WO2020236200A1

WO2020236200A1 - System for scanning digital broadcast radio content

Info

Publication number: WO2020236200A1
Application number: PCT/US2019/050181
Authority: WO
Inventors: Marek Milbar
Original assignee: Ibiquity Digital Corporation
Priority date: 2019-05-20
Filing date: 2019-09-09
Publication date: 2020-11-26

Abstract

A radio broadcast signal receiver comprises tuner circuitry configured to receive a radio broadcast signal including digital audio content and processing circuitry. The processing circuitry is configured to: scan for radio broadcast signals by tuning the tuner circuitry to multiple radio broadcast signal frequencies and vary a time duration that the tuner circuitry is tuned to the radio broadcast signal frequencies during the scanning according to when digital audio content of the radio broadcast signals becomes available for play by the radio broadcast signal receiver.

Description

SYSTEM FOR SCANNING DIGITAL BROADCAST RADIO CONTENT

Claim of Priority

[0001] This application claims priority to US. Provisional Application Serial

No. 62/850,398, filed on May 20, 2019, and is hereby incorporated by reference herein in its entirety.

Technical Field

[0002] This invention relates to methods and apparatuses for radio signal broadcasting, and more particularly, to methods and apparatuses for receiving and processing in-band on-channel (IBOC) radio signals.

Background

[0003] Digital radio broadcasting technology delivers digital audio and data services to mobile, portable, and fixed receivers. One type of digital radio broadcasting, referred to as in-band on-channel (IBOC) radio broadcasting uses terrestrial transmitters in the existing Medium Frequency (MF) and Very High Frequency (VHF) radio bands. HD Radio™ technology, developed by iBiquity Digital Corporation, is one example of an IBOC implementation for digital radio broadcasting and reception. IBOC radio signals can be transmitted in a hybrid format including an analog modulated carrier in combination with a plurality of digitally modulated carriers. Digital Audio Broadcasting (DAB) or Digital Radio Mondiale (DRM) are digital-only formats where the analog modulated carrier is not used.

[0004] One feature of digital transmission systems is the ability to simultaneously transmit both digitized audio and data. Thus, the technology also allows for wireless data services from radio stations. The broadcast signals can include metadata, such as the artist, song title, or station call letters. Special messages about events, traffic, and weather can also be included. For example, traffic information, weather forecasts, news, and sports scores can all be scrolled across a radio receiver's display while the user listens to a radio station.

[0005] Using the hybrid format, broadcasters may continue to transmit analog audio simultaneously with higher-quality and more robust digital signals, allowing themselves and their listeners to convert from analog-to-digital radio while maintaining their current frequency allocations. Using the all-digital format, additional data channels are available for broadcasters to transmit more data with the audio program as well as unrelated data services.

[0006] A hybrid radio receiver is able to receive and play the analog and digital radio broadcasts. The radio receiver should provide the ability to scan for all available stations and programs. Scanning the radio broadcast frequency band for all available radio stations and programs, whether analog-only, digital and analog, or digital-only, involves multiple stages. Traditionally, the stages of scanning are invoked sequentially, and the process is repeated for every radio station. Such an approach can involve silence segments, thus perceived as taking a long time and may result in an inadequate user experience.

[0007] The technology presented in this document relates to improvements in providing audio programming to digital radio receivers. Embodiments improve the user experience because of the smooth manner in which audio content remains available while scanning, thus eliminating“dead” or silent periods of time. In addition, embodiments allow for faster scanning and potential power savings. While essential stages of the scanning process are not eliminated, embodiments do change the order of events. In particular, the timing of introduction of content to the user and the timing of the frequency switching may be changed.

[0008] The embodiments described herein mitigate silent periods by having the physical layer (of the OSI model), which is scanning the frequencies, temporarily operating ahead of the application layer, which is playing the content for the user. This mitigates the user having to listen to extended periods of silence.

[0009] A radio receiver example includes tuner circuitry and processing circuitry.

The tuner circuitry is configured to receive a radio broadcast signal including digital audio content. The processing circuitry is configured to scan for radio broadcast signals by tuning the tuner circuitry to multiple radio broadcast signal frequencies; and vary a time duration that the tuner circuitry is tuned to the radio broadcast signal frequencies during the scanning according to when digital audio content of the radio broadcast signals becomes available for play by the receiver. The tuner circuitry may be temporarily tuned to a frequency other than the frequency from which the audio content is currently played.

[0010] A method example comprises includes scanning for radio broadcast signals using the receiver by tuning to multiple radio broadcast signal frequencies; tuning to the radio broadcast signal frequencies for a varying time duration during the scanning; and playing digital audio content included in received radio broadcast signals for a fixed time duration using the receiver.

[0011] This section is intended to provide a brief overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application such as a discussion of the dependent claims and the interrelation of the dependent and independent claims in addition to the statements made in this section.

Brief Description of the Drawings

[0012] FIG. 1 is a schematic representation of a hybrid radio waveform.

[0013] FIG. 2 is a schematic representation of an extended hybrid radio waveform.

[0014] FIG. 3 is a schematic representation of an all-digital radio waveform.

[0015]

[0016] FIG. 4 is a functional block diagram of a radio receiver.

[0017] FIG. 5 is a diagram of radio logical protocol stack from the receiver perspective.

[0018] FIG. 6 is a timing diagram of an example of a method of radio program scanning.

[0019] FIG. 7 is a flow diagram of a method of controlling operation of radio broadcast signal receiver.

[0020] FIG. 8 is a timing diagram of another example of a method of radio program scanning.

[0021] FIG. 9 is a timing diagram of an example of a method of scanning for digital-only broadcast signals.

[0022] FIG. 10 is a timing diagram of another example of a method of scanning for digital-only broadcast signals.

Description

[0023] The following description describes various embodiments of methods and apparatuses that provide improved scanning of audio programs that are broadcast using hybrid (e g., IBOC) or digital-only (e.g., DAB) radio signals. The radio broadcast signal receiver should scan through the available analog and digital radio broadcasts to sample audio content of the broadcasts for the user and display radio station information with the audio content.

[0024] A conventional approach is to tune to a frequency for a constant or fixed duration to play the audio content for the user. Audio from the analog signal is typically played first for a specified time potentially followed by the audio from the digital signal if available until the duration for play has been reached and audio content for the next tuned frequency is played. If digital content is not available, the audio from the analog signal is played for the entire duration. While the analog audio is played, attempts to detect digital are continuously carried through during the duration. The continued attempts to detect digital signal audio may waste power and computation resources of the radio broadcast signal receiver.

[0025] FIG. 1 is a schematic representation of a hybrid frequency modulation

(FM) in-band on-channel (IBOC) waveform 70. The waveform includes an analog modulated signal 72 located in the center of a broadcast channel 74, a first plurality of evenly spaced orthogonally frequency division multiplexed sub carriers 76 in an upper sideband 78, and a second plurality of evenly spaced orthogonally frequency division multiplexed sub carriers 80 in a lower sideband 82. The digitally modulated sub carriers are divided into partitions and various sub carriers are designated as reference sub carriers. A frequency partition is a group of 19 orthogonal frequency division multiplexing (OFDM) sub carriers containing 18 data sub carriers and one reference subcarrier.

[0026] The hybrid waveform includes an analog FM-modulated signal, plus digitally modulated primary main sub carriers. The sub carriers are located at evenly spaced frequency locations. The sub carrier locations are numbered from -546 to +546.

In the waveform of FIG. 1, the sub carriers are at locations +356 to +546 and

-356 to -546. Each primary main sideband is compri sed of ten frequency partitions.

Sub carriers 546 and -546, also included in the primary main sidebands, are additional reference subcarriers. The amplitude of each sub carrier can be scaled by an amplitude scale factor.

[0027] FIG. 2 is a schematic representation of an extended hybrid FM IBOC waveform 90. The extended hybrid waveform is created by adding primary extended sidebands 92, 94 to the primary main sidebands present in the hybrid waveform. One, two, or four frequency partitions can be added to the inner edge of each primary main sideband. The extended hybrid waveform includes the analog FM signal plus digitally modulated primary main sub carriers (sub carriers +356 to +546 and -356 to -546) and some or all primary extended sub carriers (sub carriers +280 to +355 and-280 to -355). [0028] The upper primary extended sidebands include sub carriers 337 through

355 (one frequency partition), 318 through 355 (two frequency partitions), or 280 through 355 (four frequency partitions). The lower primary extended sidebands include sub carriers -337 through -355 (one frequency partition), -318 through -355 (two frequency partitions), or -280 through -355 (four frequency partitions). The amplitude of each sub carrier can be scaled by an amplitude scale factor.

[0029] FIG. 3 is a schematic representation of a digital-only FM DAB waveform

100. The digital-only waveform is constructed by disabling the analog signal, fully expanding the bandwidth of the primary digital sidebands 102, 104, and adding lower- power secondary sidebands 106, 108 in the spectrum vacated by the analog signal . The all-digital waveform in the illustrated embodiment includes digitally modulated sub carriers at subcarrier locations -546 to +546, without an analog FM signal .

[0030] In addition to the ten main frequency partitions, all four extended frequency partitions are present in each primary sideband of the all-digital waveform. Each secondary sideband also has ten secondary main (SM) and four secondary extended (SX) frequency partitions. Unlike the primary sidebands, however, the secondary main frequency partitions are mapped nearer to the channel center with the extended frequency partitions farther from the center.

[0031] Each secondary sideband also supports a small secondary protected (SP) region 110, 112 including 12 OFDM sub carriers and reference subcarriers 279 and -279. The sidebands are referred to as "protected" because they are located in the area of spectrum least likely to be affected by analog or digital interference. An additional reference sub carrier is placed at the center of the channel (0). Frequency partition ordering of the SP region does not apply since the SP region does not contain frequency partitions.

[0032] Each secondary main sideband spans subcarriers 1 through 190 or -1 through -190. The upper secondary extended sideband includes sub carriers 191 through 266, and the upper secondary protected sideband includes sub carriers 267 through 278, plus additional reference sub carrier 279. The lower secondary extended sideband includes sub carriers -191 through -266, and the lower secondary protected sideband includes sub carriers -267 through -278, plus additional reference subcarrier -279. The total frequency span of the entire all-digital spectrum is 396,803 Hz. The amplitude of each sub carrier can be scaled by an amplitude scale factor. The secondary sideband amplitude scale factors can be user selectable. Any one of the four may be selected for application to the secondary sidebands. [0033] In each of the waveforms, the digital signal is modulated using orthogonal frequency division multiplexing (OFDM). OFDM is a parallel modulation scheme in which the data stream modulates a large number of orthogonal subcarriers, which are transmitted simultaneously. OFDM is inherently flexible, readily allowing the mapping of logical channels to different groups of subcarri ers.

[0034] In the hybrid waveform, the digital signal is transmitted in primary main

(PM) sidebands on either side of the analog FM signal in the hybri d waveform. The power level of each sideband is appreciably below the total power in the analog FM signal. The analog signal may be monophonic or stereo, and may include subsidiary communications authorization (SCA) channels.

[0035] In the extended hybrid waveform, the bandwidth of the hybrid sidebands can be extended toward the analog FM signal to increase digital capacity. This additional spectrum, allocated to the inner edge of each primary main sideband, is termed the primary extended (PX) sideband.

[0036] In the all-digital waveform, the analog signal is removed and the bandwidth of the primary digital sidebands is fully extended as in the extended hybrid waveform. In addition, this waveform allows lower-power digital secondary sidebands to be transmitted in the spectrum vacated by the analog FM signal .

[0037] FIG. 4 is a functional block diagram of an FM IBOC radio receiver 450.

