ES3017708B2 - COMMUNICATION PROCEDURE BETWEEN AT LEAST ONE STREET PANEL AND ONE HOME TERMINAL, OF A TWO-WIRE MULTI-CHANNEL ELECTRONIC DOOR ENTRY SYSTEM - Google Patents

Description

[0001] DESCRIPTION

[0003] COMMUNICATION PROCEDURE BETWEEN AT LEAST ONE STREET PLAQUE AND

[0004] A HOUSING TERMINAL, OF AN ELECTRONIC DOOR ENTRY SYSTEM

[0005] BIFIL MULTICHANNEL

[0007] Technical field

[0009] The present invention belongs to the technical fields of communications and building access control.

[0011] More particularly, the object of the invention is a communication procedure between at least one street panel and a home terminal of a two-wire (bi-wire) electronic door entry system that makes it possible to establish more than one simultaneous communication between several pairs of system elements and that also allows communication between the street panel (or panels) with home terminals of different characteristics.

[0013] This implies that, thanks to the present invention, it is possible to integrate different versions of apartment terminals into a single electronic door entry system: for example, terminals equipped only with conventional handsets (i.e., capable of transmitting and receiving audio only, lacking a video monitor), terminals equipped with low-quality audio and video, and/or terminals equipped with high-quality audio and video. Furthermore, the invention makes it possible to upgrade older electronic door entry systems while retaining the existing wiring, so that only the outdoor panel(s) and the apartment terminals need to be replaced, resulting in significant savings in labor and material costs. Likewise, the communication method of the invention is capable of providing—in each case—the best audio and video quality available to the specific apartment terminal to which an outdoor panel is connected at any given time.

[0015] Background

[0017] Currently, several two-wire electronic door entry systems are known, which are equipped with a street panel with a video camera. This street panel communicates via a communication line with multiple apartment terminals, each equipped with an intercom and an image display monitor, to transmit audio and video over the communication line. These systems are therefore capable of supporting a conversation between two elements of the same installation, transmitting over the two wires of the communication line two audio channels (upstream and downstream), one video channel (usually upstream), and one data channel for system management.

[0019] Thus, for example, patent ES2315138 B1 describes a system of this type that employs distribution elements to create a point-to-point link between the street panel and the terminal in the dwelling. This system uses frequency modulation (FM) of the various analog signals, employing different carriers or frequencies for each signal (uplink audio, downlink audio, video, and data). In addition, FSK modulation is used for the data.

[0021] US patent application US5923363A describes a similar system with FM modulation, but the installation is not truly bus-based since it uses switching devices, resulting in a star topology. It also requires batteries at the terminals to provide the power that the cable cannot simultaneously supply to the data.

[0023] European patent application EP1569454A2 describes a bus system that allows only one voice channel since the video channel is not modulated. The upstream and downstream audio channels are FM modulated. It also employs two infrastructure elements: a negative charge simulator next to the power supply, which must be adjusted according to the number of terminals present, and another simulator at the last terminal of each branch, which makes the installation more complex.

[0025] European patent application EP1843590 A1 describes another two-wire bus video intercom system that requires powering the monitors locally in the home, thus not resulting in an integral two-wire system since the monitor's power supply does not come from the bus.

[0027] Likewise, PCT application WO2004090833 A1 describes a two-wire line data transmission system for a fieldbus that powers the devices, but which has the following limitations: transmission rates are very low, unsuitable for transmitting audio and even less video; it uses a master-slave system that slows down communication by having to query each slave device individually to see if they need to transmit information; it requires continuous calibration of the slave devices for synchronization; and finally, changes in device power consumption are only allowed at certain times when data transmission is not permitted because the information is affected.

[0029] However, none of the systems mentioned above are capable of transmitting multiple simultaneous audio and video conversations over a communications line consisting exclusively of two conducting wires, through which data is also transmitted and which are used to power the devices.

[0031] This disadvantage was overcome by means of the Spanish utility model ES1187384 U, in which a two-wire electronic door entry system is disclosed that allows simultaneous audio and video conversation between at least one pair of devices in the system, without requiring infrastructure elements for the distribution of signals.

[0033] Nevertheless, this two-wire, multi-channel video intercom system still has some disadvantages. First, it is not backward compatible. That is, it cannot be implemented in older installations that are equipped with components (e.g., apartment terminals and/or outdoor panels) of earlier technologies, nor in installations that comprise components of several different technologies.

