TWI393397B - Carrier recovery apparatus and method thereof - Google Patents

Description

Carrier recovery device and related method

The present invention relates to a carrier recovery device and related method, and more particularly to a pilot-based FPLL based on a pilot signal based on a pilot signal strength of an input signal. A pilot-less PLL with no pilot signal performs a carrier recovery action on the input signal.

In most communication systems, pilot signals are often deliberately added to the receiving end to help the carrier to recover. For these systems, the traditional pilot-based FPLL is often used. To achieve a wider range of capture and faster capture speed. However, in a heavily attenuated channel, if the pilot signal is severely weakened or even unable to detect the pilot signal, the conventional pilot-based lock-frequency phase-locked loop will not continue to lock the frequency/phase and will cause reception. mistake.

In order to solve the above problems, in the past few years, many scholars have proposed various solutions for pilot-less FPLLs without pilot signals. However, these solutions are still too complicated. It will cause practical difficulties and increase costs. Therefore, how to overcome these shortcomings and reduce costs has become one of the important topics in the technical field.

Accordingly, it is an object of the present invention to provide a carrier recovery apparatus and related method for solving the above problems.

One embodiment of the present invention discloses a carrier recovery device. The carrier recovery device includes a pilot signal strength detector, a first lock loop, a second lock loop, and a controller. The pilot signal strength detector is configured to determine whether one of the input signals directs the signal strength to be greater than a threshold to generate a control signal. The first locked loop is configured to perform a first carrier return action on the input signal. The second locking circuit is configured to perform a second carrier recovery action on the input signal. The controller is coupled to the pilot signal strength detector, the first lock loop, and the second lock loop, and is configured to selectively utilize the first lock loop according to the signal to perform the first carrier recovery action on the input signal or utilize the first The second lock loop performs a second carrier recovery action on the input signal. The first locked loop is a pilot-based FPLL based on a pilot signal, and the second locked loop is a pilot-less PLL with no pilot signal.

Another embodiment of the present invention discloses a carrier recovery method. The method includes the steps of: determining whether one of the input signals directs the signal strength to be greater than a threshold to generate a control signal; and selectively allowing a lock-frequency phase-locked loop based on the pilot signal to perform a first The carrier reply acts on the input signal or allows a phase-locked loop without a pilot signal to perform a second carrier reply action on the input signal. Wherein, when the control signal indicates that the pilot signal strength of the input signal is greater than a threshold value, the first carrier recovery action is performed on the input signal by using a lock-frequency phase-locked loop based on the pilot signal; and when the control signal indicates the guidance of the input signal When the signal strength is not greater than the threshold, the phase-locked loop without the pilot signal is used to perform the second carrier recovery action on the input signal.

Certain terms are used throughout the description and following claims to refer to particular elements. It should be understood by those of ordinary skill in the art that hardware manufacturers may refer to the same elements by different nouns. The scope of this specification and the subsequent patent application do not use the difference of the names as the means for distinguishing the elements, but the difference in function of the elements as the criterion for distinguishing. The term "including" as used throughout the specification and subsequent claims is an open term and should be interpreted as "including but not limited to". In addition, the term "coupled" is used herein to include any direct and indirect electrical connection. Therefore, if a first device is coupled to a second device, it means that the first device can be directly electrically connected to the second device or indirectly electrically connected to the second device through other devices or connection means.

Please refer to FIG. 1. FIG. 1 is a functional block diagram of a first embodiment of a carrier recovery apparatus 100 according to the present invention. As shown in FIG. 1, the carrier recovery device 100 includes, but is not limited to, a pilot signal strength detector 110, a pilot-based FPLL 130, and a bootless signal-free phase lock. A pilot-less PLL 140 and a controller 120. The pilot signal strength detector 110 determines whether a pilot signal strength of one of the input signals SIN is greater than a threshold TH1 to generate a control signal SC. The lock-frequency phase-locked loop 130 based on the pilot signal is used to perform a first carrier recovery operation on the input signal SIN, and the phase-locked loop 140 without the pilot signal is used to perform a second carrier recovery action on the input signal SIN. . The controller 120 is coupled to the pilot signal strength detector 110, the pilot-based frequency-locked phase-locked loop 130, and the non-guided phase-locked loop 140, which selectively allows the boot-based lock based on the control signal SC. The frequency-locked loop circuit 130 performs the first carrier to return to the input signal SIM, or allows the phase-locked loop 140 without the pilot signal to perform the second carrier to return to the input signal SIN.

