CN86200971U

CN86200971U - Wireless multiple spot thermometer

Info

Publication number: CN86200971U
Application number: CN 86200971
Authority: CN
Inventors: 张发国; 方瑜
Original assignee: CHINA AGRICULTURAL ENG
Current assignee: CHINA AGRICULTURAL ENG
Priority date: 1986-02-25
Filing date: 1986-02-25
Publication date: 1987-01-14

Abstract

The utility model relates to a portable wireless multiple spot thermometer, comprising a plurality of transmitters and a receiver. The transmitter transforms the temperature scale into low-frequency cycle square wave of corresponding frequency through a multivibrator temperature sensed by thermal resistors and composed of an operational amplifier, and directly modulates the emission of the high-frequency carrier. The receiver selects out the signal of one of a plurality of emission machines through double conversion. The temperature value is directly displayed by digital circuits after the processing of enlarging, controlling and digital tamper resistance. The measuring precision can be improved through twice linear compensation.

Description

Wireless multiple spot thermometer

The utility model is a kind of multi-point temperature measurement instrument of portable radio wave transmissions.

In the Air-conditioner design and debugging of agri-scientific research, greenhouse, storage and building, often need the probe temperature distribution field.The general at present multipoint temperature measuring instrument that adopts the fax sense is in a centrostigma or the place remote measurement outside measured place.10 temperature measurers of XH2008C as the production of Beijing radio four factories, the DYZ-1 type remote measurement multiple spot humiture instrument of Jing Zhou, Hubei Electronic Instruments Plant, 50 temperature measurers of the big magnificent radio factory in Shanghai etc., wherein XH2008C has used triplet in order to improve measuring accuracy.But this measuring method is the same with various traditional fax sensed quantity methods, need be connected lead or cable between measurement point and measuring instrument, and specification, the length of cable or wire is all had certain technical requirements, otherwise will influence the accuracy of measuring.Under some occasion, field wiring is very difficult, also can be subjected to as various natural and destructions machinery such as temperature, humidity, even be broken by the worm damaged by rats.And the measuring error after the triplet compensation is still bigger.

The purpose of this utility model is to provide a kind of multi-point temperature measurement instrument that can connect the radio wave transmissions of measuring lead, and improves the measuring accuracy of existing triplet.Be suitable for the test in research of microclimates such as greenhouse, hot house, warehouse, farmland, mountain region, forest, animal house, building and heating and temperature field.

The wireless multipoint temperature measurer is to be temperature-sensing element by thermistor among Fig. 1 (1), forms multivibrator by resistance, electric capacity and operational amplifier and constitutes temperature frequency transducer (2), and the temperature value that (1) is gone up perception becomes the cycle square wave of respective frequencies.And carry out preliminary triplet linear compensation.In order to improve the frequency stability of transmitter high frequency carrier, produce high frequency carrier with quartz oscillator (5).In amplifying modulator (3), the low-frequency cycle square wave corresponding with temperature directly modulated high frequency carrier, forms pulse-modulated signal and launches by antenna (6).Supply convertor (4)+6V power conversion one-tenth+12V ,-12V ,+6V.Such transmitter can have many, is example with 50 now, and the high frequency carrier work of 50 whiles with different frequency then can be arranged altogether.

The high frequent carrier frequency of 50 transmitters can be divided into five groups, ten every group.Its frequency interval is 20KHZ, every group of occupied bandwidth 200KHZ.The radiowave of 50 transmitters is received antenna (7) and receives, and puts through height and sends into first frequency mixer (9) mixing after amplify (8).The oscillation frequency of first local oscillator (10) has five kinds of selections, each is corresponding to above-mentioned one group of transmission frequency, produce one group of difference frequency after the oscillation frequency mixing of this class frequency and local oscillator (10), its central value is 10.7MHZ, to be 10.7MHZ, bandwidth through centre frequency amplify for intermediate frequency amplifier (11) frequency-selecting of ± 100KHZ this group difference frequency signal, from 50 signal, elect, be sent to second frequency mixer (12) mixing.

