Yusim 21.4MHz Filta insait long Walkie-Talkie Fil

Yusim 21.4MHz Filta insait long Walkie-Talkie Fil

Ol i save yusim 21.4MHz filta olsem wanpela intamediet frikwensi (IF) filta insait long ol 'walkie-talkie risiva, na wok bilong en i makim stret tupela bikpela samting bilong 'walkie-talkies: selektiviti na sensitiviti.

Mipela bai tok klia long ol dispela samting:

1. Wanem em i "Intermediate Frequency" bilong wanpela Walkie-Talkie?

Long mekim gutpela wok, ol 'walkie-talkies (na tu ol narapela 'superheterodyne receiver') i no save strongim na daunim ol redio frikwensi (RF) signal (olsem, 400-470MHz). Nogat, ol i bihainim ol dispela step: 1 Miksim: Ol i miksim hai-frikwensi RF signal wantaim signal we lokal oscillator i kamapim. filterim strong.

Gutpela samting bilong "superheterodyne" straksa em olsem planti bilong ol 'gain' na 'selectivity' (inap long rausim ol 'adjacent channel interference') i kamap long dispela 'fixed IF' seksen, na dispela i mekim 'circuit design' i stap gut na pefomens i gutpela tru.

2. Bilong wanem 21.4MHz?

21.4MHz em i wanpela standet IF frikwensi we ol manmeri i save laikim tru insait long ol VHF/UHF ben (inkludim ol ben we ol 'walkie-talkies' i save yusim). Ol as bilong en long histori na teknikel em:

Mature industrial chain: Long 21.4MHz frikwensi, i gat planti ol mature, stebol, na low-kost filta, amplifaia, na ol narapela samting i stap.

Balens namel long pefomens na kos: Dispela frikwensi i antap inap long daunim gut piksa intaferens (wanpela komon risipsen intaferens); long wankain taim, em i liklik inap long helpim wok bilong disainim na wokim ol hai-Q (kwaliti fakta) filta (olsem ol kristal filta na ol seramik filta).

Historical inheritance: Dispela frikwensi i bin stap insait long komyunikesen indastri long planti yia, na planti ol klasik 'walkie-talkie chips' na ol rot bilong stretim hevi i kamap long dispela namel frikwensi.

3. Bikpela wok bilong 21.4MHz filta insait long Walkie-Talkies

Insait long 21.4MHz IF seksen, filta em i "geitkipa" tru. Wok bilong en i bikpela samting: 1 Mekim Selektiviti i kamap gutpela moa

Wok: Selektiviti i makim strong bilong risiva long luksave long signal we em i laikim long planti signal na pasim ol signal we i stap klostu long en.

Em i wok olsem wanem: 21.4MHz filta i gat wanpela 'frequency response curve' we i antap tru (planti taim em i olsem wanpela "brik wol"). Em i larim wanpela signal segmen tasol we i gat 21.4MHz olsem senta na wanpela stretpela 'bandwidth' long go insait (olsem, ±6.25kHz, ±7.5kHz, ±12.5kHz we ol i save yusim long ol 'walkie-talkies', we i stret long ol narapela narapela 'channel spacings').

Praktikel ifek: Taim tupela redio stesin wantaim klostu frikwensi i wok long salim tok wantaim, wanpela 'walkie-talkie' we i gat wanpela 'high-performance 21.4MHz filta inap long harim gut krai bilong redio stesin, na tu, em i ken pasim gut signal bilong narapela redio stesin we i stap klostu long en long abrusim 'crosstalk'. Sapos yu no gat dispela filta o sapos yu no wok gut, bai yu harim nois bilong "channel crosstalk".

Mekim gutpela pasin bilong pilim gut

Wok: Sensitiviti i makim strong bilong risiva long kisim ol wik signal.

Em i wok olsem wanem: Pastaim long strongim IF signal, ol i yusim filta long rausim -bilong-band nois na intaferens pastaim. Long dispela rot, bikpela amplifikesen em i "klinpela" gutpela signal yet. Sapos ol i mekim 'amplification' na i no gat 'filtering', aut-of-band nois bai kamap bikpela tu, na dispela bai daunim wikpela 'effective signal'.

Gutpela wok: Larim 'walkie-talkie' bilong yu long holim gutpela toktok maski yu stap longwe o wantaim ol liklik signal.

4. Ol kain 21.4MHz filta

Insait long ol 'walkie-talkies, ol 21.4MHz filta i save gat ol dispela kain:

Seramik Filta:

Ol samting: I no gat bikpela pe, liklik sais, yu ken bilip long en, na yu no nidim senis.

Ol aplikesen: Planti taim ol i save yusim long namel-i go long-low-end 'walkie-toktok, na pefomens bilong en i inap long inapim planti nid bilong ol manmeri. Bandwidth na shape factor bilong en (wanpela indiketa bilong skelim 'steepness' bilong arere bilong filta) i save nogut liklik long ol 'crystal filter' tasol i gutpela moa long ol LC filta.

Kristal Filta:

Ol samting: Em i gat bikpela Q veliu tru, olsem na 'selectivity' bilong en i gutpela tru, na 'shape factor' i klostu tru long 'ideal state'.

Ol aplikesen: Planti taim ol i save yusim long ol 'high-profesenel 'walkie-tok o long ol taim we i nidim bikpela 'anti-interference capabilities. Pe bilong en i antap moa long ol 'ceramic filter'.