The receiver includes an input 452 connected to an antenna 454 and tuner circuitry 456. The remainder of the blocks in FIG. 4 may be included in a baseband processor of the radio receiver. A received signal is provided to an analog-to-digital converter and digital down converter 458 to produce a baseband signal at output 460 comprising a series of complex signal samples. The signal samples are complex in that each sample comprises a "real" component and an "imaginary" component, which is sampled in quadrature to the real component. An analog demodulator 462 demodulates the analog modulated portion of the baseband signal to produce an analog audio si gnal on line 464. The digi tally modulated portion of the sampled baseband signal is next filtered by sideband isolation filter 466, which has a pass-band frequency response comprising the collective set of sub carriers fi-f_n present in the received OFDM signal. Filter 468 suppresses the effects of a first-adj acent interferer. Complex signal 498 is routed to the input of acquisition module 496, which acquires or recovers OFDM symbol timing offset or error and carrier frequency offset or error from the received OFDM symbols as represented in received complex signal 498. Acquisition module 496 develops a symbol timing offset At and carrier frequency offset Af, as well as status and control information. The signal is then demodulated (block 472) to demodulate the digitally modulated portion of the baseband signal. Then the digital signal is deinterleaved by a deinterleaver 474 and decoded by a Viterbi decoder 476. A service demultiplexer 478 separates main and supplemental program signals from data signals. A processor 480 processes the main and supplemental program signals to produce a digital audio signal on line 482. The analog and main digital audio signals can be blended as shown in block 484, or the digital signal audio can be passed through, to produce an audio output on line 486. A data processor 488 processes the data signals and produces data output signals on lines 490, 492 and 494.

The data signals can include, for example, a station information service (SIS), main program sendee data (MPSD), supplemental program service data (SPSD), and one or more advanced application services (AAS). The data output signals may be provided to a host controller (not shown) of the radio receiver. In practice, many of the signal processing functions shown in the radio receiver 450 can be implemented using one or more integrated circuits.

[0038] FIG. 5 shows the logical protocol stack of a radio signal receiver such as the radio signal recei ver of FIG. 4. An IBOC waveform is received by the physical (PHY) layer, Layer 1 (505), which demodulates the signal and processes it to separate the signal into logical channels. The number and kind of logical channels will depend on the service mode, and may include logical channels P1-P4, PIDS, S1-S5, and SIDS. Layer 1 produces LI PDUs corresponding to the logical channels and sends the PDUs to Layer 2 (510), which demultiplexes the LI PDUs to produce SIS PDUs, AAS PDUs, PSD PDUs for the main program service and any supplemental program services, and Stream 0 (core) audio PDUs and Stream 1 (optional enhanced) audio PDUs. The SIS PDUs are then processed by the SIS transport 515 to produce SIS data, the AAS PDUs are processed by the AAS transport 520 to produce AAS data, and the PSD PDUs are processed by the PSD transport 525 to produce MPS data (MPSD) and any SPS data (SPSD). The SIS data, AAS data, MPSD and SPSD are then sent to a user interface 530. The SIS data, if requested by a user, can then be displayed. Likewise, MPSD, SPSD, and any text based or graphical AAS data can be displayed. The Stream 0 and Stream 1 PDUs are processed by Layer 4, comprised of audio transport 535 and audio decoder 540. Decoded audio is converted by the digital-to-analog converter (DAC) 545 for play by speaker 550. There may be up to N audio transports corresponding to the number of programs received on the IBOC waveform. Each audio transport produces encoded MPS packets or SPS packets, corresponding to each of the received programs. Layer 4 receives control information from the user interface, including commands such as to store or play programs, and to seek or scan for radio stations broadcasting an all-digital or hybrid radio signal. Layer 4 also provides status information to the user interface.

[0039] FIG. 6 is a timing diagram of an example of a method of radio program scanning. The approach is based on tuning to a frequency for a constant duration when a signal is detected. The tuning duration is always the same and is independent of the content provided by the station. As shown in FIG. 6, the analog signal audio is always played, potentially followed by one digital signal audio program only, until the tuning/screening duration has been reached. The tuning duration to a radio frequency, before determining availability of a digital audio signal, may reach seven seconds (approximately) before searching for the next radio frequency but may be as little as four seconds in ideal reception conditions.

[0040] For example, when scanned to the first radio broadcast signal frequency

(F0), in FIG. 6 the radio receiver plays the analog signal audio 602 which is available within less than a second of the tuning to F0. The analog signal audio 602 is played for the first four seconds (approximately) while the radio receiver attempts to acquire digital si gnal audio at 604. After the four seconds and following successful acquisiti on of the digital signal, the radio receiver plays digital signal audio 606 for three seconds for screening purposes (e.g., introduction to the user). Only one digital audio program (e.g., HD1) is played. The radio receiver display shows frequency FO to the user during the seven seconds immediately upon tuning to that frequency. The radio receiver may indicate FO-digital (e.g., F0 - HD1 ) at 610 when the digital signal audio 606 is played.

[0041] For the next radio broadcast signal frequency (FI), the analog signal audio

612 is played while the radio receiver tries to acquire digital signal audio at 614.

However, digital signal audio is intermittent and is inadequate for being played, and the analog signal audio is played for the entire constant tuning duration of seven seconds.

The radio receiver attempts to detect digital signal audio continuously through the entire tuning duration. This may be considered a waste of power and computati on resources, as much less time is needed to know when digital signal audio may be inadequate for being played, and the detection process could be halted instead of continuing to attempt to detected digital audio. A display indication of FI is presented immediately to the user upon tuning to FI.

[0042] The scanning process for the following radio broadcast signal frequencies

F2 and F3 follow the example of F0. Four seconds of the analog signal audio is played followed by three seconds of digital signal audio to fill out the constant tuning duration of seven seconds. Only one digital audio program of the digital signal audio is played. For radio broadcast signal frequencies F4 and F5, no audio is available; either analog or digital. The scanning is ended early, but the radio receiver provides a segment of silence 620. The display shows frequencies F4 and F5 to the user. For the next radio broadcast signal frequency (F6), analog signal audio and then digital signal audio is played as in the example of frequency F0.

[0043] FIG. 7 is a flow diagram of a method 700 of controlling operation of a radio broadcast signal receiver. The method 700 includes varying the tuning duration for which the radio signal receiver is tuned to a radio broadcast signal frequency but attempts to maintain a constant audible duration for every digital and analog program that is played. At 705, the radio receiver scans for radio broadcast signals by tuning to multiple radio broadcast signal frequencies. The radio broadcast signals may be analog-only, digital and analog, or digital-only signals. At 710, the radio receiver tunes to the radio broadcast signal frequencies for a varying time duration during the scanning. In contrast to the example of FIG. 6, the time duration that the radio receiver is tuned to a frequency can vary and is not a constant or fixed time duration, such as the 7 seconds time duration of the example of FIG. 6.