Second local oscillator (13) can produce ten kinds of fixed frequencies, and it is corresponding to put one of ten signals (11) passing through in each frequency and first, and its difference frequency is 465KHZ.To be 465KHZ, bandwidth through centre frequency amplify for second intermediate frequency amplifier (14) frequency-selecting of ± 2.5KHZ for signal after the mixing, selects the signal of one of them transmitter, delivers to wave detector (15) after the amplification.As long as select different first local oscillator and second local frequency, just can select in 50 transmitters arbitrary signal by above-mentioned special double conversion circuit exactly.

By after wave detector (15) detection with the corresponding low-frequency cycle signal of temperature value, through amplification and rectification circuit (16), be reduced into the low-frequency cycle square wave, passing through digitizing anti-jamming circuit (17) again removes the high frequency interference in the transmission, send into multistage binary counter (18) counting, by read-only memory (19) the existing theoretical error value of temperature frequency transducer (2) in the transmitter is further compensated, and be converted to binary-coded decimal code (BCD code) by deposit, decoding, display (20) shows.(21) among the figure for counting, deposit the control circuit of display, this controller can also be controlled two group relaies, changes the oscillation frequency of first local oscillator (10) and second local oscillator (13) respectively by relay, reaches the touring automatically purpose that detects.Can be sent to printer to shown temperature value by print interface circuit (22).

The utility model arranges that test point is easy, and mobile test is convenient, does not also influence test even there is buildings in general to stop between test point and acceptance point.(as long as this buildings does not influence radio wave transmissions).Measuring distance is far away, ratio of precision triplet height.The oscillation frequency of 50 transmitters is used the 50MHZ amateur band of national regulation, from 49.9MHZ to 51.68MHZ.Certainly also can select other frequency range that meets national regulation for use.

Fig. 1 is the transmitter and receiver block scheme.

Fig. 2 is transmitter principle figure.

Fig. 3 is receiver principle figure.

Fig. 4 is a digital display circuit.

Realize concrete scheme of the present utility model such as Fig. 2, Fig. 3 and Fig. 4.

Thermistor Rt and RM, RN, W, IC form the temperature frequency transducer in Fig. 2 transmitter, and wherein RM, RN, W and Rt form three point calibration circuit.

First local oscillator has five oscillation circuits in Fig. 3 receiver, and second local oscillator has ten oscillation circuits, so just can receive the signal of 50 transmitters.The loop number that changes the two-stage local oscillator just can change the capacity of receiver.

4 Sheffer stroke gates are formed anti-high-frequency interferencing circuit in Fig. 4 digital display circuit.Carry out fine compensation and use two ROM (read-only memory) 2716.

Claims

1, a kind of portable electric signal teletransmission multi-point temperature measurement instrument is characterized in that temperature measurer is made up of a receiver and Duo Tai transmitter.

Transmitter becomes corresponding low-frequency cycle square wave to temperature value by thermistor (1) temperature-sensitive by temperature frequency transducer (2), directly modulates high frequency carrier and is launched by antenna (6).

Receiver has antenna (7), height to put (8), first mixing (9), can produce in first local oscillator (10), first of M kind local frequency and put (11), second mixing (12), can produce in second local oscillator (13), second of N kind local frequency and put (14) and wave detector (15) etc.After the signal of many transmitter emissions enters receiving antenna (7) simultaneously, select M/one of whole transmitter signals by first order frequency conversion, from M/one, select N/one again through second level frequency conversion again, receive function and distinguish M * N signal.A receiver can adapted M * N platform transmitter.The road signal that second level frequency conversion is selected amplifies the low-frequency cycle signal that is detected representation temperature by wave detector (15) by putting (14) in second, goes out Temperature numerical through the digital circuit processes and displays.

2, press the temperature measurer of claim 1, it is characterized in that adopting thermistor, electric capacity and operational amplifier to form multivibrator, temperature signal is converted to frequency and temperature value is approximated to the low-frequency cycle square wave of direct ratio and carries out preliminary linear compensation with triplet, between counting circuit and digital display circuit, insert one group of ROM (read-only memory) then and carry out fine compensation.

3, it is characterized in that by claim 1,2 temperature measurer: the low-frequency cycle signal of representation temperature after the demodulation, be reduced into the cycle square wave through shaping circuit, through digital anti-jamming circuit filtering high frequency interference clutter, deliver to counter again.