CN112134824A - Low-complexity high-performance GFSK demodulation method - Google Patents
Low-complexity high-performance GFSK demodulation method Download PDFInfo
- Publication number
- CN112134824A CN112134824A CN202010991947.9A CN202010991947A CN112134824A CN 112134824 A CN112134824 A CN 112134824A CN 202010991947 A CN202010991947 A CN 202010991947A CN 112134824 A CN112134824 A CN 112134824A
- Authority
- CN
- China
- Prior art keywords
- signal
- error
- symbols
- value
- symbol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
- H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
- H04L27/38—Demodulator circuits; Receiver circuits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/80—Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/0035—Synchronisation arrangements detecting errors in frequency or phase
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
A low-complexity high-performance GFSK demodulation method belongs to the technical field of modulated carrier systems and comprises the following steps: s1, differential demodulation; s2, time offset compensation; and S3, frequency offset compensation. The scheme provides an improved GFSK differential demodulation scheme, and high-performance receiving performance is achieved under low complexity. The invention has frequency deviation compensation and time deviation compensation scheme to improve the receiving performance.
Description
Technical Field
The invention belongs to the technical field of modulated carrier systems, and particularly relates to a low-complexity high-performance GFSK demodulation method.
Background
With the rapid development of the internet technology, the communication network technology related to the internet gradually matures, mobile devices and products are increasingly increased, and the role in life is more and more prominent. "Bluetooth" is an open specification that enables wireless voice and data communication over short distances. It provides low-cost, short-range wireless communication, can provide cheap access service for fixed or mobile terminal equipment, and enables various equipment in short range to realize seamless resource sharing.
The modulation technology adopted by other wireless communication standard low-power-consumption technologies such as Bluetooth and 802.11 is GFSK, so that the research on GFSK has profound significance.
Gaussian Frequency Shift Keying (GFSK) is a continuous phase frequency modulation. Unlike the general frequency modulation, in the GFSK modulation, the transmitted data symbols are passed through a gaussian filter; the transition between the two different frequencies is thus continuous, limiting the spectral bandwidth of the modulated signal. The amplitude of the GFSK signal is constant, which can significantly reduce the linearity requirements of the transmitter on the power amplifier. The GFSK modulation is widely applied to the fields of low-power transmission and internet of things, such as Bluetooth (Bluetooth), low-power Bluetooth (BLE), and the like.
The GFSK demodulation method is a key technology of a digital communication system based on GFSK modulation, and the performance and the structure of the GFSK demodulation method determine the sensitivity of a receiver and the complexity of digital integrated circuit implementation.
The traditional differential demodulation method has lower complexity, however, the receiving performance of the method is relatively poor, and the performance of the existing differential demodulation algorithm of the GFSK is lower than that of the coherent demodulation algorithm.
Coherent demodulation must recover coherent carrier, and use this coherent carrier and modulated signal function, get the original digital baseband signal, and this coherent carrier is with the same frequency and in phase of the original carrier signal that modulates this baseband signal at the sending end, and noncoherent demodulation does not need to recover coherent carrier, so is simpler than coherent demodulation mode. However, in most cases, the coherent demodulation method has a better demodulation effect.
1) The traditional differential demodulation method has lower complexity, however, the receiving performance of the method is relatively poor, and the performance of the existing differential demodulation algorithm of the GFSK is lower than that of the coherent demodulation algorithm.
2) In the coherent demodulation algorithm of the GFSK, correlation between a received signal and a local waveform is required, and the coherent demodulation has good receiving performance, but the algorithm has high complexity and high implementation cost.
3) The existing Bluetooth receiver scheme lacks frequency offset tracking and time offset tracking strategies, and the stability and robustness of the system are not high.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a low-complexity high-performance GFSK demodulation method.
In order to achieve the above object, the present invention adopts the following technical solutions.
