PATENT DOCUMENT

Publication Number: US-7616683-B2
Application Number: US-36306106-A
Country: US
Kind Code: B2

Title: Automatic switching between DSL and analog on a single RJ-11 DSL/analog combo modem

Abstract:
A modem for providing both DSL and analog signal connection capability with a single RJ-11 jack via an automatic switching mechanism. The switching mechanism is controlled by software, which is responsive to user connection preference (i.e., for DSL or analog connection) and/or the detection that a DSL service is available. Dependent on whether DSL is detected on the signal line coupled to the jack and/or whether the user selects a DSL connection, the switching mechanism routes the signal received on the RJ-11 jack through either a path having the DSL modem circuitry or a path having analog modem circuitry.

Claims:
1. A modem, comprising:
 a first modem circuit and a second modem circuit; 
 an input jack for receiving a signal; 
 a detector that detects whether a signal received at said jack is of a first type containing only analog data, or a second type containing DSL data; and 
 a switching mechanism that selectively couples the input jack to the first modem circuit and disconnects the input jack from the second modem circuit, when the received signal is detected to be of said first type, and couples the input jack to the second modem circuit and disconnects the input jack from the first modem circuit, when the received signal is detected to be of said second type. 
 
     
     
       2. The modem of  claim 1 , wherein the signal of the second type also contains analog data. 
     
     
       3. The modem of  claim 1 , wherein the first circuitry is analog modem circuitry and the second circuitry is DSL, modem circuitry. 
     
     
       4. A switching system, comprising:
 an input jack; 
 a detector that determines whether a signal received at said jack is of a first type containing only analog data, or a second type containing DSL data; and 
 a switching circuit that selectively couples the input jack to a first modem circuit and disconnects the input jack from a second modem circuit when the received signal is of said first type, and couples the input jack to the second modem circuit and disconnects the input jack from the first modem circuit when the received signal is of said second type. 
 
     
     
       5. The system of  claim 4 , wherein said input jack is an RJ-11 jack. 
     
     
       6. The system of  claim 4 , wherein the signal of the second type also contains analog data. 
     
     
       7. The system of  claim 4 , wherein the first circuitry is analog modem circuitry and the second circuitry is DSL modem circuitry. 
     
     
       8. A method of providing DSL and analog signal capability with a single input jack comprising:
 receiving a signal at the input jack; 
 detecting whether the signal received at the input jack is of a first type containing only analog data, or a second type containing DSL data; 
 selectively coupling the input jack to a first modem circuit and disconnecting the input jack from a second modem circuit, when the received signal is detected to be of said first type, and selectively coupling the input jack to the second modem circuit and disconnecting the input jack from the first modem circuit, when the received signal Is detected to be of said second type. 
 
     
     
       9. The method of  claim 8 , where the signal of the second type also contains analog data. 
     
     
       10. The method of aim  8 , wherein the first modem circuit is analog modem circuitry and the second modem circuit is DSL modem circuitry.

