JPH05102957A - Circuit and method for detecting frame synchronization pattern - Google Patents

Abstract

PURPOSE:To correctly detect a frame synchronization signal by forming a synchronization pattern signal by joining a part of a bit synchronization signal of a receiving signal and a frame synchronization signal, and detecting the synchronization pattern signal whose number of bits is larger than that of the frame synchronization signal. CONSTITUTION:When a car portable telephone equipment receives a signal from a base station, a modem in a radio part 1 takes synchronization with a receiving signal in a stability waiting time by bit synchronization of 15 bits added to the part of the head of the receiving signal, but leading-in is completed by first 8 bits or so in 15 bits, and a phase lock can be taken. Accordingly, in 15 bits, 5 bits in the end can always be detected correctly. Therefore, a control part 2 generates a synchronization pattern of 16 bits by joining 5 bits of a bit synchronization signal and an original frame synchronization signal, and regards it as a frame synchronization signal and detects it. In such a way, probability that the same pattern is generated in the data of 140 bits becomes small, and the frame synchronization signal can be detected surely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame synchronization pattern detection circuit for a mobile telephone device for vehicles and a detection method thereof.

[0002]

2. Description of the Related Art In recent years, the technical field of mobile communication has been rapidly developing. In particular, car mobile phone devices have been made smaller, more portable, have lower current consumption, and have higher functionality. In such a car mobile phone device, it is important to obtain error-free received data even if external noise is mixed into the received data.

FIG. 3 shows the configuration of a conventional car mobile telephone device. In FIG. 3, reference numeral 1 is a wireless unit that transmits and receives signals, 2 is a control unit that performs various control of the apparatus, 3 is a baseband unit that generates a baseband signal, 4 is a power supply unit, and 5 is a handset that is a handset. The part 6 is an antenna terminal part.

Next, the operation of the above conventional example will be described. First, when the power is turned on by the operation from the handset unit 5 or when the call with another terminal station is finished,
The car mobile phone device is in a reception waiting state. Thereafter, at the time of incoming call, a data signal is transmitted from the base station.
This data signal is subjected to Hagerberger conversion of 64-bit data into 140-bit data. Furthermore, NMT
The system standard defines a format in which a 15-bit bit synchronization signal and an 11-bit frame synchronization signal are added to the beginning of data. Therefore, the signal received by the car mobile phone device is also in the above format.
In the radio unit 1, the modem transmits 1200 Hz and 1800 H from a discriminator (discriminator).
z MSK signal (minimum shift keying signal) received signal is a balanced code demodulation signal (NR
Z). FIG. 4 shows a timing chart of the operation of the modem and the format of the received signal. The modem is in phase synchronization with the received signal by the bit synchronization added to the first part of the received signal. Then, after phase synchronization is achieved and bit synchronization can be recognized, the received signal is demodulated to generate a demodulated signal. This demodulated signal is sent to the CPU in the control unit, and the frame synchronization pattern detection circuit causes the 11-bit frame synchronization signal (111000).
10010) is detected. Thereafter, the 140-bit Hagerberger-converted data is demodulated, and subsequently, error correction of the received data is performed.

[0005]

However, in the above-mentioned conventional frame synchronization pattern detection circuit, data having the same pattern as the frame synchronization signal pattern is generated as pseudo frame synchronization signals in the Hagerberger converted data. There is a high possibility that the original frame synchronization signal cannot be detected correctly.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an excellent frame synchronization pattern detection circuit and a detection method thereof, which can correctly detect a frame synchronization signal.

[0007]

In order to achieve the above object, the present invention arbitrarily increases the number of bits of the original frame synchronization signal to provide a pattern signal for synchronization detection.
Further, it has a plurality of detection pattern states when the frame synchronization signal is detected.

[0008]

With the above arrangement, the present invention can indirectly detect the original frame synchronization signal by detecting a pattern signal that is not confused with the pseudo frame synchronization signal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a frame sync pattern detection circuit according to the present invention will be described with reference to the drawings. FIG. 1 is a timing chart of the operation of the modem and a format of a received signal in the embodiment of the present invention. The operation of this embodiment will be described with reference to FIG.

