Wat is die ontvangsbereik van die ISDB-T-antenna in km?

Die ontvangreeks van digitale antennas word deur baie faktore beïnvloed. Dit kan gewoonlik bereik 50 aan 100 kilometers onder ideale omstandighede, maar in werklike toepassings kan dit aansienlik verskil as gevolg van verskille in omgewing, toerusting parameters, ens. Die volgende is 'n spesifieke ontleding:

Kern beïnvloedende faktore

Sender toestande

• Dra krag: Hoe groter die stuurkrag van die hoofstasie, hoe groter die seindekkingsreeks. Byvoorbeeld, die uitsaaikrag moet minstens 5KW wees (digitale krag) om oor te dek 90 kilometers onder ideale omstandighede.
• Sender toring hoogte: Die hoogte van die sendertoring beïnvloed direk die siglynvoortplantingsafstand. As die sender toring is 400 meter hoog en die ontvangsantenna is 2 meter hoog, die teoretiese siglyn-dekking kan bereik 90 kilometers.

Antenna prestasie

• Wins en tik: Hoë-versterking antennas (soos Yagi-antennas) kan die ontvangsafstand aansienlik vergroot, maar die balkwydte is smal en moet akkuraat in lyn gebring word met die seinrigting. Rigtingantennas en reflektorantennas is geskik vir langafstand-ontvangs.
• Polarisasiemodus en frekwensie: Terrestriële digitale televisie (DTMB) gebruik die UHF-band (470-806MHz), en 'n antenna wat hierdie band ondersteun, moet ooreenstem. Vertikale polarisasie het minder verswakking op reënerige dae, en horisontale polarisasie het 'n lae grondrefleksieverlies.

Omgewingsfaktore

• Terrein en hindernisse: Plat terrein is bevorderlik vir seinvoortplanting, while obstacles such as mountains and tall buildings will block the signal, causing multipath effects or attenuation.
• Atmospheric conditions: Humidity and temperature gradients may cause signal refraction or beyond-line-of-sight propagation, but extreme weather (such as heavy rain) will increase signal attenuation.

Tipiese ontvangsafstandreeks

Konvensionele dekking (50-90 km)

• ISDB-T signals usually cover a radius of about 50 km, suitable for cities and surrounding areas. If the transmission tower is high, the power is sufficient and there are no obstacles, the coverage can be extended to 90 km.
• Byvoorbeeld, using a Yagi antenna in an open area with high transmission power can achieve stable reception.

Langafstand verlenging (meer as 100 km)

• If coverage of more than 100 km is required, a higher gain antenna (such as a multi-unit Yagi antenna) or an additional relay station is required to supplement the transmission.
• The nominal “120-160 km reception range” of commercial antennas is mostly based on ideal conditions, and actual optimization needs to be combined with terrain and installation height.

Optimeringsvoorstelle

Antenne keuse en installasie

• Outdoor priority: Yagi antennas are suitable for medium and long-distance reception due to their high gain and directivity; avoid obstacles when installing and try to place them at a high place.
• Indoor antenna restrictions: only suitable for strong signal areas (such as within 10 kilometers from the transmission tower), and avoid electrical interference and concrete obstructions.

Stelsel ontfouting

• Calibration direction: Use a compass or signal strength detection tool to adjust the antenna direction to ensure that it is aligned with the transmission tower.
• Signal enhancement: Adding a low noise amplifier (LNA) can improve the reception capability of weak signals.

Omgewingsaanpassing

• Complex terrain: In mountainous areas or areas with severe obstruction, try different installation locations or use relay equipment.
• Anti-interference measures: Stay away from interference sources such as microwave ovens and WiFi routers, and use coaxial cables with good shielding performance.

Bedryfstandaarde en toepassingsvoorbeelde

• Automobile and aviation: Antennas with vibration resistance and wide temperature range (-40℃~125℃) are required, which meet USCAR-21 or SAE AS7928 standards.
• Rural and remote areas: ISDB-T is used as a supplement to cable TV and needs to be matched with high-gain antennas to achieve stable coverage.

Opsomming: The receiving range of digital antennas is not a fixed value and needs to be comprehensively evaluated in combination with transmitter parameters, antenna performance and environmental conditions. In practical applications, by optimizing antenna selection, installation location and system debugging, the theoretical coverage range can be maximized.