Hpa majaw Spectrum Analyzer langai mi hta OCXO hpe n-gun kaba ai hte n-gun n-ja ai OCXO ra ai kun?

Ndai ga san hpe spectrum analyzer langai mi gaw teng sha hpa hpe shadawn ai hpe sawk sagawn yu yang, kadun dawk chye na la mai ai. Madung hku nna, shi a local oscillator hpe lang nna, na a signal hpe "shingdaw" galaw ai. Dai majaw, local oscillator (OCXO hku nna shingdaw ai) gaw laklai ai hku san seng nna ngang grin ai hku rai ra ai.

I. Hpa majaw Ultra-N-gun n law ai nsen hpe ra sharawng ai kun?

Essence: Chyam dinglik nga ai Signal a matu Instrument Nsen hpe Shut kau na hpe pat shingdang ai

Spectrum analyzer a asan sha galaw da ai kata na hkrang masa:

Crystal n-gun → buga n-gun (LO) → kayau kaya → nsam hpe madun dan ai

Crystal oscillator hta phase nsen grai law ai rai yang lawu na zawn re ai lam ni byin chye ai.

1. "Noise Skirt" (Grau ahkyak ai) hpe shalat ai

N-gun ja ai signal a maga lahkawng maga de tsaw ai nsen npu (elevated noise floor) dan dawng wa nna, "n-gup" (sh) galu kaba wa ai hte bung ai.

Akyu ara hku n na:

Makau na n-gun kya ai signal ni hpe hkrak mask galaw da ai.

Spurious signal ni, shingjawng ai lam ni, harmonics ni gaw n mu lu mat ai.

2. Dynamic Range hpe shadawn sharam tawn da ai
Dynamic range gaw n-gun ja ai signal kaw na pru wa ai nsen hte n-gun kya ai signal ni a amplitude hta madung nga ai.

>>Phase nsen kaba → n-gun ja ai signal gaw grup yin na frequency ni hpe "n san seng shangun ai".

>>Nsen hpe kaja wa sharawt ya ai.

Mahtai:Shawng nnan -90 dBc kaw mu lu ai signal gaw -70 dBc du hkra sha mu lu na re.

Shadawn shadang shagu hpe "Blurring Filter" langai mi gaw hkra machyi shangun ai.
>>Ideal, san seng ai signal hpe bang ai shaloi pyi: Shapraw ai gaw "galu kaba wa ai" (spectral line galu kaba wa ai) naw rai nga ai.

>>Madun ai lam:Shadawn shadang a mahtai hpe gaw, jak rung hkum nan hku nna shadawn sharam da ai.

Lahta e high vs low phase noise hpe shingdaw ai chart hpe madun da ai:

Nsen kaba (Matsan ai Crystal)                                                                             

Madung signal grup yin hta laklai ai "noise skirt" langai mi dan dawng wa ai.

N-gun gaw makau grup yin na frequency ni de chyam bra wa ai.

N-gun kya ai signal ni hpe nsen hta lup tawn da ai.

Dai spectrum gaw "htuk manu ai zawn rai nga ai."

Mahtai:Htingbu htingbyen na n-gun kya ai signal ni hpe n mai shadawn ai; dynamic range gaw n kaja ai.

Nyem aiPhase nsen(Madang tsaw ai - OCXO)

Madung signal gaw sharp hte san seng ai.

Noise floor gaw n law ai.

Makau na n-gun kya ai signal ni hpe asan sha mu lu ai.

Mahtai:Lawu-madang na spurs ni hpe hparan mai ai; dynamic range hpe grai kaja hkra galaw ya lu ai.

II. Hpa majaw High Stability (OCXO) ra ai kun?

Madung: Frequency Reference hpe n htingnut hkra galaw na matu

Dai kristal oscillator frequency gaw shadawn shadang yawng a matu "ruler" hku nna magam gun nga ai.

1. Katsi kahtet ai lam → Frequency galai shai ai lam
Standard kristal ni a matu (TCXO a lawu):

Katsi majan galai shai ai lam → ppm-madang galai shai ai lam.

Hkrang shapraw ai lam ni:

Spectral peak gaw hkra maga de mung, pai maga de mung galai shai nga ai.

Aten galu laman n bung ai shadawn shadang ni.

2. Tengman ai shadawn shadang ni hta hkra machyi ai lam
Lahta na shadawn shadang ni gaw ngang grin ai lam hpe grai kam hpa nga ai:

Chyahkring hkring shut ai lam

Htingbu htingbyen n-gun (ACP)

Galai shai ai lam hpe sawk sagawn ai lam (EVM)

Phase nsen chyam dinglik ai
Reference source gaw hprawng mat yang:

"Signal manghkang" hte "instrument manghkang" hpe n mai ginhka ai.

3. OCXO a lit

Dai kristal hpe n galai shai ai nbung katsi ai shara de (ga shadawn, 70℃) katsi shangun ai.

Ndai hku galaw yang, nbung katsi ai-hkam sha ai shara hpe koi lu ai.

Akyu:

Stability gaw ppm kaw nna ppb madang de rawt jat wa ai.

Grai tsaw ai aten kadun-a aten n-gun (low jitter).

III. Law htam ai hku hkau lam, jat bang ai n re

Daw dan lam:
Asan sha yu u + Drift n nga ai=Tengman ai shadawn shadang

IV. Engineer langai a ningmu kaw na ga si langai-Sumtang tsun dan ai

Spectrum analyzer langai a bungli galaw lu ai atsam gaw, madung hku nna shi a buga na oscillator a hkam kaja lam rai nga ai.

Nsen kaji→ Spectrum hpe "chye na hkra" galaw ya ai (details ni hpe mu lu hkra galaw ya ai).

N-gun ja ai ngang grin ai lam (OCXO)→ Spectrum hpe "kam mai ai" byin shangun ai (drift hpe pat shingdang ai).

Lahkawng yan gaw n mai malap ai. Ndai lam gaw, n-gun ja ai spectrum analyzer ni gaw, n-gun n rawng ai, n-gun n rawng ai OCXO ni hpe n galai shai ai sha lang ai lam rai nga ai.

V. HCI Tsaw-N-gun ja ai, Ultra-N-gun n-rawng ai arung arai ni

100MHz hta HCI 25x25mm OCXO gaw -168dBc/Hz @ 1kHz daram n-gun n law ai nsen hpe lu la ai.

Chyam dinglik ai jahpan:

Nang gaw -n-gun ja ai, ultra-n-gun n-rawng ai arung arai ni ra ai rai yang, na a ap nawng ai HCI dut shabra ai dat kasa (sh) hpaji hparat hpaji ninghkring hpe matut mahkai mai ai.