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昨晚看新聞, 聽說香港下月要試播 AM 的數碼廣播電台. 但是沒有看到很多細節. 於是上網看看到底是啥東東. 基本的資料沒有很多, 只是用 AM 810 kHZ 一個頻率發射, 覆蓋全港, 內容是數碼廣播, 可同時傳送文字. 評語好壞參半, 有人為了發射塔的建設提出反對. 但是這些都不是俺要關注的.
俺要看的是, 沒有買到 AM 的數碼收音機以前, 如何自製. 查了 GOOGLE. 現有的, 如果要用 AM 作為數碼廣播, DRM (Digital_Radio_Mondiale) 是現成的技術. 到底是不是香港要套用的, 有待觀察.
老外一直在搞的 DDS 加上 Software Defined Radio, 應該可以對俺有幫助. 所以寫了下面的信給老外, 看看他的意見, 如果可以, 這就是俺開學無線電 (Radio) 的第一個練習題目, 而且成果是可以用在日常聽收音機. 根據人家的說法, AM 收音機可以改裝, 輸出的訊號用電腦配備 DRM 的軟件解碼, 就可以聽到數碼廣播. 老外上次來示範用他的電腦配合 DDS 和 Software Defined Radio, 的確可以聽到世界各地的 AM 電台. 而且還可以配合 SKYPE, 跟其他的 HAM RADIO (擁有牌照的個人無線電台) 通訊. 當然 MORSE CODE (摩司碼) 都可以直接用電腦接收傳送及翻譯.
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Hong Kong is going to have
AM radio broadcasting with digital content next month. It is planed with AM 810 kHz, a single
frequency for this purpose. No much detail of technical detail is available, and
then I searched the web for some more.
AM radio broadcasting with digital content next month. It is planed with AM 810 kHz, a single
frequency for this purpose. No much detail of technical detail is available, and
then I searched the web for some more.
most likely, it should
be used for DRM if AM is used.
be used for DRM if AM is used.
I have found another
website about the modification to existing AM radio then feed this
into computer's microphone, with the DRM software, the people will be able to
listen to such AM digital radio. perhaps this is the one I can learn from start
about radio receiver.
website about the modification to existing AM radio then feed this
into computer's microphone, with the DRM software, the people will be able to
listen to such AM digital radio. perhaps this is the one I can learn from start
about radio receiver.
and there even someone
posted a simple homebrew version of the receiver front end.
posted a simple homebrew version of the receiver front end.
I remember your software
radio with the cool screen of the computer. please help me to understand if DRM
software, and the circuit below is able to fit my interesting (it is download
from the link above)
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什麼是 IF transformer, 基本上是 FM 和 AM 兩種, 人家說的
http://hem.passagen.se/communication/ifcan.html
RED - Oscillator. With 30pf - 300pf = 1MHz to 2MHz
YELLOW - First 455KHz IF filter transformer
White - Second 455KHz IF filter transformer (not always used)
Black - Last 455KHz IF filter transformer
這種 IC 的 FM 收音機, 居然沒有 IF transformer
再來看看爛電話, 有 IF transformer, 可以改裝, 但是沒有器材, 如何設計及校正共振頻率 (Resonans Frequency) ??
Silconlab 出品 AM / FM 或 其他 IC 接收器, 可是沒有樣品可取.
http://www.silabs.com/products/audiovideo/amfmreceivers/Pages/Si473637.aspx
radio with the cool screen of the computer. please help me to understand if DRM
software, and the circuit below is able to fit my interesting (it is download
from the link above)
---------------
什麼是 IF transformer, 基本上是 FM 和 AM 兩種, 人家說的
http://hem.passagen.se/communication/ifcan.html
RED - Oscillator. With 30pf - 300pf = 1MHz to 2MHz
YELLOW - First 455KHz IF filter transformer
White - Second 455KHz IF filter transformer (not always used)
Black - Last 455KHz IF filter transformer
這種 IC 的 FM 收音機, 居然沒有 IF transformer
再來看看爛電話, 有 IF transformer, 可以改裝, 但是沒有器材, 如何設計及校正共振頻率 (Resonans Frequency) ??
Silconlab 出品 AM / FM 或 其他 IC 接收器, 可是沒有樣品可取.
http://www.silabs.com/products/audiovideo/amfmreceivers/Pages/Si473637.aspx
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