When the control signal SC indicates that the pilot signal strength of the input signal SIN is greater than the threshold TH1, the controller 120 uses the lock-frequency phase-locked loop 130 based on the pilot signal to perform the first carrier recovery action on the input signal SIN; When the control signal SC indicates that the pilot signal strength of the input signal SIN is not greater than the threshold TH1, the controller 120 uses the phase-locked loop 140 without the pilot signal to perform the second carrier recovery action on the input signal SIN. In other words, the controller 120 can selectively perform the carrier recovery action on the input signal SIN by using the pilot signal-based lock frequency phase-locked loop 130 or the non-guided phase-locked loop 140 by the control signal SC, that is, Said that if the pilot signal is severely weakened or even unable to detect the pilot signal, the phase-locked loop 140 without the pilot signal will replace the pilot-based lock-frequency phase-locked loop 130 to perform the carrier recovery action on the input signal. On the SIN, in this way, problems such as inability to continue to lock the frequency/phase and cause errors in reception can be avoided, and the overall stability of the system can be improved. In addition, the phase-locked loop 140 without pilot signals can be more easily implemented than the conventional lock-locked loop without pilot signals, thereby reducing design complexity and cost.

Please note that the lock-frequency phase-locked loop 130 based on the pilot signal and the phase-locked loop 140 without the pilot signal can be implemented in a digital manner, but the present invention is not limited thereto, and can also be implemented in an analogous manner.

Please refer to FIG. 2, which is a functional block diagram of a second embodiment of a wave recovery device 200 of the present invention. As shown in FIG. 2, the architecture of the carrier recovery device 200 is similar to that of the carrier recovery device 100 of FIG. 1, the difference being that the controller of the carrier recovery device 200 is a selector 220, and the selector 220 is This is achieved by a switch SW1, but this is not a limitation of the invention. In this embodiment, the selector 220 includes an input terminal 221, a control terminal 222, a first output terminal 223, and a second output terminal 224. The input terminal 221 is configured to receive the input signal SIN, and the control terminal 222 is coupled to the control terminal 222. The pilot signal strength detector 110 is configured to receive the control signal SC. The first output terminal 223 is coupled to the lock-frequency phase-locked loop 130 based on the pilot signal, and the second output terminal 224 is coupled to the lock-free signal. Loop 140. When the control signal SC indicates that the pilot signal strength of the input signal SIN is greater than the threshold TH1, the selector 220 transmits the input signal SIN to the lock-frequency phase-locked loop 130 based on the pilot signal; otherwise, the selector 220 will input the signal. The SIN is transmitted to the phase locked loop 140 without the pilot signal.

It should be noted that the above-described embodiments are merely illustrative of the invention and are not limiting of the invention. It will be appreciated by those skilled in the art that various changes in the controller (or selector) are possible without departing from the spirit of the invention, which is also within the scope of the invention. In addition, the above-mentioned threshold TH1 is not a fixed value, and can be adjusted according to actual needs. For example, the threshold TH1 can be adjusted according to the state of the channel or the specification of the received input signal SIN.

Please refer to FIG. 3, which is a flow chart illustrating an operation example of a carrier recovery method of the present invention, including but not limited to the following steps (note that if substantially the same result is obtained, These steps are not necessarily performed in the order of execution shown in Figure 3):

Step 302: Start.

Step 304: Determine whether the intensity of the pilot signal of an input signal is greater than a threshold to generate a control signal. When the control signal indicates that the pilot signal strength of the input signal is greater than the threshold, step 310 is performed; otherwise, step 320 is performed.

Step 310: The input signal is transmitted to the frequency-locked phase-locked loop based on the pilot signal. Then, step 312 is performed.

Step 312: Perform a first carrier recovery action on the input signal by using the lock-frequency phase-locked loop based on the pilot signal.

Step 320: The input signal is transmitted to the phase locked loop without the pilot signal. Then, step 322 is performed.

Step 322: Allow the phase-locked loop without the pilot signal to perform the second carrier reply action on the input signal.

Please refer to Figure 3 and Figure 1 (or Figure 2) at the same time. Next, how each element operates will be described in conjunction with each step shown in FIG. 3 and each element shown in FIG. 1 (or FIG. 2). In step 304, the pilot signal strength detector 110 determines whether the pilot signal strength of the input signal SIN is greater than a threshold TH1 to generate the control signal SC. If the pilot signal strength of the input signal SIN is greater than the threshold TH1, steps 310 and 312 are performed; otherwise, steps 320 and 322 are performed. When the pilot signal strength of the input signal SIN is greater than the threshold TH1, the controller 120 or the selector 220 transmits the input signal SIN to the lock-frequency phase-locked loop 130 based on the pilot signal to perform the first carrier recovery action on the input signal SIN. Up (steps 310, 312); and when the pilot signal strength of the input signal SIN is not greater than the threshold TH1, the controller 120 or the selector 220 transmits the input signal SIN to the phase-locked loop 140 without the pilot signal to perform the first The two carrier replies act on the input signal SIM (steps 320, 322).

Please note that the steps of the flow in FIG. 3 are not limited to be performed in the order shown in the embodiment, and other intermediates may be added without departing from the spirit of the present invention. A step of.

