Amasu Okwenza Umsakazo we-FM Wezimpawu Ezizinzile
Umsakazo we-FM uhlala uyindlela ewusizo, engabizi, futhi efinyeleleka kalula yokulalela ulwazi nokuzijabulisa. Naphezu kwentuthuko esheshayo yesikhathi sedijithali, abantu abaningi basathanda umsakazo we-FM ngenxa yokuzizwa kwawo okuhlukile nokuthembeka lapho i-inthanethi ingazinzile. Kodwa-ke, inselele enkulu ekwakheni idivayisi yomsakazo we-FM—kungakhathaliseki ukuthi isekethe yokwamukela elula noma inguqulo eyinkimbinkimbi kakhulu—ukuqinisekisa ukuthi isignali eyamukelwe ihlala izinzile, ayishintshi kalula (i-shift), ayigcwali umsindo, futhi inokukhetha okuhle lapho iziteshi eziningi zisondelene kakhulu emvamisa. Lesi sihloko sixoxa ngamasu okwakha umsakazo we-FM ukuze kufezwe isignali ezinzile kakhudlwana, kusukela emqondweni oyisisekelo, ukukhethwa kwezingxenye, ukwakheka kwesekethe ye-RF, kanye nesigaba sokuhlola.
1. Ukuqonda Ukuzinza Kumsakazo we-FM
Ukuzinza emsakazweni we-FM kuvame ukubhekisela ezintweni eziningana:
1. Ukuzinza kwemvamisa ye-oscillator yendawo (LO) kuma-receiver e-superheterodyne noma ukuzinza kokulungisa kuma-receiver alula.
2. Ukuzinza kokwamukela (ukuzwela nokukhetha) ukuze kungaphazanyiswa kalula ezinye izimpawu.
3. Ukuqina kokunikezwa kwamandla ukuze izinguquko ze-voltage zingashintshi izici ze-oscillator kanye ne-RF amplifier.
4. Ukuzinza komshini nokushisa, ngoba izinguquko ekushiseni noma ekudlidlizeni zingashintsha inani lama-inductor/capacitors azwelayo.
Ngaphandle kokuqina okwanele, umsakazo uzolahlekelwa kalula iziteshi ezilungisiwe, ukhale, noma uzwakale sengathi “uyagxuma” uma uthintekile.
2. Thola Ukwakheka: TRF, Superregen, noma Superheterodyne
Ngaphambi kokuqala ukuhlanganiswa, nquma ukwakheka kwesamukeli se-FM:
– I-TRF (Imvamisa Yomsakazo Elungisiwe): isekethe elula enokukhulisa umsindo kumvamisa ye-RF etholakala ngqo. Ngokuvamile ayikhethi kakhulu i-FM yesimanje.
– I-Superregenerative: iyazwela kodwa ivame ukuba nomsindo futhi ingakhipha ukuphazamiseka. Ukuqina kwayo kunzima ukuyigcina.
– I-Superheterodyne: indinganiso yesimanje yomsakazo we-FM. Isebenzisa i-oscillator yendawo kanye ne-10,7 MHz IF (Intermediate Frequency) ukuze ikhetheke kangcono futhi izinze.
Ukuze uthole isignali ezinzile, i-superheterodyne iyindlela enconywa kakhulu, ikakhulukazi uma usebenzisa i-IC ye-tuner ye-FM ezinikele.
3. Ukukhethwa kwe-Tuner IC: Indlela Esheshayo Eya Ekuqineni
Uma ugxile kumsakazo we-FM ozinzile, sebenzisa i-IC yokwamukela eyenzelwe ngqo i-FM, isibonelo:
– I-IC ye-analog/yedijithali ene-PLL (Phase Locked Loop).
– Imojuli yomsakazo we-FM elungele ukusetshenziswa (ngokuvamile kakade ine-RF front-end, i-IF, i-demodulator, futhi ngezinye izikhathi i-amplifier yomsindo).
Inzuzo ye-PLL ukukhiya imvamisa ngendlela enembile, ngakho-ke umsakazo awushintshi kalula noma ngabe kukhona izinguquko ekushiseni noma ku-voltage.
Uma usafuna ukuklama kusukela ekuqaleni, sebenzisa isihlungi se-IF se-ceramic esingu-10,7 MHz kanye nesivimbeli/isitholi esifanelekile ukuze imiphumela ingabi nomsindo.