Similar to the conventional example, when the power is turned on by the operation from the handset unit 5 or when the call with another terminal station (not shown) is completed, the car mobile phone device is operated by the base station (not shown). It will be in the waiting state for receiving the incoming call from (No.). Upon receiving a signal from the base station, a modem (not shown) in the radio unit 1 balances the 1200 Hz and 1800 Hz MSK signals sent from the discriminator (not shown) with the reception clock. Convert to a demodulated signal of the code. The modem establishes phase synchronization with the received signal during the stable waiting time by the 15-bit bit synchronization added to the beginning of the received signal, but the pull-in is completed within about the first 8 bits of the 15 bits ( That is,
Phase can be synchronized). Therefore, the last 5 bits out of 15 bits can always reliably obtain normal 10101.

Therefore, the 16-bit sync pattern is provided with a sync signal generating means (not shown) for generating the 16-bit sync pattern signal by combining the 5-bit bit sync signal and the original frame sync signal. The signal is detected by considering it as the original frame synchronization signal. The 16-bit sync pattern signal is much less likely to generate the same pattern in 140-bit data than the original 11-bit frame sync signal. Therefore, by detecting the 16-bit sync pattern signal, the original frame sync signal can be reliably detected.

Next, an embodiment of the frame synchronization pattern detecting method according to the present invention will be described. FIG. 2 shows the control unit 2.
7 is a state transition diagram of a frame synchronization pattern detection process in a CPU (not shown) in FIG. In FIG. 2, 7
Is the state of detection pattern 1, 8 is the state of detection pattern 2,
9 is the state of detection pattern 3.

The operation of frame synchronization pattern detection will be described based on the above state transition diagram. First, the state 7 of the detection pattern 1 is a reception waiting state, which is a state after starting the data reception and before detecting the frame synchronization signal. In this state, it is possible to make a determination for each bit of the received data and correct an error of up to 2 bits. Also, by setting a relatively large number of redundant bits for error detection / correction, erroneous detection due to noise or the like is prevented.

State 8 of detection pattern 2 is a state in which a frame synchronization signal is detected at the same time as data reception,
A pseudo frame synchronization signal generated in bit data is detected. In this state, the received data can be judged bit by bit and the error up to 1 bit can be corrected.

The state of the detection pattern 3 is the same as the detection pattern 2
This is a subsequent processing state when the pseudo frame synchronization signal is detected in. Since it is not possible to determine whether the detected pseudo frame sync signal is a correct frame sync signal, it is correct by checking the pattern of the leading 6 bits of the information bits and the parity bits of 3 bits in the 140 bits of the data section. The frame sync signal is detected.

As described above, when the frame synchronization signal is detected, the detection of the frame synchronization signal is ensured by always selecting the state of the optimum detection pattern according to the reception state and the state of the mobile phone unit of the car. Can be something.

[0017]

As is apparent from the above embodiment, the present invention combines a part of the bit synchronization signal of the received signal and the frame synchronization signal into a synchronization pattern signal, and synchronizes with a larger number of bits than the frame synchronization signal. By detecting the pattern signal, it is possible to detect the correct frame synchronization signal.

When detecting the frame synchronization signal,
By always selecting the optimum detection pattern state,
It is possible to reliably detect the frame synchronization signal.

[Brief description of drawings]

FIG. 1 is a timing chart of a modem operation and a format diagram of a received signal according to an embodiment of the present invention.

FIG. 2 is a state transition diagram of frame synchronization pattern detection processing according to the embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of a car mobile phone device.

FIG. 4 is a timing chart of a conventional modem operation and a format of a received signal.

[Explanation of symbols]

 1 Radio | wireless part 2 Control part 3 Baseband part 4 Power supply part 5 Handset part 6 Antenna terminal part 7 State of detection pattern 1 8 State of detection pattern 2 9 State of detection pattern 3

Claims (2)

[Claims] 1. A frame synchronization pattern detection circuit for a mobile phone unit for a vehicle, which receives a Hagerberger-converted data signal transmitted from a base station and detects a frame synchronization signal included in the data signal. Sync signal generating means for generating a sync pattern signal by combining a part of the bits of the bit sync signal added to the data signal and all the bits of the frame sync signal. A frame synchronization pattern detection circuit that detects it as if it were. 2. A frame synchronization pattern detection method for a mobile phone unit for vehicles, which receives a Hagerberger-converted data signal transmitted from a base station and detects a frame synchronization signal included in the data signal. A method for detecting a frame synchronization pattern, characterized in that, when detecting a frame synchronization signal, detection is performed in a plurality of detection pattern states.