[0035] In addition, it would also be desirable for the intercom system to be able, at all times, to detect the optimal audio and video quality, depending on which street panel(s) and home terminal(s) are connected to each other at any given moment and transmit the corresponding signals with that quality.

[0037] Summary description of the invention

[0039] In order to address the limitations of the prior art indicated above, the present invention relates, firstly, to a communication method between at least one street panel and a dwelling terminal of a two-wire multi-channel electronic door entry system that uses:

[0041] - at least one street sign, equipped with a video camera, a speaker and a microphone;

[0042] - a plurality of dwelling terminals, each dwelling terminal being provided with a conventional intercom or alternatively, with a video monitor intercom and;

[0043] - a non-polarized two-wire communications bus, configured to establish communication, at least, between said street panel and said home terminal, the street panel and the home terminals being configured to transmit and receive signals through the communications bus using time-division multiplexing, TDM;

[0045] characterized in that said procedure comprises, at least, the following steps:

[0047] a) activate the street panel to initiate communication with a dwelling terminal; b) send from the street panel to said dwelling terminal, a supported quality query signal;

[0048] c) send, in response to the quality query signal, from the home terminal to the street panel a quality confirmation signal, indicating the maximum audio and video quality supported by the home terminal;

[0049] d) send, from the street sign to the dwelling terminal, a call request signal;

[0050] e) send, in response to the call request signal, a call reception confirmation signal, from the home terminal to the street panel;

[0051] f) send in response to the call reception confirmation signal, from the street panel to the home terminal, a communication channel reservation signal; g) send, in response to the communication channel reservation signal, a communication channel reservation confirmation signal, from the home terminal to the street panel;

[0052] h) enable, in response to the communication channel reservation confirmation signal, at least one time-division multiplexing (TDM) window (or slot) for communication between the street panel and the home terminal;

[0053] i) send, using said time window, a signal with the video captured by the street panel camera to the home terminal, at the highest quality supported by said home terminal,

[0054] j) sending, from the dwelling terminal to the street panel, an off-hook signal when the intercom is picked up from the dwelling terminal, indicating, in addition, whether or not said dwelling terminal is provided with a video monitor;

[0055] k) send, in response to the off-hook signal, a first signal with the audio captured by the microphone, from the street panel to the dwelling terminal and a second signal with the audio captured by the intercom, from the dwelling terminal to the street panel, at the highest supported quality; also, if said dwelling terminal is not provided with a video monitor, cease the transmission of the video signal;

[0056] (l) sending, from the dwelling terminal to the street panel, an end-of-talk signal when the handset is hung up from the dwelling terminal or, alternatively, sending said end-of-talk signal from the street panel if a predetermined time has elapsed without said handset being hung up; (m) sending, in response to the end-of-talk signal, a communication channel release signal from the street panel to the dwelling terminal; (n) sending, in response to the communication channel release signal, a communication channel release confirmation signal from the dwelling terminal to the street panel; and

[0057] o) disable, in response to the communication channel release confirmation signal, the time-division multiplexing (TDM) window intended for communication between the street panel and the home terminal.

[0059] The communication method according to the present invention allows the integration of components (e.g., apartment terminals and/or door entry panels) from prior technologies, as well as components belonging to several different technologies (e.g., those supporting audio and video or audio only), into a single two-wire, multi-channel intercom system. This is possible because, when communication is established between at least one pair of elements of said system (typically a door entry panel and an apartment terminal), these elements receive the corresponding communication instructions to adapt their audio and video configuration to the requirements of the older or more functionally limited component, ensuring that both elements are compatible with each other.

[0061] Furthermore, the communication procedure of the invention ensures that, at all times, the transmission of audio and video between the street panel and the home terminal is of the highest possible quality, compatible with the specific type of street panel (or panels) and the specific type of home terminal (or terminals) that are connected to each other at any given time.

[0063] Throughout this description, for simplicity, the terminals to which the street panel connects are referred to as "residential terminals." However, it is important to note that these residential terminals do not necessarily have to be installed inside a dwelling; they can also be installed in other locations such as commercial premises, industrial premises, offices, headquarters of official entities, and building concierges. Similarly, "street panels," in addition to being installed on public roads, can also be installed in other locations, for example, in the common areas of a building or residential community.