[0044] At 715, digital content included in received radio broadcast signals is played for a fixed time duration using the receiver. Although, the duration that a digital audio program is played is constant, the total duration time that the radio receiver is tuned to a frequency can vary. This varying in duration time may be due to changing the duration time during which analog is played, or playing each of multiple digital audio programs, that may have been buffered following the acquisition of the digital signal audio, for the constant digital duration time while possibly tuning to the next frequency.

[0045] FIG. 8 is a timing diagram of an approach for combined analog and digital radio program scanning. The program scanning may be performed by a digital radio broadcast signal receiver, such as radio receiver 450 of FIG. 4. The processing circuitry of the radio receiver scans for radio broadcast signals by tuning the tuner circuitry of the radio receiver to radio broadcast frequencies of the frequency band. In contrast to the approach of FIG. 6, a constant audible duration is provided for every digital program that is played. When a digital program becomes available, the combined cycle (analog and digital signal audio) may be shortened, but the digital program audible duration is kept constant.

[0046] Similar to the example of FIG. 6, when scanned to frequency F0 in FIG. 8,

Layer 4 of the radio signal receiver plays the analog signal audio 802. The analog signal audio 802 is played for the first four seconds while the radio receiver acquires digital signal audio at 804. Four seconds is only an example and other tuning durations for the analog signal audio can be used. After the four seconds, the radio receiver stops play of the analog signal audio and initiates play of the acquired digital signal audio 806 for a fixed tuning duration (three seconds in the example of FIG. 8) when a digital audio program is available. Digital signal audio is also buffered at 822. The buffered or stored digi tal audio may include compressed audio programs. In the example of FIG. 8, only one digital audio program (e.g., HD1) is available for F0 and the digital audio program is played. The radio receiver display shows frequency F0 to the user during the seven seconds of tuning immediately upon tuning to that frequency. The radio receiver may indicate a digital program (e.g., F0 - HD1) 810 when the digital signal audio 806 is played.

[0047] For the next frequency (FI), the analog signal audio 812 is played while the radio receiver tries to acquire digital signal audio at 814. Digital signal audio is unavailable, but the analog signal audio is played for a four second tuning duration time as for frequency F0 instead of filling out a seven second scan time as in the example of FIG. 6.

[0048] At the end of the four second tuning duration time, the radio receiver tunes to frequency F2 and plays the analog signal audio 824 available on F2 for four seconds while the radio receiver acquires digital audio 826. The digital content includes more than one digital audio program. When digital signal audio is detected, the first digital audio program (e.g., HDl) is played 828 for the fixed tuning duration while all available digital (compressed) audio is buffered 830 or stored. In the example of FIG. 8, the storage duration of compressed digital audio is 3 seconds. Depending on the service mode, the radio receiver may allocate different amounts of receiver memory for dynamic (but temporary) storage of compressed digital audio.

[0049] Following the play of the first digital audio program, the remaining digital programs (e.g., HD2, HD3, HD4) are played in tandem, allowing screening of all available digital audio program s. Each of the digi tal audio programs is played for the fixed time duration of three seconds. It is noted here that for the purpose of expediting the scanning process, the receiver can tune to the next frequency F3 immediately upon completion of the buffering 830. However, in order to allow the user to select any of the screened programs HDl, HD2, HD3 without causing additional digital signal acquisition time by tuning from frequency F3 back to frequency F2, the tuning to the next frequency F3 is delayed to coincide (approximately) with the play of the last stored digital audio program. In the example of FIG. 8, one second before the last stored digital audio program 834 for frequency F2 is being played (e.g., HD4), the receiver tunes to the next frequency F3 and starts the acquisition process 836 for digital signal audio. If digital signal audio becomes available on frequency F3 during the acquisition process, there is no need to play analog signal audio for frequency F3. The receiver omits play of the analog signal audio of frequency F3 and only plays digital signal audio 838 on frequency F3 after the last stored digital audio program for frequency F2 is played for the fixed time duration. Additional compressed digital audio for frequency F3 is buffered 840.

[0050] In the example shown, the digital audio signal for frequency F3 includes two digital audio programs (e.g., FID1, HD2). As the buffering 840 is completed, the receiver immediately begins the acquisition process 844 for the next frequency F4 during play of the last stored audio program 842. No audio signal is available for F4 and the receiver switches to the next frequency F5 to begin the acquisition process 844 for F5 during the play of the last stored digital audio program 842 for frequency F3. Again, no audio signal is available for frequency F5 and the receiver begins the acquisition process 846 for the next frequency F6. The receiver continues to display frequency F3 as the tuned frequency during play of the F3 digital audio program, and the radio receiver does not display frequencies F4 or F5 to which the radio receiver is tuned but no audio signal is available. The accumulated time spent on frequencies F5 and F6 is illustrated as two seconds in this example but may be less than one second, as it takes less than half a second for determining that no valid signal (analog or digital) is available on a frequency.

[0051] The radio broadcast signal on frequency F6 includes analog and digital content. When the digital content from frequency F3 is played in full at least once, the analog content 848 on frequency F6 is played when it becomes available. When digital content on frequency F6 is detected, the digital content 850 is immediately played, and the analog audio is played for a shortened tuning duration (e.g., 2 seconds shortened from 4 seconds). When the first digital audio program (e.g., F6 - HDl) is played, the available compressed digital audio is buffered 852 or stored.

[0052] Alternati vely, if no useable analog or digital audio content is available on frequency F6, the receiver may re-play the most recently stored digital programs (e.g., one or both of HDl and HD2 for frequency F3) while at the same time it continues switching to another frequency in an attempt to detect audio. As a result, the user may not experience silence during the scanning, thus perceiving the constant availability of audible content.

[0053] The receiver displays frequency F6 following frequency F3. Display indications are provided to the user only for a frequency that has yielded the audio being played, immediately upon playing that audio program, regardless of the actual tuner frequency (as for frequencies F2 and F3). No indication is provided for frequencies not containing any useful signal (as for frequency F4 and F5). Therefore, the user may perceive the processes as continuously providing useful content.

