JP2929849B2 - Transmit / receive frequency converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception frequency converter, and more particularly to a digital transmission / reception local oscillator frequency reference for changing a shift frequency which is a difference between a transmission frequency and a reception frequency of a heterodyne radio transmission / reception apparatus. PL
The present invention relates to a transmission / reception frequency converter that can be handled only by controlling the frequency division number in an L-type frequency synthesizer.

[0002]

2. Description of the Related Art Generally, transmission, reception frequencies, shift frequencies, etc. of a microwave communication line are defined by the International Unified Code (CCIR).
Etc.). For example, recommendation number 387-1
1 GHz band (10.7 to 11.7 GHz), 600 to
1. 800ch transmission, TV transmission, medium and small capacity
The frequency arrangement of the digital system is 10.7-11.7 GHz.
500MHz for low band and 500MHz for high band
And 12 transmission channels [2ch to 12ch] in each band.
ch, 2Uch to 11Uch are the main channels (1) (12
U) mainly sets the control line ch] at 40 MHz intervals.
I can. Now focusing on one relay station or terminal station, 1ch to 12c
If h is the transmission frequency, it corresponds to each of these transmission channels
And the receiving frequency of the pair is 1Uch to 12Uch
Therefore, for example, if attention is paid to transmission 6ch reception 6Uch, transmission and reception
The shift frequency interval f _S becomes 530MHz. Other
The same applies to f _{S of the} transmission / reception channel . Where the transmission frequency
To maintain the frequency accuracy of each
Naturally, the shift frequency f _S also maintains a constant interval.
Need to be In the heterodyne transmission / reception device,
Frequency conversion of reception frequency by mixing with local oscillator frequency
Generated IF frequency is 70MHz in Japan
It is common that there are many. However, in some domestic and local governments, the shift frequency and the like are operated under different frequency rules. For example, f _R = 3 shown in FIGS. 2 and 1
8.2 GHz, f _T = 37 GHz , f _S = 1.2 GHz
Pair of reception channel and transmission channel adjacent to the frequency combination
According to the Japanese domestic regulations, f _R2 = 38.525 GHz
Combination of f _T2 = 37.525 GHz and f _S2 = 1 GHz
Since also been regulations, unions f _R, f _T, f _S in FIG. 2
Luck change the Align to the combination of the aforementioned f _R2, f _T2, f _S2
It is necessary to respond to requests to operate. In order to respond to such a request from each country, a transmission / reception integrated frequency converter in which a shift frequency can be changed relatively easily has been manufactured.

Conventionally, as shown in FIG. 2, a transmission / reception apparatus including this type of transmission / reception frequency converter has an IF
Input terminal 1, frequency converter 2, band-pass filter 3, amplifier 4, band-pass filter 5, voltage-controlled oscillator (referred to as VCO) 6 as a local oscillator, fixed frequency divider (frequency division ratio 1 /
M) 7, a switchable variable frequency divider 8, a synthesizer integrated into an IC, a low-frequency amplifier 10, a low-pass filter 11, a reference oscillator 16, and a switch 17 for changing the number of divisions in steps. The synthesizer 9 includes a counter 13 for counting a frequency-divided signal from a local oscillator, a counter 14 for counting a signal from a reference oscillator 16, a counter 12 for counting a control signal to a variable frequency divider, and counters 13 and 14. It comprises an output signal phase detector (referred to as PO) 15.
As a receiving unit, a band-pass filter 25, an amplifier 24, a frequency converter 22, an IF output terminal 21, a VCO 26 serving as a local oscillator, a fixed frequency divider 27, a switchable variable frequency divider 28,
Synthesizer 29, low-frequency amplifier 30, low-pass filter 3
1, a switch 35 is provided. As can be seen from the figure, a PLL control loop is formed by the VCO 6, the fixed frequency divider (frequency division ratio 1 / M) 7, the variable frequency divider 8, the synthesizer 9, the low-frequency amplifier 10, and the low-pass filter 11, and the reference oscillator 16 , The local signal of the VCO 6 is phase-locked to the phase of the reference signal. Since the transmission and reception system is shared, the transmission and reception are combined by the demultiplexing circuit 42 and connected to the antenna 43.

[0004] Next, of the conventional example, an operation mainly when the shift frequency is changed will be described. Now, the transmission frequency f _T , the reception frequency f _R , the transmission and reception local oscillation frequencies are _denoted by f _LT and f _LR , and the transmission and reception IF frequencies are denoted by f
_Assuming that _IFT and _fIFR , these relations are expressed by equation (1).