[0065] In a preferred embodiment of the invention, step b), which consists of sending the quality query signal from the street panel to the said dwelling terminal, and step c), which consists of sending the quality confirmation signal from the dwelling terminal to the street panel, indicating the maximum audio and video quality supported by the dwelling terminal; are performed immediately after step a), which consists of activating the street panel to initiate communication with a dwelling terminal.

[0067] Therefore, in the implementation described in the previous paragraph, before the call request signal, a quality confirmation signal is transmitted (indicating the maximum audio and video quality supported by the outdoor panel and the apartment terminal). In this way, the first call signal sent will be encoded with all supported qualities, and subsequent response signals will take into account the qualities supported by the elements of the intercom system between which communication is established, filtering out those marked as unsupported. This reduces the number of signals sent on the communication bus and, therefore, reduces the time until video begins transmitting from the outdoor panel to the apartment terminal.

[0069] Preferably, the quality confirmation signal, sent in stage c) from the home terminal to the street panel and indicating the maximum audio and video quality supported by the home terminal, contains information relating at least to:

[0071] - audio codec used, and/or

[0072] - the number of lines of vertical and/or horizontal resolution of the video; and/or

[0073] - the number of frames per second.

[0075] In a preferred embodiment of the invention, the signals transmitted through the time-division multiplexing (TDM) window between the street panel and the home terminal are modulated differently depending on the type of information they contain (data, audio, and/or video). Thus, according to the present invention, one or more different modulations can be used within the same TDM window, depending on the signals to be transmitted.

[0076] In a further preferred embodiment of the invention, the street panel is further provided with a first modem unit and each of the home terminals is provided with a second modem unit, each of said first and second modem units being provided with a pulse-position modulated (PPM) modulator and demodulator set and a frequency-shift keyed (FSK) modulator and demodulator set. Furthermore, the signals transmitted through the time-division multiplexing (TDM) window are modulated and demodulated as follows:

[0078] - by frequency shift keying, FSK, if they are data or audio signals when the communication involves home terminals with conventional intercoms that do not support video;

[0079] - by frequency modulation, at a frequency different from those used in the modulation and demodulation of data or audio signals, if they are transmission start signals; and

[0080] - by pulse position, PPM, if they are video signals and/or audio signals when the communication involves home terminals with video monitor intercoms.

[0082] In a preferred embodiment of the invention, in step h) - which consists of enabling time-division multiplexing (TDM) windows in response to the communication channel reservation confirmation signal - one, two or more different time-division multiplexing windows are enabled for the same communication between the street panel and the home terminal.

[0084] This particular embodiment of the invention, by allocating more resources to communication, allows for higher-quality video transmission without requiring the use of higher-performance codecs such as H265. However, and logically, enabling more than one TDM window for communication can only be used in cases where the outdoor unit and the home terminal involved in said communication have sufficient video quality to support this format. Furthermore, it is also possible to use each TDM window to maintain independent communication between pairs of outdoor units and home terminals, or in other words, to maintain multiple simultaneous communications between different outdoor units and home terminals.

[0085] Any of the communication procedures of a two-wire multi-channel electronic door entry system according to the invention described above may, optionally, be executed by a computer.

[0087] Furthermore, a second object of the invention relates to a computer-readable medium comprising instructions which, when executed on a computer, cause said computer to carry out the steps of any of the communication procedures of the invention, described above.

[0089] Brief description of the figures

[0091] The foregoing and other advantages and features will be more fully understood from the following detailed description of an exemplary embodiment with reference to the accompanying drawings, which are to be regarded as illustrative and not limiting, in which:

[0093] Figure 1 is a flowchart illustrating a first embodiment of the communication procedure for electronic door entry systems according to the present invention;

[0095] Figure 2 is a schematic view of the two-wire multi-channel electronic door entry system to which the communication procedure of Fig. 1 is applied; and

[0097] Figure 3 is a time-lapse representation of some of the signals used during the communication procedure of the invention of Fig. 1.