A low-complexity high-performance GFSK demodulation method comprises the following steps:
s1, differential demodulation: calculating a group of coefficients h according to the relation between the original bit and the differential angle, solving a reconstruction signal by using h and traversing all possible original bits during demodulation, and solving the minimum mean square error value of the received signal and the reconstruction signal to obtain a demodulated bit;
s2, time offset compensation:
s201, a reconstructed signal restoradsig corresponding to the symbol X is obtained by using the demodulated symbol X, the former N-2, N-1 symbol and the h parameter;
s202, the received signal respectively subtracts a frequency offset value freqOffset from a current sampling point, a front sampling point 1 and a rear sampling point 1, then obtains an Error Error by subtracting a reconstructed signal restodedSigX corresponding to the X, and sequentially obtains LongErrPrompt, LongErrEarly and LongErrLate through smooth accumulation of 256 symbols; LongErrPrompt represents the cumulative error value at the current sample point; LongErrEarly represents the cumulative error value of the previous sample point; LongErrLate represents the cumulative error value of the post-sampling point;
s203, the minimum of the longErrPrompt, the longErrEarly and the longErrLate is selected to determine whether the optimal sampling point is moved forward by 1 point or moved backward by one point or kept unchanged.
S3, frequency offset compensation:
the difference between the reconstructed signal restoradsig, i.e. the reference signal, and the actual received signal is the error signal, which is recorded as X = rxSig-restoradsig-freqOffset, and is fed back to the source adjusting error signal after passing through the 2-order loop filter, and the Z-domain transfer function is:
wherein the parameter W0>0 and is set to match if X>0, the value of Y is increased after passing through the loop filter, and then Y is fed back to freqOffset to reduce X; on the contrary, if X<0, the value of Y is decreased after passing through the loop filter, and is fed back to freqOffset to increase X, so that the loop functions to stabilize the error signal X around 0, that is, the value of freqOffset can track the real frequency offset change; w0The value of (a) determines the bandwidth of the loop,
specifically, step S1 includes the following steps:
at step S101, the differential Angle of each symbol actually has a relationship with only three consecutive original bits. Here, let 5 input symbols be associated, and let Len be long enough, as shown in the following formula:
denoted r = X × h, where matrix r is the received differential Angle, matrix X is the bipolar symbol of the modulation, and matrix h is the product of each input symbol weight and the differential Angle mean, then matrix h can be found according to:
step S102, adopting h = [ 107010 ] through a large number of simulations]For the continuous 4 symbols, traversing all the demodulated bits, calculating the reconstructed signal corresponding to the 4 symbols, and calculating the minimum of the error square accumulation by using the received signal and the reconstructed signal to obtain the demodulated bit, i.e. calculating
Wherein:
x, Y, Z respectivelyIndicating bit to be solvedn，bitn+1，bitn+2All three bits will traverse both 1 and-1 values;
after a received signal rxSig finds a synchronous head, the optimal sampling points N-1, N, N +1, N +2 of the continuous 4 symbols are taken, wherein N-1 is the last 1 symbol of Trailer, and N-N +2 is the first 3 symbols of the head; subtracting the frequency offset freqoffset to obtain ideal rxSig;
taking known N-2 and N-1, adding unknown symbols of X, Y and Z, traversing values of X, Y and Z by using the theory discussed above and the calculated h parameter, and calculating 8 reconstruction signals restoradsig; and solving the mean square error MSE by using the received signal and the reconstructed signal, and solving the values of X, Y and Z corresponding to the minimum mean square error MSE to demodulate an X symbol, namely a main path of differential demodulation.
The scheme provides an improved GFSK differential demodulation scheme, and high-performance receiving performance is achieved under low complexity. The invention has frequency deviation compensation and time deviation compensation scheme to improve the receiving performance.