F _T −f _R = (f _LT ± f _IFT ) − (f _LR ± f _IFR ) (1) Received frequency f _R = 38.2 GHz, f _T =
37 GHz, shift frequency f _S = 1.2 GHz, transmission IF frequency 800 MHz, reception IF frequency 1.3 GH
Assuming that z, the transmitting station oscillation frequency needs to be set to 37.8 GHz, and the receiving station oscillation frequency needs to be set to 36.9 GHz. Here, a case of changing the shift frequency f _s from 1.2GHz to 1 GHz. For example, f _R = 38 GHz, f _T
Assuming that the reception IF frequency is 1.3 GHz, it is necessary to set the reception local oscillation frequency to 36.7 GHz. Now, assuming that the fixed dividing ratio is 1 / M, the switch 35
Divides the frequency division step of the switching type variable frequency divider 28 by the previous P +
From divide-by-1 when transformed into P frequency division, if the reference frequency of the reference oscillator 16 and the frequency f _ref of the R frequency _{division, f ref = 36.9 × (1} / M) × (1 / P + 1) = 36 0.7 × (1 / M) × (1 / P) (1A) It is necessary to satisfy the expression (1A). That is, the IF frequency can be kept constant for a specific shift frequency f _S and reference frequency f _ref , but the frequency division ratio is changed in a step-like manner to correspond to an arbitrary shift frequency. As long as the IF frequency could not be kept constant.

[0006]

As described above, the conventional transmission / reception frequency converter is manufactured by manufacturing an integrated transmission / reception frequency converter in order to cope with various shift frequency changes of customers including the regulations of each country. For each customer who complies with different customers or complies with different laws and regulations, the modulator or demodulator or the transmitter / receiver converter has an IF output terminal 21 or an IF output terminal 21.
However, there is a drawback in that devices connected after the device must be provided with devices having different IF frequencies.

[0007]

SUMMARY OF THE INVENTION A transmitting / receiving converter according to the present invention comprises:
Transmitting local oscillation signal of the transmitting / receiving frequency converter and receiving station
Two voltage-controlled oscillators each generating a local oscillation signal, a frequency divider for dividing the output signal of the voltage-controlled oscillator by a fixed frequency division ratio, and further dividing the output signal of the frequency divider A variable frequency divider that changes the frequency division ratio in steps according to a signal input from the control terminal, and compares the phase of the output signal of the variable frequency divider with the reference signal of the reference oscillator so that a predetermined frequency division ratio is obtained. A transmitting local oscillator and a receiving local oscillator including a synthesizer that controls the variable frequency divider and sends a phase control signal to the voltage controlled oscillator to form a phase locked loop. in transceiver frequency converter having independently is the frequency difference between the receiver local oscillator and the transmission local oscillator switches the frequency division ratio of the variable frequency divider handset simultaneously through the synthesizer sheet Transmitting ROM for transmitting the control information for controlling stepwise to the door frequency becomes a constant value
And a receiving ROM, and one switch for commonly controlling reading from the ROM for each step.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention. FIG.
2, the same reference numerals as in the conventional example of FIG. 2 have the same configuration and function. That is, in this embodiment, the ROMs 16 and 36 and the switch 44 are added, and the switches 17 and 35 provided for each transmission and reception in the conventional example are stopped.

Next, the operation of this embodiment will be described. Some signals of the outputs of the voltage controlled oscillators 6 and 26 are fixed frequency dividers 7 and 2
7, the frequency is divided by a frequency division ratio of 1 / M, and the switching type variable frequency dividers 8 and 28 divide the frequency by P + 1. Next, the signals are input to synthesizers 9 and 29 having N, A and R counters 12, 13 and 14 and phase comparators 15 and 35, respectively. After the signal repetition waveform is counted A times, the switchable variable frequency divider 8, 2
After outputting a signal for changing the frequency division number of P to P, and counting the P frequency-divided signal N−A times, the phase comparators 15, 3
Enter 5 That is, a variable frequency divider determined by N and A is configured to divide the input frequency of the switching type variable frequency dividers 8 and 28 by the frequency division number shown in the equation (2).

P (NA) + (P + 1) A (2) The divided output signal is input to phase comparators 15 and 35. The signal is compared with the phase of the reference signal at a phase comparison frequency obtained by dividing the reference signal of the reference oscillator 41 by R, and an error voltage corresponding to the phase difference is amplified by the low frequency amplifiers 10 and 30, and the low pass filter 11 and The DC voltage integrated by 31 is applied to the control voltage application terminals of the voltage controlled oscillators 6, 26. That is, the oscillation signals of the voltage controlled oscillators 6 and 26 are obtained by dividing the frequency of the signal by M × (PN + A) and the R signal of the reference oscillator 41.
A phase-locked oscillator that is a PLL circuit that operates so that the phase difference between the divided signals becomes zero is configured. As the reference oscillator 41, a crystal oscillator of several MHz to several hundred MHz is usually used to obtain high stability. Assuming that the frequency of the phase comparison is f _ref , the frequencies f _LT , f
The relationship between _LR is expressed by Expressions (3) and (4).

