『一人之海』之一
從答應兩廳院的邀約開始，拍了宣傳素材，票卷開賣，三月演出前一週延期，退票。然後，重新開賣，票房完售....心裡仍然不踏實，真的要上音樂廳了？
我是誰？我要演奏什麼？為什麼要聽我演奏？為什麼要演奏，演唱這些音樂？我不是鋼琴，管風琴演奏家，我能提供大家什麼？
從劇場開始，我喜歡發掘新的聲音，常常沾沾自喜亂彈一通寫出的怪怪合聲。用管風琴音色彈奏巴哈創意曲中右手聲部，電子音色彈奏左手，想像這是魔鬼與天使的交戰。用合成器的調變頻率的LFO製造波動，說那是角色心裡的震盪。數位mixer 裡的test tone，經過AKAI S5000 取樣後，彈奏成不成調的旋律，賦予他詮釋文本的功能。好像，這就是我愛的，也是我唯一會的。那，就這樣吧，小時候玩小琴（小鋼琴），長大玩大琴（管風琴），無論大小，都要玩。
我知道我要彈什麼了。
第一次到音樂廳試彈管風琴，我戰戰兢兢按下第一個鍵，慢慢拉出第一支音栓的時候，我聽見空氣吹入管子的聲音，隨之而來是音高慢慢從不知道幾分之幾音高到預定音高的過程。腳踩低音，拉出音栓產生超低音外，也能產生大輪船的汽笛聲（原理其實是一樣的吧？）。這些聲音完全吸引住我。其實，傳統的演奏法，是必須先拉好音栓確定好音色後再彈奏的。我就當不知者不罪吧 ! 我請音響公司幫我放大短風琴的低音，送入超低音喇叭，加上長 reverb 和 delay，我的開場，在霧藍中鳴笛開船了。
所謂亂彈，就是給左右手不同的指令，比如：右手只能上行，左手只能下行; 右手一次只能彈2個音，左手一次3個。然後，會亂彈出意想不到的合聲和旋律。『一人之海』的主題旋律就是這樣來的。左右手好像有關，卻又像毫無關係，各自旋律邏輯不同產生合聲效果，遊走在好聽與不好聽，對與不對，有與沒有之間。
我受巴哈創意曲影響很大，相似的旋律線在精密（應該是吧）的構思下，各聲部可以互為伴奏，合聲，主題。但如果.... 三台鋼琴彈奏不同調的同一個旋律呢？從一隻手，到兩隻....到六隻？有些時候，音層成了詭譎的黑洞漩渦，有時，平靜如鏡。
好聽的，過往的作品裡很多，成為配樂，成為歌。
這次新寫的音樂，就是來玩的。原來，這就是我愛的，也是我唯一會的。
mixer原理 在 [請益] - 精華區ck55th320 的推薦與評價
請教一下各位~
因為小妹之前沒接觸過MIXER
現在想做一個MIXER跟LNA的電路整合
但無從下手 PAPER 裡有提到 LO IF...等等
想請教一下這些是啥??
還是說哪邊可以查到MIXER的原理
拜託高手了!!
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※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 140.134.30.130
※ 編輯: poppyya 來自: 140.134.30.130 (09/09 12:50)
> -------------------------------------------------------------------------- <
作者: Lary (PTTuser) 看板: comm_and_RF
標題: Re: [請益] RF MIXER
時間: Wed Sep 9 23:43:22 2009
※ 引述《poppyya (yeh)》之銘言：
: 請教一下各位~
: 因為小妹之前沒接觸過MIXER
: 現在想做一個MIXER跟LNA的電路整合
: 但無從下手 PAPER 裡有提到 LO IF...等等
: 想請教一下這些是啥??
: 還是說哪邊可以查到MIXER的原理
: 拜託高手了!!
我覺得如果你對RF完全外行
你可以看一下Razavi的書瞭解一下RF system的架構
detail的mixer電路如果是CMOS製程的話
我個人推薦Thomas Lee的書
至於你要做的mixer要看你是用在怎樣的system
若是protable的話可能要找passve mixer
若是不考慮耗電的話可以找active mixer
differential signal
不需要產生IQ的話可以用Giber cell
若是要產生IQ的話可能要用double balance的結構
single signal的話只要一顆device
detail可能就要自己看書囉
我也不是很熟
一點點自己的看法
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※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 123.195.2.141
> -------------------------------------------------------------------------- <
作者: carrack (.....) 看板: comm_and_RF
標題: Re: [請益] RF MIXER
時間: Sun Sep 13 23:38:59 2009
Hey Lary thanks for your opinion!