[0054] The scanning process described in relation to FIG. 8 reduces computations needed by the processing circuitry of the receiver and saves power used in the scanning.

These advantages are achieved by early tuning to the next frequency to attempt to acquire digital signal audio on that frequency (e.g., as for frequency F3 at 836, frequencies F4 and F5 at 844, and frequency F6 at 846 in FIG. 8). Also, no analog or digital detection is performed when playing multiple digital programs from stored compressed audio (as for frequency F2 before 834 in FIG. 8). Further, no analog signal audio detection needs to be performed when early acquisition of digital audio is successful (as for frequency F3 at 838 in FIG. 8). In addition, the scanning process of FIG. 8 can be faster than the scanning process of the example of FIG. 6, allowing for scanning (and screening) much more content within either the same time frame or a slightly longer time frame.

[0055] FIG. 9 is a timing diagram of an example of a method of scanning for digital-only broadcast signals. In some cases, the radio receiver can allow a user to elect to scan for digital signal audio only, or the tuning circuit of the radio recei ver may tune to digital-only signals.

[0056] The radio receiver tunes to frequency F0 and begins the acquisition process 904 for digital signal content. The audio from the receiver is silent for the first tuning duration 902 while the radio receiver acquires digital audio. The digital audio 906 is played by the receiver when it is detected. The processing circuitry of the radio receiver maintains a constant tuning duration for each scanned frequency (7 seconds in this example). The receiver displays frequency F0 during the silent segment and during the playing of the digital content. When finished playing the digital content of frequency F0, the receiver tunes to the next frequency FI . No digital content adequate for playing is available, and the receiver continues the acquisition process for the 7 second duration time. The output of the recei ver is silence for the duration time, and the receiver displays frequency FI during the silent duration time.

[0057] The receiver tunes to the next frequency F2 and starts the acquisition process

926 for digital signal audio. The output of the radio receiver is silent 924 for a 4 second duration while the radio receiver acquires digital content 926 and then plays the digital content 928 for a 3 second duration time. Frequency F3 is scanned similar to frequency F2.

Frequencies F4 and F5 include 7 seconds of silence (as in frequency FI in this example), and frequency F6 is scanned similar to frequency F2. [0058] Display indications are provided to the user for every frequency, immediately upon tuning to that frequency. Because the tuning to a frequency uses a constant tuning duration, the scanning process for digital -only may take noticeably long time. The user may experience prolonged silence, which can potentially compromise the experience of the user.

[0059] FIG. 10 is a timing diagram of another example of a method of scanning for digital-only broadcast signals. The radio receiver tunes to frequency F0 and begins the acquisition process 1004 for digital signal content. The audio from the receiver is silent for the first tuning duration 1002 while the radio receiver acquires digital audio, or the receiver may instead play a tone for the first tuning duration 1002. The digital audio 1006 is played by the radio receiver when it is detected, and the receiver buffers 1030 a digital audio program (e.g., F0 - HDl).

[0060] The radio receiver tunes to the next frequency F 1. As in the example of

FIG. 9, no digital audio content is available, but in contrast to the example of FIG. 9 the receiver replays the buffered digital audio program 1032 to avoid a long silent segment. In contrast to the example of FIG. 9, in FIG. 10 the receiver does not attempt a prolonged acquisition of digital signal audio and terminates the acquisition immediately when it determines that although digital signal may be present, the digital audio is inadequate for playing. During the replay of the buffered digital audio program 1032, the receiver tunes to frequency F2 and begins to acquire digital audio 1026 and buffers 1036 the digital audio. The receiver determines that adequate digital audio may be acquired on frequency F2 and therefore does not repeat replaying the digital audio program from frequency F0. The acquired audio includes multiple digital audio programs (e.g., F2 - HDl, F2 - HD2, F2 - HD3, F2 - HD4). Because digital audio program F0 - HDl is only replayed once, there is a short 2.5 second silent segment 1034. The early detection of lack of availability of adequate digital audio signal during frequency F 1 is used to initiate tuning to the next frequency F2, which also reduces the silent segments.

[0061] The digital content may be replayed only once or possibly twice (e.g., in cases where the receiver determines that no digital audio may be available on multiple contiguously scanned frequencies) in order to avoid an adverse user experience. Using replay, the user benefits from near continuous digital audio, perceiving it as continuously providing useful audio content. The radio receiver is more likely to re-play stored digital audio content in the digital -only signal case (as for frequency F0 in FIG. 10) than in the combined analog-digital case.

[0062] The digital audio programs for frequency F2 are played in tandem.

During the play of the last buffered digital audio program for frequency F2, the radio receiver tunes to frequency F3 to acquire digital audio 1038 and buffer the digital audio 1040. The digital audio signal of frequency F3 includes two digital audio programs. In this example one second before play of the last digital audio program, the radio receiver tune to frequency F4 and frequency F5 to acquire audio. Because digital audio is unavailable for frequencies F4 and F5, the radio receiver replays 1042 the two digital audio programs for frequency F3 in tandem, and during the replay the radio receiver eventually tunes to frequency F6 were digital audio is detected. Replay of the two digital audio programs avoids a silent segment at the audio output when tuning to frequencies F4 and F 5. Display indications are provided to the user mostly for a frequency that has yielded the digital audio being played, with rare cases of silent frequency (as for frequencies F2 and F3 in FIG. 10).

[0063] In the systems and methods described, stored content can be played or re played by the radio receiver while re-tuning to frequencies, and yet audio related indications (rather than frequency related indications) may be distributed between a baseband processor and a host controller of the radio receiver during the re-tuning. The baseband processor may be limited to the sequential acti vity of tuning to frequency, acquiring audio, storing 3 seconds of compressed audio while playing all available digital content in tandem until content from new frequency becomes available. The tuning to a frequency may be by command from the host controller. In some aspects, the host controller may be limited to instructing the baseband processor when to tune to the next frequency and to provide the user with adequate information on the display. The techniques for scanning for audio content have been described as performed by one radio tuner. In some aspects, the tuning circuitry' of a radio receiver can include multiple tuners that may each independently tune to a frequency, and the techniques can be performed by each of the tuners, or by multiple tuners working in tandem. The methods and devices described herein allow for a fast scan process that minimizes silent segments for the user while reducing the computational resources used by the radio receiver for the scanning.

