Automatic gain control in a personal navigation device

Copyright Notice

© 2010 Airbiquily, Inc. A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 37 CFR § 1.71(d).

Background of the Invention

Navigation devices (including Personal Navigation Devices (PNDs) and in-car electronic devices) output information to a user based on a location of the navigation devices. These navigation devices generally utilize the Global Positioning System (GPS) to determine the location, and then use speakers and/or displays to output map information, directions, etc. To continue expanding and/or improving the features provided by navigation devices, there is a need to maximize opportunities for navigation devices to obtain network access, such as to the Internet. The disclosure that follows solves this and other problem.

<patcit id="pcit0001" dnum="US5864578A"><text>US 5,864,578</text></patcit> discusses a method for handing off a remote unit from a first base station to a second base station of a cellular spread-spectrum communications network. Responsive to monitoring and comparing signal quality of received spread spectrum signals, the remote unit initiates hand off when predetermined conditions are met.

Summary of the Invention

The following is a summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later. The scope of the invention is defined by the accompanying claims.

In one example, a Bluetooth enabled navigation device pairs with a mobile phone and then sends a plurality of tuning transmissions, each at a different transmission power gain amount, to a remote server using the mobile phone. These tuning transmissions are encoded using frequency tones that synthesize speech for transmission through the mobile phone and a voice channel of its wireless telecommunications network. The navigation device then tunes transmit power settings according to a received response to the tuning transmissions and uses the tuned transmit power settings for subsequent transmission to the remote server using this particular mobile phone. Additional aspects and advantages of this invention will be apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings.

Brief Description of the Drawings

<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIG. 1</figref> illustrates a system for accessing a remote server with a navigation device using a Bluetooth capable mobile phone.</li><li><figref idref="f0002">FIG. 2</figref> illustrates the navigation device shown in <figref idref="f0001">FIG. 1</figref> as well as interactions between the navigation device and the remote server for tuning transmit power gain.</li><li><figref idref="f0003">FIG. 3</figref> illustrates how the navigation device shown in <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> tunes transmit power gain.</li><li><figref idref="f0004">FIG. 4</figref> illustrates how the server shown in <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> tunes transmit power gain.</li></ul>

Detailed Description of Preferred Embodiments

<figref idref="f0001">FIG. 1</figref> illustrates a system for accessing a remote server with a navigation device using a Bluetooth capable mobile phone.

The system 100 includes a navigation device 5 configured to upload data to the remote Internet Protocol (IP) server 15 through an available one of the mobile phones 1A-B. The software 8 exchanges tuning communications with the software 18 to tune transmit power gain on at least a per-phone basis, and then subsequently uses the tuned transmit power gain amounts according to which one of the mobile phones 1 A-B is currently available. This tuning on at least a per-phone basis allows the navigation device 5 to communicate with the remote server 15 over a wide variety of mobile phones and wireless telecommunications networks, which in turn maximizes communication opportunities for the navigation device 5.

To appreciate how such tuning maximizes opportunities for the navigation device 5 to communicate with the server 15, consider how communications transmitted from the navigation device 5 to the server 15 are processed differently depending on which mobile phone 1A or 1B is used. Initially, depending on which one of the mobile phones 1A and 1B are used, the communications will be processed by different communication circuitry such as vocoders 20 and 21. Each of the vocoders 20 and 21 could affect the power gain of the signal differently, such as by changing the power gain by different amounts. Furthermore, the different wireless telecommunications networks 26 and 27 respectively associated with the mobile phones 1A and 1B can also have different vocoders 22 and 23, which can also affect signals differently. As a result of these differences, in the absence of tuning on at least a per-phone basis, a receiver can receive a signal that is too weak or too strong depending on which combination of vocoders process transmissions. While it is possible for the server 15 and/or its In-Band Signaling (IBS) modem 19 to detect errors resulting from recovery of a signal that is too weak or too strong and request retransmission, such retransmission takes time and can still result in a signal that is too weak or too strong.

