Hoʻohana ʻia o kāna kānana 21.4MHz i ka Walkie -Talkie Field

Hoʻohana ʻia o kāna kānana 21.4MHz i ka Walkie -Talkie Field

Hoʻohana mau ʻia ka kānana 21.4MHz ma ke ʻano he kānana waena (IF) ma nā mea hoʻokipa walkie -talkie, a ʻo kāna hana e hoʻoholo pololei i nā hōʻailona kumu ʻelua o nā kamaʻilio walkie-: ke koho a me ka naʻau.

E wehewehe hohonu mākou mai nā ʻaoʻao aʻe:

1. He aha ka "Intermediate Frequency" o kahi Walkie-Talkie?

No ka ho'okō 'ana i ka hana maika'i, 'a'ole e ho'onui a ho'oha'aha'a i nā hō'ailona lekiō (RF) i loa'a (e like me 400-470MHz). Akā, hoʻohana lākou i kēia mau ʻanuʻu: ① Mixing: Hoʻohui ʻia ka hōʻailona RF kiʻekiʻe i loaʻa me ka hōʻailona i hana ʻia e ka oscillator kūloko.② Hanana o ka Frequency Intermediate: Ma hope o ka hui ʻana, hana ʻia kahi hōʻailona hou me kahi alapine paʻa, ʻo ia ke alapine waena.

ʻO ka maikaʻi o ka hoʻolālā "superheterodyne" ʻo ia ka hapa nui o ka loaʻa a me ke koho (ka hiki ke kānana i ka hoʻopili ʻana i ke kahawai pili) i loaʻa i kēia ʻāpana IF paʻa, e hana i ka hoʻolālā kaapuni a paʻa ka hana.

2. No ke aha 21.4MHz?

ʻO 21.4MHz kahi alapine IF maʻamau maʻamau ma nā pūʻulu VHF/UHF (me nā pūʻulu i hoʻohana ʻia e nā walkie{1}}talkies). ʻO kāna mau kumu mōʻaukala a me ka ʻenehana:

Kaila ʻoihana oʻo: No ka alapine 21.4MHz, loaʻa ka heluna nui o nā kānana oo, paʻa, a haʻahaʻa -kuai, nā mea hoʻonui, a me nā ʻāpana pili.

Ke kaulike ma waena o ka hana a me ke kumukūʻai: He kiʻekiʻe kēia alapine e hoʻopau pono i ka hoʻopili kiʻi (kahi hoʻokipa maʻamau); i ka manawa like, ua lawa ka ha'aha'a no ka ho'olālā a me ka hana 'ana i nā kānana -Q (quality factor) ki'eki'e (e like me nā kānana kristal a me nā kānana ceramic).

Hoʻoilina mōʻaukala: Ua hoʻohana ʻia kēia alapine i ka ʻoihana kamaʻilio no nā makahiki he nui, a ua hoʻolālā ʻia ka nui o nā pahu kamaʻilio walkie -talkie a me nā haʻina e pili ana i kēia alapine waena.

3. Kohu Kohu o 21.4MHz Kānana ma Walkie -Talkies

Ma ka ʻāpana 21.4MHz IF, ʻo ka kānana ka "puka kiaʻi". He mea koʻikoʻi kāna kuleana: ① Hoʻomaikaʻi i ke koho

Hana: ʻO ke koho e pili ana i ka hiki i ka mea hoʻokipa ke hoʻokaʻawale i ka hōʻailona i makemake ʻia mai nā hōʻailona he nui a hoʻopaʻa i nā hōʻailona hoʻopilikia i ke kahawai pili.

Pehea e hana ai: ʻO ka kānana 21.4MHz he piʻi kiʻekiʻe loa ka pane alapine (e like me ka "pā pōhaku"). ʻAe wale ia i kahi ʻāpana hōʻailona me 21.4MHz ma ke kikowaena a me ka bandwidth pololei loa e hele (e laʻa, ± 6.25kHz, ±7.5kHz, ±12.5kHz maʻamau i hoʻohana ʻia i nā kamaʻilio walkie -like, e pili ana i nā spacing channel like ʻole).

Ka hopena maʻamau: Ke hoʻolele like ʻia nā lekiō ʻelua me nā alapine kokoke loa, hiki i kahi walkie -talkie i hoʻolako ʻia me kahi kānana -kiʻekiʻe 21.4MHz hiki ke lohe pono i ke kani o ka lekiō i hoʻopaʻa ʻia, ʻoiai e hoʻopaʻa pono i ka hōʻailona o ke kahawai ʻē aʻe e pale aku i ke kamaʻilio ʻana. Me ka ʻole o kēia kānana a i ʻole me kahi kānana maikaʻi ʻole, e lohe ʻoe i ka leo "channel crosstalk".

② Hoʻonui i ka ʻike

Hana: ʻO ka Sensitivity e pili ana i ka hiki i ka mea hoʻokipa ke loaʻa nā hōʻailona nāwaliwali.

Pehea e hana ai: Ma mua o ka hoʻonui ʻana i ka hōʻailona IF, hoʻohana ʻia ka kānana no ka kānana ʻana i waho o ka -ka -band leo a me ke keakea mua. Ma kēia ala, ʻo ka hoʻonui nui ka hōʻailona pono "maʻemaʻe" ponoʻī. Inā hoʻokō ʻia ka hoʻonui ʻana me ka kānana ʻole, e hoʻonui ʻia ka -ma waho o-leo kani, a laila e hoʻopau i ka hōʻailona ikaika nāwaliwali.

Ka hopena maʻamau: E ʻae i kāu walkie -talkie e mālama i ke kamaʻilio hoʻomaopopo ʻana ma nā mamao lōʻihi a i ʻole me nā hōʻailona nāwaliwali.

4. Nā ʻano o nā kānana 21.4MHz

I loko o nā kamaʻilio walkie-, ʻo nā kānana 21.4MHz maʻamau ka nui o nā ʻano penei:

Kānana Ceramic:

Nā hiʻohiʻona: ʻO ke kumukūʻai haʻahaʻa, ka liʻiliʻi liʻiliʻi, ka hilinaʻi kiʻekiʻe, a ʻaʻohe pono hoʻololi.

Nā mea hoʻohana: Hoʻohana nui ʻia i waena o -a-haʻahaʻa-hope walkie-talkies, a ua lawa kāna hana no ka hoʻokō ʻana i nā pono maʻamau. ʻO kona bandwidth a me kona ʻano kumu (he hōʻailona e ana i ka ʻoi o ka lihi kānana) ʻoi aku ka ʻino ma mua o nā kānana aniani akā ʻoi aku ka maikaʻi ma mua o nā kānana LC.

Kānana Crystal:

Nā hiʻohiʻona: Loaʻa ka waiwai Q kiʻekiʻe loa, no laila maikaʻi ke koho, a kokoke loa ke ʻano kumu i ke kūlana kūpono.

Hoʻohana: Hoʻohana mau ʻia i nā kamaʻilio walkie ʻoihana kiʻekiʻe-a i ʻole nā ​​manawa e koi ana i ka hiki kiʻekiʻe kiʻekiʻe -keakea. ʻOi aku ke kumukūʻai ma mua o nā kānana seramika.