Site Logo Home
 
rOm
Quest
Glossary
 
Random
Page
Search
Site
Lush
Sim
Class
Subject
Images
 
Help
FAQ
Sign
Up
Log
In
A Level     Radio     >Digital<     Simple Receiver        Extras Non Exam     Radio     Simple TRF     Superhet    

Radio Digital


Site for Eduqas/WJEC - Go to the AQA site.

  Extras Non Exam    Radio  0 of 66    Question 1345    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set1 of 66    Question 1346    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set2 of 66    Question 1347    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set3 of 66    Question 1348    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set4 of 66    Question 1349    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set5 of 66    Question 1350    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set6 of 66    Question 1351    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set7 of 66    Question 1352    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set8 of 66    Question 1353    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set9 of 66    Question 1354    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set10 of 66    Question 1355    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set11 of 66    Question 1356    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set12 of 66    Question 1357    Basic Receiver 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set13 of 66    Question 1061    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set14 of 66    Question 1062    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set15 of 66    Question 1063    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set16 of 66    Question 1087    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set17 of 66    Question 1343    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set18 of 66    Question 1088    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set19 of 66    Question 1089    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set20 of 66    Question 977    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set21 of 66    Question 979    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set22 of 66    Question 980    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set23 of 66    Question 981    DAB 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set24 of 66    Question 1090    FM Band 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set25 of 66    Question 1091    FM Band 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set26 of 66    Question 1092    FM Band 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set27 of 66    Question 1286    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set28 of 66    Question 1360    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set29 of 66    Question 1362    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set30 of 66    Question 1363    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set31 of 66    Question 1364    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set32 of 66    Question 1365    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set33 of 66    Question 1258    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set34 of 66    Question 1261    Radio Systems 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set35 of 66    Question 67    Radio Terminology 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set36 of 66    Question 68    Radio Terminology 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set37 of 66    Question 69    Radio Terminology 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set38 of 66    Question 70    Radio Terminology 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set39 of 66    Question 71    Receiver Terminology 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set40 of 66    Question 72    Receiver Terminology 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set41 of 66    Question 314    Sub-systems Radio Modules 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set42 of 66    Question 316    Sub-systems Radio Modules 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set43 of 66    Question 317    Sub-systems Radio Modules 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set44 of 66    Question 1064    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set45 of 66    Question 1358    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set46 of 66    Question 1359    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set47 of 66    Question 915    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set48 of 66    Question 495    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set49 of 66    Question 496    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set50 of 66    Question 497    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set51 of 66    Question 498    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set52 of 66    Question 499    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set53 of 66    Question 500    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set54 of 66    Question 501    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set55 of 66    Question 502    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set56 of 66    Question 503    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set57 of 66    Question 504    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set58 of 66    Question 505    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set59 of 66    Question 506    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set60 of 66    Question 507    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set61 of 66    Question 508    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set62 of 66    Question 509    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set63 of 66    Question 510    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set64 of 66    Question 511    Superhet 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set65 of 66    Question 103    Tuned Circuit Cores 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set66 of 66    Question 54    VHF Radio - Modulation Type 
Score 0/0 
Not attempted  
Last Answer  
Deadline not set  Questions 0 to 66   -->  View All  

Digital Audio Broadcasting

A Receiver Design

DAB Receiver

Digital Audio Broadcasting (DAB) on VHF - Key Facts

Bandwidth: Music channels use 192 kilobits/second. Channels carrying mainly speech and phone-ins don't need such high quality and they use as little as 80 kilobits/second. These figures can change at different times of day as the broadcast content changes.

Data Streams: DAB multiplexes can also carry data streams. 32 kilobits per second is a typical data rate. This is used for the station ID and for information about the music, artist, track or other program content.

Data Compression

Interleaving

Time and Frequency Interleaving make DAB much more likely to work under adverse conditions.

Time Interleaving

Frequency Interleaving

Space Interleaving

Digital Radio Mondiale - MF and HF Digital Radio - Not an exam topic

Analogue and Digital Samples

Here is a downloadable video of a DRM broadcast. There are no nasty effects on the sound. The red, blue and black array of dots is a visual representation of the Quadrature Amplitude Modulation data stream.

Compare this analogue AM sample with the DRM above. The quality is quite nasty. There is a high pitched audible heterodyne whistle and periods of deep signal fading causing serious distortion.

This is very similar to DAB described above but it is designed to work on the MF and HF bands. Each digital transmission occupies the same bandwidth as a traditional AM transmission. The sound quality of the decoded data stream is far superior to AM radio. The transmitters can send audio data and digital data allowing programme schedules and other data to be transmitted alongside the audio. This is a simplified version of the "red button" service available with digital TV.

The screen shot below shows the output from a short wave receiver being decoded by the sound card in a computer. Software called DREAM is used to decode the data stream.

DRM Modulation on Short Wave

To receive DRM using the Dream software, a modified superhet receiver is needed. The blue RF stages and red IF stages are identical to a normal superhet receiver. Instead of demodulating the IF, a second mixer is needed. Its output is on 12kHz. The bandwidth is 10kHz spanning frequencies from 7 to 17kHz. (All these frequencies are audible). This audio signal is demodulated using the computer sound card and processing power from the computer's CPU.

DRM Modulation Superhet

Subject Name     Level     Topic Name     Question Heading     First Name Last Name Class ID     User ID    

fff
Home
<<<
ppw
Pg Up
<<
ppp
Up
<
|||

>|<
nnn
Down
>
nnw
Pg Down
>>
lll
End
>>>

Close
Escape
X

Q: qNum of last_q     Q ID: Question ID         Score: num correct/num attempts         Date Done    

 

Submit
Enter

 

Question Text

image url

 


Help Link

Add     Delete     Clone     Edit     Hardness

Help Text
Debug


 

 

 

Contact, Copyright, Cookies and Legalities: C Neil Bauers - reviseOmatic V4 - © 2016/17

Hosted at linode.com - London