In contrast, the system 100 tunes transmit power gain on at least a per-phone basis, which allows a transmission 29A from the navigation device 5 to be received and recovered by the IBS 19 with no errors or minimal errors regardless of which transmission path 30A or 30B is used by the navigation device 5. In other words, transmissions 29B and 29C can have substantially similar power gains despite the differences between the paths 30A and 30B.

This tuning on at least a per-phone basis means that transmit power gain can be set according to the specific available phone, not just tuned to the particular make or model of the available phone. Two mobile phones of the same make or model can also affect signal strength differently because the components within the mobile phones can have different operational characteristics. For example, electronic components are typically rated for performance within a range of values. Accordingly, some of these electronic components operate at the high end of the range while others operate at the low end of the range, which can result in two vocoders of the same model amplifying a signal differently during processing. For example, two resistors of the same model can exhibit different resistances, and these differences in turn affect power gain. For this reason, the software 8 and 18 tunes transmit power on at least a per-phone basis rather than a per-model basis.

Although the software 8 and 18 tunes transmit power on at least a per-phone basis, it should be noted that such tuning can be even more granular in some examples. This will be discussed later in greater detail with reference to <figref idref="f0002">FIG. 2</figref>.

Referring still to <figref idref="f0001">FIG. 1</figref>, it should be appreciated that the system 100 thus maximizes upload opportunities for the navigation device 5. Stated another way, the navigation device 5 is not restricted to communicate with the IP server 15 using any particular designated phone but rather can access server 15 when in range of nearly any Bluetooth enabled mobile phone.

Further to the point made in the previous paragraph, it is preferable for the navigation device 5 to utilize a mobile phone for uploads to the IP server 15 without regard to whether the available mobile phone supports a packet data connection over its wireless telecommunication network. For example, the illustrated mobile phones 1A-B do not support packet data connections over the wireless telecommunications networks 26 and 27, yet can be utilized by the navigation device 5 for IP network access, as will be described in the next paragraph.

For this and other reasons, transmissions from the navigation device 5 to the server 15, including the tuning transmissions that will be discussed later in greater detail, are modulated by the IBS modem 9 for transmission across a voice channel of the wireless telecommunication network. The IBS modem 9 modulates received digital data into audio frequency tones. These frequency tones are selected to synthesize speech so that the frequency tones will pass with minimal attenuation or corruption through the vocoder 20/21 of the available one of the mobile phones 1A-B and any vocoders 22/23 in the available wireless telecommunication network 26/27 (other networks between network 26/27 and the server 15 could operate vocoders as well). Before encoding and modulation into audio tones, the digital data preferably is formatted into one or more packets. A packet formatter may prepend, for example, a header and a sync pattern prior to the payload. Error correction bits, checksums and other enhancements to the packet may be added as well. The navigation device 5 can then transmit the IBS modulated communications 29A over a Bluetooth connection for voice data, to be forwarded over a voice channel of the wireless telecommunications network, through any intervening networks such as the IP network 28, received and demodulated by the IBS modem 19 (recovered into a bitstream), and then finally processed by the server 15.

It should be understood that reliable access to the server 15, or for that matter any remote network, can enable a wide variety of applications for the navigation device. Applications on the navigation device 5 that are part of the navigation system can obtain location-based information in real time can obtain real-time location based information. For example, the navigation device 5 could obtain real-time information about traffic accidents near a current location determined via GPS. The navigation device 5 can also download updates to an internal navigation database, e.g. updating a stored map to information about a new route.

Furthermore, any other type of application on the navigation device 5 can also be provided with remotely stored data using the tuned transmissions described herein. This allows the feature set of the navigation device 5 to be expanded to other applications not necessarily related to navigation. For example, an application on the navigation device 5 could be used to obtain stock quotes or other information available via the Internet. It should be understood it is possible for any type of application operating on the navigation device 5 to obtain access to any type of network as well.