Additional Examples and Disclosure

[0064] Example 1 includes subject matter (such as radio broadcast signal receiver) comprising tuner circuitry configured to receive a radio broadcast signal including digital audio content, and processing circuitry. The processing circuitry is configured to scan for radio broadcast signals by tuning the tuner circuitry to multiple radio broadcast signal frequencies, and vary a time duration that the tuner circuitry is tuned to the radio broadcast signal frequencies during the scanning according to when digital audio content of the radio broadcast signals becomes available for play by the radio broadcast signal receiver.

[0065] In Example 2, the subject matter of Example 1 optionally includes tuner circuitry configured to receive a radio broadcast signal including both digital audio content and analog audio content, and processing circuitry configured to initiate play of the analog audio content when the digital audio content is unavailable for play, stop play of the analog audio content when the digital audio content becomes available, and initiate play of the digital audio content for a fixed time duration.

[0066] In Example 3, the subject matter of Example 2 optionally includes digital audio content in the received radio broadcast signal that includes multiple digital audio programs, and processing circuitry configured to initiate play of each of the multiple digital audio programs for the fixed time duration in tandem.

[0067] In Example 4, the subject matter of one or both of Examples 2 and 3 optionally includes digital audio content in the received radio broadcast signal that includes compressed digital audio data of multiple digital audio programs, and processing circuitry configured to initiate play of a first digital audio program of the multiple digital audio programs when the digital audio data is available, store compressed versions of the multiple digital audio programs in the memory, and initiate play of each of the stored multiple digital audio programs for the fixed time duration in tandem.

[0068] In Example 5, the subject matter of one or any combination of Examples

2-4 optionally includes tuner circuitry configured to receive another different radio broadcast signal including both digital audio content and analog audio content, and processing circuitry is configured to omit play of the analog audio content and initiate play of the digital audio content of the other radio broadcast signal when the digital audio content is available at the end of the fixed time durati on.

[0069] In Example 6, the subject matter of one or any combination of Examples

1 -5 optionally includes a display and processing circuitry configured to tune the tuner circuitry to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies, initiate play of analog or digital audio content of a first radio broadcast signal corresponding to a first radio broadcast signal frequency, tune the tuner circuitry to a second radio broadcast signal frequency during playing of the analog or digital audio content first radio broadcast signal, display tuning of the radio broadcast signal receiver to the first radio broadcast signal frequency during play of the analog or digital audio content of the first radio broadcast signal frequency instead of the tuned second radio broadcast signal frequency. [0070] in Example 7, the subject matter of Example 6 optionally includes processing circuitry configured to replay the digital audio content included in the first radio broadcast signal when there is no useable audio content included in a radio broadcast signal of the second radio broadcast signal frequency.

[0071] In Example 8, the subject matter of Example 7 optionally includes processing circuitry configured to tune the tuner circuitry to one or more additional radio broadcast signal frequencies during the replay of the digital audio content of the first radio broadcast signal, and not display radio broadcast signal frequencies for which useable audio content is not detected.

[0072] In Example 9, the subject matter of Example 1 optionally includes tuner circuitry configured to receive a digital-only radio broadcast signal, and processing circuitry configured to scan the multiple radio broadcast signal frequencies and tune the tuning circuitry to a digital-only radio broadcast signal, play a first digital audio program of the digital-only broadcast radio signal when digital audio content is detected, and store compressed versions of the first digital audio program and other digital audio programs received on the digital-only broadcast radio signal, play the other digital audio programs in tandem, and tune to a next digital-only radio broadcast signal frequency when a stored digital audio program is played by the radio broadcast signal receiver.

[0073] In Example 10, the subject matter of Example 9 optionally includes processing circuitry configured to replay previously played digital audio content when there is no useable audio content detected for a radio broadcast signal of the next digital- only radio broadcast signal frequency.

[0074] In Example 11, the subject matter of one or any combination of Examples

1-10 optionally includes tuning circuitry that includes multiple tuners, each configured to independently tune to a radiobroadcast frequency.

[0075] Example 12 includes subject matter (such as a method of controlling operation of a radio broadcast signal receiver), or can opti onally be combined with one or any combination of Examples 1-11 to include such subject matter, comprising scanning for radio broadcast signals using the receiver by tuning to multiple radio broadcast signal frequencies, tuning to the radio broadcast signal frequencies for a varying time duration during the scanning, and playing digital audio content included in received radio broadcast signals for a fixed time duration using the radio broadcast signal receiver.

[0076] In Example 13, the subject matter of Example 12 optionally includes tuning the receiver to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies, playing the digital content of a first radio broadcast signal corresponding to the first radio broadcast signal frequency, tuning the radio broadcast signal receiver to a next radio broadcast signal frequency during playing of the digital audio content for the fixed time duration, and displaying tuning of the first radio broadcast signal frequency during playing of the digital audio content instead of the tuned next radio broadcast signal frequency.

[0077] In Example 14, the subject matter of Example 13 optionally includes playing only digital audio content of the next radio broadcast si gnal frequency when available after playing the digital audio content of the first radio broadcast signal frequency.

[0078] In Example 15, the subject matter of one or any combination of Examples

12-14 optionally includes the digital audio content included in the received radio broadcast signals includes multiple digital audio programs, and playing each of the multiple digital audio programs for the fixed time duration in tandem using the radio broadcast signal receiver.

[0079] In Example 16, the subject matter of one or any combination of Examples

12-15 optionally includes tuning the receiver to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies, playing digital audio content included in a radio broadcast signal of the first radio broadcast signal frequency for the fixed time duration, tuning the radio broadcast signal receiver to a second radio broadcast signal frequency of the scanning, and replaying the digital audio content included in the radio broadcast signal of the first radio broadcast signal frequency when there is no useable audio content included in a radio broadcast signal of the second radio broadcast signal frequency.

[0080] In Example 17, the subject matter of Example 16 optionally includes tuning the radio broadcast signal receiver to one or more additional radio broadcast signal frequencies of the scanning during the replaying of the digital audio content, and not displaying radio broadcast signal frequencies for which useable audio content is not detected.