[0099] Figure References

[0101] 1 Street sign;

[0102] 2 Housing Terminal;

[0103] 3 Non-polarized two-wire communication bus;

[0104] 4 First modem unit (from street plate);

[0105] 5 Second modem unit (from the home terminal);

[0106] 6 Video camera (street plate);

[0107] 7 Speaker (from the street plate);

[0108] 8 Microphone (from the street sign);

[0109] 9 Video monitor (from the home terminal);

[0110] 10 Stage that consists of activating the street panel to initiate communication with the terminals of a dwelling;

[0111] 20 Stage that consists of sending the quality query signal;

[0112] 30 Step which consists of sending, in response to the quality query signal, a quality confirmation signal;

[0113] 40 Stage that consists of sending a call request signal;

[0114] 50 Step which consists of sending, in response to the call request signal, a call confirmation signal;

[0115] 60 Stage that consists of sending, in response to the call confirmation signal, a communication channel reservation signal;

[0116] 70 Step consisting of sending, in response to the communication channel reservation signal, a communication channel reservation confirmation signal; 80 Step consisting of enabling, in response to the communication channel reservation confirmation signal, at least one TDM time window for communication; 90 Step consisting of sending, using said time window, a signal with the video (V) captured by the street sign camera;

[0117] 100 Stage which consists of sending an off-hook signal when the intercom is picked up at the home terminal;

[0118] 110 Stage which consists of sending, in response to the off-hook signal, a first audio signal and a second audio signal;

[0119] 120 Stage that consists of sending an on-hook signal when the intercom is hung up at the home terminal;

[0120] 130 Stage that consists of sending, in response to the hang-up signal, a communication channel release signal;

[0121] 140 Step consisting of sending, in response to the communication channel release signal, a communication channel release confirmation signal; 150 Step consisting of disabling, in response to the communication channel release confirmation signal, the TDM time window for communication;

[0122] C Quality query signal;

[0123] CC Quality confirmation signal;

[0124] LL Call request signal;

[0125] CLL Call reception confirmation signal;

[0126] CO Communication channel reservation signal;

[0127] CCO Communication channel reservation confirmation signal;

[0128] V Signal with the video captured by the street sign camera;

[0129] DC Off-hook signal;

[0130] A1 First audio signal (signal with the audio captured by the microphone from the street panel);

[0131] A2 Second audio signal (signal with the audio captured by the microphone of the intercom of the home terminal);

[0132] CG Hanging signal;

[0133] DS Communication channel release signal;

[0134] CDS Communication channel release confirmation signal;

[0135] 51 First communications signal (Fig. 3);

[0136] 52 Second communications signal (Fig. 3);

[0137] 53 Third communications signal (Fig. 3);

[0138] 54 Fourth communications signal (Fig. 3);

[0139] 55 Fifth communications signal (Fig. 3);

[0140] 56 Sixth communications signal (Fig. 3);

[0141] INI Transmission start marker (Fig. 3);

[0142] CMD Command (Fig. 3);

[0143] ESP Waiting time (FIG. 3);

[0144] t Elapsed time (Fig. 3);

[0145] SL1 First TDM time slot (Fig. 3); and

[0146] SL2 Second TDM time window (slot) (Fig. 3).

[0148] Detailed description of an implementation example

[0150] Next, with the help of the attached figures cited, a detailed description is provided of an example of a preferred embodiment of the communication procedure of the invention, for use in a two-wire multi-channel electronic door entry system.

[0152] Fig. 1 shows, in a flow diagram, a first embodiment of the communication procedure according to the present invention which, in this particular case, is applied to the electronic door entry system illustrated in Fig. 2.

[0154] As can be seen in this last figure, said electronic door entry system is of the two-wire multi-channel type and comprises a single street panel 1 and five different home terminals 2, said street panel 1 being connected to each of the home terminals 2, by means of a non-polarized two-wire communication bus 3.

[0155] However, the present invention expressly contemplates other possible embodiments in which the electronic door entry system comprises more than one street panel 1 and/or a different number of dwelling terminals 2.

[0157] As shown in Figure 2, the street panel 1 is provided, in this particular case, with a first modem unit 4, a video camera 6, a speaker 7 and a microphone 8 and each of the dwelling terminals 2 is likewise provided with a second modem unit 5. In addition, some of the dwelling terminals 2 are provided with conventional intercoms, while others are more modern intercoms, provided with a video monitor 9.

[0159] Said modem units 4 and 5 (first and second respectively) further comprise a pulse position modulated (PPM) signal modulator and demodulator set and a frequency shift modulated signal modulator and demodulator set.