Drawings
FIG. 1 is a diagram of a GFSK digital receiver architecture;
FIG. 2 is a diagram of a differential GFSK demodulation implementation architecture;
FIG. 3 is a diagram of a frequency offset tracking loop;
fig. 4 is a block diagram of a differential demodulation main path implementation.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
A low-complexity high-performance GFSK demodulation method comprises the following steps:
in the receiving process, the data source of the synchronization and the differential demodulation is a differential Angle, as shown in fig. 1, the flow of the received algorithm is just opposite to the transmission, the physical meaning of the differential Angle is frequency, the original bit is 1 and generates positive frequency, the original bit is 0 and generates negative frequency, the differential Angle is judged with 0 to obtain the demodulation bit, only the frequency offset exists in the actual system, the frequency center value is not 0, and a frequency offset loop needs to be added. Because the receiving end crystal oscillator is deviated relative to the transmitting end, the demodulation needs to add a time deviation loop. And finding the synchronization position according to the correlation peak value by using a method of correlating the original bit and the differential Angle in the synchronization module.
Differential demodulation main path:
as can be seen from the nature of GFSK modulation, each output symbol is associated with only 3 input symbols. The invention provides a novel GFSK differential demodulation method, which has the main idea that a group of coefficients h is calculated according to the relation between an original bit and a differential Angle, a reconstructed signal is obtained by h and traversal of all possible original bits during demodulation, and a demodulated bit is obtained by obtaining minimum mean square MMSE (minimum mean square error) of a received signal and the reconstructed signal. How to find the coefficient h is described below.
It has been mentioned above that the differential Angle of each symbol actually has a relationship with only three consecutive original bits. Here, let 5 input symbols be associated, and let Len be long enough, as shown in the following formula:
denoted r = X × h, where matrix r is the received differential Angle, matrix X is the bipolar symbol of the modulation, and matrix h is the product of each input symbol weight and the differential Angle mean, then matrix h can be found according to:
adopting h = [ 107010 ] through a large number of simulations]For the continuous 4 symbols, traversing all the demodulated bits, calculating the reconstructed signal corresponding to the 4 symbols, and calculating the minimum of the error square accumulation by using the received signal and the reconstructed signal to obtain the demodulated bit, i.e. calculating
Wherein:
x, Y, Z respectively represent bits to be solvedn，bitn+1，bitn+2All three bits will traverse 1 and-1.
As shown in fig. 2, which is a schematic diagram of an algorithm for differential GFSK demodulation, after a synchronization header is found in a received signal rxSig, optimal sampling points N-1, N +1, N +2 of 4 continuous symbols are taken, where N-N +2 is the first 3 symbols of a received packet header; subtracting the frequency offset freqOffset to obtain an ideal rxSig (wherein freqOffset is the frequency offset calculated by the synchronization module using 60 access code symbols and has average meaning);
the other path takes known N-2 and N-1, adds unknown symbols of X, Y and Z, and uses the theory discussed above and the calculated h parameter to traverse the values of X, Y and Z and calculate 8 reconstruction signals restodedsig; and solving the mean square error MSE by using the received signal and the reconstructed signal, and solving the values of X, Y and Z corresponding to the minimum mean square error MSE to demodulate an X symbol, namely a main path of differential demodulation.
The implementation process of the time offset loop is as follows:
(1) using the demodulated symbol X together with the previous N-2, N-1 symbol and h parameter to calculate the reconstructed signal restoradsig corresponding to X;
(2) the method comprises the steps that a received signal respectively subtracts a frequency offset value (freqOffset) from a current sampling point, a front sampling point and a rear sampling point 1, then the difference is obtained between the received signal and a reconstructed signal restoradsix corresponding to the X to obtain an Error, and the errors of the three sampling points are sequentially subjected to smooth accumulation of 256 symbols to obtain longerrPrompt, longerrEarly and longerrLate; LongErrPrompt represents the cumulative error value at the current sample point; LongErrEarly represents the cumulative error value of the previous sample point; LongErrLate represents the cumulative error value of the post-sampling point;
(3) taking the minimum of LongErrPrompt, LongErrEarly and LongErrLate, and determining the optimal sampling point is moved forward by 1 point or moved backward by one point or kept unchanged.
Assuming that the time offset of bluetooth is 2Oppm, one sampling point will be offset by M sampling points, and M is calculated as follows:
the data sampling rate is 12Msps, namely more than 4000 symbols can deviate from 1 sampling point, and the time deviation is adjusted once every 256 symbols set by an actual algorithm, so that the requirement can be met. f denotes the clock frequency and Δ f denotes the clock frequency offset.