Sorry I am not in Taiwan and need to use English typing sys.
Yes, I agree with you zero-IF has some DC issue compared with low-IF.
However, we are not necessary to use "physical" HPF to deal with that in
the industry.
Why I said maybe you are talking about zero-IF system is because of the
image rejection issue.
Because the image of zero/low-IF system is usually located in your own
application band, it is impossible to design a image rejection filter to
kill them. That's why we need image cancellation Mixer/sys.
Sure, as you said the mismatch of IQ path will degrade the image rejection,
if we don't do any correction I think maybe only ~ -40dB we can get in current
technology.
In heterodyne system, it is a different story. If we can choose the IF cleverly
then the image can be located some less interference band and we don't need
high rejection level.
Also, the IF selection will affect the channel filter and image(band) filter
design. In most cases, they are directly trade-off.
Anyway, really appreciate your idea and I agree with you direction conversion
type sys is the main-stream now and maybe IQ mismatch has more effect on the
image issue.
※ 引述《Lary (PTTuser)》之銘言：
: 推 poppyya:嗯~ 謝謝各位^^ 114.46.113.58 09/11 00:27
: → poppyya:再問一下喔~ IF 中頻 要去哪裡查? 114.46.113.58 09/11 00:31
: → poppyya:我的意思是 如果我做2.4GHz的MIXER 那IF? 114.46.113.58 09/11 00:31
: → poppyya:這要到哪裡才查的到??? 謝謝了!! 114.46.113.58 09/11 00:32
: → Lary:也許你應該先說妳到底要做什麼樣的系統? 123.195.2.141 09/11 00:38
: → Lary:不同調變方式需要不同的頻寬 這可能需要做 123.195.2.141 09/11 00:39
: → Lary:system或baseband的人來訂到底if的center 123.195.2.141 09/11 00:40
: → Lary:freq. 和band width是多少 然後決定DAC到 123.195.2.141 09/11 00:41
: → Lary:mixer間的LPF design 123.195.2.141 09/11 00:41
: 推 Gocoba:不同的架構有不同的IF 同時也牽扯到Image 72.222.132.58 09/11 01:12
: → Gocoba:rejection的問題 還有filter的設計 72.222.132.58 09/11 01:12
: → Lary:image rejection感覺跟poly-phase filter 140.113.228.149 09/11 17:29
: → Lary:以及LO的I-Q error比較有關係ㄟ... 140.113.228.149 09/11 17:30
: 推 carrack:Lary, you are talking about zero-IF sys 63.239.159.137 09/11 23:44
: → Lary:I am talking about low IF system 60.250.197.166 09/12 11:53
: → Lary:I'm not sure if the mixer design is differ 60.250.197.166 09/12 12:02
: → Lary:ent for zero-IF and low-IF. However, the 60.250.197.166 09/12 12:02
: → Lary:difficult part of zero-IF design would be 60.250.197.166 09/12 12:03
: → Lary:how to remove DC offset due to device mism 60.250.197.166 09/12 12:04
: → Lary:atch or other factors without affecting th 60.250.197.166 09/12 12:04
: → Lary:e wanted signal. A HPF with very low 3dB 60.250.197.166 09/12 12:05
: → Lary:freq will need a large layout area and lon 60.250.197.166 09/12 12:06
: → Lary:g stable time. I did not do it myself. 60.250.197.166 09/12 12:07
: → Lary:I do not know it very well and we can 60.250.197.166 09/12 12:09
: → Lary:discuss if you are interested. 60.250.197.166 09/12 12:09
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 66.27.100.30
> -------------------------------------------------------------------------- <
作者: Lary (PTTuser) 看板: comm_and_RF
標題: Re: [請益] RF MIXER
時間: Mon Sep 14 20:48:13 2009
Hi Carrack
Thank you for your valuable opinion.