Description:
This application is a divisional of application Ser. No. 09/792,946, filed Feb. 26, 2001 now U.S. Pat. No. 7,006,559. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to telecommunications devices and more particularly to the use of modems in DSL and analog environments. 
     2. Background Information 
     Standard analog modems (modulator-demodulator devices) are currently commonplace in the home and office environments, where they are used to enable electronic devices, such as personal computers, to transmit data over existing telephone lines (made of small gauge copper wire) to other electronic devices. Data is stored digitally in such devices, but is converted by an analog modem to be transmitted over the lines in analog form. A data stream is established between a sender (i.e., originating electronic device) and a receiver (i.e., receiving electronic device) by using the resources of an entire telecommunications system. In other words, data is transmitted from the sender&#39;s local loop, through the a telephone switching system, and to the receiver&#39;s local loop. Because the lines used by analog modems to transmit data only use a frequency range of about 0-3400 Hz, a data transmittance limit of about 56,000 bits-per-second (bps) exists for communication through the lines. An analog modem operating at this high end may, for example, be a modem operating under the ITU V.90 standard. 
     An emerging technology called Digital Subscriber Line (DSL) offers users data transmittance speeds much higher than those offered by standard modem systems. Unlike the switching systems associated with analog communications, modems that support DSL must be physically connected at one end of a telephone line (i.e., copper wire) to a phone company central office at the other end of the line, which is typically no longer than 18,000 feet. However, by using a much greater bandwidth (from 60 KHz to 1 MHz), DSL allows higher transfer rates, but is limited to about 18,000 feet in reach. Currently, DSL modems are capable of transmitting data from around 8.128 Mbps to 512 Kbps (downstream) and 128 Kbps to 800 Kbps (upstream). 
     In addition, because DSL technology uses a different area of the spectrum than regular telephony, it is possible to have simultaneous voice and data use of a single copper connection. One example of communications technology that provides this is called Asymmetric DSL (ADSL). In other words, the “lower” range of frequencies (i.e., up to 3400 Hz) is used for the transmittance of voice data, while the “higher” range is used by a DSL modem to transmit digital data. In this way, a DSL connection is always “on” and separate from any voice data transmissions. However, many phones may pass onto the copper frequencies higher than 3400 kHz and allow voice data to interfere with a DSL data stream. Conversely, the higher frequencies used by a DSL modem may be picked up by a phone, which will cause static in the voice data stream. 
     Two methods currently exist for countering these problems. The first one creates a “spluttered” environment, where devices called “splitters” are attached to phone lines in close proximity to the home or office where data is to be received. As shown in the  FIG. 2  example, a nixed-signal S( 1 ) is received by a splitter  205  from center  201 , which may be, for example, a phone company central office. The mixed-signal S( 1 ) includes both analog and DSL data and is spectrally separated by splitter  205  into analog signal S( 2 ) and DSL signal S( 3 ). Phone  202  receives analog signal S( 2 ) through wall jack  206  and DSL modem  203  receives DSL signal S( 3 ) through wall jack  207 . Data from DSL signal S( 3 ) is then processed and sent by DSL modem  203  to a processor  204 , where information may be presented to a user (e.g., via an Internet browser). Splitter  205  also acts as a low pass filter, allowing only voice data frequencies (i.e., 0-3400 Hz) to be transmitted to and from the phone, thereby eliminating any interference between a phone and a DSL modem. 
     The second method creates a “splitterless” environment, where lower frequency data (i.e., analog voice) is not separated or “split” from the higher frequency data (i.e., digital DSL) before being received from a wall jack. As shown in the  FIG. 3  example, center  301  transmits a mixed-signal S( 4 ), which is received by microfilter  305  and DSL/analog combo modem  303  through wall jacks  306  and  307 , respectively. In such an environment, the installation of a separate splitter (e.g., splitter  205  in  FIG. 2 ) is avoided. Instead, a customer-installable microfilter  305  is used to eliminate interference between voice and data frequencies. Combo modem  303  is a modem which is capable of supporting both DSL and analog transmission. Thus, processor  304  is able to receive converted DSL data and analog data from combo modem  303 . 
     As DSL is a new technology, DSL/Analog combo modems, such as combo modem  303 , are not yet widely available. Those that are available are equipped with two RJ-11 jacks: one for connection to a DSL outlet and the other to an analog outlet. In the interest of cost and space reduction, it would be preferable to have such a combo modem with only a single RJ-11 jack; however, such a configuration, without further alteration, would not be able to receive both DSL and analog signals. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a modem that provides both DSL and analog signal connection capability with a single jack. 
     According to a first embodiment of the present invention, a modem is provided to support both DSL and analog signal connection capability, comprising a first circuitry, a second circuitry, an input jack for receiving a signal, a detector for detecting whether the received signal is of a first or second type, and a switching mechanism, wherein the switching mechanism selectively couples the input jack to the first or second circuitry based on the detected signal type, further wherein a user is able to uncouple the input jack from the second circuitry and to couple the input jack to the first circuitry. 