F _LT = f _ref × M × (P · N + A) (3) f _LR = f _ref × M × (P · N _r + A _r ) (4) where N, A, N _r , Ar are set by data in the ROMs 16 and 36. Correspondence with the address values of the ROMs 16 and 36 is represented by the equations (5) and (6).

N = N _D (X), A = A _D (X) (5) N _r = N _Dr (X), A _r = A _Dr (X) (6) X is the ROM address. Indicates a value. X is designated by the switch 44.

Next, the flow from the IF signal to the RF signal as the transmitting / receiving apparatus in FIG. 1 will be described. The transmission IF signal input from the IF input terminal 1 is converted into a transmission frequency by the frequency converter 2 with the local oscillation signal of the voltage controlled oscillator 6, the unnecessary wave is suppressed by the bandpass filter 3, and the desired signal is output by the amplifier 4. , The band-pass filter 5 and the duplexer 4
The light is radiated from the antenna 43 through 2. On the other hand, the received signal is transmitted from the antenna 43 to the splitter 42 and the bandpass filter 25.
The received IF signal is generated by the frequency converter 22 using the signal and the local oscillation signal from the voltage controlled oscillator 26 via the amplifier 24 and output from the IF output terminal 21. (1), (3),
From the equations (4), (5), and (6), the shift frequency f _S is expressed by the equation (7).

F _S = f _ref × M × {P × (N _D (X) −N _Dr (X)) + (A _D (X) −A _Dr (X))} ± (f _IFT + f _IFR ) ... (7) corresponding to the difference of f _S = f _T -f _R is, f _IFT, f
_IFR , M, P, etc. are values that cannot be changed unless the device is changed.
A data _{N D (X), N Dr} (X), A D (X),
A _Dr (X) should be changed. The value of regardless of the address _{X N D (X) -N Dr} (X) and _{A D (X) -A Dr (} X) is a constant value. The transmission and reception frequencies are changed by changing the address X of the ROM by a switch. In the equation (7), N _D (X) −N _Dr (X) and A _D (X) are used.
Since -A _Dr (X) is changed while being kept constant, the frequency difference f _T -f _R between transmission and reception is constant.

[0015]

As described above, according to the present invention, the difference frequency between the transmitting station oscillation frequency and the receiving station oscillation frequency is determined by determining the frequency division number of the variable frequency divider of the frequency synthesizer based on the ROM data. The effect is that the data can be changed just by changing the data.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of a conventional transmission / reception frequency converter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 IF input terminal 2,22 Frequency converter 3,5,25 Bandpass filter 4,24 Amplifier 6,26 Voltage controlled oscillator 7,27 Fixed frequency divider 8,28 Switching type variable frequency divider 9,29 Synthesizer IC 10, 30 Low-frequency amplifier 11, 31 Low-pass filter 12, 32, 13, 33, 14, 34 Counter divider 15 Phase detector (PD) 16, 36 ROM 41 Reference oscillator 42 Duplexer 43 Antenna 44 Switch

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H03D 7/00-9/06 H04B 1/26-1/28

Claims (2)

(57) [Claims] 1. A transmission local oscillation signal of said transmission / reception frequency converter.
Two voltage-controlled oscillators for respectively generating a signal and a reception local oscillation signal, a frequency divider for dividing the output signal of the voltage-controlled oscillator by a fixed frequency division ratio, and an output of the frequency divider In order to further divide the signal, a variable frequency divider that changes the frequency division ratio in a step-like manner by a signal input from the control terminal, and compares the phase of the output signal of the variable frequency divider with the reference signal of the reference oscillator,
A transmission local oscillation unit and a reception local oscillation unit including a synthesizer that controls the variable frequency divider so as to have a predetermined frequency division ratio and sends a phase control signal to the voltage controlled oscillator to form a phase locked loop. In a transmission / reception frequency converter independently provided in a transmission / reception frequency converter main body, the frequency division ratio of the variable frequency divider is switched at the same time via the synthesizer to transmit and receive the transmission local oscillation unit and the reception local oscillation unit. The shift frequency, which is the frequency difference, is a fixed value
Having a transmission for ROM and reception ROM sends control information for controlling stepwise so, and one Sui <br/> pitch for controlling reading from the ROM in common at each step A transmission / reception frequency converter characterized by the above-mentioned. 2. The transmission ROM and the reception ROM store a plurality of pieces of information for changing a transmission / reception frequency difference,
2. The transmission / reception frequency according to claim 1, wherein the switch outputs control information in pairs in a step-like manner, and controls the transmission / reception IF frequency to be constant even if the transmission / reception frequency difference is changed. converter.