Frequency offset tracking loop:
fig. 3 is a schematic diagram of a frequency offset loop, where a difference between a reconstructed signal, i.e., a reference signal, and an actual received signal is an error signal, which is recorded as X = rxSig-restoradsig-freqOffset, and the error signal is fed back to a source to adjust the error signal after passing through a 2-order loop filter, and a Z-domain transfer function of the error signal is:
wherein the parameter W0>0 and is set to match if X>0, the value of Y is increased after passing through the loop filter, and then Y is fed back to freqOffset to reduce X; on the contrary, if X<0, the value of Y is decreased after passing through the loop filter, and is fed back to freqOffset to increase X, so that the loop functions to stabilize the error signal X around 0, that is, the value of freqOffset can track the real frequency offset change. W0The value of (A) determines the bandwidth of the loop, W0The larger, the larger the bandwidth, the faster the loop tracks, but also introduces unwanted noise.
Currently, the synchronization and demodulation algorithm of the GFSK is implemented on the bluetooth chip YC 1121F of jammer microelectronics by hardening. The block diagram architecture of the implementation of the receiver is shown in fig. 4.
The sensitivity performance of the Bluetooth realized under the scheme is shown in the following table and is far better than the sensitivity index specified by Bluetooth Spec.
| Mode(s) | Power(dBm) |
| BR(BER<0.1%) | -94.8 |
| BLE1M(BER<0.1%) | -93.9 |
| BLE2M(BER<0.1%) | -96.5 |
| LongRange S=2（BER<0.02% ||PER<10%） | -98.9 |
| LongRange S=8（BER<0.02% ||PER<10%） | -105 |
It should be understood that equivalents and modifications of the technical solution and inventive concept thereof may occur to those skilled in the art, and all such modifications and alterations should fall within the scope of the appended claims.
Claims (2)
1. A low-complexity high-performance GFSK demodulation method is characterized by comprising the following steps:
s1, differential demodulation: calculating a group of coefficients h according to the relation between the original bit and the differential angle, solving a reconstruction signal by using h and traversing all possible original bits during demodulation, and solving the minimum mean square error value of the received signal and the reconstruction signal to obtain a demodulated bit;
s2, time offset compensation:
s201, a reconstructed signal restoradsig corresponding to the symbol X is obtained by using the demodulated symbol X, the former N-2, N-1 symbol and the h parameter;
s202, the received signal respectively subtracts a frequency offset value freqOffset from a current sampling point, a front sampling point 1 and a rear sampling point 1, and then obtains an Error Error by subtracting from a reconstructed signal restodedSigX corresponding to X, and the Error is subjected to smooth accumulation of 256 symbols to sequentially obtain LongErrPrompt, LongErrEarly and LongErrLane; LongErrPrompt represents the cumulative error value at the current sample point; LongErrEarly represents the cumulative error value of the previous sample point; LongErrLate represents the cumulative error value of the post-sampling point;
s203, taking the minimum of the longErrPrompt, the longErrEarly and the longErrLate, and determining that the optimal sampling point is moved forward by 1 point or moved backward by one point or kept unchanged;
s3, frequency offset compensation:
the difference between the reconstructed signal restoradsig, i.e. the reference signal, and the actual received signal is the error signal, which is recorded as X = rxSig-restoradsig-freqOffset, and is fed back to the source adjusting error signal after passing through the 2-order loop filter, and the Z-domain transfer function is:
wherein the parameter W0>0 and is set to match if X>0, the value of Y is increased after passing through the loop filter, and then Y is fed back to freqOffset to reduce X; on the contrary, if X<0, the value of Y is decreased after passing through the loop filter, and is fed back to freqOffset to increase X, so that the loop functions to stabilize the error signal X around 0, that is, the value of freqOffset can track the real frequency offset change; w0The value of (d) determines the bandwidth of the loop.