It should be understood that the principles described herein can be applied to any Bluetooth capable mobile device regardless of whether such device has any navigation capabilities. Also, the principles described above can be applied regardless of whether the communication between the device and the mobile phone uses Bluetooth or some other wireless protocol.

It should be understood that power gain is based on the ratio of the signal output of a system to the signal input of the system. When the term transmit power gain is used, the relevant system is the navigation device 5 (or another device configured to upload data to a server). When the term receive power gain is used, the relevant system is the server 15.

Transmit power gain can be adjusted on the navigation device 15 using any known method for adjusting gain. This can include adjusting amplifiers, variable resistors, or other circuit components, in either an input stage or an output stage of a circuit on the navigation device 15.

<figref idref="f0002">FIG. 2</figref> illustrates the navigation device shown in <figref idref="f0001">FIG. 1</figref> as well as interactions between the navigation device and the remote server for tuning transmit power gain.

The navigation device 5 includes a table 38 to be updated by the software 8. The table 38 is later used to set a power gain used for transmitting data based at least in part on the available mobile phone.

In the example, the navigation device 5 pairs 41 with mobile phone 31 to establish a Bluetooth connection between the navigation device 5 and the mobile phone 31. This Bluetooth connection can be established according to the principles described in Patent Application <patcit id="pcit0002" dnum="US2010752911A"><text>US 2010 752911</text></patcit> "USING A BLUETOOTH CAPABLE MOBILE PHONE TO ACCESS A REMOTE NETWORK". Also, the pairing can be triggered by a request from an application operating on the navigation device 15 or from a user interface of the navigation device 15.

During pairing, the software 8 learns a Bluetooth client ID for the mobile phone 31. This Bluetooth client ID is a globally unique identifier that will be used to uniquely identify the mobile phone 31 in the table 38.

The mobile phone 31 receives a session initiation request from the IP server 15. The navigation device 5 processes the request 43 and then the software 8 uses a mechanism to delay session initiation. For example, the software 8 can causes the session initiation to be delayed by using a bit setting 44 in the acknowledgement or any other mechanism for delaying the session initiation. The software 18 is configured to observe the bit setting 44 and delay the session initiation accordingly.

The software 8 then generates test data 45 to be transmitted by modulating received digital data into audio frequency tones using IBS modem 9. These frequency tones are selected to synthesize speech so that the frequency tones will pass with minimal attenuation or corruption through any intervening vocoders. Before encoding and modulation into audio tones, the digital data may be formatted into one or more packets. A packet formatter may prepend, for example, a header and a sync pattern prior to the payload. Error correction bits, checksums and other enhancements to the packet may be added as well.

The software 8 then transmits the modulated test data 45 a plurality of times with each transmission 51 being at a different transmit power gain amount. For example, the test data 45 may be transmitted three times with each transmission being at a different power gain amount.

On the server 15 the software 18 receives the transmissions and determines a receive power gain. The software 18 sends back response 52 to indicate the determined receive power gain.

On the navigation device 5 the software 8 correlates the receive power gain for each transmission of the test data with the transmit power gain for that transmission. This correlation may be conducted according to information included in the response 52.

The software 8 then analyzes the receive power gain amounts. This analysis can include generating a graph containing receive power gain on one axis and transmit power gain on another axis. If the graph is used, the software 8 can connect points on the graph to generate a line graph. The line on the generated graph can then be used to interpolate transmit power gain that will generate a desired receive transmit power gain at the server 15. It should be apparent that the analysis of the receive power gain can operate completely independently of graphs but in any case a transmit power gain is interpolated based on the analysis of the receive transmit power gain. The interpolated transmit power gain will typically be a different value than the transmit power gain used in transmission 51, but it is possible to simply select from one of the transmit power gain amounts used in transmission 51.

The software 8 configures the navigation device 5 so that transmission will be at the power gain identified during the analysis. This can include setting a Bluetooth transceiver on the navigation device 5 or controlling any other software or hardware component on the navigation device 5. Accordingly, when delayed session initiation 61 occurs, transmissions 66 are at the set transmit power gain.