Since I am just a freshman in RF field, I am not familiar with HPF in baseband
and image rejection correction in baseband.
I am very intersted in both of them, especially the correction for image
rejection (Did they control the IQ phase by baseband?)x.
Can you kindly provid some relative paper, patent, or books for me?
Recently I also face some problems of adjacent channel rejection ration due to
insufficient image rejection ratio.
In our case, the poly-phase filter can only provid 30 dB image rejection.
I am wondering how can we improve it in baseband.
Thank you for your reply.
※ 引述《carrack (.....)》之銘言：
: Hey Lary thanks for your opinion!
: Sorry I am not in Taiwan and need to use English typing sys.
: Yes, I agree with you zero-IF has some DC issue compared with low-IF.
: However, we are not necessary to use "physical" HPF to deal with that in
: the industry.
: Why I said maybe you are talking about zero-IF system is because of the
: image rejection issue.
: Because the image of zero/low-IF system is usually located in your own
: application band, it is impossible to design a image rejection filter to
: kill them. That's why we need image cancellation Mixer/sys.
: Sure, as you said the mismatch of IQ path will degrade the image rejection,
: if we don't do any correction I think maybe only ~ -40dB we can get in current
: technology.
: In heterodyne system, it is a different story. If we can choose the IF cleverly
: then the image can be located some less interference band and we don't need
: high rejection level.
: Also, the IF selection will affect the channel filter and image(band) filter
: design. In most cases, they are directly trade-off.
: Anyway, really appreciate your idea and I agree with you direction conversion
: type sys is the main-stream now and maybe IQ mismatch has more effect on the
: image issue.
: ※ 引述《Lary (PTTuser)》之銘言：
: : 推 poppyya:嗯~ 謝謝各位^^ 114.46.113.58 09/11 00:27
: : → poppyya:再問一下喔~ IF 中頻 要去哪裡查? 114.46.113.58 09/11 00:31
: : → poppyya:我的意思是 如果我做2.4GHz的MIXER 那IF? 114.46.113.58 09/11 00:31
: : → poppyya:這要到哪裡才查的到??? 謝謝了!! 114.46.113.58 09/11 00:32
: : → Lary:也許你應該先說妳到底要做什麼樣的系統? 123.195.2.141 09/11 00:38
: : → Lary:不同調變方式需要不同的頻寬 這可能需要做 123.195.2.141 09/11 00:39
: : → Lary:system或baseband的人來訂到底if的center 123.195.2.141 09/11 00:40
: : → Lary:freq. 和band width是多少 然後決定DAC到 123.195.2.141 09/11 00:41
: : → Lary:mixer間的LPF design 123.195.2.141 09/11 00:41
: : 推 Gocoba:不同的架構有不同的IF 同時也牽扯到Image 72.222.132.58 09/11 01:12
: : → Gocoba:rejection的問題 還有filter的設計 72.222.132.58 09/11 01:12
: : → Lary:image rejection感覺跟poly-phase filter 140.113.228.149 09/11 17:29
: : → Lary:以及LO的I-Q error比較有關係ㄟ... 140.113.228.149 09/11 17:30
: : 推 carrack:Lary, you are talking about zero-IF sys 63.239.159.137 09/11 23:44
: : → Lary:I am talking about low IF system 60.250.197.166 09/12 11:53
: : → Lary:I'm not sure if the mixer design is differ 60.250.197.166 09/12 12:02
: : → Lary:ent for zero-IF and low-IF. However, the 60.250.197.166 09/12 12:02
: : → Lary:difficult part of zero-IF design would be 60.250.197.166 09/12 12:03
: : → Lary:how to remove DC offset due to device mism 60.250.197.166 09/12 12:04
: : → Lary:atch or other factors without affecting th 60.250.197.166 09/12 12:04
: : → Lary:e wanted signal. A HPF with very low 3dB 60.250.197.166 09/12 12:05
: : → Lary:freq will need a large layout area and lon 60.250.197.166 09/12 12:06
: : → Lary:g stable time. I did not do it myself. 60.250.197.166 09/12 12:07
: : → Lary:I do not know it very well and we can 60.250.197.166 09/12 12:09
: : → Lary:discuss if you are interested. 60.250.197.166 09/12 12:09
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 123.195.37.160
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