4. Umklamo We-RF Front-End: Ama-Antenna, Ukufanisa, kanye Nezihlungi
Ingxenye ebaluleke kakhulu yokusebenza komsakazo we-FM yi-RF front-end. Amasu abalulekile:
a. I-antenna efanele
Ku-FM (88–108 MHz), i-antenna efanelekile yile:
– I-dipole engamagagasi ayisithupha (cishe ubude obuphelele bungu-75 cm, umlenze ngamunye ±37,5 cm).
– I-antenna ende ye-teleskopu esondela kulolo sayizi.
I-antenna emfushane kakhulu izonciphisa ukuzwela. I-antenna ende kakhulu ngaphandle kokuqondaniswa okufanele ingabonisa izimpawu futhi iholele ekwamukelweni okungekuhle.
b. Ukungavimbeli kanye nokufanisa
Umsakazo we-FM uvame ukusebenza nge-antenna impedance engu-75 ohms. Qinisekisa ukuthi umugqa wokufaka kanye nezixhumi zisekela i-impedance efanele ukuze kuncishiswe ukulahleka. Ukuhambisana okuhle kunegalelo ekwamukelweni okuzinzile ngoba isignali engenayo "ihlelekile" kakhulu futhi ayishintshi kakhulu lapho isikhundla se-antenna sishintshwa kancane.
c. Isihlungi se-RF band-pass
Engeza isihlungi se-band-pass cishe esingu-88–108 MHz. Umgomo uwukuthi:
– Kunciphisa ukuphazamiseka okuvela kumaza angaphandle kwebhendi ye-FM (isb. ezinye izimpawu ze-VHF).
– Gwema ukulayisha ngokweqile i-RF amplifier kanye ne-mixer.
Isihlungi singaba yisekethe ye-LC elula noma sisebenzise izingxenye zesihlungi ezingasetshenziswanga eshalofini. Ikhwalithi ye-inductor (i-Q factor) ibaluleke kakhulu.
5. I-Stable Oscillator: Isihluthulelo Sokungasebenzisi Imvamisa
Kumukeli we-superheterodyne, i-oscillator yendawo (LO) kumele iqine. Amasu okuthuthukisa ukuzinza:
1. Sebenzisa i-synthesizer ye-PLL uma kungenzeka. Lena yindlela ezinzile kakhulu.
2. Uma usebenzisa i-LC oscillator evamile:
– Sebenzisa ama-capacitor e-NP0/C0G engxenyeni enquma imvamisa ngoba ukugeleza kwawo kokushisa kuncane.
– Sebenzisa i-inductor enomgogodla oqinile kanye ne-mechanics ukuze ingashintshi uma ithintwa.
– Gwema ukwakheka okwenza i-oscillator “ithinteke” kalula yizandla noma izinto zensimbi eziseduze.
I-oscillator “ezwela ukudlidliza” (ethinta ukudlidliza) izokwenza umsindo ubonakale ushintshashintsha.
6. UMA 10,7 MHz: Ukukhetha Kunquma Ukuhlanzeka Komsindo
Ngemva kokuxuba, isignali ye-FM yehla iye ku-IF engu-10,7 MHz. Lapha, sebenzisa:
– Isihlungi se-ceramic esingu-10,7 MHz sokukhetha iziteshi.
– I-amplifier ye-IF enomkhawulo wokunciphisa ithonya lokushintshashintsha kwe-amplitude.
– Isitholi se-FM esihlukanisayo/isitholi se-quadrature sihambisana nesihlungi.
Ukukhetha okuhle kuvimbela umsakazo ukuthi ungasebenzisi iziteshi ezimbili ngesikhathi esisodwa (ukuphazamiseka kwesiteshi esiseduze). I-limiter isiza ukwenza ukususwa komsindo kuvikeleke kakhulu.
7. Ukunikezwa Kwamandla: Ngokuvamile Akunakwa, Kodwa Umphumela Wawo Mkhulu
Amasekethe amaningi omsakazo awazinzile ngenxa yokuphakelwa kwamandla okungasebenzi kahle. Indlela ephakanyisiwe:
– Sebenzisa isilawuli se-voltage (isb. i-LDO) esine-ripple encane.
– Engeza ama-capacitor okuhlukanisa esigabeni ngasinye: i-ceramic engu-100 nF eduze kwamaphini e-IC, kanye nama-elcos angu-10–100 µF emigqeni yokuphakelwa.
– Hlukanisa imigqa yokuphakelwa kwe-RF/IF endleleni yomsindo uma kungenzeka; umsindo ovela ku-amplifier yomsindo ungangena ku-RF.
