Granted Patent B1

US 7,801,497 · App. 11/810,535 · Granted Sep 21, 2010

Abstract

Claims (51)

1. A radio modulator apparatus, having a radio band scan function, comprising:

a frequency selectable RF signal transmitter;

a switch that couples said RF signal to an antenna;

a demodulator coupled to mix a received antenna signal with said RF signal to produce an indicia of signal strength at the receive frequency resulting from the mix;

a channel memory coupled to store plural indicia of signal strength values corresponding to plural receive frequencies;

a controller coupled to said transmitter, said switch, said channel memory, and a display, and wherein

said controller enables the frequency scan function by decoupling said switch, tuning said transmitter RF signal to plural frequencies, thereby causing said demodulator to receive plural receive frequencies within the radio band, and storing the resultant plural corresponding indicia of signal strength in said channel memory, and

said controller compares said stored plural indicia of signal strength to select a present transmit frequency that has a low signal interfering level, couples said transmitter to said antenna, tunes said RF signal to said present transmit frequency, and displays said present transmit frequency on said display.

2. The apparatus of claim 1 , further comprising:

an actuator coupled to said controller, and wherein

actuation of said actuator initiates said frequency scan function.

3. The apparatus of claim 1 , further comprising:

a demodulator power source switch coupled to said controller, and wherein

said controller decouples power to said demodulator while said RF signal is coupled to said antenna.

4. The apparatus of claim 1 wherein the radio band is the commercial FM broadcast band, and wherein

said controller sequentially tunes the entire FM broadcast band in 200 kHz increments.

5. The apparatus of claim 1 and wherein said indicia of signal strength is a DC voltage level proportional to said receive frequency signal level.

6. The apparatus of claim 1 and wherein said switch is a diode that is reverse-biased to decouple said RF signal from said antenna.

7. The apparatus of claim 1 , further comprising:

an audio signal input coupled to provide a base band signal to said transmitter, and adapted to interface with a portable audio signal playing device.

8. The apparatus of claim 1 , further comprising:

a power supply circuit having a power input connector, and coupled to provide electric power the radio modulator apparatus.

9. The apparatus of claim 8 , and wherein said transmitter is supplied power continuously while said power input connector is couple to an external power supply.

10. The apparatus of claim 8 , further comprising:

an audio signal input, with an input connector, coupled to provide a base band signal to said transmitter, and wherein

said power supply circuit couples operating power through said input connector, for use in powering a portable audio player connected to said input connector.

11. A method of scanning a radio band using a radio modulator having a frequency selectable RF signal transmitter, an antenna, a demodulator, a display, and a channel memory, the method comprising the steps of:

scanning plural receive frequencies in the radio band by;

decoupling the RF signal from the antenna;

tuning the RF signal transmitter to plural frequencies;

mixing a received antenna signal with each of said plural RF signal frequencies in the demodulator, and producing an indicia of signal strength at each of plural receive frequencies resulting from said mixing;

storing said plural indicia of signal strength in the channel memory at locations corresponding to plural receive frequencies, and

selecting a present transmit frequency from amongst said plural receive frequencies by;

comparing said stored plural indicia of signal strengths;

selecting one of said plural receive frequencies, based on a low stored indicia of signal strength, as a present transmit frequency, and

enabling said present transmit frequency by;

coupling the RF signal to the antenna;

tuning the RF signal transmitter to said present transmit frequency, and

displaying said present transmit frequency.

12. The method of claim 11 , further comprising the step of:

actuating an actuator to manually initiate said scanning, selecting and enabling steps.

13. The method of claim 11 , further comprising the steps of:

connecting power to the demodulator in preparation for said scanning sequence, and

disconnecting power from the demodulator in preparation for said enabling sequence.

14. The method of claim 11 wherein the radio band is the FM broadcast band, and wherein

said tuning the RF signal transmitter to plural frequencies includes sequentially tuning entire FM broadcast band in 200 kHz increments.

15. The method of claim 11 and wherein the indicia of signal strength is a DC voltage level proportional to the receive frequency signal level.

16. The method of claim 11 , further comprising the step of:

manually selecting said present transmit frequency.

17. The method of claim 11 , further comprising the step of:

maintaining electrical power to the RF signal transmitter during all of the foregoing method steps.

Assignments (14)