As discussed previously, the IBS modem 9 is used to modulate the packet data 67 of the transmissions 66. The IBS modem 19 recovers the data from the received communications, which are at a tuned receive power gain.

The software 8 also stores the interpolated transmit power gain in table 38 in association with the unique Bluetooth client identifier for the mobile phone 31. The table 38 shows entries in the mobile phone column and the transmit power gain column to illustrate such association. Thereafter, the transmit power gain amounts from the table 38 are used when transmitting data according to which mobile phone is used for the transmission.

The illustrated table 38 also includes the optional column including a network identifier to specify the wireless telecommunications network used during the tuning. This column can be used to provide additional granularity to the tuning. As discussed previously, different wireless telecommunication networks utilize different vocoders, which in at least some cases will have a significant effect on the receive power gain. Therefore, in some examples the tuning can be on a per-phone and per-network basis. This is illustrated in the table 38 where the Bluetooth client ID C is associated with two different transmit power gain amounts, 2.5 dB and 3.1 dB.

It should be understood that the principles described above can be used to add even more granularity to the tuning, e.g. further columns in the table. For example, the same phone/network vocoder combination can be associated with a plurality of tuned power gain amounts depending on the currently utilized mode of the vocoders. Vocoders can operate in different modes, e.g. full rate and half rate, and depending on which mode is used receive power gain can be affected differently. Accordingly, in one example the navigation device 5 determines a current mode of the vocoders and selects between the transmit power gain for this particular phone/network combination based on the current mode. Other possible columns include time of day, the identity of other networks intervening between the wireless telecommunications network and the server 15 (other networks such as IP networks can include vocoders), etc.

Thereafter, the software 8 can compare the Bluetooth client ID of an available mobile phone (and possibly other variables such as the network ID) to the table 38 and identify transmit power gain amounts. The software 8 then sets the Bluetooth transceiver on the mobile phone using the identified transmit power gain amount.

Once the transmit power gain has been set, the software 18 on the server 15 can continually monitor received transmissions from the navigation device. It is possible that receive power gain can "drift" or otherwise change over time despite the navigation device 5 continuing to use the same transmission settings with the same mobile phone. This can occur for many reasons such as the navigation device 5 and the available mobile phone roaming between networks, simply changing a distance from a tower, entering or leaving a power saving mode, etc. In any case, the software 18 can trigger the software 8 on the navigation device 5 to initiate a new tuning process at any time.

The software 18 can determine when a new tuning process is needed using any process. In one example, the software 18 continuously monitors receive power gain of transmissions from the navigation device and triggers initiation of a new tuning process if this receive power gain falls outside a threshold range. In another example, the software 18 monitors a rate of transmission errors over time and triggers initiation of a new tuning process if this transmission error rate exceeds a threshold. Since transmission errors can be related to other factors besides power gain, the software 18 could do some minimal troubleshooting to exclude transmission errors that are unlikely to be caused by power gain from this transmission error rate.

Although the session initiation request 43 was sent by the server 15 in the above described example, in other examples the navigation device 5 can send the session initiation request with the tuning performed before, after, or during the sending. In such an example it may not be necessary for the software 8 to cause a delay in session initiation.

<figref idref="f0003">FIG. 3</figref> illustrates how the navigation device shown in <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> tunes transmit power gain.

In block 301, the navigation device establishes a Bluetooth connection with a mobile phone for communicating with a remote server. The Bluetooth connection can be established as described in Patent Application <patcit id="pcit0003" dnum="US2010752911A"><text>US 2010 752911</text></patcit>, "USING A BLUETOOTH CAPABLE MOBILE PHONE TO ACCESS A REMOTE NETWORK".