[0081] In Example 18, the subject matter of one or any combination of Examples

12-17 optionally includes tuning the receiver to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies, receiving compressed digital audio data including multiple digital audio programs in a radio broadcast signal in response to the tuning, playing a first digital audio program of the multiple digital audio programs when the digital audio data is received and buffering compressed versions of the multiple digital audio programs in memory of the radio broadcast signal receiver, and playing each of the multiple digital audio programs for the fixed time duration in tandem.

[0082] In Example 19, the subject matter of Example 18 optionally includes tuning the radio broadcast signal receiver to a second radio broadcast signal frequency of the scanning during pl aying of a digital audio program of the multiple digital audio programs, and tuning the radio broadcast signal receiver to a third radio broadcast signal frequency of the scanning during the pl aying of the digital audio program when the second radio broadcast signal frequency does not include useable audio content.

[0083] In Example 20, the subject matter of one or any combination of Examples

12-19 optionally includes scanning the multiple radio broadcast signal frequencies for digital-only radio broadcast signals, receiving a digital-only broadcast radio signal when the radio broadcast signal receiver is tuned to a first radio broadcast signal frequency, play a first digital audio program of the digital-only broadcast radio signal when digital audio content is detected, and store compressed versions of the first digital audio program and other digital audio programs received on the digital-only broadcast radio signal, play the other digital audio programs in tandem, and tune to a next radio broadcast signal frequency when a stored digital audio program is played on the radio broadcast signal receiver.

[0084] In Example 21, the subject matter of Example 20 optionally includes replaying previously played digital audio content when there is no useable audio content detected for a radio broadcast signal of the next radio broadcast signal frequency.

[0085] Example 22 includes subject matter (or can optionally be combined with one or any combination of Examples 1-21 to include such subject matter) such as a computer readable storage medium including instructions that, when performed by processing circuitry of a radio broadcast signal receiver, cause the processing circuitry to perform acts comprising scanning for radio broadcast signals by tuning the radio broadcast signal receiver to multiple radio broadcast signal frequencies, playing analog audio content included in the received radio broadcast signals using the radio broadcast signal receiver, changing to playing digital audio content included in received radio broadcast signals for a fixed time duration using the radio broadcast signal receiver when digital audio content becomes available, varying a time duration of playing the analog audio content according to when the digital audio content becomes available.

[0086] In Example 23, the subject matter of Example 22 optionally includes a computer readable storage medium including instructions for playing each of multiple digital audio programs included in the digital audio content for the fixed time duration in tandem using the radio broadcast signal receiver.

[0087] In Example 24, the subject matter of one or both of Examples 22 and 23 optionally include a computer readable storage medium including instructions for tuning the radio broadcast signal recei ver to a first radio broadcast si gnal frequency of the multiple radio broadcast signal frequencies, playing digital audio content included in a radio broadcast signal of the fi rst radio broadcast signal frequency for the fixed time duration, tuning the radio broadcast signal receiver to a second radio broadcast signal frequency of the scanning, and replaying the digital audio content included in the radio broadcast signal of the first radio broadcast signal frequency when there is no useable audio content detected in a radio broadcast signal of the second radio broadcast signal frequency.

[0088] These non-limiting Examples can be combined in any permutation or combination. The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as“examples.” All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

[0089] In this document, the terms“a” or“an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of“at least one” or“one or more” In this document, the term“or” is used to refer to a nonexclusive or, such that“A or B” includes“A but not B,”“B but not A,” and“A and B,” unless otherwise indicated. In this document, the terms“including” and“in which” are used as the plain-English equivalents of the respective terms“comprising” and “wherein” Also, in the following claims, the terms“including” and“comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,”“second,” and“third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. [0090] The above description is intended to be illustrative, and not restrictive.

For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to allow the reader to qui ckly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, the subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

CLAIMS What is claimed is:

1. A radio broadcast signal receiver comprising:

tuner circuitry configured to receive a radio broadcast signal including digital audio content; and

processing circuitry configured to:

scan for radio broadcast signals by tuning the tuner circuitry to multiple radio broadcast signal frequencies; and

vary a time duration that the tuner circuitry is tuned to the radio broadcast signal frequencies during the scanning according to when digital audio content of the radio broadcast signals becomes available for play by the radio broadcast signal receiver.

2. The radio broadcast signal receiver of claim 1 ,

wherein the tuner circuitry is configured to receive a radio broadcast signal including both digital audio content and analog audio content;

wherein the processing circuitry is configured to:

initiate play of the analog audio content when the digital audio content is unavailable for play;

stop play of the analog audio content when the digital audio content becomes available; and

initiate play of the digital audio content for a fixed time duration.

3. The radio broadcast signal receiver of claim 2,

wherein the digital audio content included in the received radio broadcast signal includes multiple digital audio programs; and

wherein the processing circuitry is confi gured to initiate play of each of the multiple digital audio programs for the fixed time duration in tandem.

4. The radio broadcast signal receiver of claim 2, including a memory;

wherein the digital audio content included in the received radio broadcast signal includes compressed digital audio data of multiple digital audio programs;

wherein the processing circuitry is configured to: initiate play of a first digital audio program of the multiple digital audio programs when the digital audio data is available;

store compressed versions of the multiple digital audio programs in the memory; and

initi ate play of each of the stored multiple digital audio programs for the fixed time duration in tandem.

5. The radio broadcast signal receiver of claim 2,

wherein the tuner circuitry is configured to receive another different radio broadcast signal including both digital audio content and analog audio content; and

wherein the processing circuitry is configured to omit play of the analog audio content and initiate play of the digital audio content of the other radio broadcast signal when the digital audio content is available at the end of the fixed time duration.

6. The radio broadcast signal receiver of claim 1, including a display; and

wherein the processing circuitry is configured to:

tune the tuner circuitry to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies;

initiate play of analog or digital audio content of a first radio broadcast signal corresponding to a first radio broadcast signal frequency;

tune the tuner circuitry to a second radio broadcast signal frequency during playing of the analog or digital audio content first radio broadcast signal; and

display tuning of the radio broadcast signal receiver to the first radio broadcast signal frequency during play of the analog or digital audio content of the first radio broadcast signal frequency instead of the tuned second radio broadcast signal frequency.

7. The radio broadcast signal receiver of claim 6, wherein the processing circuitry is configured to replay the digital audio content included in the first radio broadcast signal when there is no useable audio content included in a radio broadcast signal of the second radio broadcast signal frequency.

8. The radio broadcast signal receiver of claim 7, wherein the processing circuitry is configured to: tune the tuner circuitry to one or more additional radio broadcast signal frequencies during the replay of the digital audio content of the first radio broadcast signal; and

not display radio broadcast signal frequencies for which useable audio content is not detected.

9. The radio broadcast signal receiver of claim 1,

wherein the tuner circuitry is configured to receive a digital-only radio broadcast signal;

wherein the processing circuitry is configured to:

scan the multiple radio broadcast signal frequencies and tune the tuning circuitry to a digital-only radio broadcast signal;

play a first digital audio program of the digital-only broadcast radio signal when digital audio content is detected, and store compressed versions of the first digital audio program and other digital audio programs received on the digital-only broadcast radio signal;

play the other digital audio programs in tandem; and

tune to a next digital-only radio broadcast signal frequency when a stored digital audio program is played by the radio broadcast signal receiver.

10. The radio broadcast signal receiver of claim 9, wherein the processing circuitry is configured to replay previously played digital audio content when there is no useable audio content detected for a radio broadcast signal of the next digital-only radio broadcast signal frequency.

11. The radio broadcast signal receiver of claim 1, wherein the tuner circuitry includes multiple tuners each configured to independently tune to a radio broadcast frequency.

12. A method of controlling operation of a radio broadcast signal receiver, the method comprising:

scanning for radio broadcast signals using the receiver by tuning to multiple radio broadcast signal frequencies;

tuning to the radio broadcast signal frequencies for a varying time duration during the scanning; and playing digital audio content included in received radio broadcast signals for a fixed time duration using the radio broadcast signal receiver.

13. The method of claim 12,

wherein the scanning includes tuning the receiver to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies;

wherein playing the digital content includes:

playing the digital content of a first radio broadcast signal corresponding to the first radio broadcast signal frequency;

tuning the radio broadcast signal receiver to a next radio broadcast signal frequency during playing of the digital audio content for the fixed time duration; and displaying tuning of the first radio broadcast signal frequency during playing of the digital audio content instead of the tuned next radio broadcast signal frequency.

14. The method of claim 13, including playing only digital audio content of the next radio broadcast signal frequency when available after playing the digital audio content of the first radio broadcast signal frequency.

15. The method of claim 12,

wherein the digital audio content included in the received radio broadcast signals includes multiple digital audio programs; and

wherein playing the digital audio content includes playing each of the multiple digital audio programs for the fixed time duration in tandem using the radio broadcast signal receiver.

16. The method of claim 12,

wherein the scanning includes tuning the receiver to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies; and

wherein playing the digital content includes:

playing digital audio content included in a radio broadcast signal of the first radio broadcast signal frequency for the fixed time duration;

tuning the radio broadcast signal receiver to a second radio broadcast signal frequency of the scanning; and replaying the digital audio content included in the radio broadcast signal of the first radio broadcast signal frequency when there is no useable audio content included in a radio broadcast signal of the second radio broadcast signal frequency.

17. The method of claim 16, including:

tuning the radio broadcast signal receiver to one or more additional radio broadcast signal frequencies of the scanni ng during the replaying of the digital audio content; and

not displaying radio broadcast signal frequencies for which useable audio content is not detected.

18. The method of claim 12, including:

wherein playing the digital content includes:

receiving compressed digital audio data including multiple digital audio programs in a radio broadcast signal in response to the tuning;

pl aying a first digital audio program of the multipl e digital audio programs when the digital audio data is received and buffering compressed versions of the multiple digital audio programs in memory of the radio broadcast signal receiver; and

playing each of the multiple digital audio programs for the fixed time duration in tandem.

19. The method of claim 18, including:

tuning the radio broadcast signal receiver to a second radio broadcast signal frequency of the scanning during playing of a digital audio program of the multiple digital audio programs; and

tuning the radio broadcast signal receiver to a third radio broadcast signal frequency of the scanning during the playing of the digital audio program when the second radio broadcast signal frequency does not include useable audio content.

20. The method of claim 12, wherein the scanning radio broadcast signal frequencies includes:

scanning the multiple radio broadcast signal frequencies for digital-only radio broadcast signals; receiving a digital-only broadcast radio signal when the radio broadcast signal receiver is tuned to a first radio broadcast signal frequency;

play the other digital audio programs in tandem; and

tune to a next radio broadcast signal frequency when a stored digital audio program is played on the radio broadcast signal receiver.

21. The method of claim 12, including replaying previously played digital audio content when there is no useable audio content detected for a radio broadcast signal of the next radio broadcast signal frequency.

22. A computer readable storage medium including instructions that, when performed by processing circuitry of a radio broadcast signal receiver, cause the processing circuitry to perform acts comprising:

scanning for radio broadcast signals by tuning the radio broadcast signal receiver to multiple radio broadcast signal frequencies;

playing analog audio content included in the received radio broadcast signals using the radio broadcast signal receiver;

changing to playing digital audio content included in received radio broadcast signals for a fixed time duration using the radio broadcast signal receiver when digital audio content becomes available; and

varying a time duration of playing the analog audio content according to when the digital audio content becomes available.

23. The computer readable storage medium of claim 22, including instructions that cause the processing circuitry to perform acts comprising:

playing each of multiple digital audio programs included in the digital audio content for the fixed time duration in tandem using the radio broadcast signal receiver.

24. The computer readable storage medium of claim 22, including instructions that cause the processing circuitry to perform acts comprising: tuning the radio broadcast signal receiver to a first radio broadcast signal frequency of the multiple radio broadcast signal frequencies;

tuning the radio broadcast signal receiver to a second radio broadcast signal frequency of the scanning; and

replaying the digital audio content included in the radio broadcast signal of the first radio broadcast signal frequency when there is no useable audio content detected in a radio broadcast signal of the second radio broadcast signal frequency.