[0161] The communication procedure begins when a user who wishes to communicate with one of the dwelling terminals 2 activates the street panel, according to step 10, to initiate such communication.

[0163] In response to that interaction, stage 20 takes place, in which a quality C query signal is sent from street plate 1 to the user's chosen home terminal 2.

[0165] Next, in stage 30, in response to the quality query signal C, a quality confirmation signal CC is sent from said dwelling terminal 2 to street board 1, indicating the maximum audio and video quality that dwelling terminal 2 supports.

[0167] In this particular embodiment of the invention, the CC quality confirmation signal contains a data byte consisting of eight bits and whose composition is as follows:

[0169]

[0172] Where:

[0173] - V3 quality implies a video quality of 240p (i.e., 240 lines of vertical resolution) 12.5 fps (frames per second) and an audio quality according to the G726.5 standard, developed by the ITU (International Telecommunication Union);

[0174] - Quality V4.0 implies 288p video quality (288 lines of vertical resolution), 25 fps and audio quality according to the OPUS standard, developed by the Xiph.com Foundation in collaboration with the Mozilla Foundation and Skype; and

[0175] - V5 Quality, implies a video quality of 480p (480 lines of vertical resolution), 25 fps and an audio quality according to the OPUS standard.

[0177] If home terminal 2 does not send a CC quality confirmation signal in the form of a data byte (or the value of all bits in that byte is zero), then the maximum audio and video quality supported by home terminal 2 is interpreted as Quality V1. That is, 240p video, 8 fps and audio according to the G726.3 standard, developed by the ITU.

[0179] Next, once the maximum audio and video quality supported by dwelling terminal 2 is known, a call request signal LL is sent in stage 40 from street panel 1 to dwelling terminal 2. Alternatively, dwelling terminal 2 could not support video, being a conventional intercom without a video monitor 9, in which case the response to the call request signal LL, sent in the next stage, would be evaluated.

[0181] In response to said LL call request signal, at stage 50 a CLL call receipt confirmation signal is sent from dwelling terminal 2 to street plate 1.

[0183] The procedure continues with step 60, in which, in response to the CLL call confirmation signal, a communication channel reservation signal CO is sent from street panel 1 to home terminal 2, which serves to reserve at least one TDM time window for that communication that will be used by both the street panel and the home terminal.

[0185] Next, in stage 70, in response to the communication channel reservation signal CO, a communication channel reservation confirmation signal CCO is sent from the housing terminal (2) to the street plate (1).

[0187] Furthermore, in step 80, in response to the communication channel reservation confirmation signal, one or more time-division multiplexing (TDM) windows are enabled for communication between the door station 1 and the apartment terminal 2. Thus, in this particular case, if the maximum audio and video quality supported by the apartment terminal 2 is V3 or V4, then a single TDM window is enabled for communication. If, on the other hand, the maximum supported quality is V5, then two different TDM windows are enabled for communication. In this latter case, if any additional TDM windows are available, they can also be optionally enabled for communication or reserved for another conversation between another door station 1 and another apartment terminal 2.

[0189] This allows that in stage 90, if dwelling terminal 2 is provided with a video monitor intercom, a signal with the video V captured by the street panel camera 1 is sent using said TDM window or windows to dwelling terminal (2), at the maximum quality supported by said dwelling terminal 2.

[0191] Next, stage 100 begins, when the intercom is picked up from the home terminal 2 and a DC pick-up signal is sent from home terminal 2 to street panel 1.

[0193] Next, in response to the DC off-hook signal, stage 110 takes place, establishing audio communication between the outdoor panel 1 and the apartment terminal. More specifically, a first signal is sent with audio A1 captured by the microphone (from outdoor panel 1 to apartment terminal 2), and a second signal with audio A2 captured by the handset (from apartment terminal 2 to outdoor panel 1). Both signals A1 and A2 are sent at the highest quality supported by both components of the intercom system.

[0195] Once the conversation between the users of the street panel 1 and the apartment terminal has ended, the latter hangs up the intercom 2, which starts stage 120, in which a call end signal (CG) is sent from apartment terminal 2 to street panel 1. Alternatively, the call end signal (CG) may be emitted if a predetermined time has elapsed without the intercom being hung up.

[0197] Next, in response to the CG hang-up signal, at stage 130 a DS communication channel release signal is sent from street plate 1 to housing terminal 2.

