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Microwave integrated teleradioinformation MITRIS system (Transmitting part)

A low-power MITRIS system is intended for channel "shifting" from the main head-end to new locations for a distance of 8km. It is impossible to use digital tuners in the new locations because signal reception is conducted by analog tuners from a low-power MITRIS system. The price of this system can be compared to the price of digital tuners.

MITRIS.jpg

                          * The system is compatible with the existing cable networks and is intended for a directive transmission of
                            TV signals from the main head-end for a distance of 8-20km
                          * A broad frequency range provides transmission of great information streams over-the-air, including digital
                            streams from IKM-15, IKM-30 telephone multiplexers, etc.
                          * It occupies an intermediate position between television market and telephony market
                          * It is based on use of frequency modulation
                          * Compact design
                          * Delivery set for MITRIS-5: AVT-300F modulator - 5pc, UCA-5 up-converter - 1pc, dish 0.6m - 1pc,
                            power supply device 12V - 1pc, infeed - 1 pc

Product specifications
Operating frequency range 11.70 - 12.2 GHz
Video input frequency band 20 Hz - 6 MHz
level/impedance 1V / 75 Ω
Audio input frequency band 20Hz - 20 kHz
level/impedance 775mV/6.8 kΩ
Frequency band width of one radiochannel 30 MHz
Frequency spectrum step 50 MHz
Modulation kind FM
Frequency modulator output level 100 dB/µV
Depth of control of frequency modulator output Level 20 dB
Power emitted "on-air" by one radiochannel (while transmitting 10 TV channels) 2 mW
Emitted radiochannel polarization linear
Voice subcarrier of each radio signal not higher 3
Heterodyne oscillator stability in a -50...60 operating temperature range 2.5x10-5
Heterodyne oscillator signal suppression in output signal spectrum not less 20 dB
Harmonic and compound signal suppression at the transmitter output not less 50 dB
Dimensions 146x105x105 mm
Transmitting antenna diameter/Antenna gain 0.64m / 35dB


The up-converter appearance without protective cover

A MITRIS receiving part comprises standard satellite equipment: a dish antenna and analog tuners (see the fig. at the left side) or a SAT receiver SR-100, manufactured by Beta TV com. The explanation of this part's operation is not necessary.

     A Supposed Procedure of Operation with MITRIS System Transmitting Part.
    Inject group signal from frequency modulator outputs to an up converter (see fig.1). Signal levels of each modulator at the up-converter input should be set according to the table given in the MITRIS datasheet. It should be done with the help of an output level adjuster on a faceplate of every modulator or with the help of an additional continuous attenuator which can reduce group signal. (A device LFM-320 or an analogous one can be used for measuring). While having the set output levels, signal power is the same for each channel at the up-converter output. The signal power amounts to 2 mW (level spread of signals arriving to the up-converter is caused by amplitude frequency response unevenness of a transmission path and the up-converter).
    Power equalization at the up-converter output is needed for a qualitative signal reception. The dynamic range of a receiving converter is not high because of its higher gain of ≈40...50dB. Its dynamic range amounts approximately to 10 dB and ranges (output) from 41dB/µV (for a channel) to 51dB/µV (for a channel). The information is given for a AP8-74C converter of the company MICROELECTRONICS TECHNOLOGY. (The lower level of dynamic range is defined by converter noise power led to the input - Ueff.n ≈8dB/µV and the necessary store of SNR which amounts to 33dB. Altogether 33+8=41dB/µV. The upper level is defined by the maximum possible output amplifier level of a receiving converter IMA3 of which is 100dB/µV according to DIN 45004. While having 10 channels the maximum output level for a channel is a bit higher than 93 dB/µV. While having a 40dB gain of the 8-74 converter the upper level amounts to 93-40=53dB/µV and dynamics amounts to 53-41 ≈10dB. Irregularity of the 8-74 receiving converter is slight, not more than 1dB. That is why it was not considered in the description above).
     Thus while using the 8-74 receiving converter the signals at its output should be within the limit of 41+40=81 dB/µV to 53+40=93 dB/µV for a channel (the control can be effected by connecting a LFM-320 device to the output of the receiving converter). In case of an 93dB/µV upper threshold excess the group signal power at a sending end should be lowered (with the help of a group signal continuous attenuator). If a signal level at a receiving-end is lower than a lower threshold give consideration to a more precise transmitting and receiving antenna orientation or change the secondary radiators to those with a greater diameter. Use the description given above while using receiving converters of other companies.