     According to a second embodiment of the present invention, a system is provided for switching, comprising means for receiving a signal, means for detecting whether the received signal is of a first or second type, means for selectively coupling the means for receiving to a first circuitry if the received signal is of a first type, or to a second circuitry if the received signal is of a second type, and means for allowing a user to uncouple the means for receiving from the second circuitry and to couple the means for receiving to the first circuitry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments, when read in conjunction with the accompanying drawings wherein like elements have been represented by like reference numerals and wherein: 
         FIG. 1  illustrates a combo modem in accordance with an embodiment of the present invention; 
         FIG. 2  illustrates a DSL/analog spluttered environment; and 
         FIG. 3  illustrates a DSL/analog splitterless environment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Combo modem  100 , as shown in  FIG. 1 , includes a combo jack  101 , a set of switches  102 , DSL modem circuitry  103 , and analog modem circuitry  104 . Combo jack  101  is preferably a RJ-11 jack and digital modem circuitry  103  is preferably circuitry operable to process DSL signals. 
     Command signals from software modules  107  and  108  are transmitted to command module  106 , and these signals are transmitted to switches  102  through opto-coupler  105 . Opto-coupler  105  also acts to isolate the command signal path of software  106  from switches  102  by severing the connection between them. It will be appreciated that alternatively, signal isolation can be implemented at switches  102 , which can accordingly be optical switches, for instance. Switches  102  are connected to terminals (a) and (b) of combo jack  101 , which are commonly termed the TIP and RING lines of the circuit, and the received command signals from software  106  are able to switch both lines using switches  102 . 
     Software  106  transmits command signals to switches  102  based on user preference and/or detected signal type. In the case of user preference, a user instructs software  108  (e.g., through a user-computer interface device) that combo modem  100  should be either set in a DSL mode or an analog mode. To do this, software  106  sends command signals to switches  102  via module  106 , which internally connect combo jack  101  to DSL modem circuitry  103  if a digital mode is desired, or to analog modem circuitry  104  if an analog mode is desired. To connect combo jack  101  to DSL modem circuitry  103 , switches  102  are commanded to connect terminals (a) and (b) of combo jack  101  with terminals (d) and (c) of DSL modem circuitry  103  through connection paths  111  and  112 , respectively. This switching configuration is shown by the solid-line representation of switches  102  in the figure. To connect combo jack  101  to analog modem circuitry  104 , switches  102  are commanded to connect terminals (a) and (b) of combo jack  101  with terminals (e) and (f) of analog modem circuitry  104  through connection paths  109  and  110 , respectively. This configuration is shown by the dotted-line representation of switches  102  in the figure. Switches  102  can be for instance standard CMOS switches, mechanical relays, or opto-coupler switches as mentioned above. 
     Software  107  may be provided in order to automatically detect whether a signal line connected to combo jack  101  carries DSL frequencies, which may indicate that DSL service is available. One method for implementing automatic detection is to configure the combo modem  100  to enter DSL mode at power up, as a default condition. If a DSL signal is not detected after a certain period of time, the switch to analog mode is effected. Specifically, the combo modem tries to establish a DSL connection, and if it is unable, then it switches to analog mode. When DSL signals are not detected by software  106  on the line connected to the external side of combo jack  101 , software  106  automatically instructs switches  102  to connect combo jack  101  to analog modem circuitry  104  by switches  102 . When DSL signals are detected on the connected line, which may occur either in a splittered or splitterless environment, combo jack  101  is by default connected to DSL modem circuitry  103 . In a splitterless environment, where the connected line also carries analog frequencies, a user may want to use the analog capability of combo modem  100  (e.g., to send a facsimile message) and to “override” the initial switching instructed by software  106 . In this case, the user can instruct software  106  to disconnect combo jack  101  from DSL modem circuitry  103  and switch the connection to analog modem circuitry  104 . 
     In this way, a DSL/analog combo modem with a single RJ-11 jack is able to switch its circuitry between a digital DSL connection and an analog connection, based on user preference and/or detected signal type. 
     It will be appreciated by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restricted. The scope of the invention is indicated by the appended claims rather than the foregoing description and all changes that come within the meaning and range and equivalence thereof are intended to be embraced therein.

Metadata:
Filing Date: 20060228
Publication Date: 20091110
Grant Date: 20091110
Priority Date: 20010226
Inventors: MARDINIAN OLIVIER
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L25/0272", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L25/0272", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 35922853