[0198] In response to said DS communication channel release signal, step 140 takes place, in which a CDS communication channel release confirmation signal is sent from home terminal 2 to street board 1.

[0200] Finally, the communication procedure of the invention shown in Fig. 1 concludes with step 150, in which the time-division multiplexing (TDM) window(s) intended for communication between home terminal 2 and street panel 1 are disabled in response to the communication channel release confirmation signal, freeing them up for other street panels to use.

[0202] Figure 3 is a time-domain representation of different signals S1, S2, S3, S4, S5, and S6, used during the communication procedure of the invention, indicating the order in which these signals are sent, their nature, and their modulation in a TDM time window. In Figure 3, the time interval t represented for each of these signals S1, S2, S3, S4, S5, and S6 is 10 ms.

[0204] The first S1 signal visible in that figure, i.e., the one located at the top in Fig. 3, corresponds to a signal in which only data is transmitted, such as, for example, the quality query signal C, the quality confirmation signal CC, the call request signal LL, the call confirmation signal CLL, the communication activation signal CO, and the communication activation confirmation signal CCO.

[0206] Each of these data signals C, CC, LL, CLL, CO, CCO begins with a frequency-modulated INI transmission start marker. This is followed by the actual CMD command (or data frame): quality check, quality confirmation, call request, or call confirmation, modulated with FSK using a different frequency pair than the one used in the INI transmission start marker.

[0208] The second S2 signal visible in Fig. 3 (starting from the top) corresponds to the signals sent in stage 110, when audio transmission between street panel 1 and apartment terminal 2 has been enabled, for audio signals A1 and A2 (in which case the apartment terminal only supports audio). As in the previous case, the information transmitted through the TDM time window begins with a transmission start marker (INI), using frequency modulation. This is followed by the audio corresponding to signal A1, which travels from street panel 1 to apartment terminal 2 and is encoded with FSK modulation using a different frequency pair than the one used in the transmission start marker (INI).

[0210] After a predefined ESP safety delay, the second part of the signal is included in the TDM time window. This signal also begins with a frequency modulation (INI) transmission start marker. The audio corresponding to signal A2, transmitted from terminal 2 to street panel 1, is then included. This audio is encoded using FSK modulation, employing a different frequency pair than the one used for the INI transmission start marker.

[0212] The third signal S3 visible in Fig. 3 (starting from the top) corresponds to the signals sent in stages 120, 130, and 140, where audio transmission has already been enabled and where data transmission is also required. As in the previous case, the information transmitted through the TDM time window begins with a transmission start marker (INI), using frequency modulation. This is followed by the audio signal A1, which travels from street panel 1 to apartment terminal 2, and is encoded using FSK modulation, employing a different frequency pair than the one used in the transmission start marker (INI).

[0214] After the predefined ESP waiting time, the second part of the signal is included in the TDM time window. This signal also begins with a frequency modulated INI transmission start marker. The audio corresponding to signal A2, transmitted from home terminal 2 to street panel 1, is then included. This audio is encoded with FSK modulation, using a different frequency pair than the one used for the INI transmission start marker.

[0216] Finally, after a second predefined waiting time, the third and final part of the signal is included in the TDM time window. This begins with a frequency-modulated INI transmission start marker. This is followed by the actual command (or data frame): hang-up, communication channel release, or communication channel release confirmation, modulated FSK to a frequency pair different from that used in the INI transmission start marker.

[0218] The fourth S4 signal visible in Fig. 3 (starting from the top) corresponds to the signals sent in stage 110, when audio and video transmission has been enabled between street panel 1 and apartment terminal 2 (in which case apartment terminal 2 supports audio and video). As in the previous case, the information transmitted through the TDM time window begins with a transmission start marker (INI), using frequency modulation. This is followed by a signal indicating the audio and video frame type (TYPE) with FSK modulation, using a different frequency pair than the one used in the transmission start marker (INI). Next comes the audio corresponding to signal A1, which travels from street panel 1 to apartment terminal 2, and then the video from street panel 1 to apartment terminal 2, both encoded with PPM modulation.