2. A low-complexity high-performance GFSK demodulation method as claimed in claim 1, wherein: in step S1, the method includes the steps of:
step S101, the differential Angle of each symbol is actually only related to three continuous original bits; here, let 5 input symbols be associated, and let Len be long enough, as shown in the following formula:
denoted r = X × h, where matrix r is the received differential Angle, matrix X is the bipolar symbol of the modulation, and matrix h is the product of each input symbol weight and the differential Angle mean, then matrix h can be found according to:
step S102, adopting h = [ 107010 ] through a large number of simulations]For the continuous 4 symbols, traversing all the demodulated bits, calculating the reconstructed signal corresponding to the 4 symbols, and calculating the minimum of the error square accumulation by using the received signal and the reconstructed signal to obtain the demodulated bit, i.e. calculating
Wherein:
x, Y, Z respectively represent bits to be solvedn，bitn+1，bitn+2Three bits will all traverse both 1 and-1 values;
after a received signal rxSig finds a synchronous head, the optimal sampling points N-1, N, N +1 and N +2 of the continuous 4 symbols are taken, wherein N-N +2 are the first 3 symbols of a receiving packet head; subtracting the frequency offset freqoffset to obtain ideal rxSig;
taking known N-2 and N-1, adding unknown symbols of X, Y and Z, traversing values of X, Y and Z by using the theory discussed above and the calculated h parameter, and calculating 8 reconstruction signals restoradsig; and solving the mean square error MSE by using the received signal and the reconstructed signal, and solving the values of X, Y and Z corresponding to the minimum mean square error MSE to demodulate an X symbol, namely a main path of differential demodulation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010991947.9A CN112134824B (en) | 2020-09-21 | 2020-09-21 | Low-complexity high-performance GFSK demodulation method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010991947.9A CN112134824B (en) | 2020-09-21 | 2020-09-21 | Low-complexity high-performance GFSK demodulation method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112134824A true CN112134824A (en) | 2020-12-25 |
| CN112134824B CN112134824B (en) | 2021-06-15 |
Family
ID=73841151
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010991947.9A Active CN112134824B (en) | 2020-09-21 | 2020-09-21 | Low-complexity high-performance GFSK demodulation method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112134824B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113098811A (en) * | 2021-04-01 | 2021-07-09 | 高拓讯达（北京）科技有限公司 | Demodulation and decoding method and device for GFSK signal |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7039132B1 (en) * | 2001-03-07 | 2006-05-02 | Integrated Programmable Communications, Inc. | Differential detection of GFSK signal using decision feedback and preamble for carrier, clock and frame synchronization |
| CN101047677A (en) * | 2006-03-31 | 2007-10-03 | 捷顶微电子（上海）有限公司 | Low complexity, high performance GFSK signal multi-bit demodulation method |
| CN204518093U (en) * | 2015-01-21 | 2015-07-29 | 北京华强智连微电子有限责任公司 | A kind of OFDM carrier wave of low-power consumption and GFSK wireless double mode communication chip |
| CN109039966A (en) * | 2018-08-01 | 2018-12-18 | 上海华虹集成电路有限责任公司 | A kind of demodulation method based on decision-feedback, the GFSK signal of low complex degree |
| CN111181600A (en) * | 2019-12-31 | 2020-05-19 | 北京升哲科技有限公司 | Chirp spread spectrum modulation and demodulation method and system based on QPSK |
-
2020
- 2020-09-21 CN CN202010991947.9A patent/CN112134824B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7039132B1 (en) * | 2001-03-07 | 2006-05-02 | Integrated Programmable Communications, Inc. | Differential detection of GFSK signal using decision feedback and preamble for carrier, clock and frame synchronization |
| CN101047677A (en) * | 2006-03-31 | 2007-10-03 | 捷顶微电子（上海）有限公司 | Low complexity, high performance GFSK signal multi-bit demodulation method |