Uma umsakazo usebenzisa i-adaptha yokushintsha, qiniseka ukuthi kukhona isihlungi esengeziwe ngoba lolu hlobo lwe-adaptha luvame ukukhiqiza umsindo.
8. Ukuhlelwa kwe-PCB kanye nokuGxila: Imfihlo Yokuzinza Ngemvamisa Ephakeme
Kumaza e-FM, ukwakheka kwe-PCB kubaluleke njengohlelo lwesekethe. Izimiso eziyinhloko:
- Dala izindlela zesignali ze-RF ezimfushane neziqondile.
– Sebenzisa indiza ebanzi yomhlabathi.
– Hlukanisa indawo ye-RF nomsindo ukuze uvimbele impendulo.
– Gwema izihibe ezinkulu zomhlabathi ezingasebenza njenge-antenna yomsindo.
– Beka izingxenye ezinquma imvamisa (i-LC oscillator, isihlungi) eduze ngangokunokwenzeka.
Uma usebenzisa izintambo ezinde ze-jumper (isb., ebhodini lokufaka isinkwa), isekethe ye-FM ivame ukungazinzile. Ukuze uthole imiphumela emibi, sebenzisa i-PCB noma okungenani ibhodi lokufaka i-perf elinesakhiwo esiqinile.
9. Ukuvikela: Ukuvala iSekethe Ekuphazamisekeni Kwangaphandle
Ngomsakazo ozinzile ngempela, ikakhulukazi ezindaweni ezinezithumeli eziningi:
– Faka isivikelo (ibhokisi lensimbi) engxenyeni engaphambili ye-RF.
– Sebenzisa ikhebula elifushane le-coaxial ukuze uxhume i-antenna.
– Qiniseka ukuthi isivikelo sixhunywe kahle emhlabathini.
Ukuvikela kunciphisa ithonya lezandla, amadivayisi edijithali aseduze, kanye nokuphazamiseka kwe-electromagnetic.
10. Isigaba Sokuhlola Nokuqondanisa
Uma umsakazo usuvuliwe, unganeliseki. Yenza ukulungiswa:
1. Hlola ukuzwela: qhathanisa ukwamukelwa komsakazo nomsakazo wezohwebo endaweni efanayo.
2. Hlola ukuzulazula: vula umsakazo imizuzu engama-30-60, ubone ukuthi imvamisa iyashintsha yini.
3. Ukuqondanisa kwe-IF: Setha isihlungi/i-transformer ye-IF (uma ikhona) ngokwenqubo yokuphendula okuphezulu kanye nokuphambuka okuncane.
4. Hlola umsindo: qiniseka ukuthi ukususwa kwezwi kuhlanzekile nokuthi i-amplifier yomsindo ayibangeli umsindo.
Uma kukhona amathuluzi anjengomkhiqizi wesignali ye-RF kanye nekhawunta yemvamisa, imiphumela yokuqondanisa izoba nembe kakhulu.
Isiphetho
Ukwakha umsakazo we-FM ozinzile kuncike ekuhlanganisweni komklamo ofanele, izingxenye zekhwalithi, ukwakheka kwe-PCB okufanele, kanye nokunikezwa kwamandla okuhlanzekile. Kumaphrojekthi lapho ukuzinza kuyinto eza kuqala, ukwakheka kwe-superheterodyne—ikakhulukazi i-PLL—kuyisinqumo esingcono kakhulu. Ukuzinza kungathuthukiswa ngezihlungi ezinhle ze-RF, i-oscillator engangeni ukukhukhuleka, i-10,7 MHz IF ekhethiwe, kanye nokuvikela nokusekela okufanele. Ngale ndlela, umsakazo wakho we-FM ngeke "ubambe ukusakaza" kuphela kodwa futhi uzoletha ukwamukelwa okucacile, okuqinile, nokungenaziphazamiso ekusetshenzisweni kwansuku zonke.
Uma ufisa, ngingabhala futhi inguqulo yobuchwepheshe yalesi sihloko ngezibonelo zamadayagramu ebhulokhi yesekethe, uhlu lwezingxenye ezinconywayo, kanye nezinyathelo zokuhlanganisa isinyathelo ngesinyathelo ngokuya ngenhloso (umsakazo we-FM olula, umsakazo we-FM osekelwe ku-PLL IC, noma umsakazo we-FM onamamojula alungele ukusetshenziswa).