[0220] After a predefined ESP safety delay, the second part of the signal is included in the TDM time window. This signal also begins with a frequency-modulated INI transmission start marker. Next, a signal indicating the audio and video frame type (TYPE) is included, using FSK modulation and a different frequency pair than the one used for the INI transmission start marker. Following this, the audio corresponding to signal A2, transmitted from apartment 2 to door station 1, is included, followed by further video information from door station 1 to apartment 2, encoded with PPM modulation.

[0222] The fifth signal S5 visible in Fig. 3 (starting from the top) corresponds to the signals sent in stages 120, 130, and 140, where audio and video transmission has already been enabled and where data transmission is also required. As in the previous case, the information transmitted through the TDM time window begins with a transmission start marker (INI), using frequency modulation. This is followed by a signal indicating the audio and video frame type (TYPE) with FSK modulation, using a different frequency pair than the one used in the transmission start marker (INI). Next comes the audio signal (A1) traveling from street panel 1 to apartment terminal 2, followed by the video signal (V) from street panel 1 to apartment terminal 2, both encoded with PPM modulation.

[0224] After the predefined ESP waiting time, the second part of the signal is included in the TDM time window. This signal also begins with a transmission start marker (INI) using frequency modulation. Next, a signal indicating the audio and video frame type (TYPE) is included, using FSK modulation and a different frequency pair than the one used in the transmission start marker (INI). Following this, the audio corresponding to signal A2 is included, transmitted from apartment 2 to door station 1, and then further video information from door station 1 to apartment 2, encoded with PPM modulation.

[0226] After a second predefined ESP timeout, the third and final part of the signal is included in the TDM time window, which begins an INI transmission start marker with FSK modulation. This is followed by the actual CMD command (or data frame): hang-up, communication channel release, or communication channel release confirmation, with FSK modulation at a different frequency pair than the one used for INI.

[0228] The sixth signal S6 in Fig. 3 is similar to the fifth signal S5, with the difference that the dwelling terminal 2 is, in this case, capable of supporting high definition video, so two different TDM time windows, SL1 and SL2, are used to establish communication.

[0230] As in the previous case, the information transmitted through the first time window SL1 begins with a frequency-modulated start marker (INI). This is followed by a signal indicating the audio and video frame type (TYPE) using FSK modulation and a different frequency pair than the one used in the INI start marker. Next comes the audio A1 signal traveling from street panel 1 to apartment 2, followed by the first part of the video V from street panel 1 to apartment 2, both encoded with PPM modulation. After the predefined ESP delay, the second part of the signal, also beginning with a frequency-modulated start marker (INI), is included in the first time window TDM. This is followed by a signal indicating the audio and video frame type (TYPE) using FSK modulation and a different frequency pair than the one used in the INI start marker. The audio corresponding to signal A2, which is transmitted from home terminal 2 to street panel 1, and a second part of video V, which are encoded with PPM modulation, are then included.

[0232] Similarly, the information transmitted through the second time window SL2 also begins with a transmission start marker INI, using frequency modulation. This is followed by a signal indicating the audio and video frame type TYPE with FSK modulation, using a different frequency pair than the one used in the transmission start marker, and then the third part of the video V. After the predefined waiting time ESP, the second time window TDM includes the second part of the signal, which also begins with a transmission start marker INI, using frequency modulation. Finally, a signal indicating the audio and video frame type TYPE with FSK modulation is included, using a different frequency pair than the one used in the transmission start marker INI.

Claims (8)