The embodiments described above are only intended to illustrate the technical features of the present invention and are not intended to limit the scope of the present invention. As can be seen from the above, the present invention provides a carrier recovery apparatus and related methods. The carrier recovery device disclosed in the present invention combines two lock loops, a lock-frequency phase-locked loop 130 based on the pilot signal, and a phase-locked loop 140 without a pilot signal, and determines when to use based on the pilot signal strength of the input signal SIN. The frequency-locked phase-locked loop 130 of the pilot signal or the phase-locked loop 140 without the pilot signal performs a carrier recovery operation on the input signal SIN. In this way, the above-mentioned unlockable frequency/phase and reception failure can be avoided, and the overall stability of the system can be improved even if the pilot signal is severely weakened due to channel attenuation or even unable to detect the pilot signal. . Moreover, the phase-locked loop with no pilot signal disclosed in the present invention is easier to implement than the conventional frequency-locked loop with no pilot signal, which can reduce complexity and save more cost. In addition, the threshold TH1 of the pilot signal strength detector can be adjusted according to the actual channel state or the received input signal SIN, and is suitable for use in a wide variety of situations.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100, 200. . . Carrier recovery device

110. . . Guided signal strength detector

120. . . Controller

130. . . Frequency-locked phase-locked loop based on pilot signal

140. . . Phase-locked loop without pilot signal

SIN. . . Input signal

SC. . . Control signal

TH1. . . Threshold

220. . . Selector

SW1. . . switch

221. . . Input

222. . . Control terminal

223. . . First output

224. . . Second output

302～322. . . step

1 is a functional block diagram of a first embodiment of a carrier recovery device of the present invention.

Figure 2 is a functional block diagram of a second embodiment of a carrier recovery device of the present invention.

Figure 3 is a flow chart showing an example of the operation of one carrier recovery method of the present invention.

100. . . Carrier recovery device

110. . . Guided signal strength detector

120. . . Controller

130. . . Frequency-locked phase-locked loop based on pilot signal

140. . . Phase-locked loop without pilot signal

SIN. . . Input signal

SC. . . Control signal

TH1. . . Threshold

Claims (6)

A carrier recovery device includes: a pilot signal strength detector for determining whether one of the input signals has a pilot signal strength greater than a threshold to generate a control signal; and a first lock loop for performing a a carrier response is performed on the input signal; a second lock loop is configured to perform a second carrier recovery operation on the input signal; and a controller coupled to the pilot signal strength detector, the first The lock loop and the second lock loop are configured to selectively allow the first lock loop to perform the first carrier return action on the input signal or allow the second lock loop to execute the second carrier according to the control signal Responding to the input signal; wherein the controller is a selector, and the first locking circuit is a lock-frequency phase-locked loop based on a pilot signal, and the second locking circuit is a lock without a pilot signal a phase loop; when the control signal indicates that the pilot signal strength of the input signal is greater than the threshold, the controller transmits the input signal to the first lock Circuit; and when the control signal indicating signal strength of the guide lines of the input signal is not greater than the threshold value, the controller transmits the input signal to the second locked loop. The carrier recovery device of claim 1, wherein the selector, the package The input end is configured to receive the input signal; a control end is coupled to the pilot signal intensity detector for receiving the control signal; a first output end coupled to the first lock loop; And a second output end coupled to the second locking circuit; the selector selectively transmitting the input signal to the first locking circuit or the second locking circuit according to the control signal. The carrier recovery device of claim 1, wherein the first locking circuit is implemented in a digital manner, and the second locking circuit is implemented in a digital manner. The carrier recovery device of claim 1, wherein the first locking circuit is implemented in an analogous manner, and the second locking circuit is implemented in an analogous manner. A carrier recovery method includes: determining whether a pilot signal strength of one of the input signals is greater than a threshold to generate a control signal; and selectively enabling a lock-frequency phase-locked loop based on the pilot signal according to the control signal a first carrier is responsive to the input signal, or a phase-locked loop without a pilot signal is allowed to perform a second carrier replies to the input signal; wherein the control signal indicates the strength of the pilot signal of the input signal When the system is greater than the threshold, the input signal is transmitted to the pilot-based lock frequency lock phase a loop; and when the control signal indicates that the pilot signal strength of the input signal is not greater than the threshold, the input signal is transmitted to the phase-locked loop without the pilot signal. The method of claim 5, wherein the pilot-based lock-frequency phase-locked loop is selectively enabled to perform the first carrier reply action on the input signal according to the control signal, or the non-boot is allowed. The step of the signal phase-locking loop to perform the second carrier recovery operation on the input signal includes: allowing the pilot signal-based lock when the control signal indicates that the pilot signal strength of the input signal is greater than the threshold value The frequency-locked loop circuit performs the first carrier recovery operation on the input signal; and when the control signal indicates that the pilot signal strength of the input signal is not greater than the threshold, the phase-locked loop without the pilot signal is allowed to Performing the second carrier reply action on the input signal.