Wireless radio system optimization by persistent spectrum analysis
Apparatuses and methods for simultaneously operating as a wireless radio and monitoring the local frequency spectrum. For example, described herein are wireless radio devices that use a secondary receiver to monitor frequencies within the operating band and prevent or avoid interferers, including in particular half-IF interferers. The systems, devices, and methods described herein may adjust the intermediate frequency in a superheterodyne receiver to select an intermediate frequency that minimizes interference. In particular, described herein are apparatuses and methods that use a second receiver which is independent of the first receiver and may be connected to the same receiving antenna to monitor the geographically local frequency spectrum and may detect spurious interferers, allowing the primary receiver to adjust the intermediate frequency and avoid spurious interferes.
1. A method for controlling reception of a wireless broadband radio by selecting between a plurality of intermediate frequencies (IFs), the method comprising:
receiving, by a first receiver, a radio frequency (RF) signal having a frequency fsg;
generating, by a mixer, an intermediate frequency signal based on the RF signal and a local oscillation (LO) signal having a local oscillation frequency f LO , wherein the intermediate frequency signal has a first frequency, f IF1 ;
determining, by a controller, if an interference in the RF signal at a first predetermined frequency exceeds a threshold level, and switching the intermediate frequency signal to a second frequency, f IF2 , if the interference in the RF signal at the first predetermined frequency exceeds the threshold level; and
receiving, by a second receiver, the RF signal, wherein the controller causes the second receiver to process the received RF signals while switching the intermediate frequency signal to f IF2 to prevent an interruption in data traffic during the switching.
2. The method of claim 1 , wherein the first predetermined frequency is one-half of f IF1 .
3. The method of claim 1 , wherein the frequency fsg of the RF signal is within a frequency band and wherein the second receiver is further configured to scan the frequency band for interference independently of the first receiver.
4. The method of claim 1 , wherein switching the intermediate frequency signal to the second frequency comprises modifying the LO signal to shift the IF to f IF2 .
5. The method of claim 1 , further comprising: switching, by the controller, the intermediate frequency signal to f IF2 if the interference at the first predetermined frequency is greater than an interference at a second predetermined frequency.
6. The method of claim 1 , further comprising switching, by the controller, the intermediate frequency signal to f IF2 if the interference at the first predetermined frequency is greater than 10 dB higher than an interference at a second predetermined frequency.
7. The method of claim 1 , further comprising determining, by the controller, if the interference in the RF signal at the first predetermined frequency exceeds the threshold level by comparing the interference in the RF signal at the first predetermined frequency with an interference in the RF signal at a second predetermined frequency.
8. The method of claim 1 , further comprising determining by the controller, if the interference in the RF signal at the first predetermined frequency exceeds the threshold level by comparing an error rate at the first predetermined frequency with the threshold level.
9. The method of claim 1 , further comprising determining an interference in the RF signal at a second predetermined frequency that is one-half of f IF2 (a half-IF 2 frequency).
10. The method of claim 9 , wherein switching comprises switching the intermediate frequency signal to f IF2 and generating the intermediate frequency signal from the RF signal at f IF2 if the interference in the RF signal at the first predetermined frequency is greater than the interference in the RF signal at the second predetermined frequency.
11. A wireless broadband radio apparatus adapted to select between a plurality of intermediate frequencies to minimize interference, the apparatus comprising:
a first receiver configured to receive a radio frequency (RF) signal having a frequency fsg;
a mixer configured to generate an intermediate frequency signal based on the RF signal and a local oscillation (LO) signal having a local oscillation frequency f LO , wherein the intermediate frequency signal has a first frequency, f IF1 ;
a controller configured to determine if an interference in the RF signal at a first predetermined frequency exceeds a first threshold level, and to switch the intermediate frequency signal to a second frequency of fire if the interference in the RF signal at the first predetermined frequency exceeds the first threshold level; and
a second receiver configured to receive the RF signal, wherein the controller is configured to process the received RF signals using the second receiver while switching the intermediate frequency signal to f IF2 to prevent an interruption in data traffic during switching.
12. The apparatus of claim 11 , wherein the first predetermined frequency is one-half of f IF1 .
13. The apparatus of claim 11 , wherein the RF signal has a frequency fsg within a frequency band and wherein the second receiver is further configured to monitor the frequency band and to scan the frequency band for interference independently of the first receiver.
14. The apparatus of claim 11 , further comprising an antenna coupled to the first receiver and the second receiver.
15. The apparatus of claim 11 , wherein the controller is configured to switch the intermediate frequency signal to f IF2 if the interference at the first predetermined frequency is greater than an interference at a second predetermined frequency.
16. The apparatus of claim 11 , wherein the controller is configured to switch the intermediate frequency signal to f IF2 if the interference at the first predetermined frequency is greater than 10 dB higher than an interference at a second predetermined frequency.
17. The apparatus of claim 11 , wherein f IF2 is between about 10 MHz and about 250 MHz from f IF1 .
18. The apparatus of claim 11 , wherein the controller is configured to determine if the interference in the RF signal at the first predetermined frequency exceeds the first threshold level by comparing the interference in the RF signal at the first predetermined frequency with an interference in the RF signal at a second predetermined frequency.
19. The apparatus of claim 11 , wherein the controller is configured to determine if the interference in the RF signal at the first predetermined frequency exceeds the first threshold level by comparing an error rate at the first predetermined frequency with the first threshold level.
20. The apparatus of claim 11 , wherein the second receiver is further configured to switch the mixer in the first receiver back to f IF1 when a second interference in the RF signal exceeds a second threshold level and the second threshold level is approximately the first threshold level.