1. CLAIMS 1.- Communication procedure between at least one street panel (1) and one dwelling terminal (2), of a two-wire multi-channel electronic door entry system, which uses: - at least one street sign (1), equipped with a video camera (6), a speaker (7) and a microphone (8); - a plurality of dwelling terminals (2), each dwelling terminal (2) being provided with a conventional intercom or alternatively, with a video monitor intercom (9) and; - a non-polarized bi-wire communications bus (3) configured to establish communication, at least, between said street panel (1) and said home terminal (2), the street panel (1) and the home terminals (2) being configured to transmit and receive signals through the communications bus (3) using time-division multiplexing, TDM; characterized in that said procedure comprises, at least, the following stages: a) activate (10) the street panel (1) to initiate communication with a home terminal (2); b) send (20) from the street sign (1) to said dwelling terminal (2), a supported quality query signal (C); c) send (30), in response to the quality query signal (C), from the home terminal (2) to the street panel (1) a quality confirmation signal (CC), indicating the maximum audio and video quality supported by the home terminal (2); d) send (40), from the street plate (1) to the housing terminal (2), a call request signal (LL); e) send (50), in response to the call request signal (LL), a call receipt confirmation signal (CLL), from the home terminal (2) to the street panel (1); f) send (60) in response to the call reception confirmation (CLL) signal, from the street panel (1) to the home terminal (2), a communication channel reservation (CO) signal; g) send (70), in response to the communication channel reservation (CO) signal, a communication channel reservation confirmation (CCO) signal, from the housing terminal (2) to the street panel (1); h) enable (80), in response to the communication channel reservation confirmation signal, at least one time-division multiplexing (TDM) window for communication between the street panel (1) and the home terminal (2); i) send (90), using said time window, a signal with the video (V) captured by the street panel camera (1) to the home terminal (2), at the maximum quality supported by said home terminal (2), j) send (100), from the dwelling terminal (2) to the street plate (1), an off-hook signal (DC) when the intercom is taken off the dwelling terminal (2), indicating further whether said dwelling terminal (2) is provided, or not, with a video monitor (9); k) send (110), in response to the off-hook signal (DC), a first signal with the audio (A1) captured by the microphone from the street panel (1) to the dwelling terminal (2) and a second signal with the audio (A2) captured by the intercom from the dwelling terminal (2) to the street panel (1), at the highest supported quality, also if said dwelling terminal (2) is not provided with a video monitor (9), cease the transmission of the video signal; l) send (120), from the dwelling terminal (2) to the street panel (1), an end-of-conversation (CG) signal when the intercom is hung up at the dwelling terminal (2) or, alternatively, send said end-of-conversation (CG) signal from the street panel (1), if a predetermined time has elapsed without the intercom being hung up at the dwelling terminal (2); m) send (130), in response to the end-of-talk (CG) signal, a communication channel release (DS) signal from the street panel (1) to the home terminal (2); n) send (140), in response to the communication channel release signal (DS), a communication channel release confirmation signal (CDS) from the home terminal (2) to the street panel (1); and o) disable (150), in response to the communication channel release confirmation signal, the time-division multiplexing (TDM) window intended for communication between the home terminal (2) and the street panel (1). 2. Communication procedure, according to claim 1, wherein: - the stage (20) which consists of sending the quality query signal (C) from the street panel (1) to said housing terminal (2); and - the stage (30) which consists of sending from the home terminal (2) to the street panel (1), the quality confirmation signal (CC), indicating the maximum audio and video quality that the home terminal supports; They are performed immediately after step (10) which consists of activating the street panel to initiate communication with a home terminal. 3. - Communication procedure, according to any of the preceding claims, wherein the quality confirmation (QC) signal contains information relating, at least, to: - audio codec used, and/or - number of lines of vertical and/or horizontal resolution of the video; and/or - number of frames per second. 4. - Communication method, according to any of the preceding claims, wherein the signals transmitted through the time-division multiplexing (TDM) window between the street panel (1) and the home terminal (2) are modulated differently depending on the type of information they contain. 5. - Communication method, according to claim 4, wherein the street panel (1) is provided with a first modem unit (4); and each of the home terminals (2) is provided with a second modem unit (5); each of said first (4) and second (5) modem units being provided with a pulse position modulated (PPM) signal modulator and demodulator set and a frequency shift key (FSK) signal modulator and demodulator set; and Furthermore, the signals transmitted through the time-division multiplexing (TDM) window are modulated and demodulated as follows: - by frequency shift keying, FSK, if they are data or audio signals when the communication involves home terminals (2) with conventional intercoms, which do not support video; - by frequency modulation, at a frequency different from that used in the modulation and demodulation of data and audio signals, if they are transmission start marking signals; and - by pulse position, PPM, if they are video signals and/or audio signals when the communication involves home terminals (2) with intercoms with video monitor (9). 6.- Communication procedure, according to any of the preceding claims, wherein in the step (80) which consists of enabling time-division multiplexing (TDM) windows in response to the communication activation confirmation (CCO) signal, two or more different time-division multiplexing windows are enabled for the same communication between the street panel (1) and the home terminal (2). 7.- Communication procedure, according to any of the preceding claims, wherein said procedure is executed by a computer. 8.- Computer-readable medium comprising instructions which, when executed on a computer, cause said computer to carry out the steps of a communication procedure according to claim 7.