JPH02312411A - Enlarging method for dynamic range in fm tuner - Google Patents

Abstract

PURPOSE:To obtain a real dynamic range by detecting a compressor start point by a frequency deviation, and executing an expander by controlling an amplifier or an attenuator of a low frequency stage. CONSTITUTION:A radio wave received in a front end 2 is inputted to an FM demodulator.stereo demodulator 3, its output is outputted to a loudspeaker through an expander/amplifier 9, and also, the radio wave is allowed to branch and inputted to said converter 5, as well, and converted to a second intermediate frequency in the converter 5. This second intermediate frequency is amplified and shaped by an amplifier/limiter 6, and inputted to a counter 7. By the counter 7, a deviation of the frequency is compared with a reference frequency of a reference crystal oscillator 10 and detected, the deviation to the plus side and the deviation to the minus side are outputted as an overflow (O.F) and an underflow (U.F), respectively, and it becomes a control signal. In such a way, a wide dynamic range is obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a dynamic range expansion method in an FM tuner that can avoid reproducing a wide dynamic range by expanding compression applied on the broadcasting station side on the receiving side. [Prior art]

Traditionally, in FM broadcasting, there were strict broadcast regulations regarding the sideband of radio waves, and there were

A compressor is added to the modulated signal, and it is broadcast with a reduced dynamic range than it actually is. Therefore, the FM tuner on the receiving side receives the signal only in a compressed state, so the wide dynamic range that should originally be reproduced cannot be obtained. [Problem to be solved by the invention]

In the conventional example above, compression is applied.

[I'm listening to a broadcast where the dynamic range has been reduced, so it's not realistic and lacks a sense of place. Therefore, in this type of FM tuner, there is a need to expand the part where the compressor is applied to make it more realistic. [Means to solve the problem]

As a specific means for solving the problems of the conventional example, the present invention detects the compressor start point by frequency shift for the radio waves received at the front end, and controls the expander amplifier based on the detected data to perform the expansion. The present invention provides a method for expanding the dynamic range in an FM tuner characterized by the following: a converter and a reference crystal oscillator, and means for comparing the frequency of the reference crystal oscillator with the input signal frequency to form detection data. The expander amplifier is equipped with at least a counter capable of generating detection data, and outputs an overflow or underflow signal by the counter. By having a configuration with this function, it is possible to expand the compressed portion of the airwaves and listen to broadcasts that are close to reality.

【Example】

Next, a specific example of implementing the method of the present invention will be explained based on the illustrated block diagram. 1 is a reception antenna, the radio waves received by the antenna are input to the front end 2, and the front end 2 to the FM demodulator/stereo demodulator 3. This configuration is no different from the conventional example, and in the conventional example, the input radio wave is demodulated into an audio signal, and the audio signal or music signal is amplified by an appropriate amplifier and reproduced from the speaker. be. The present invention is characterized in that an expander mechanism 4 is added to the configuration of the conventional example, and the expander mechanism 4 detects frequency shifts in the radio waves received by the front end 2 and applies compression. Converter 5, amplifier/limiter 6, counter 7, control section 8
and an expander amplifier 9. The outputs of the FM demodulator/stereo demodulator 3 hl, etc. are input to an expander amplifier 9, and the expander amplifier 9 is configured to be controlled by a control signal based on detection data from the controller 8. , further includes a reference crystal oscillator 10 that serves as the M quasi of the detected data, and an attenuator 1 for the expander amplifier 9.
1 or a digital signal processing function (1). That is, the radio waves received by the front end 2 are 1M1S!
It is input to the modulation/stereo demodulator 3 and its output 4
- The power is outputted to a speaker (not shown) via the expander amplifier 9, and the radio wave is branched and inputted to the converter 5, where the second intermediate frequency (2ndlF = e.g. 390~ 540KH
2). This second intermediate frequency is amplified and shaped (equalized in size) by an amplifier/limiter 6, and then input to a counter 7. This counter 7 detects the frequency shift by comparing it with the reference frequency of the reference crystal oscillator 10, and defines the shift to the positive side as an overflow (0-F),
A shift to the negative side is output as an underflow (U/F), which becomes a control signal. In this case, when the transition rate is 0 to 90%, linear modulation is performed,
A compressor is applied to the remaining 10%, and this 10% is detected and detected as O.
-F or U-F. This output is input to the control section 8, and in the control section 8, 0.F
Alternatively, it identifies the U-F and outputs a signal for controlling the expander amplifier 9, which is the audio amplifier. When the spander amplifier 9 receives the control signal, the gain changes depending on the signal, and the spander amplifier 9 is configured to operate in such a way that the gain increases. . Effects of the Invention 1 As explained above, the method for expanding the dynamic range in an F:M tuner according to the present invention detects the compressor starting point by frequency shift, and controls the amplifier or attenuator in the low frequency stage using the detected data. By configuring it to perform LA spander with a single channel, the broadcast station can expand the part of the conbrella 4 that is based on the broadcasting regulations, thereby increasing the realistic dynamic range that should be reproduced on the receiving side. Moreover, by providing a counter capable of forming at least detected data and outputting overflow and underflow signals by the counter, it is possible to improve the efficiency of the amplifier or attenuator in the low frequency stage. Con1~]I]- can be easily performed, and it also has the excellent effect of expanding the part of the airwaves where the []nbre1/no is applied, allowing you to listen to a broadcast that is close to reality. .

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a system implementing the dynamic range expansion method according to the present invention.

Claims (4)

[Claims] (1) A method for expanding the dynamic range in an FM tuner, which is characterized by detecting a compressor start point by frequency shift in radio waves received by a front end, and controlling an expander amplifier based on the detected data to perform expansion. (2) The method for expanding the dynamic range in an FM tuner according to claim (1), further comprising: a converter and a reference crystal oscillator; the frequency of the reference crystal oscillator is compared with the input signal frequency to form detection data. (3) Claim (1) further comprising a counter capable of forming at least detection data, and the counter outputs an overflow or underflow signal.
) or (2), the method for expanding the dynamic range in an FM tuner. (4) The method for expanding the dynamic range in an FM tuner according to claim (1), (2) or (3), wherein the expander amplifier has a low frequency stage amplifier or attenuator, or a digital signal processing function.