Electronic Components Datasheet Search |
|
FX929AP4 Datasheet(PDF) 8 Page - CML Microcircuits |
|
FX929AP4 Datasheet(HTML) 8 Page - CML Microcircuits |
8 / 44 page 4-Level FSK Modem Data Pump FX929A © 1996 Consumer Microcircuits Limited 8 D/929A/4 FEC Generator/Checker In transmit mode, this circuit adds Forward Error Correction bits to the transmitted data, then converts the resulting binary data to 4-level symbols. In receive mode, it translates received 4-level symbols to binary data, using the FEC information to correct a large proportion of transmission errors. Interleave/De-interleave Buffer This circuit interleaves data symbols within a block before transmission and de-interleaves the received data so that the FEC system is best able to handle short noise bursts or fades. Frame Sync Detect This circuit, which is only active in receive mode, is used to look for the 24-symbol Frame Synchronisation pattern which is transmitted to mark the start of every frame. Rx I/P Amp This amplifier allows the received signal input to the modem to be set to the optimum level by suitable selection of the external components R1 and R2. The value of R1 should be calculated to give 0.2 x VDD pk-pk at the RXFB pin for a received '...+3 +3 -3 -3 ...' sequence. A capacitor may be fitted in series with R1 if ac coupling of the received signal is desired (see Section 1.6.4), otherwise the dc level of the received signal should be adjusted so that the signal at the modem's RXFB pin is centred around VBIAS (½ VDD). RRC Low Pass Filter This filter, which is used in both transmit and receive modes, is a linear-phase lowpass filter with a 'Root Raised Cosine' frequency response defined by: H(f) = 1 for 0 <= f < (1-b)/(2T) = square root of {0.5 [1 - sin( π T (f - 0.5/T)/b)]} for (1-b)/(2T) <= f <= (1+b)/(2T) = 0 for (1+b)/(2T) < f where b = 0.2, T = 1/symbol rate This frequency response is illustrated in Figure 5. In transmit mode, the 4-level symbols are passed through this filter to eliminate the high frequency components which would otherwise cause interference into adjacent radio channels. Figure 4 Translation of Binary Data to Filtered 4-Level Symbols in Tx Mode |
Similar Part No. - FX929AP4 |
|
Similar Description - FX929AP4 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |