Verification of radio station watermarking with software defined radios
Methods, apparatus, systems and articles of manufacture to verify radio station watermarking with software defined radios are disclosed. Example apparatus disclosed herein include a notch filter having a bandwidth and a center frequency corresponding to a first radio station broadcast signal, and a software defined radio front-end to downconvert a radio frequency band to a baseband signal, the radio frequency band including a second radio station broadcast signal different from the first radio station broadcast signal. Disclosed example apparatus also include a software defined radio application to tune to a portion of the baseband signal corresponding to the second radio station broadcast signal and to demodulate the portion of the baseband signal to generate audio data corresponding to the second radio station broadcast signal. Disclosed example apparatus further include a watermark decoder to detect a watermark in the audio data corresponding to the second radio station broadcast signal.
1. An apparatus to detect watermarking of radio station broadcasts, the apparatus comprising:
a notch filter having a bandwidth and a center frequency corresponding to a first radio station broadcast signal;
a software defined radio front-end to downconvert a radio frequency band to a baseband signal, the radio frequency band including a second radio station broadcast signal different from the first radio station broadcast signal;
a software defined radio application executable by a processor to tune to a portion of the baseband signal corresponding to the second radio station broadcast signal and to demodulate the portion of the baseband signal to generate audio data corresponding to the second radio station broadcast signal; and
a watermark decoder to detect a watermark in the audio data corresponding to the second radio station broadcast signal.
2. The apparatus of claim 1 , wherein the center frequency of the notch filter is adjustable.
3. The apparatus of claim 1 , wherein the software defined radio front-end is to accept a configuration input specifying a center frequency corresponding to a midpoint of the radio frequency band.
4. The apparatus of claim 3 , wherein the radio frequency band further includes the first radio station broadcast signal.
5. The apparatus of claim 1 , wherein the software defined radio application is to accept a configuration input specifying a carrier frequency of the second radio station broadcast signal, and the software defined radio application implements at least one of a frequency modulation (FM) demodulator or an amplitude modulation (AM) demodulator to demodulate the portion of the baseband signal to generate the audio data corresponding to the second radio station broadcast signal.
6. The apparatus of claim 1 , further including memory to store an audio file including the audio data corresponding to the second radio station broadcast signal, and wherein the watermark decoder is to access the audio data from the audio file.
7. The apparatus of claim 1 , wherein the notch filter is a first notch filter, and further including a second notch filter having a bandwidth and a center frequency corresponding to a third radio station broadcast signal, the third radio station broadcast signal different from the first radio station broadcast signal and the second radio station broadcast signal.
8. An apparatus to detect watermarking of radio station broadcasts, the apparatus comprising:
means for attenuating a first radio station broadcast signal;
means for downconverting a radio frequency band to a baseband signal, the radio frequency band including a second radio station broadcast signal different from the first radio station broadcast signal;
means implemented by a processor for tuning to a portion of the baseband signal corresponding to the second radio station broadcast signal and for demodulating the portion of the baseband signal to generate audio data corresponding to the second radio station broadcast signal; and
means for detecting a watermark in the audio data corresponding to the second radio station broadcast signal.
9. The apparatus of claim 8 , wherein the means for attenuating the first radio station broadcast signal is adjustable to attenuate a third radio station broadcast signal different from the first radio station broadcast signal.
10. The apparatus of claim 8 , wherein the means for downconverting the radio frequency band to the baseband signal is to accept a configuration input specifying a center frequency corresponding to a midpoint of the radio frequency band.
11. The apparatus of claim 10 , wherein the radio frequency band further includes the first radio station broadcast signal.
12. The apparatus of claim 8 , wherein the means for tuning to the portion of the baseband signal corresponding to the second radio station broadcast signal and for demodulating the portion of the baseband signal to generate the audio data includes at least one of a frequency modulation (FM) demodulator or an amplitude modulation (AM) demodulator to demodulate the portion of the baseband signal to generate the audio data corresponding to the second radio station broadcast signal.
13. The apparatus of claim 8 , further including means for storing an audio file including the audio data corresponding to the second radio station broadcast signal, and wherein the means for detecting the watermark is to access the audio data from the audio file.
14. The apparatus of claim 8 , further including means for attenuating a third radio station broadcast signal different from the first radio station broadcast signal and the second radio station broadcast signal.
15. A method to detect watermarking of radio station broadcasts, the method comprising:
configuring, by executing an instruction with a processor, a software defined radio front-end to downconvert a radio frequency band including a first radio station broadcast signal to a baseband signal;
executing a software defined radio application with the processor to tune to a portion of the baseband signal corresponding to the first radio station broadcast signal and to demodulate the portion of the baseband signal to generate audio data corresponding to the first radio station broadcast signal; and
detecting, by executing an instruction with the processor, a watermark in the audio data corresponding to the first radio station broadcast signal.
16. The method of claim 15 , wherein the configuring of the software defined radio front-end includes configuring a center frequency of the software defined radio front-end via a configuration input of the software defined radio front-end, the center frequency corresponding to a midpoint of the radio frequency band.
17. The method of claim 16 , wherein the radio frequency band further includes a second radio station broadcast signal different from a first radio station broadcast signal.
18. The method of claim 17 , wherein the radio frequency band corresponds to an output of a notch filter attenuating the second radio station broadcast signal.
19. The method of claim 18 , further including performing a calibration procedure to adjust the notch filter to attenuate the second radio station broadcast signal.
20. The method of claim 15 , further including configuring the software defined radio application with a carrier frequency of the first radio station broadcast signal.