TV, SAT TV
Rendszerek telepítése
SURVEILLANCE IN COMMUNITY AND CABLE NETWORKS
The ways to adopt existing community installation or cable network to surveillance system using CCTV cameras.
Concept:
- Possibility of monitoring the surroundings of the building on TV sets,
- Use of existing antenna / cable network,
- Cooperation with standard televisions,
- Affordable price,
- Unchanged performance of the installation,
- Possibility of using every CCTV camera generating complete video signal (CVBS),
- Possibility of using color cameras with microphones.
The ways of cameras signals distribution in community installations or cable networks:
- adaptation of community installation based on channel amplifiers (fig. 1),
- adaptation of community installation based on broadband amplifier (fig. 2),
- adaptation of cable TV network - connection before building amplifier (fig. 3),
- adaptation of cable TV network - connection after building amplifier (fig. 4),
- utilization of low attenuation of RF loop US-501 modulators (fig. 5).
Used: channel amplifiers ZG-401 or ZG-301, R90515, R90517, power supply adaptor for ZG AS-101, R90510 broadband amplifier PA-004, R91278, power supply adaptor for PA and MS FA-202, R91226frame MS-011, R91229modulator with partially attenuated side coil MS-501, R91227power supply adaptor for cameras and MT ZS-12/400, M1810, double coil modulator MT-09, R87162.
The use of community installation built on the base of channel amplifiers
Simple solution, it depends on adding next channel amplifiers to those that are already present. Parameters of installation remain the same.
Adaptation of community installation built on broadband amplifier
Simple solution, with combining signals from RF modulators and the signals from the antennas, at the input of the amplifier. Its disadvantage is additional attenuation of antenna signals in the combiner. In the case when terrestrial TV does not use channels above 60, there may be used diplexer/multiplexer.
Adaptation of cable TV network - connection before building amplifier
Rather complicated implementation, with combining signals from RF modulators and the signals coming from the distribution network, at the input of the amplifier. Its disadvantage is attenuation of the input signals by the combiner. In the case when cable television does not use channels above 60, it is possible to employ a diplexer (lower attenuation). There may be problems with equalization of channel levels and nonlinear distortions.
Adaptation of cable TV network - connection after building amplifier
Complicated implementation, it consists in connecting channel amplifiers in series (via RF loops) with the output of building amplifier. There are no problems with channels leveling, and equalization of channel levels and nonlinear distortions, but it is rather controversial solution due to necessity of using filters between the building amplifier and the channel amplifiers. It should be used carefully, after a thorough analysis.
Modulators for home use application:
MOD-2 (Inel):
- channels 29 - 43,
- sound 5,5 or 6,5 MHz, switched,
- test signal,
- output level 65 dBuV,
- EURO input,
- own power adaptor 12V/100mA,
Modulators for professional applications:
MS-401 (Alcad):
- channels 21 - 69,
- sound 6,5 MHz,
- output level 82 dBuV,
- RCA input,
- double coiled,
- own power adaptor 220 V/50 Hz,
MS-501 (Alcad):
- channels 1 - 5, 6 - 12, 21 - 69, S1 - S18, S19 - S38,
- sound 5,5 MHz,
- output level 82 dBuV, regulation-10 dBuV,
- mini-DIN input,
- single coiled,
- it requires power adaptor FA-202,
MT-09 (Terra):
- channels 21, 69
- sound 5,5 or 6,5 MHz, switched,
- output level 85 dBuV, regulation -15 dBuV,
- RCA input,
- it requires power adaptor 12V/200mA,
Main features:
- Sound and channels in D/K standard,
- Microcontroller,
- Frequency synthesis,
- RF loop allowing cascade connection of several modulators and simple combining with existing signals,
- Non-volatile memory, adjustment of output level.
Basic parameters:
Model | MT09 | MT09P | MT10 | MT10P |
| Output level [dBuV] | 70 - 85 | |||
| Output channels | 21 - 69 | 21- 69 | 6 -S18 (OIRT)/ 5 - S20 (CCIR) | 6 - S18 (OIRT)/ 5 - S20 (CCIR) |
| Sound sub carrier [MHz] | 6,5 (OIRT)/5,5 (CCIR) | |||
| Sound signal level [mV] | 150 - 775 | |||
| Frequency range and deduct attenuation | 47- 862 MHz/ 2 dB maks. | |||
| Power consumption | 11,5 - 13 V /200mA | 220V/50Hz/ 5VA | 11,5 - 13 V /200mA | 220V/50Hz/5VA |
| Dimensions and weight [mm] [kg] | 54x120x100/ | 54x120x142/ | 54x120x100/ | 54x120x142/ |
Basic requirements of antenna community installations and cable networks.
The measurements of basic parameters of RF network can be done with a signal level meter, e.g. TC-402.
- Frequency ranges used in antenna community installations:
Table 1. Frequency ranges used in ACI and cable networks.
Range | Frequency band [MHz] | Channel's symbols |
| Ultra High Frequency I | 66,0 - 74,0 | UKF - FM I |
| Ultra High Frequency II | 87,5 - 108,0 | UKF - FM II |
| Down special band | 110 - 174 | S01 - S08 |
| Range III | 174 - 230 | K06 - K12 |
| Upper special band | 230 - 302 | S09 - S17 |
| Extended special band | 302 - 470 | S18 - S38 |
| Range IV | 470 - 606 | K21 - K37 |
| Range V | 606 - 862 | K38 - K69 |
Detailed TV channel frequency list can be found here
Main features of community / cable installations:
- As the sources of signals distributed in these installations can be terrestrial and satellite radio and TV broadcasts, as well as locally prepared/played audio-video materials,
- Distribution of RF signals to the subscribers' outlets should be performed according to the standards used in the country,
- There are allowed only the components/devices having appropriate certificates valid in the country,
- There should be used components/devices of 75 ohm impedance,
- The power of parasite radiation of any device cannot exceed 100 pW,
- The attenuation of outer radiation should guarantee that, in any output of the installation and at any frequency, the ratio of the carrier to the interfering signal caused by electromagnetic field of intensity equal 3V/m will be not less than 64 dB for television signals and 50 dB for FM signals.
- Recommended minimum signal level in subscriber's outlet Uabmin = 62 dBuV (depended on the band),
- Recommended maximum signal level in subscriber's outlet Uabmax = 80 dBuV (depended on the band),
- Minimum signal to noise ratio - S/Nmin = 44 dB (TV, AM mod., 5 MHz band), 15 dB (TV FM mod., 27 MHz band), 54 dB (FM-stereo, 0.25 MHz band), 44 dB (FM-mono, 0.15 MHz band),
- Minimal signal to intermodulation products ratio - S/Imin = 60 dB, enforcing reduction of the maximum output level in amplifier's output, accordingly to the table 2.
Table 2. Reduction of the maximum output level dependent on the number of active channels
Number of channels | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 12 | 16 | 20 | 24 | 28 | 36 |
| Reduction of level [dB] | 0 | 2 | 3,5 | 4,5 | 5 | 5,5 | 6 | 8 | 9,5 | 10,5 | 11,5 | 11,7 | 12,5 |
- All programs should have the same power level,
- The maximum difference in signal levels cannot exceed:
-3dB (for neighbor channels),
- 6dB (in any band with width 60 MHz),
- 12dB ( in full frequency band),
- Minimum separation between two receivers: 44dB,
- All parameters should be kept during 95% of the time,
- The gain of TV antennas within one channel or the FM antenna within FM band shouldn't change more than 0.5dB.
Modulators
There are two types of modulators that are used in television technique:
- Double coiled DSB - AM,
- With partially attenuated side coil VSB - AM.
They differ only a spectrum, and what goes after that - bandwidth. Modulation VSB-AM is used in ground television and higher class modulators, i.e. used in head stations of cable television. Modulator using modulation VSB can work without channel spacing (i.e. channels 50, 51, 52, 53, 54, 55 et al.) that allows to accommodate more programs.
DSB-AM modulation is used in simple modulators built in SAT receivers, VCRs, TV games, etc. Generally, due to a wider spectrum, DSB-AM modulators have to be set every second channel - with one channel space - (e.g. in channels 50, 52, 54, 56, 58, etc).
Spectrum of signal modulated amplitudely DSB - AM and VSB - AM
We also advise to visit the website that contains installation diagrams.
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