Kushandiswa kwe21.4MHz Sefa muWalkie-Talkie Field

Kushandiswa kwe21.4MHz Sefa muWalkie-Talkie Field

Sefa ye21.4MHz inowanzo shandiswa sefirita yepakati (IF) muwalkie-talkie receiver, uye kushanda kwayo kunotara zvakananga zviratidzo zviviri zvewalkie-talkies: selectivity and sensitivity.

Tichatsanangura zvakadzama kubva pazvinhu zvinotevera:

1. Chii chinonzi "Intermediate Frequency" yeWalkie-Talkie?

Kuti ubudirire kuita zvakanaka, mawalkie-talkies (pamwe chete nemamwe ma superheterodyne receiver) haakudze zvakananga nekudzikisa masiginecha akagamuchirwa eredhiyo (RF) (semuenzaniso, 400-470MHz). Pane kudaro, vanotora matanho anotevera:① Kusanganisa: Iyo yakagamuchirwa yakakwirira-frequency RF chiratidzo inosanganiswa nechiratidzo chinogadzirwa neoscillator yeko.

Kubatsira kwe "superheterodyne" chimiro ndechekuti yakawanda yekuwana uye kusarudzwa (kukwanisa kusefa kunze kwepedyo chiteshi kupindira) kunowanikwa neino yakagadziriswa IF chikamu, zvichiita kuti dhizaini dhizaini igadzikane uye inoshanda zvakanakisa.

2. Sei 21.4MHz?

21.4MHz inonyanyozivikanwa yakajairika IF frequency mumabhendi eVHF/UHF (kusanganisira mabhendi anoshandiswa newalkie-talkies). Zvikonzero zvayo zvekare uye zvehunyanzvi zvinosanganisira:

Mature industry cheni: Pamafaro e21.4MHz, pane nhamba huru yemafirita akura, akatsiga, uye akaderera-, maamplifaya, nezvimwe zvinodyidzana zviripo.

Kuenzana pakati pekuita uye mutengo: Iyi frequency yakakwirira zvakakwana kuti ibudirire kudzvanya kukanganiswa kwemufananidzo (kukanganisa kunowanzo kugamuchirwa); panguva imwe cheteyo, yakadzikira zvekugonesa magadzirirwo nekugadzirwa kwepamusoro-Q (quality factor) mafirita (akadai sekristaro mafirita nemasefa eceramic).

Nhoroondo yenhaka: Iyi frequency yakashandiswa muindasitiri yezvekufambiswa kwemashoko kwemakumi emakore, uye akawanda classic walkie-talkie machipisi nemhinduro dzakagadzirwa maererano neaya epakati frequency.

3. Basa Rinokosha re21.4MHz Sefa muWalkie-Talkies

Muchikamu che21.4MHz IF, sefa ndiyo chaiyo "muchengeti wegedhi". Basa rayo rakakosha: ① Kuvandudza Kusarudzika

Basa: Kusarudzika kunoreva kugona kweanogamuchira kusiyanisa chiratidzo chinodiwa kubva kune akawanda masaini uye kudzvanyirira ari padyo nechiteshi chekukanganisa masaini.

Mashandiro ayo: Iyo 21.4MHz sefa ine yakanyanyisa frequency yekupindura curve (kazhinji se "madziro ezvidhinha"). Inongobvumira chikamu chechiratidzo chine 21.4MHz sepakati uye bandwidth chaiyo kuti ipfuure (semuenzaniso, ± 6.25kHz, ± 7.5kHz, ± 12.5kHz inowanzoshandiswa muwalkie-talkies, inoenderana neyakasiyana chiteshi).

Chiitiko chinoshanda: Kana nhepfenyuro mbiri dzine maredhiyo ari pedyo zvikuru dzichifambisa panguva imwe chete, walkie-talkie yakashongedzerwa-kuita 21.4MHz sefa inokwanisa kunyatsonzwa ruzha rwenhepfenyuro yainonangwa, uku ichidzvanya masaini eimwe chiteshi chiri padhuze kuti isatambudzike. Pasina iyi sefa kana nesefa isingaite zvakanaka, unonzwa "channel crosstalk" ruzha.

② Kuvandudza Sensitivity

Basa: Sensitivity inoreva kugona kweanogamuchira kugamuchira masaini asina simba.

Mashandiro ainoita: Usati wakudza siginecha yeIF, sefa inoshandiswa kubvisa-ye-ruzha kana kukanganisa kutanga. Nenzira iyi, iyo huru yekusimudzira ndiyo "yakachena" chiratidzo chinobatsira pachayo. Kana kukwidziridzwa kukaitwa pasina kusefa, kubuda{{4}kwe-kuruzha kwebhendi kunowedzerwawo, zvichidzikamisa chiratidzo chisina simba.

Practical effect: Inobvumira walkie yako-talkie kuchengetedza kutaurirana kunonzwisisika kunyangwe uri kureba kana nemasaini asina simba.

4. Mhando dze21.4MHz Filters

Muwalkie-talkies, mafirita akajairika 21.4MHz anosanganisira marudzi anotevera:

Ceramic Sefa:

Zvimiro: Mutengo wakaderera, saizi diki, kuvimbika kwakanyanya, uye hapana kugadzirisa kunodiwa.

Zvishandiso: Inoshandiswa zvakanyanya pakati pe-kusvika{1}}pasi-pakupedzisira walkie-talkies, uye kuita kwayo kunokwana kuzadzisa zvinodikanwa zvakajairika. Iyo bandwidth uye chimiro chechimiro (chiratidzo chekuyera kukwira kwesefa mupendero) inowanzoipa zvishoma kupfuura mafirita ekristaro asi zviri nani kupfuura mafirita eLC.

Sefa yeCrystal:

Zvimiro: Iine yakanyanya kukwirisa Q kukosha, saka kusarudza kwacho kwakanakisa, uye chimiro chechimiro chiri padyo nenzvimbo yakaringana.

Zvishandiso: Inowanzo shandiswa-muhurukuro dzepamusoro-soro-dzekutaura kana nguva dzinoda kukwanisa kupikisa-kukanganisa kwakanyanya. Mutengo wacho wakakwira kupfuura weceramic filters.