STR (amplitude also promptly) and changing.In the case, can use estimated STR value (such as, but corresponding to the mean value of tensible duration that maybe amplitude range).

Accuracy to the measurement of M receives to limit owing to low-frequency quantization error of clock 46.The quantization error of given measurement can be zero with whole clock circulation between any one (or the circulation of whole clock is half the, as if the rising edge of use clock as indicated above and drop edge both).For the balanced error that provides in the final result distributes, synchronizer can add the estimation of its unit duration with the correction (COR) of 1/2 circulation of clock 46 (maybe rising and during the drop edge 1/4 circulation when using).

Therefore, generally speaking, synchronizer 38 based on each the duration value M that the measures output in the CETR agreement of its processing with lower unit duration (CD):

RC-5:CD=M-STR+COR, or CD=(M-STR)/2+COR (if M is greater than programmable maximum of unit duration).

NEC：CD＝(M-STR)/16+COR。

RC-6：CD＝M/8+COR。

Measure because between the rising edge, carry out RC-6, so the stretching, extension after computing unit need not during the duration to consider trailing edge.Be suitable for confirming the unit duration though it has been observed by the present inventors that signal component and formula that preceding text are mentioned, can use other components and formula similarly and think that it is in category of the present invention.

Fig. 8 is for schematically to explain according to embodiments of the invention under the control of synchronizer 38, by 36 pairs of signal timing diagrams through the sampling of the signal 90 of modulation of sampler.Signal 90 in this instance comprises the high levels unit 72 that replaces with low level unit 74.Synchronizer 38 triggers clock counter 42 to begin the clock cycle count on each signal transition (being labeled as ST in the accompanying drawings) of being reported by edge detector 40.The half of the unit duration value CD that arrive to estimate when the clock counter, synchronizer 38 indication samplers 36 (being labeled as the sampling point place of SA in the accompanying drawings) are to this sample of signal.As a result, taken a sample middle roughly in each unit.At each subsequent transition place, synchronizer restarts the clock cycle count, make keep sample time with signal in units synchronization.

Fig. 9 A and Fig. 9 B are for schematically explaining the signal timing diagram to taking a sample through the signal 92 and 94 (wherein a plurality of high levels unit 72 or low level unit 74 occur continuously) of separating modulation according to an embodiment of the invention.Under these situation, do not exist signal transition to trigger restarting of clock cycle count.Alternatively, when clock cycle count arrival value CD, synchronizer 38 independently is labeled as the heavily loaded timer in heavy duty point place (also promptly, restarting clock counter) of R in the accompanying drawings.

Be different from actual cell in the signal that is transmitted with regard to the duration with regard to the CD value of estimating, continuous sampling point SA will squint away from the central point of corresponding unit with accumulating.The error that CD estimates can as noted abovely be derived from through the stretching, extension STR of the signal of separating modulation and/or be derived from the quantization error owing to the low rate of clock 46.Error can through in a large amount of unit on the cycle (as in Fig. 5 and Fig. 6) measure duration M and alleviate, therefore provide the more accurate estimation of CD.

In the CEIR agreement each is to the maximum number dielectric imposed limits of the unit that can contain in the single information, and this maximum number multiply by the maximum possible error that CD estimates and provides the cumulative maximum skew that possibly occur.Usually select clock rate and extension parameters, and the number of measuring the unit of M in the above, make the cumulative maximum skew not reach CD/2, guarantee by this correctly being taken a sample in all unit.

Though the embodiment of above description is with reference to specific concrete agreement, principle of the present invention can change the signal envelope that is applied to similarly the other types of obeying different agreement necessarily and take a sample.Above-mentioned technology is particularly useful when agreement to be decoded has the begin symbol that is different from subsequent data symbols and the limited running length of continuous time slot of low and/or high levels is provided.Therefore should be appreciated that the foregoing description sets forth by way of example, and the content that the invention is not restricted to the preceding text particular display and describe.But category of the present invention comprises above-mentioned various combination of features and son combination, and has the knack of this art and reading variation and the modification that will understand and not be disclosed in the above-mentioned various characteristics in the prior art after preamble is described.