| CN204518093U (en) * | 2015-01-21 | 2015-07-29 | 北京华强智连微电子有限责任公司 | A kind of OFDM carrier wave of low-power consumption and GFSK wireless double mode communication chip |
| CN109039966A (en) * | 2018-08-01 | 2018-12-18 | 上海华虹集成电路有限责任公司 | A kind of demodulation method based on decision-feedback, the GFSK signal of low complex degree |
| CN111181600A (en) * | 2019-12-31 | 2020-05-19 | 北京升哲科技有限公司 | Chirp spread spectrum modulation and demodulation method and system based on QPSK |
Non-Patent Citations (3)
| Title |
|---|
| CHARLES TIBENDERANA ， STEPHAN WEISS: "LOW-COMPLEXITY HIGH-PERFORMANCE GFSK RECEIVER WITH CARRIER FREQUENCY OFFSET CORRECTION", 《2004 IEEE INTERNATIONAL CONFERENCE ON ACOUSTICS, SPEECH, AND SIGNAL PROCESSING》 * |
| HARTWIG UNTERASSINGER、MARTIN FLATSCHER等: "Investigation of Two-Point Modulation to Increase the GFSK Data Rate of PLL-Based Wireless Transceivers of Wireless Sensor Nodes", 《PRIME 2013, VILLACH, AUSTRIA》 * |
| YADONG YIN, YUEPENG YAN, CHENJUN WEI: "A Low-Power Low-Cost GFSK Demodulator With a Robust Frequency Offset Tolerance", 《IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113098811A (en) * | 2021-04-01 | 2021-07-09 | 高拓讯达（北京）科技有限公司 | Demodulation and decoding method and device for GFSK signal |
| CN113098811B (en) * | 2021-04-01 | 2022-06-28 | 高拓讯达（北京）科技有限公司 | Demodulation decoding method and demodulation decoding device for GFSK (Gaussian filtered Shift keying) signals |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112134824B (en) | 2021-06-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103248593B (en) | Offset estimation and removing method and system | |
| TWI597957B (en) | Low-power, noise insensitive communication channel system and related method using logarithmic detector amplifier (lda) demodulator | |
| TWI431988B (en) | Receivers and symbol decoders thereof | |
| US7994933B2 (en) | Frequency shift compensation, such as for use in a wireless utility meter reading environment | |
| CN101965721A (en) | I/q imbalance estimation and correction in a communication system | |
| CA2163744A1 (en) | Diversity pi/4-dqpsk demodulation | |
| CN109039966B (en) | Decision feedback and low-complexity demodulation method of GFSK (Gaussian frequency Shift keying) signal | |
| WO2001020831A1 (en) | Ofdm communication device and detecting method | |
| KR20020075836A (en) | Pilot signal transmission technique and digital communication system using same | |
| CN111901269B (en) | Gaussian frequency shift keying modulation method, device and system with variable modulation index | |
| TW201038028A (en) | Carrier recovery device and related method | |
| CN112134824B (en) | Low-complexity high-performance GFSK demodulation method | |
| CN111800364B (en) | Method for estimating and correcting frequency offset of coded CPM (continuous phase modulation) signal based on waveform matching | |
| CN106452652B (en) | A kind of MPI suppression method based on chaos wireless communication system | |
| CN114338297B (en) | Combined timing synchronization and frequency offset estimation method under incoherent LoRa system | |
| TWI398139B (en) | Optimal initial gain selection for wireless receiver | |
| CN112134825B (en) | Low-complexity high-performance GFSK baseband timing synchronization method | |
| Nguyen et al. | A receiver for resource-constrained wireless sensor devices to remove the effect of multipath fading | |
| KR100795716B1 (en) | Mutimode receiver for frequency error mitigation | |
| CN1305285C (en) | Method and device for realing differential-deviation four-phase key-control coherent demodulation | |
| CN112671684B (en) | Self-adaptive demodulation method of short-time burst BPSK signal | |
| CN114050845A (en) | Coherent demodulation method of Bluetooth EDR receiver | |
| CN100518158C (en) | Method and apparatus for frequency tracking based on recovered data | |
| KR102267324B1 (en) | Device and Method to Frequency Offset Estimating in Low Power Wide Area Communication Network | |
| US20030112061A1 (en) | Method for demodulating signal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |