Register

Welcome to the RDI-Board Community.

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed.


Donate Now Goal amount for this month: 100 EUR, Received: 100 EUR (100%)
Donate to support this site...

Results 1 to 4 of 4
  1. #1
    Junior Member Master
    Join Date
    Dec 2012
    Posts
    84
    Posts Thanks / Likes

    Default Statie pmr 446mhz cobra

    Buna ziua am 2 statii cobra marca Cobra MT975.
    Antena e in forma de spirala cam de 5 centimetri.

    Descriere Produs
    Producator: COBRA
    Canale: P1 - P8 PMR
    Frecventa: 446.00625 - 446.09375 MHz
    Temperaturi functionare: de la -20 la +55
    Dimensiuni: 295 x 202 x 90 mm
    Greutate: 120
    Putere emisie: 500 mW
    CTCSS sau DCS: 38 CTCSS + 83 DCS
    Vox: ajustabil in 3 nivele
    Conector Jack: 1.5 mm
    Operabil cu bateri: 4 acumulatori tip AAA NiMH
    Autonomie: aprox. 12 ore
    Raza de actiune: aprox. 5 Km
    :
    FUNCTII SUPLIMENTARE: VibrAlert / VOX / 10 Channel Memory / Dual Watch / Battery Level Meter / Scan Channels - Privacy Codes - Memory / Key Lock / Baby Monitor / Intercom capable
    :

    Intrebarea mea ar fi: Cum sa ii maresc puterea de emisie si de receptie ?

    Unde stau eu bate cam 2 kilometri.

  2. #2
    Junior Member Master
    Join Date
    Dec 2012
    Posts
    84
    Posts Thanks / Likes

    Default

    Mda, vad ca nu imi raspunde nimenea (

  3. #3
    Junior Member Master
    Join Date
    Aug 2007
    Posts
    94
    Posts Thanks / Likes

    Default

    Uite cam care sunt variabilele:
    http://www.youtube.com/watch?v=CRICOv3Ptz0
    Fiind vorba totusi de walkie-talkie nu prea ai cum sa maresti puterea (depinde de finali, voltaj....).
    Primul amplificator in lantul radio este totusi antena.

    O alta varianta e sa mufezi o antena cu lungimea, lambda/2 sau lambda/4 unde lambda e lungimea de unda dar cam renunti la "mobilitate" (bagat in buzunar)
    Lungimea de unda/viteza de transmitere a undei radio in vid (300000) (calculele precise ale vitezei spun ca este 299.792.458 m/s) in aer e vreo 297000 in conditii "standard" (fara ploaie, ninsoare, ceata, poluare, praf)
    Deobicei calculul empiric se face luand in considerare viteza in vid.
    446006/300000=1,486 m deci 1,486/2 sau 1,486/4

    Raza de emisie scade foarte mult in mediul urban (printre blocuri) apa reflectate.
    Adevarata verificare se face pe camp "spatiu deschis"
    Last edited by triceraptor; 19th July 2013 at 19:15.

  4. #4
    Junior Member Master
    Join Date
    Dec 2012
    Posts
    84
    Posts Thanks / Likes

    Default

    Cine este de prin Alba-Iulia si vrea sa faca ceva probe, sa imi trimita pm.
    Am cobra mt975

 

 

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Back to Top