In block 302, the navigation device compares a unique identifier for the mobile phone (and possibly other attributes such as a network identifier) with a table that correlates mobile phones to tuned transmit power gain amounts. If there is an entry for the mobile phone in the table in diamond 303, then in block 304A the navigation device sets a Bluetooth transceiver according to the tuned transmit power gain for the mobile phone. The navigation device initiates a session with the remote server for uploading data at the set transmit power gain in block 305.

If there is no entry in the table in diamond 303, then in block 304B the navigation device delays initiation of a session with the remote server. In block 306, the navigation device modulates a received digital bit sequence into an audio signal that has different frequency tones for different bit values where the frequency tones are selected to pass through a wireless voice channel. The navigation device transmits the audio signals using different transmit power gain amounts in block 307.

In block 308, the navigation device receives back a response to the transmissions indicating receive power gain amounts at a remote server. In block 309, the navigation device determines a tuned transmit power gain for the mobile phone by analyzing the receive power gain amounts. The navigation device generates an entry in the table for the mobile phone to associate the tuned transmit power gain with the mobile device in block 310. The process then returns to block 304A.

<figref idref="f0004">FIG. 4</figref> illustrates how the server shown in <figref idref="f0001">FIGS. 1</figref> and <figref idref="f0002">2</figref> tunes transmit power gain.

In block 401, the server receives a plurality of transmissions of an audio signal. In block 402, the server determines a receive power gain for each of these transmissions and sends a communication identifying the receive power gain to a navigation device.

Thereafter, the server receives a transmission having a tuned receive power gain in block 403. If a subsequently received transmission has a receive power gain outside a threshold range, in block 404 the server can signal the navigation device to conduct a new tuning process. The process then returns to block 401.

It will be obvious to those having skill in the art that many changes may be made to the details of the above-described embodiments without departing from the underlying principles of the invention. The scope of the present invention should, therefore, be determined only by the following claims.

Most of the equipment discussed above comprises hardware and associated software. For example, the typical navigation device is likely to include one or more processors and software executable on those processors to carry out the operations described. We use the term <i>software</i> herein in its commonly understood sense to refer to programs or routines (subroutines, objects, plug-ins, etc.), as well as data, usable by a machine or processor. As is well known, computer programs generally comprise instructions that are stored in machine-readable or computer-readable storage media. Some embodiments of the present invention may include executable programs or instructions that are stored in machine-readable or computer-readable storage media, such as a digital memory. We do not imply that a "computer" in the conventional sense is required in any particular embodiment. For example, various processors, embedded or otherwise, may be used in equipment such as the components described herein.

Memory for storing software again is well known. In some embodiments, memory associated with a given processor may be stored in the same physical device as the processor ("on-board" memory); for example, RAM or FLASH memory disposed within an integrated circuit microprocessor or the like. In other examples, the memory comprises an independent device, such as an external disk drive, storage array, or portable FLASH key fob. In such cases, the memory becomes "associated" with the digital processor when the two are operatively coupled together, or in communication with each other, for example by an I/O port, network connection, etc. such that the processor can read a file stored on the memory. Associated memory may be "read only" by design (ROM) or by virtue of permission settings, or not. Other examples include but are not limited to WORM, EPROM, EEPROM, FLASH, etc. Those technologies often are implemented in solid state semiconductor devices. Other memories may comprise moving parts, such as a conventional rotating disk drive. All such memories are "machine readable" or "computer-readable" and may be used to store executable instructions for implementing the functions described herein.

A "software product" refers to a memory device in which a series of executable instructions are stored in a machine-readable form so that a suitable machine or processor, with appropriate access to the software product, can execute the instructions to carry out a process implemented by the instructions. Software products are sometimes used to distribute software. Any type of machine-readable memory, including without limitation those summarized above, may be used to make a software product. That said, it is also known that software can be distributed via electronic transmission ("download") in which case there will typically be a corresponding software product at the transmitting end of the transmission or the receiving end, or both.

Having described and illustrated the principles of the invention in a preferred embodiment thereof, it should be apparent that the invention may be modified in arrangement and detail without departing from such principles.