Claims

1. the method for the signal envelope that produces through the signal of separating modulation and receiving of a processing; The signal that this received comprises with the carrier frequency transmission and according to the pulse train of predefined communication protocol with given Baud rate regulation data symbol; This predefined communication protocol defines the characteristic of the signal of this process modulation, and this method comprises:

The duration of the selected characteristic in the described signal envelope that measurement is defined by described communication protocol, separate the described signal of modulation cause described envelope with respect to the time of the transmission cycle of described pulse train stretch form described through the described selected characteristic in the signal of modulation;

Estimate the baud rate of described signal and need not based on the described measured duration the step-by-step counting in the described signal that receives; And

Decipher described data symbol through handling described signal envelope in response to described estimated baud rate.

2. the method for claim 1; It is characterized in that; Described signal comprises infrared signal, and it is according to consumer electronics infrared ray agreement and modulation, and described consumer electronics infrared ray agreement comprises in RC-5 agreement, RC-6 agreement and the NEC agreement.

3. the method for claim 1 is characterized in that, estimates wherein that described baud rate comprises to deduct described time from the described measured duration and stretch so that estimate described baud rate.

4. method as claimed in claim 3; It is characterized in that; Described time stretching, extension is looked the amplitude of the described signal that receives and is decided; And wherein deduct described time stretching, extension and comprise the mean value of confirming that the described time on the amplitude range of described signal stretches, and deduct described mean value from the described measured duration.

5. the method for claim 1 is characterized in that, measures described duration that the described duration is included in described selected characteristic continuous rising and the drop edge counting to clock signal.

6. the method for claim 1 is characterized in that, measures the described duration to comprise and use the clock signal be independent of described carrier frequency to measure the described duration.

7. the method for claim 1 is characterized in that, described communication protocol defines the initial symbol with transmission when each information begins, and wherein said selected characteristic comprises at least a portion of described initial symbol.

8. an equipment that is used to communicate by letter is characterized in that, this equipment that is used to communicate by letter comprises:

Demodulator; Configuration is to receive signal and to separate this signal of modulation to produce signal envelope; Described signal comprises with the carrier frequency transmission and according to the pulse train of predefined communication protocol with given Baud rate regulation data symbol, and described predefined communication protocol defines the characteristic of the signal of described process modulation;

Synchronizer; Couple to measure the duration of the selected characteristic in the described signal envelope that defines by described communication protocol; Described demodulator causes that described envelope stretched with respect to time of the transmission cycle of described pulse train and forms describedly through the described selected characteristic in the signal of modulation, and estimates the baud rate of described signal and need not the described step-by-step counting in the described signal that receives based on the described measured duration;

Sampler couples in response to described estimated baud rate described signal envelope is taken a sample, so that produce the sequence of output sample; And

Decoder couples to handle described output sample so that decipher described data symbol.

9. equipment as claimed in claim 8; It is characterized in that; Described signal comprises infrared signal, and it is according to consumer electronics infrared ray agreement and modulation, and described consumer electronics infrared ray agreement comprises in RC-5 agreement, RC-6 agreement and the NEC agreement.

10. equipment as claimed in claim 8 is characterized in that, wherein said synchronizer deducts described time stretching, extension so that estimate described baud rate through being configured to from the described measured duration.

11. equipment as claimed in claim 10; It is characterized in that; Described time stretching, extension is looked the amplitude of the described signal that receives and is decided, and wherein said synchronizer is through being configured to deduct from the described measured duration mean value of the described time stretching, extension that obtains on the amplitude range at described signal.

12. equipment as claimed in claim 8 is characterized in that, described synchronizer is measured the described duration based on the counting of the continuous rising of clock signal and drop edge at the described duration of described selected characteristic through being configured to.

13. equipment as claimed in claim 8 is characterized in that, described synchronizer is through being configured to use the clock signal that is independent of described carrier frequency to measure the described duration.

14. equipment as claimed in claim 8 is characterized in that, described communication protocol defines the initial symbol with transmission when each information begins, and wherein said selected characteristic comprises at least a portion of described initial symbol.