JPH04504935A - Receiving Device Threshold Expansion - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Receiving Device Threshold Expansion Technical field TECHNICAL FIELD The present invention relates generally to radio frequency receiving devices, and more particularly, to receiving devices with improved sensitivity. related to the field of

Background technology One measure of a receiving device's performance is that it clearly derives the desired signal while eliminating noise. It is the ability to eliminate The higher the S/N ratio, the better the sensitivity (and performance) of the receiving device. Get better.

Those skilled in the art will appreciate the use of complex detection devices and compensation circuits aimed at improving the sensitivity of a receiving device. I've been using it. However, if the received amplitude of the desired information signal is close to the noise level, Technology to improve the sensitivity of existing receiving devices (“click swallowing”) ” etc.) do not work well. This noise barrier is called the noise range. This is almost below the 3 dB S/N ratio that is often achieved.

Therefore, a simple method is needed to improve the sensitivity of the receiving device under the noise range. It is considered essential.

Summary of the invention Therefore, it is an object of the present invention to reduce the reception when the information signal is close to the noise level. The objective is to improve the sensitivity of the communication device.

In summary, according to the invention, after the information signal is received, the signal strength is determined. be inspected for. If the signal strength is at least equal to the threshold, the receiving device To improve sensitivity, unmodulated signals are added to the received signal. Ingna! ) is added.

Brief description of the drawing FIG. 1 is a block diagram of a receiving device according to the present invention.

Detailed description of the preferred embodiment Referring to FIG. 1, a receiving device 1 processes an information signal 11 received by an antenna 12. 0 is shown. The received information signal (and the received noise) is sent to the oscillator preselector 1 before being mixed (in mixer 16) with the injection signal from 18. Filtered (band limited) via 4. Oscillator 18 is used to obtain a suitable injection signal. programmed (34) by the controller 32 so as to receive the desired information signal; can do. The mixer 16 transfers the intermediate frequency (IF) signal to the IF amplifier 20. and is amplified before being filtered by IF filter 22. filtered signal is processed by a detection device 24 to obtain a reproduced signal. Before mixer 16, Additional intermediate frequency stages may be added along with additional bypasses and filters.

The detected or reproduced signal is amplified in audio amplification device 26. After that, it is output via the speaker 28.

According to the invention, the signal of the desired received IF signal (processed at IP frequency) or Carrier strength is determined and compared to a signal threshold. Preferably, the receiving device Signal strength display (R35I) Detection of signal strength within the IF amplifier 20 with output It is desirable that this be done. Further, preferably, the IF amplifier 20 is a Motorola MC3362 or a functionally equivalent amplifier. .

The present invention allows the received IF multiplied signal to be set at a predetermined threshold (S/N ratio of 3 dB). If the received IP signal is lower than the IP address (which can be used), add the unmodulated signal to the received IP multiplied signal. Reception IP Double the signal signal threshold (set approximately 3 dB of the noise level) or If the R55I output (30) indicates that the Program the frequency of another oscillator 40 to generate the signal (42). its frequency If the number is set to the same frequency as the frequency of the received IF signal, the unmodulated signal is added to the received IF signal at the input to router 22 (added at 39). before the amplifier 3 is controlled by a control device 32 (via line 36). It is amplified within 8. The gain of the amplifier 38 is such that the amplitude of the unmodulated carrier signal is 5 dB above the signal threshold (set approximately 3 dB above the noise level). dB or more, or 8 dB above the signal level. (36). Addition mode may occur before and after the filter 22 will be understood.

Audio amplification to compensate for the suppression of the desired signal due to the injection of a non-modulated signal Additional amplification is provided by adjusting the gain (44) of device 26. of the received signal If the amplitude is below the signal threshold, the injection of the unmodulated signal will cause the noise to exceed the desired signal. Suppress Is. As a result, the SZN ratio of the reproduced signal will be much larger.

Therefore, the sensitivity of the receiving device is improved. The unmodulated signal is sent to the preselector 14. Any location after mixer 16 or antenna 12 but before detection device 24 The same benefit of improved receiver sensitivity can be obtained by adding

Claims (18)

[Claims] 1. In a method for receiving an information signal: (a) a receiver having a first signal-to-noise ratio; (b) receiving the information signal to derive a received FM signal; determining when the signal strength of is below the signal threshold: and (c) if said signal strength is below said signal threshold, the F of said information signal; In order to improve the sensitivity of the M receiver and make the S/N ratio larger than the first S/N ratio. , the receiving signal receives an unmodulated signal having a frequency that is substantially the same as the frequency of the receiving signal. Steps to add to the signal: A method characterized by comprising: 2. further comprising controlling the gain of the amplifier stage in response to step (b). 2. The method according to claim 1, further comprising: 3. a stage for detecting the received signal and the untuned signal to derive an output signal; 2. The method of claim 1, further comprising a step. 4. 4. The method of claim 3, further comprising the step of amplifying the output signal. Method. 5. Claim further comprising the step of synthesizing frequencies of the unmodulated signal. The method described in Section 1. 6. The signal threshold is set to an S/N ratio of approximately 3 dB. 2. The method according to claim 1. 7. Claim further comprising the step of amplifying the amplitude of the unmodulated signal. The method described in 1. 8. the amplitude of the untuned signal is amplified approximately 5 dB above the signal threshold; 7. The method according to claim 6, characterized in that: 9. In a receiving device for receiving an FM information signal: having a first S/N ratio. Means for receiving said FM information signal to derive a received signal: means for determining when the signal strength of the received signal is below a signal threshold; Beauty (c) if said signal strength is below said signal threshold, the F of said information signal; In order to improve the sensitivity of the M receiver and make the S/N ratio larger than the first S/N ratio. , the receiving signal receives an unmodulated signal having a frequency that is substantially the same as the frequency of the receiving signal. Means of adding to the signal: A receiving device comprising: 10. controlling the gain of an amplifier of the receiving device as a function of the signal strength; 10. The receiving device according to claim 9, further comprising means for controlling. 11. detecting the received signal and the untuned signal to derive an output signal; 10. The receiving device according to claim 9, further comprising means for. 12. 12. The method of claim 11, further comprising means for amplifying the output signal. Receiving device included. 13. further comprising means for programming a frequency source to derive said unmodulated signal; 10. The receiving device according to claim 9, further comprising: 14. The signal threshold is set to approximately 3 dB S/N ratio. 9. The receiving device according to claim 9. 15. Claim further comprising means for amplifying the amplitude of the unmodulated signal. Item 9. Receiving device according to item 9. 16. the amplitude of the out-of-tuned signal is greater than approximately 5 dB above the signal threshold; 15. The receiving device according to claim 14, wherein the receiving device is amplified to a large extent. 17. The unmodulated signal is transmitted between the antenna of the receiving device and the detecting device. 10. The receiving device according to claim 9, wherein the receiving device is added to a location. 18. In a receiving device for receiving an FM information signal: having a first S/N ratio. means for receiving said FM information signal to derive a received IF signal: for determining when the signal strength of the received IF signal is below a signal threshold; Means: and If the signal strength is below the signal threshold, the noise is suppressed more than the signal. The FM reception sensitivity of the information signal is improved by increasing the S/N ratio by substantially the same frequency as the received IF signal in order to make the signal-to-noise ratio larger than the first S/N ratio. Means for adding a non-modulated signal having a certain frequency to the received IF signal: A receiving device comprising: